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Crop Science Abstracts

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M.S. Swaminathan

The paper begins by examining recent progress in yield and area of the major world crops, and the general underlying technologies which have driven this progress. But despite these successes of crop science, yield growth rates have now fallen to levels below those needed to both substantially alleviate the remaining serious malnutrition and poverty in the developing world and as well as to protect non-cropped areas. Slowing farm yield growth appears to be related to slowing yield potential progress in major crops, at least in percentage terms, and to persistent yield gaps in less well endowed cropping areas where the adoption of better technology has never been strong and new extension paradigms are being attempted. Besides over all cropping environments the natural resource base must be maintained or, more often, restored. All of this represents a huge challenge for crop science, and for politicians and policy makers whose increased investments in rural infrastructure and institutions are also a necessary component of the progress to which we all aspire. On top of this we are currently faced with the special challenges represented by uncertainty surrounding GMOs, by inevitable but poorly predictable climate change, and by perceived inequity in access to the essential intellectual property necessary for crop research. This paper can only touch upon these critical issues; the subsequent Congress will examine them and others in depth.

Yanhua Liu

Nowadays world food security and agricultural product trade are confronted with new challenges. On the one hand, growth of gross food output has come to a standstill, and gross food output in 2002 declined compared with that in 1997. On the other hand, per capita food consumption increases continuously. Therefore, the prospects of world food security are not very bright. In recent years, world food trade increased rapidly, but the growth was chaotic, liberalization progressed slowly and was largely independent of the world multilateral trade system. The imbalance between developing members and developed members was serious. To comprehensively solve the problems in world agriculture and agricultural product trade, firstly, it’s necessary for developing countries to use more science and technology, to improve traditional agricultural technology, build modern biotechnology, and strengthen technologies associated with food safety, environmental ecology, and efficient water resources utilization, while extending the agricultural industries value-chain and guaranteeing stable and efficient growth of food output. Secondly, it’s necessary to establish a fair and free international environment for agricultural product trade. We must pay close attention to the existence and development of small farmers, to establish a fair and reasonable environment for agriculture development, strengthen international exchanges and cooperation, and promote the construction of agricultural organizations. All these measures are needed for better world food security and trade in agricultural products.

Michael Lipton

Family farming, crop science and ‘globalisation’ together largely determine progress against poverty. Faster in 1960-90 than at any time in world history, such progress has slowed down. So have ‘land reform’ and science-based rises in small farmers’ staples food productivity, while aid to agriculture has fallen by over two-thirds and farm prices have been further forced down (and farm science distorted) by EU and US farm policies. All these things hang together. Most of the world’s poor are in, or employed mainly on, family farms. Big gains for all main groups of dollar-poor need, first, a special type of growth in farm productivity; partly by luck, the Green Revolution was of the right type. To resume and spread such processes, the tasks and organisation of pro-poor farm science need radical reform, especially for the crops and soil-water regimes of rainfed Africa, allowing for the new water crisis. Yet farm supports in Europe and the USA (apart from directly undermining developing countries’ farm incentives) misdirect world farm science, shifting its goals away from the needs of the poor for employment-intensive, robust and water-economising farm yield growth. Privatisation of research has sharpened this misdirection; science requires new incentives, if the great hope of biotechnology is to cut world poverty. Today, paradoxically, the relative-poor among family farms in rich countries cause their governments to depress world farm prices. Partly by distorting science, that makes it harder to renew or spread the attack on absolute poverty. Remedies are urgent, to use a ‘window of opportunity’ in developing countries due to changing population structures, and to realise the poor’s large, but too often subverted, gains from globalisation.

Frank R. Rijsberman

It is surprisingly difficult to determine whether water is truly scarce in the physical sense at a global scale (a supply problem) or whether it is available but should be used better (a demand problem). The paper reviews water scarcity indicators and global assessments based on these indicators. The most widely used indicator, the Falkenmark Indicator, is popular because it is easy to apply and understand but it does not help to explain the true nature of water scarcity. The more complex indicators are not widely applied because data are lacking to apply them and the definitions are not intuitive. Water is definitely physically scarce in densely populated arid areas, Central and West Asia, and North Africa, with projected availabilities of less than 1,000 cubic meters per capita per year. This scarcity relates to water for food production, however, and not to water for domestic purposes that are minute at this scale. In most of the rest of the world water scarcity at a national scale has as much to do with the development of the demand as the availability of the supply. Accounting for water for environmental requirements shows that abstraction of water for domestic, food and industrial uses already have a major impact on ecosystems in many parts of the world, even those not considered “water scarce”. Water will be a major constraint for agriculture in coming decades and particularly in Asia and Africa this will require major institutional adjustments. A “soft path” to address water scarcity, focusing on increasing overall water productivity, is recommended.

John Passioura1

To increase crop yield per unit of scarce water requires both better cultivars and better agronomy. The challenge is to manage the crop or improve its genetic makeup to: capture more of the water supply for use in transpiration; exchange transpired water for CO2 more effectively in producing biomass; and convert more of the biomass into grain or other harvestable product. In the field, the upper limit of water productivity of well-managed disease-free water-limited cereal crops is typically 20 kg ha-1mm-1 (grain yield per water used). If the productivity is markedly less than this, it is likely that major stresses other than water are at work, such as weeds, diseases, poor nutrition, or inhospitable soil. If so, the greatest advances will come from dealing with these first. When water is the predominant limitation, there is scope for improving overall water productivity by better matching the development of the crop to the pattern of water supply, thereby reducing evaporative and other losses and fostering a good balance of water-use before and after flowering, which is needed to give a large harvest index. There is also scope for developing genotypes that are able to maintain adequate floret fertility despite any transient severe water deficits during floral development. Marker-assisted selection has helped in controlling some root diseases that limit water uptake, and in maintaining fertility in water-stressed maize. Apart from herbicide-resistance in crops, which helps reduce competition for water by weeds, there are no genetic transformations in the immediate offing that are likely to improve water productivity greatly.

Pedro A. Sanchez1

What would major crop production systems look if by mid-century the world's population is stable, the Millennium Development Goals are achieved, the Kyoto Protocol or a similar instrument is in full force, perverse agricultural trade subsidies have been eliminated, and the world has otherwise come to its senses in terms of healthy diets, peace, democracy and good governance? In other words, what would the major crop production systems be in a rational world? What would happen if all what the international community were fighting for is really attained? What would the tradeoffs be? Would there be major synergies? Who would be the winners and the losers? In such scenario, the world's population is stable at 9 billion people. The Millennium Development Goals have been achieved, meaning that the proportion of people suffering from hunger, absolute poverty, HIV-AIDS, malaria, tuberculosis, and lack of access to water, sanitation and essential medicines have been reduced in half, discrimination against women and girls has been eliminated, primary education is available to all, child and maternal mortality have been reduced by two thirds, the rural and urban environments are protected and enhanced, all through the work of an effective global partnership between rich and poor countries. By 2050 hunger, absolute poverty, HIV-AIDS, malaria, tuberculosis, lack of access to water, sanitation, child and maternal mortality have been reduced to insignificant levels. Greenhouse gas emissions are now at the level of 1990. Terrestrial and aquatic biodiversity are effectively protected; new genetic resources are being utilized, biotechnology and nanotechnology are mature industries and a much more powerful internet is accessible to all. I obviously do not know the answers, but the paper will set up a framework to address the question.

J.L. Hatfield1 and J.H. Prueger1

Nitrogen is a critical element for plant growth and plant response to added nitrogen (N) has proven to be a valuable agronomic practice. However, N is subject to losses from a number of pathways of which leaching of nitrate is one of the most important because it is extremely mobile leading to increases in nitrate concentrations in surface and ground water. These detections are often attributed to application rates to crops that exceed agronomic needs. Nitrate in water is a world-wide problem and agriculture is being asked to develop farming systems that will reduce the leaching of nitrate from fields and decreases both the concentration and load of nitrate in water. Nitrogen fertilizer use in the world continues to increase in many countries and has remained relatively constant for the past 15 years in Western Europe and the United States. Nitrogen Use Efficiency (NUE), expressed as grain production per unit of N applied, has shown a decrease for all countries. Grain production within each country shows a linear increase with N applied. Management of N in farming systems is difficult because of the interactions between soil mineralization potential, soil water availability, and the type of crop grown. An example of the interaction between N use and water on yield is shown in a detailed study on maize (Zea mays L.) in Iowa. Yield response to N showed a decrease with N rates above 116 kg ha-1 due to water deficits during grain-filling that reduced yield and water use efficiency. Increasing N rates decreased the yield variation within fields without increasing the yield. Management of N within fields can be improved through an analysis of the soil organic matter content and the soil water holding capacity. Integrating soil water with N management will increase the efficiency of N use and decrease the environmental impact of agriculture.

John H Skerritt

The discussion on GMOs and society is constructed around 12 major questions that have polarised debate on the subject, namely:

What is the current status of GM crops, particularly in the Australasian region?
Are the net economic benefits of GM crops likely to be positive or negative?
Can the “Precautionary principle” ever be consistent with “Substantial equivalence”?
How important are GM crops likely to be in poverty reduction in developing countries?
Are the overall environmental benefits of GM crops positive or negative?
GM crops – health hazard, health wonder or mostly irrelevant?
Who really benefits – big business, farmers, or consumers?
IP management – necessary for research and investment in GM crop development or only a tool for the rich to get richer?
Labelling and segregation chains – consumer right to choose or unworkable apartheid?
Can regulatory systems evolve that can please everyone?
Is it possible not to take sides - Why is there so much opposition?
Hope or hype? Has the technology been oversold? Is universal adoption inevitable?

John W Snape

The development of ‘scientific’ breeding methodologies in the first half of the 20th Century was based partly on the application of genetic theory following the rediscovery of Mendel’s Laws, but mostly on developing procedures for systematic phenotypic selection. Although, new technologies in tissue culture, pathology, statistics and quantitative genetics contributed to advances in the second half of the 20th Century, these were limited. The last decade has seen an explosion of genetics and genomics information, yet this also has yet to make a major impact, and there are major challenges to be overcome in translating and integrating this information into plant breeding practice. A foremost challenge is exploiting the detailed molecular information from cloning genes and sequencing model genomes. We need methodologies for utilizing information from Arabidopsis and rice in plant breeding, particularly in cloning useful agronomic genes, and allele mining in germplasm collections. At the administrative level, we face challenges in creating the right balance of investment in model systems and crops, and in bridging the interface between them. There are, however, already significant successes emerging in the application of genetic information in plant breeding, particularly through the use of marker-assisted selection. At present this is almost exclusively used for major genes, and this needs to be extended into QTL controlling complex traits to greatly increase the impact. Coupled with this are methodologies for high-through-put genotyping, and the development of array of ‘functional’ markers. It should also not be forgotten that ‘low tech’ approaches can have major impacts on plant breeding practice, as exemplified by the application of doubled haploid systems and alien gene transfers.

Raj Paroda1

Crop science research has made tremendous contributions over the second half of the twentieth century and provided enormous economic, social and environmental benefits to the global community. It not only helped in attaining food security through path-breaking new technologies but also ensured enough food at much lower prices, since world food prices have declined in real terms by over 70 percent during the last three decades. All this was made possible by breakthroughs in crop improvement work that received wide adoption by millions of resource-poor farmers in China, India, Indonesia and other developing countries. The key to these successes had been the faster adoption of new crops, modern varieties and hybrids. Research as conducted both independently by the developing country National Agricultural Research Systems (NARS) and in partnership with International Agricultural Research Centers (IARCs) and Advanced Research Institutions (ARIs), backed appropriately by the right policies and the innovative mechanisms for technology transfer were the catalytic factors for these successes. This paper highlights some major success stories that have made significant impacts and which underline the importance of research for international public goods to meet the challenges relating to poverty reduction, food security and sustainability. In order to address these concerns, it would require scaling up of technologies using new science and more dynamic systems for technology transfer. Crop scientists would also have to promote good science practices through an inter-disciplinary and inter-institutional approach for improving productivity and would also require a paradigm shift in their research approach for affecting change in the farming practices necessary to attain sustainability.

Peter S. Carberry

Crop scientists as change agents is an ambiguous title. For many, the title promises to document the impressive impacts achieved through crop science and the efforts of its practitioners. An alternative interpretation is that it is more aspirational than reality. In adopting the latter view, I suggest that the conundrum for crop scientists is to balance the traditional performance criterion of knowledge generation with the new imperative for realising impacts. The drivers of change are seen as continued rural poverty, heightened environmental concerns and increasing criticism of our profession’s willingness to achieve purposeful benefits.

Whilst acknowledging the past achievements of crop science, this paper argues that the problems of today, as well as the opportunities for tomorrow, may be best met through reorientating our profession towards a more participative research paradigm where the intended beneficiaries of research are integral contributors to the research process and outcomes. What evidence is there to justify such reorientation? Disappointingly little if sought from the crop science literature. Therefore, documented case studies demonstrating successful implementation of participatory action research, its impacts and contributions to innovative science, will greatly enhance the attraction for the broader adoption of such approaches to crop science issues. In this paper, institutional and personal performance indicators are given for successful participatory action research both in terms of the published experience of others and my own experiences.

Marianne Bänziger1, Peter S. Setimela1, David Hodson2, and Bindiganavile Vivek1

The difficulty of choosing appropriate selection environments has restricted breeding progress for drought tolerance in highly-variable target environments. Genotype-by-environment interactions in southern African maize-growing environments result from factors related to maximum temperature, seasonal rainfall, season length, within season drought, subsoil pH and socio-economic factors that result in sub-optimal input application. In 1997 CIMMYT initiated a product-oriented breeding program targeted at improving maize for the drought-prone mid-altitudes of southern Africa. Maize varieties were selected in Zimbabwe using simultaneous selection in three types of environments, (i) recommended agronomic management/high rainfall conditions, (ii) low N stress, and (iii) managed drought. Between 2000 and 2002, 41 hybrids from this approach were compared with 42 released and prereleased hybrids produced by private seed companies in 36-65 trials across eastern and southern Africa. Average trial yields ranged from less than 1 t/ha to above 10 t/ha. Hybrids from CIMMYT’s stress breeding program showed a consistent advantage over private company check hybrids at all yield levels. Selection differentials were largest between 2 to 5 t/ha and they became less significant at higher yield levels. An Eberhart-Russell stability analysis estimated a 40% yield advantage at the 1-ton yield level which decreased to 2.5% at the 10-ton yield level. We conclude that including selection under carefully managed high priority abiotic stresses, including drought, in a breeding program and with adequate weighing can significantly increase maize yields in a highly variable drought-prone environment and particularly at lower yield levels.

M Dingkuhn1, B.B. Singh2, B. Clerget3, J. Chantereau1 and B. Sultan1

Asia’s Green Revolution of the 1960s and 70s has largely bypassed West Africa, and “modern” (high-yielding, input responsive) germplasm has found comparatively little adoption, except for the small proportion of systems that are irrigated. It is unlikely, however, that breeding traditional-type materials for better performance in subsistence systems would have been more successful. The authors thus identify systems caught in the agricultural transition from subsistence to intensified, market-oriented production as being promising targets for crop improvement, and provide examples of original breeding objectives for cowpea, sorghum and upland rice. In each of these cases, breeders, with the help of physiologists, have developed plant-type concepts that combine increased yield potential and input responsiveness with certain traditional crop characteristics that are thought to remain essential during the agricultural transition. In the case of cowpea, dual-purpose varieties were developed that produce a good grain yield due to an erect plant habit, then produce enough new leaves to enable a second harvest of green foliage. For upland rice systems that are limited by labour shortages (mainly needed to control a weed flora that abounds due to shortened fallow periods), a weed competitive, high-yielding plant type was developed from Oryza sativa x O. glaberrima crosses. Lastly, sorghum breeders who previously eliminated photoperiod sensitivity from improved materials are now re-inserting sensitivity into plants having “modern” architecture, in order to allow for flexible sowing dates while maintaining an agro-ecologically optimal flowering date near the end of the wet season. The perspectives of these plant types, as well as the problem of under-funding for their realisation, are discussed.

Boonrat Jongdee1, Grienggrai Pantuwan2, Shu Fukai3 and Ken Fischer3

A large portion of the world’s poor farm in rainfed systems where the water supply is unpredictable and droughts are common. In Thailand there are approximately 6.2 million ha of rain fed lowland rice which account for 67% of the country’s total rice-growing area. This rice system is often characterised by too much and too little water in the same season. Farmers’ estimates of their annual losses to drought are as high as 45% in the upper parts of the toposequence. In contrast to irrigated rice systems, gains from crop improvement of rainfed rice have been modest, in part because there has been little effort to breed and select for drought tolerance for the target rainfed environments.

David Dawe

Rice is the largest user of water in Asia, probably accounting for more than half of irrigation water withdrawals. Two key trends in the Asian rice economy that are affecting water productivity are the rapid spread of pump irrigation and direct seeding. The number of pumps has grown exponentially in Bangladesh and Vietnam, and pump irrigation now dominates gravity irrigation in many countries. Direct seeding accounts for about one-fifth of rice area in Asia, but this share is increasing. Comparing water productivity values is difficult across space and time; in general, it is more relevant across time. Water productivity has increased over time in several selected systems, primarily due to increased yields of modern varieties and improved management of large-scale water flows. There is less evidence of field-level water management increasing water productivity, although this may have also contributed. The extent to which agricultural water scarcity will affect poverty in Asia depends crucially on how well societies will be able to create incentives for users to save scarce water, thus facilitating the adoption of new technologies. Because of the rapid spread of pumps, incentives to save water in rice cultivation are growing. Even for gravity flow surface water, new institutions are developing in China that promise to improve incentives. International trade in agricultural products, or trade in “virtual water,” may also have a role to play and should be encouraged.

To Phuc Tuong1, Bas A.M. Bouman1, and Martin Mortimer2

The water crisis is threatening the sustainability of the irrigated rice system and food security in Asia. Our challenge is to develop novel technologies and production systems that allow rice production to be maintained or increased in the face of declining water availability. This paper introduces principles that govern technologies and systems for reducing water inputs and increasing water productivity, and assesses the opportunities of such technologies and systems at spatial scale levels from plant to field, to irrigation system, and to agro-ecological zones. We concluded that, while increasing the productivity of irrigated rice with transpired water may require breakthroughs in breeding, many technologies can reduce water inputs at the field level and increase field-level water productivity with respect to irrigation and total water inputs. Most of them, however, come at the cost of decreased yield. More rice with less water can only be achieved when water management is integrated with (i) germplasm selection and other crop and resource management practices to increase yield and (ii) system-level management such that the water saved at the field level is used more effectively to irrigate previously un-irrigated or low-productivity lands. The amount of water that can be saved at the system level could be far less than assumed from computations of field-level water savings because there is already a high degree of recycling and conjunctive use of water in many rice areas. The impact of reducing water inputs for rice production on weeds, nutrients, sustainability, and environmental services of rice ecosystems warrants further investigation.

E. Humphreys1,2, Craig Meisner3, Raj Kumar Gupta4, Jagadish Timsina2, H.G. Beecher1,5, Tang Yong Lu6, Yadvinder Singh7, M.A. Gill8, I. Masih9, Zheng Jia Guo6 and J.A. Thompson10

Water shortage is a major constraint to sustaining and increasing the productivity of rice-wheat systems. Saving water can be elusive in that reducing seepage, percolation and runoff losses from fields does not necessarily save water if it can be recaptured at some other temporal or spatial scale, for example by groundwater pumping. Many technologies appear to save substantial amounts of water through reducing irrigation water requirement, but whether these are true water savings is uncertain as components of the water balance have not been quantified. Such technologies include laser levelling, direct drilling, raised beds, non-ponded rice culture and irrigation scheduling. It is questionable whether puddling saves water. Reducing non-beneficial evaporation losses is a true water saving, and optimal planting time of rice to avoid the period of highest evaporative demand and changing to non-ponded rice culture can save significant amounts of water. However, moving away from puddled, ponded to more aerobic rice culture sometimes brings new production problems. Furthermore, farmers faced with unreliable water supplies need to store water on their fields as insurance, and puddling assists retention of water during the rice crop. Rehabilitation and improvement of canal and power systems in Asia, funded by charging according to use, are required to facilitate adoption of many water saving technologies. Australian farmers pay fixed plus volumetric charges for water to cover the cost of infrastructure and operation of irrigation systems, which are continuously being improved to provide water on demand and minimise losses. They are able to plan their plantings based on knowledge of the likely amount of irrigation water available each season and crop water use requirement, and thus avoid wasting water and financial loss by overplanting and crop failure. Such approaches have the potential to increase production and water productivity in Asia, however the challenge would be to apply them in an equitable way that benefits many millions of subsistence farmers.

William J. Davies1 and Wolfram Hartung2

This paper considers the impact on crop productivity of an enhanced understanding and subsequent manipulation of plant drought stress biochemistry and physiology. Emphasis is placed on possible exploitation of our recent increase in understanding of long-distance chemical signalling in plants, particularly in relation to soil drying. We review evidence for a variety of signalling cascades involving hormones and nutrient ions in the xylem sap. We also assess the importance of changes in the pH of the leaf cell apoplast as influenced both by edaphic and climatic variation, as a regulator of shoot growth and functioning. The sensitivity of the sensing and signalling mechanism is emphasised.

A number of possible manipulations of the long-distance signalling process are discussed but emphasis is placed on the development of a novel deficit irrigation system: partial rootzone drying (PRD). This system has been much researched and introduced into a variety of plant production systems. Substantial increases in the efficiency of water use can result from the use of PRD, along with increases in crop quality. The modification of plant performance (most commonly reduced vegetative growth with only minimal effects on reproductive development) is commonly attributed to the effects of drought signalling. We assess the evidence for this assertion and argue for more understanding of the nature of the signalling processes in the droughted plant. This can help us further develop both high-technology and low technology modifications of production systems to allow for more sustainable use of resources.

Richard A. Richards

A physiological understanding of plants’ responses to drought has often been sought on the pretext that this understanding will assist plant breeders develop higher yielding varieties for water-scarce environments. However, despite an extensive literature on plants’ response to drought there are few documented examples where a physiological understanding of drought has identified traits that limit yield under drought and where these have been used in successful crop improvement programs to enhance crop yields. This paper selects seven examples where a physiological understanding has resulted in more precise targeting of genetic variation and has resulted in higher yielding or more productive germplasm or varieties. The underlying features of these successes are then examined to identify the elements of success that may be used to further enhance yield improvement in dry environments. The conclusions are that all of these traits have directly or indirectly transfer their effects to yield over long time scales and can be shown to have these effects through influencing either water use (amount and pattern), water use efficiency and partitioning of biomass to grain.

Robert E. Sharp1, Valeriy Poroyko2, Lindsey G. Hejlek1, William G. Spollen3, Gordon K. Springer3, Hans J Bohnert2 and Henry Nguyen1

Progress in understanding the network of mechanisms involved in maize primary root growth maintenance under water deficits will be reviewed. These include adjustment of growth zone dimensions, turgor maintenance by osmotic adjustment, and enhanced cell wall loosening. The role of the hormone abscisic acid (ABA) in maintaining root growth under water deficits will also be addressed. The research has taken advantage of kinematic analysis, i.e. characterization of spatial and temporal patterns of cell expansion within the root growth zone. This approach revealed different growth responses to water deficits and ABA deficiency in distinct regions of the root tip. In the apical 3 mm region, elongation is maintained at well-watered rates under severe water deficit, although only in ABA-sufficient roots, whereas the region from 3-7 mm from the apex exhibits maximum elongation in well-watered roots but progressive inhibition of elongation in roots under water deficit. This knowledge has greatly facilitated discovery of the mechanisms involved in regulating the responses. The spatial resolution with which this system has been characterized and the physiological knowledge gained to date provide a unique and powerful underpinning for functional genomics studies. Characterization of water deficit-induced changes in transcript populations and cell wall protein profiles within the growth zone of the maize primary root is in progress. Initial results from EST and unigene analyses in the tips of well-watered and water-stressed roots highlight the strength of the kinematic approach to transcript profiling.

N. Hatibu1, E. M. Senkondo2, K. Mutabazi2 and A.S.K. Msangi2

Rainwater harvesting (RWH) is being promoted widely as a way to improve the production of crops and livestock in semi-arid areas. However, there is very limited data on the performance of RWH in terms of productivity of water, land, labor and capital resources. This paper presents results from case studies in Tanzania where farmers are using RWH technology to produce maize, paddy and vegetables in semi-arid areas where it would otherwise be impossible or very difficult. The economics of these practices is analyzed in two contrasting districts over a period of five years. Results show that most farmers have invested heavily in terms of labor to establish and maintain earth structures for the capture of runoff without corresponding investment in nutrient management, leading to low yields for the cereal enterprises. When this is coupled with low farm-gate prices, the improvements of RWH for cereal systems did not lead to corresponding increase in returns to labor for the majority. However, high returns of 10 – 200 US$ per personday were obtained when rainwater harvesting was applied to vegetable enterprises. It is concluded that for RWH to contribute to improved incomes and food security, smallholder farmers should be assisted to change from subsistent to commercial objectives with marketing-oriented production of high value crops combined with processing into value-added products. This will require farmers to participate in food markets and thus increasingly depend on the market for food security as opposed to emphasizing self-sufficiency at household level.

Thomas Gerik1 and David Freebairn2

The dryland cropping areas of North America and Australia share many common features, including crops, soil properties, farm size, and most importantly high variability in rainfall. Farmers in both regions have achieved extraordinary levels in productivity by adopting technologies and farming practices that maximize water and nutrient (nitrogen) availability for crop production and that minimize the cost and risk associated with cropping. When soil fertility is non-limiting, crop yield and water supply follow a linear model. Similarly, nitrogen and other macronutrients are proportional to crop growth and, hence, the crop water supply. This paper discusses the role of water supply on crop yield and describes how farmers, managing extensive dryland properties in North America and Australia, utilize improved tillage, residue management, plant arrangement (row spacing and plant population) to optimize the crop water supply and fertility to minimize production risk.

Theib Oweis and Ahmed Hachum

In the dry areas, water, not land, is the most limiting resource for improved agricultural production. Maximizing water productivity, and not yield per unit of land, is therefore a better strategy for dry farming systems. Under such conditions, more efficient water management techniques must be adopted. Supplemental irrigation (SI) is a highly efficient practice with great potential for increasing agricultural production and improving livelihoods in the dry rainfed areas.

In the drier environments, most of the rainwater is lost by evaporation; therefore the rainwater productivity is extremely low. Water harvesting can improve agriculture by directing and concentrating rainwater through runoff to the plants and other beneficial uses. It was found that over 50% of lost water can be recovered at a very little cost. However, socioeconomic and environmental benefits of this practice are far more important than increasing agricultural water productivity.

This paper highlights the major research findings regarding improving water productivity in the dry rainfed region of West Asia and North Africa. It shows that substantial and sustainable improvements in water productivity can only be achieved through integrated farm resources management. On-farm water-productive techniques if coupled with improved irrigation management options, better crop selection and appropriate cultural practices, improved genetic make-up, and timely socioeconomic interventions will help to achieve this objective. Conventional water management guidelines should be revised to ensure maximum water productivity instead of land productivity.

Xi-Ping Deng1,2, Lun Shan3, Heping Zhang4 and Neil C. Turner2,4

Water shortage in China, particularly in the north and northwest of China, is very serious. The region accounts for half of the total area of China, but has less than 20% of total national available water resources. While the water shortage in this region is severe, irrigation water use efficiency is only about 40%, with a typical agricultural water use efficiency of about 0.46 kg m-3. Excessive irrigation in Ningxia and Inner Mongolia has had a significant influence on downstream water users along the Yellow River. It is widely believed that an increase in the agricultural water use efficiency is the key approach to mitigate water shortages and to reduce environmental problems. This paper reviews water-saving agricultural systems and approaches to improve agricultural water use efficiency in the arid and semiarid areas of China. The paper will cover biological mechanisms of water-saving agriculture and water-saving irrigation technologies, including low pressure irrigation, furrow irrigation, plastic mulches, drip irrigation under plastic, rainfall harvesting and terracing. In addition, the paper addresses the compensatory effect of limited irrigation and fertilizer supplementation on water use efficiency and highlights the need to breed new varieties for high water use efficiency. Considerable potential for further improvement in agricultural water use efficiency in the region depends on effective conservation of moisture and efficient use of the limited water.

Enrique Playán1 and Luciano Mateos2

Population increase and the improvement of living standards brought about by development will result in a sharp increase in food demand during the next decades. Most of this increase will be met by the products of irrigated agriculture. At the same time, the water input per unit irrigated area will have to be reduced in response to water scarcity and environmental concerns. Water productivity is projected to increase through gains in crop yield and reductions in irrigation water. In order to meet these projections, irrigation systems will have to be modernized and optimized. Water productivity can be defined in a number of ways, although it always represents the output of a given activity (in economic terms, if possible) divided by some expression of water input. The authors identified five expressions for this indicator, using different approaches to water input. A hydrological analysis of water productivity poses a number of questions on the choice of the water input expression, since in many cases irrigation return flows can not be considered as a net water loss from a basin-wide perspective. A number of irrigation modernization and optimization measures are discussed in the paper. Particular attention is paid to the improvement of irrigation management, which shows much better economic return than the improvement of the irrigation structures. In closed basins the hydrological effects of these improvements may be deceiving, since they will be accompanied by larger crop evapotranspiration and even increased cropping intensity. As a consequence, less water will be available for alternative uses.

Simon Toze

There is an increasing trend to require more efficient use of water resources, both in urban and rural environments. A major mechanism that can be used to achieve greater efficiencies is the reuse of water that once would have been discarded into the environment after use. The reuse of water for agricultural irrigation is often viewed as a positive means of recycling water due to the potential large volumes of water that can be used. Recycled water can have the advantage of being a constant, reliable water source and reduces the amount of water extracted from the environment. In addition, in some cases treatment requirements may be need to be less than for water used in an urban environment due to less potential human contact. There are concerns and unknowns, however, about the impact of the quality of the recycled water, both on the crop itself and on the end users of the crops. Water quality issues that can create real or perceived problems in agriculture include nutrient and sodium concentrations, heavy metals, and the presence of contaminants such as human and animal pathogens, pharmaceuticals and endocrine disruptors. Social attitudes to the use of crops that have been irrigated with recycled waters and the resulting impact on market value of crops are also a major consideration. This paper will discuss the benefits from using different types of recycled water and outline the current knowledge and opinions relating to risks such as water quality issues.

Robert N. Carrow

Science-based, holistic, site-specific water conservation practices can reduce water use on turfgrass sites without adversely affecting turfgrass performance. However, when water use is decreased below a certain threshold, performance declines. Water conservation measures that reduce turfgrass performance essentially decrease its economic, environmental, recreational, and aesthetic values, which can in turn adversely impact many “stakeholders” ---including the local economy and those affected by increased wind erosion, water erosion, or fire hazard. On larger turfgrass sites, considerable costs are associated with some water conservation strategies---especially when the quality of an alternative irrigation water source is poor or redesign of the landscape and/or irrigation system is involved.

Louise Barton and Tim Colmer

Establishing and implementing management practices that limit N leaching from agricultural and horticultural land is a priority internationally. Movement of N through soil to surface and ground waters can degrade aquatic systems and compromise water used for drinking, industry and recreation. Reported annual rates of N leaching from turfgrass range from 0 to 160 kg N/ha/yr, representing up to 30% of applied N. Irrigation rate, fertiliser regime and turfgrass growth phase influence the amounts of N leached. Nitrogen losses tend to be low (<5% of applied fertiliser N) from established turfgrass that is not over-irrigated and has received moderate amounts of N fertiliser (i.e., 200–300 kg N/ha/yr). Efficient irrigation management is critical for efficient N use. Irrigation scheduling that does not cause water to move beyond the active rooting zone decreases the amount of N leached from established turfgrass, without being detrimental to, and in some instances enhancing, turfgrass growth and quality. Applying N fertilisers at rates and frequencies that match N requirements decreases N leaching from established turfgrass. Soil disturbance, such as during preparation of areas for planting turfgrass, can increase N leaching. Therefore the main strategies for minimising N leaching from turfgrass are i) optimise irrigation regimes, and ii) ensure N is applied at rates and frequencies that match turfgrass demand. These strategies are particularly important during turfgrass establishment. Further work is required on turfgrass-soil N cycling and partitioning of N applied to turfgrass. Research needs to be conducted for a broad range of turfgrass species, turfgrass ages, soil types and climates.

Kenneth B. Marcum

The need for salt-tolerant turfgrasses is ever-increasing. Rapid urban population growth has put enormous pressures on limited freshwater supplies. Many state and local governments have reacted by placing restrictions on the use of potable water for irrigating turfgrass landscapes, instead requiring use of reclaimed, or other secondary saline water sources. In coastal areas, overpumping, and resultant salt water intrusion of coastal wells used for irrigating turfgrass facilities has widely occurred. The nature and extent of the salinity problem, followed by basic salinity issues and available management choices, will be discussed. Issues facing the turf manager using saline water sources are soil salinization, resulting in direct salt injury to turf, and secondary problems of loss of soil structure ensuing from sodium and bicarbonate effects, resulting in loss of salt leaching potential and soil anaerobiosis. Management choices for the turf manager using saline water are limited. Soil salinity must be maintained below the level deemed detrimental to the turf, by maintaining sufficient leaching. Sodium/bicarbonate affected soils must be managed to maintain sufficient permeability to permit adequate leaching. Finally, salt tolerant turf species/cultivars must be used. Long-term solutions to the salinity problem will require development of improved salt-tolerant turfgrasses. Progress in cultivar development, and future development of potential alternative halophytic turfgrass species will also be discussed.

Shahbaz Khan1, Rana Tariq1, Cui Yuanlai2, J. Blackwell1

Globally about 10 Mha of agricultural land are lost annually due to salinisation of which about 1.5 Mha is in irrigated areas. While some climate and management aspects are common to semi-arid regions the detailed mechanisms and options to secure ecological sustainability and economic viability may vary considerably from case to case. This paper applies a whole of system water balance to compare irrigation in three semi-arid regions suffering from similar sustainability issues: Rechna Doab (RD) - Pakistan, the Liuyuankou Irrigation System (LIS) – China and Murrumbidgee Irrigation Area (MIA)-Australia. Soil salinity, lack of adequate water resources and groundwater management are major issues in these areas. The MIA and LIS irrigation systems also suffer from soil salinity and low water use efficiency issues. These similarities occur in spite of very different climatic and underlying hydrogeological conditions. The key data used to compare these different regions are climate and soils, available water resources and their use, as well as components of the water balance. In addition, the history of water resource development in these areas is examined to understand how salinity problems emerge in semi- arid regions and the consequences for production. Based on the efficiency parameters and the definitions of sustainability, approaches are explored to solve common environmental problems while maintaining economic viability and environmental sustainability for irrigation systems.

Patrick Dugan1, Madan Dey2 and V. V. Sugunan3

Faced with growing pressure upon freshwater resources, increased water productivity in agriculture is essential. Efforts to do so however need to consider the wider role of water in sustaining food production. This paper considers the importance of water management in sustaining fish production in tropical river basins, and the potential for enhancing food production and income to farmers by integrating fish production into some farming systems. Specific examples from selected river systems and irrigated farming systems in Africa and Asia are provided. These highlight the benefits of integrating the water requirements for fish into water allocation decisions. In some cases these benefits can be realised without any reduction in the water available for other purposes, while in others a trade-off needs to be considered. The nature of these trade-offs needs to be better understood for better decision making in water management.

David J. Pannell1, 2 and Michael A. Ewing1

Salt occurs naturally at high levels in the subsoils of most Australian agricultural land. As a result of clearing native vegetation, groundwater tables have risen, mobilising the stored salt and causing adverse impacts to farmland, infrastructure, water resources, and biodiversity. The main action required to prevent groundwater tables from rising is establishment of perennial plants, either herbaceous (pastures or crops) or woody (trees and shrubs). Recent technical and economic research has emphasised how difficult it will be to establish sufficient perennials to get control of groundwater tables. Where watertables are already shallow, the options for farmers are salt-tolerant plants (e.g. saltbush for grazing) or engineering (e.g. deep open drains). The existing options for farm-level salinity management are reviewed, with mixed but somewhat disappointing finding regarding their suitability for addressing salinity. However, there are also a number of good prospects for development of new and better options for plant-based management of salinity, and these are described.

John Kirkegaard1, Olaf Christen2, Joseph Krupinsky3 and David Layzell4

Changes in the sequence of crops grown on agricultural land are well known to enhance the yield of grain crops such as wheat. A survey of the literature gathered from around the world show yield benefits of up to 20% or more. Much is known about the key mechanisms responsible for these benefits, including effects on disease control, improved nitrogen nutrition and water supply, although researchers continue to be challenged by inexplicable “rotation effects” that have yet to be documented or fully understood. This review summarizes our current understanding of the ‘better-known’ mechanisms of crop rotation, and discusses other mechanisms (e.g. changes in rhizosphere biology, allelopathy or soil structure) that may help to account fully for the rotation benefits that have been observed by agricultural producers for more than 2000 years. Where possible we emphasise new techniques employed to investigate these less well understood aspects of the “rotation effect”. At the farm level, the inability to capitalize on the benefits of break crops may owe more to economics, the availability of suitable break crops and the complexity of the crop response. Computer-based decision support tools have been developed to assist growers to apply the information gathered from scientific studies, although efforts to integrate this information at whole farm scales are embryonic.

R.J. Cook1 and D.M. Weller2

Because yields typically decline, crop monoculture is commonly considered as not sustainable. This yield decline is due largely to soilborne plant pathogens adapted to/specialized for the roots of the crop. For high-value fruit and vegetable crops, yields are maintained with monoculture using soil fumigation or soil solarization. Soils can also be sanitized by flooding, which may account for the success of paddy rice monocultures. Our work in the U.S. Pacific Northwest has focused on four root and crown diseases of wheat and barley, namely take-all caused by Gaeumannomyces graminis var. tritici, Fusarium crown rot caused by Fusarium culmorum and Fusarium pseudograminearum, Rhizoctonia root rot caused by Rhizoctonia solani AG8 and R. oryzae, and Pythium root rot caused by several Pythium species. Herein, we describe a remarkable and apparently wide-spread microbiological control (disease suppression) in the rhizosphere that is responsible for the well-documented decline of take-all and coordinate increase in crop yield following one or more outbreaks of the disease and continued monoculture of wheat or barley. Since this disease suppression is specific for take-all, other strategies are under development for control of the other three root and crown diseases with wheat-intensive cropping systems, including in direct-seed systems. The strategies include the development of transgenic resistance in barley to Rhizoctonia root rot using the ThEn42 gene from Trichoderma harzianum for production of a 42-Kda endochitinase, selection of wheat cultivars for tolerance to Fusarium crown rot, and use of a systemic seed-treatment chemicals and current-year seed for seedling protection against Pythium root rot.

Herman van Keulen1 and Hans Schiere2

Drew Lyon1, Sarah Bruce2, Tony Vyn3, and Gary Peterson4.

Conservation tillage (CT) is a key tool in sustainable production systems throughout the world. It has been particularly effective at sustaining crop production in semi-arid rain-fed regions. Wherever potential evaporation exceeds precipitation during most months of the year, proper application of water-conserving CT technology is critical. This paper reviews the progress made in CT management, with particular focus on the U.S.A. and Australia, two temperate developed countries with a long history of using CT. Parallels are drawn to other regions of the world when appropriate. Data on farmer’s use of CT are provided, as are some reasons for lack of adoption by farmers. Despite decades of research and education on the benefits of CT, a majority of farmers in the U.S.A. and Australia do not practice CT on their farms. In some regions, adoption of CT is high for one crop in rotation but low for another crop in the same sequence on the same soil. The unwillingness of farmers to adopt CT, or to adopt it continuously, implies that it is either perceived to be unprofitable or that other significant constraints to adoption exist. The paper finishes with a discussion of the perceived challenges to further adoption of CT and the opportunities to overcome barriers to greater adoption. It is imperative that CT retains a flexible approach to addressing challenges while maintaining the common goal to sustain the soil resource and produce food for an ever-growing world population.

Eric Scopel1, Bernard Triomphe2, Maria de Fatima dos Santos Ribeiro3, Lucien Séguy1, Jose Eloir Denardin4, Rainoldo Alberto Kochhann4

Areas permanently cultivated under DMC systems (Direct seeding mulch-based cropping systems, which are part of the family of practices known as Conservation Agriculture) have increased remarkably in Latin America over recent decades, reaching around 50% of total cropped area in Brazil, Paraguay and Argentina. These systems have been developed to counteract soil degradation and to achieve more sustainable grain production. Under tropical and sub-tropical conditions the efficiency of such systems increases with the introduction of multi-functional cover crops growing in rotation with the main commercial crops or whenever climatic conditions are too risky for planting a commercial crop. The introduction of cover crops leads to a better utilization of available natural resources throughout the year, more biomass production, permanent soil protection and higher organic restitutions to the soil. DMC systems also offer environmental, economic and agronomic advantages to farmers. Nevertheless they are quite complex systems and their adaptation to specific local constraints and conditions is not straightforward, especially in the case of smallholder, resource-limited agriculture. Specific approaches have been designed, based on systemic and participatory research principles, to create, adapt and disseminate these systems among farmers by working mainly under actual farming conditions. The active participation of farmers and their organizations is fundamental at all stages, as well as that of other key stakeholders of the agricultural sector. Farmers, researchers and their key partners still need to meet several challenges to further increase the success and large-scale adoptability of DMC systems. These include understanding and enhancing the underlying biological processes, creating DMC systems less dependant on chemicals or external inputs, as well as fitting these systems for conditions of close interactions between agriculture and livestock production. These last two challenges are especially true for small-scale farmers operating in marginal environments. Also, the knowledge and experience about DMC systems functioning, creation and management, and about adoption stories, needs to be better systematized and made available through the development of synthetic tools such as data bases, dynamic models and global indicators of DMC system functioning and impact, as well as through enhanced networking among the different stakeholders. Putting together these various pieces will facilitate the conception and implementation of new projects aiming to enhance DMC adaptation and adoption.

Ram K. Malik1, Ashok Yadav1, Gurjeet S. Gill2, Parveen Sardana1, Raj Kumar Gupta3 and Colin Piggin4

The major challenge facing the rice-wheat cropping system in India is to sustain its long-term productivity. There are signs that the productivity and economic gains of this cropping system are consistently becoming smaller. For a populous country like India such a slow down amounts to food insecurity. One reason for the slow down in the growth of wheat productivity during the 1990s was the widespread development of herbicide resistance in Phalaris minor. Even though P. minor can now be effectively controlled with technologies introduced over the last 5 years, declining soil health has become an important constraint to the productivity of the region. The adoption of resource conservation technologies such as no-till is considered vital for maintaining the productivity of the rice–wheat system. Research undertaken in wheat has clearly shown the capacity of no-till to dramatically reduce production costs for the farmers while maintaining or sometimes increasing wheat yields. Farmer acceptance of no-till technology only became possible through a concerted farmer-participatory research program that was multidisciplinary in nature and had multi-institutional support. This effort has achieved a paradigm shift in tillage and has the makings of another green revolution to sustain the gains of the first green revolution. The introduction of no-till and other resource conservation technologies into the rice phase of the rice–wheat system has the potential to further increase the long-term profitability on Indian farms. This paper reviews no-till development and its impact on weed management, soil properties and farmer profitability in the Indo-Gangetic plains.

John L. Cisar1

Turf is often the most visible of plantings in urban areas. While crop production is not the main focus of turfgrass systems, a dense, vigorous sward of turf (often as a monoculture) is a key goal. And it is an extremely challenging one for turf managers, requiring the use of pesticides, fertilizers, and water to provide aesthetic, safe, and performance-acceptable venues. Moreover, to provide modern playing conditions, certain management practices such as mowing have been intensified to achieve desired condition. For example, modern golf course greens are mowed at a height of 2-3 mm and are designed to receive 50% of the play even though the total green area makes up less than 3% of the total playing area of a golf course. However, even under intensive management, the goal of turf sustainability is becoming more of a reality than hype or hope, as turfgrass scientists and managers have worked to identify turfgrass management systems that are more efficient, thus requiring less inputs. In addition, identification and improvements in grasses such as seashore paspalum for amenity use has increased the opportunity for improved performance with reduced quality water. New agrichemicals target pests with increased specificity at lowered rates of active ingredients. Increasing chemical use such as surfactants can also improve aspects of turf sustainability by increasing uniform soil wetting and decreasing irrigation needs by over fifty percent. With these gains, turfgrass landscapes can be maintained with reduced agrichemical and water needs that are consistent with attaining sustainability.

R.R. Duncan

Concern for the environment and the global crisis on water is transforming the agricultural industry in the 21st century. Field crops have led the technology revolution and turfgrasses have benefited from this pioneering revolution. The primary difference between the field crop and turfgrass arenas has been in scale of production and focus. Field crops target consistent and reliable yield of usable products while turfgrass performance involves cosmetic performance, playability, and human-impact challenges. Abiotic and biotic stress challenges are similar genetically, but differ in scope for mechanisms of resistance between field and turf crops. Much of the pesticide and fertilizer use is interchangeable between the two cropping systems. Similar control strategies are involved, but sophistication in management is different. Turfgrasses require smaller equipment and are usually driven by height of cut. Field crops require larger equipment driven by large scale production and harvesting. The precision is similar but at different levels. The demands for recreational turf, green space, and land reclamation/stabilization will increase the use of grasses, and products to minimize the negative environmental impact will become more available. Interchangeable use of improving technology will continue for both field and turf crops, and contribute simultaneously to mankind and environmental sustainability.

Peter M. Martin

Of the more than ten thousand species in the grass family some twelve species, divided more or less equally between the C3 and C4 groups, probably account for over 90% by area of the world’s managed turf.

Many of the species in this small group are extensively naturalized across the globe (e.g. Lolium perenne in temperate regions and Cynodon dactylon in warm regions) and widespread differentiation into ecotypes has taken place. These local ecotypes have been commercially exploited for turf for centuries, while significant breeding effort has been devoted to the most important turf species over the last 50 years. As a result, it is difficult to launch unfamiliar native species into a tightly defined market already supplied with an abundance of cultivars and ecotypic selections of the standard species.

However, as greater demands are placed on turf for high performance under increasingly difficult environmental conditions, opportunities are opening up for (i) the addition of new species to the standard list and (ii) the transferring of unusual adaptive traits found in some native grasses to traditional turf species. This review examines the potential of four native species and one native genus for use in one or both of these ways: from Australia Microlaena stipoides, Sporobolus virginicus, the Agrostis aemula complex and the genus Austrodanthonia, and from North America Buchloe dactyloides. The current status of developmental work on these plants is assessed against a twelve-point check-list of biological and technological requirements for successful entry to the turf market. In general, the findings are that much remains to be done.

Takeshi Horie, Tatsuhiko Shiraiwa, Koki Homma, Keisuke Katsura, Yohei Maeda and Hiroe Yoshida

The annual rate of rice yield increase in the world declined from 2.7 % in the 1980s to 1.1 % in the1990s. The continued world population increase requires resumption of the previous rate. The objectives of this paper are to review and assess rice production technologies for increased yield in the past and the current challenge on the basis of crop physiology and agronomy, and to discuss the way to increase irrigated rice yield to fulfill the expanding demand. Field experiments conducted in Kyoto, Japan and Yunnan, China showed that the best recent Chinese hybrid has a yield potential about 10 % higher than the best recent inbred cultivar in Japan. This result and a review on recent challenges in breeding suggested only moderate increases in the yield potential of rice genotypes in the coming decades. Contrary to the general understanding, the rapid rice yield increase in central Japan from the mid 1950s to mid 1970s was achieved mostly by improved crop and resource management. This and the fact that farmers’ contest-winning yields during 1950s and 1960s nearly doubled the current average in Japan imply that current crop and resource management is exploiting only part of large yield potential of rice.

Some of the ways to increase yields may include components of the system of rice intensification (SRI). The extremely high yields in SRI are incredible but its elements, which have been studied and practiced in Japan for the past 50 years, may lead to yield increases. The practice of transplanting one or two young seedlings per hill has advantages in reducing transplanting injury and increasing tiller and root numbers on lower nodes. Such advantages can be realized under direct-seeding systems, where they are applicable. The practice of applying a large amount of compost and intermittent irrigation were also adopted by many of the contest-winning farmers in the 1950s and 1960s. These practices increase roots in deeper soil layers, maintain their activities and presumably promote nitrogen (N) uptake at later stages. Remarkable progress has been made in improved N management; agronomic efficiency of N increased from about 15 kg kg-1 for a single dose at transplanting to 40 kg kg-1 for banded controlled release fertilizer. All of these technological elements will contribute to increased yield when they are rationally integrated into a system that is adaptable to regional environment.

Benjavan Rerkasem

The Green Revolution has benefited many people in Asia, but not everyone. This paper examines how many farmers have increased their productivity with more intensive cropping systems of fruit, vegetables, and in some cases, flowers. Total area under these crops more than doubled between 1977 and 1997. Case studies to highlight the transformation include vegetable production to feed Asia’s booming cities, diversification of export crops in Thailand, vegetable production in Malaysia’s Cameron Highlands, flower production in Yunnan Province of China and opium replacement in the Golden Triangle. Access to the market is necessary for transformation, but changes are also driven by farmers’ own innovations combined with contributions from last century’s crop science, from phytohormones to hybrid technology. Other inputs are irrigation, fertilizers and pesticides, with overuse of the last two a serious threat to the environment as well as to human health. Concerns have also been raised regarding soil erosion caused by cropping on steep slopes. In addition to building roads and airports, government support has also come in the form of cheap credit for orchard establishment and more efficient quarantine procedures to facilitate exports. Cross-border trade that brings opportunities to inaccessible border regions will be further enhanced by regional free trade policy, particularly when liberalization of trade in fruit and vegetables is specified such as that just signed by ASEAN and China. Finally, a case is made for the need to improve cropping systems in less favorable environment with limited access to the market and the means through which crop scientists can work with farmers to bring this about.

Mohd. Basri Wahid1, Siti Nor Akmar Abdullah2 and I. E. Henson1

Cultivation of the oil palm (Elaeis guineensis Jacq.) has expanded tremendously in recent years such that it is now second only to soybean as a major source of the world supply of oils and fats. Presently, Southeast Asia is the dominant region of production with Malaysia being the leading producer and exporter of palm oil. This paper reviews the various factors that have led to oil palm occupying its present position, including biological, technical, managerial, environmental, and socio-political aspects.

Biological features recognised as critical to the high productivity of the crop are examined. These include its perennial and evergreen nature (giving a continuous year-round canopy cover intercepting a high proportion of incoming radiation), the year-round production of fruit bunches and the high partition of total assimilates into harvested product.

Scientific and managerial aspects contributing to the success of the crop include the significant genetic improvements and production of high quality planting materials, the development and application of finely-tuned agronomic practices, the appropriate scale and efficient organisation of oil palm plantations and the continuous R&D and good infra-structural support provided in the main producing countries.

The programmes of crop improvement through the utilisation of traditional breeding and selection methods, the development and benefits of vegetative propagation techniques using tissue culture and ongoing efforts to apply molecular and genetic engineering techniques to improve and modify oil composition, are reviewed.

Finally, the nutritional qualities of palm oil as a healthy component of diet are briefly described.

Gary Fitt1, Lewis Wilson2, Robert Mensah3 and Joanne Daly4

Insect pests represent a significant limitation for production of many crops. Traditional reliance on pesticides brings significant economic costs and environmental liabilities of off-target drift, chemical residues and resistance. IPM has long been proposed as an alternative. The adoption of IPM in the Australian cotton industry provides a valuable overview of the key components of IPM and the issues around successful implementation. IPM must be founded on a thorough understanding of the ecology of pest and beneficial species and their interaction with the crop and will provide a range of tactics which must be integrated by the producer to achieve economic and environmental sustainability. The emerging era of insect-resistant transgenic cottons offers real prospects to provide a foundation for more sustainable, economically acceptable IPM with the integration of a range of non-chemical tactics and much less reliance on pesticides.

D.C. Heering, N. DiNicola, R. Sammons, B. Bussler, G. Elmore, J. Killmer

For Monsanto, product stewardship is a fundamental component of customer service and business practices. The issue of glyphosate resistance is important to Monsanto because it can adversely impact the utility, sales and life cycle of its products if it is managed improperly. However, the risk of developing resistance and the potential impact of resistance on the usefulness of an herbicide vary greatly across modes of action and are dependent on a combination of different factors. As leaders in the development and stewardship of glyphosate products for almost thirty years, Monsanto invests considerably in research to understand the proper uses and stewardship of the glyphosate molecule, including some of the factors that can contribute to the development of weed resistance.

Today, some 275 herbicide-resistant weed biotypes have been identified in various cropping systems in the U.S., many of which are resistant to the triazine, imidazolinone, and sulfonylurea herbicide families. The development of resistance depends on a number of factors including chemical properties of the herbicide and its target site specificity, characteristics of the plant and agronomic practices. The onset of resistance to glyphosate has taken 23 years and affected far fewer weeds with a lower level of resistance than with other herbicides. Based on current use data and the criteria listed above, glyphosate is considered to be an herbicide with a low risk for weed resistance. After almost three decades of world wide use, confirmed resistance to glyphosate exists in biotypes of Lolium rigidum (annual ryegrass) in Australia, South Africa, and California; Lolium multiflorum (Italian ryegrass) in Chile, Eleusine indica (goosegrass) in Malaysia; and Conyza canadensis (marestail) in certain states of the eastern US.

The development of weed resistance to glyphosate is considered rare due to the following characteristics:

1. Most weeds and crops are inherently susceptible to glyphosate, and the long history of extensive use of glyphosate over the past 28 years has resulted in few instances of resistant weeds;

2. Selection for glyphosate resistance using whole plant and cell/tissue culture techniques was unsuccessful, and therefore, is expected to occur rarely in nature under normal field conditions.

3. Glyphosate has many unique chemical properties, such as its mode of action, small biomimetric chemical structure, limited metabolism in plants and lack of residual activity in soil, which make the development of resistance less likely.

Michael Walsh and Stephen Powles

In most world cropping systems the evolution of herbicide resistant weeds is becoming a major issue. This problem has become most severe in Australia. In the broad-area rain-fed cropping systems of southern Australian, herbicide resistance is a widespread problem threatening cropping profitability and sustainability. Widespread herbicide resistance has forced changes in agronomic and herbicide practices towards more diversity. Judicious herbicide mixtures and rotation can reduce the selection pressure for resistance to any one specific herbicide. Additionally, agronomic practices such as the adoption of delayed seeding and increased seeding rates can also reduce selection pressure by reducing in-crop weed populations. However, these techniques are not without problems or limitations. At grain harvest, the use of machinery to capture, collect and render weed seed non-viable is a very effective technique for reducing annual weed populations. The adoption by Australian farmers of the current limited technology is clear evidence of the value placed on the use of these alternative crop weed control practices. The continued march of herbicide resistance evolution more than justifies continuing research and development efforts to develop integrated strategies and smarter herbicide use so as to achieve sustainable crop weed management.

Gilles Lemaire1, Sylvie Recous2 and Bruno Mary2

In intensive agriculture regions the use of large amounts of N fertiliser results in a progressive increase of losses in the N balance and therefore to deleterious effects on the environment. Nowadays, farmers are constrained by EU and national directives, to adopt a more cautious N fertilisation strategy; it might increase the frequency that crops will experience N deficiency. A better understanding of crop-nutrient interactions is necessary for maximising N uptake capacity of crops and for optimising the N use efficiency by crops. The theory developed in this paper supports the hypothesis that crop N uptake is co-regulated by (i) the mineral soil N concentration and (ii) the potential growth rate of the crop. The agronomic nitrogen efficiency can be split into two components (i) the N uptake efficiency, and (ii) the N conversion efficiency. These two efficiencies increase with the rate and duration of crop growth, but with some differences between species when they are compared at same crop mass. A better understanding of the mineralisation-immobilisation turn-over of N in the soil is needed for predicting soil N supply and the N recovery from crop residues. Fertiliser recovery is the result of the balance between crop N uptake and N-immobilisation by microbial processes. Therefore, the concept of “soil N supply” to a crop cannot be longer considered as a function of soil and climate conditions only, but should be considered also take into account the interactions between plant and soil processes.

Improving crop and nutrient management is a prerequisite for optimising crop production and minimizing environmental risks due to N losses. The optimum rate of N application cannot simply be determined by the balance-sheet method. The uncertainties in the prediction of crop N demand require the use of crop N status indicators. Management of crop residues by different soil tillage and the introduction of cover crops within arable crop rotation as a mean to control soil N availability and nitrate leaching are discussed. The need of research on management of N at various scales, from the field to the landscape, in space and time is also emphasised.

Stephen R Waddington1, the late Webster D Sakala2 and Mulugetta Mekuria1

Crop productivity in southern Africa is limited by poor soil nutrient status. Local farmers crop highly depleted old soils with little external support for inputs and markets, and few resources of their own. These circumstances have led to widespread low input and output farming now characterized by nutrient mining, low productivity, food insecurity and non-sustainability. In response, agricultural research and development has increasingly focused on the generation and use of a range of soil fertility technologies to better manage smallholder agricultural resources and provide useful products. Best Bet soil fertility technology options now available include zone and end-use specific mineral fertilizer recommendations, conditional fertilization based on rainfall for maize, lime amendments, improved cattle manure and compost systems, annual grain legumes, green manure rotations and intercrops, improved fallows, beneficial trees in croplands, biomass transfer systems and nutrient use efficient cereals. Specific examples are presented of mucuna green manure in combination with mineral fertilizer, groundnut-maize rotations, and pigeonpea/maize intercrops, which have short-term financial benefits plus important productivity and sustainability benefits over 10+ years. These technologies were extensively tested with smallholder farmers on their spatially and temporally diverse farms, to maximize use and benefits. Information and promotion activities are described that have been moderately successful in encouraging farmer use of the Best Bets. Greater adoption will depend on appropriate input supply policies to support farmer investments in soil fertility and provide markets for products.

Holger Kirchmann1 and Megan H. Ryan2

Nutrient additions on organic farms are designed to maintain soil fertility, but not to directly feed plants. Hence, nutrients are applied in organic or low solubility inorganic forms in the belief that plants will obtain balanced nutrition through the actions of soil microbes. This review examines the implications of organic farming fertiliser practices for the sustainability of farming systems using two contrasting regions, Europe and Australia. In both these regions, mean yields are generally 20-45% lower on organic farms than conventional farms primarily due to reduced levels of plant available nutrients. Changes in the soil biological community do not overcome this limitation. Nutrient inputs are lower on organic farms, although in Europe there is a tendency on organic farms for increased application of purchased, approved, nutrient sources other than fodder. However, these inputs simply allow organic farms to gain nutrients that originated from conventional farms. If organic farming were to be widely adopted, lower yields would require more land (25-82%) to sustain production. In Europe, organic practices increase nitrate leaching, both per unit area and per unit of food produced, due to lower N use efficiency. Despite their aim of maximizing nutrient recycling, organic farming systems recycle only on-farm wastes and approved food wastes, with most municipal wastes excluded due to concerns about pollutants. In future, easily soluble inorganic fertilizers will be extracted from organic wastes through new nutrient recovery technologies and this will make conventional agriculture more sustainable whereas organic farming excludes itself from non-farm recycling, no matter how environmentally clean and safe the new fertilizer products are. In conclusion, the current promotion of organic principles irrespective of environmental outcomes means organic farming has become an aim in itself. This approach is ideological, not scientific, and may exclude other more effective solutions to the environmental problems afflicting current agricultural systems.

Holger Meinke1, Lexie Donald1, Peter DeVoil1, Brendan Power1, Walter Baethgen2, Mark Howden3, Rob Allan4 and Bryson Bates5

Our increasing understanding of the underlaying mechanisms responsible for climate variability and change means that some of these impacts are now predictable, although the extend of predictability remains hotly debated amongst scientists. Decision influenced by climate knowledge need to be made at a range of time scales, hence climate research efforts are directed towards investigating phenomena such as the Madden-Julian Oscillation (MJO; 30-60 days), El Niño - Southern Oscillation (ENSO) related variability (2 - 10 years), decadal / multi-decadal climate variability and climate change. The challenge is to further increase our understanding of causes and consequences of climate variability and change to achieve two key outcomes: a) policies suitable for multi-goal objectives resulting in rapid and substantial societal benefits and b) risk management strategies that reduce vulnerability for individuals and businesses.

Farm risk management needs to be seen within the wider societal context: Decisions made at a point in the landscape have implications downstream. Hence, environmental and societal risks (e.g. run-off, drainage, erosion, salinity, nutrient / pesticide movements, health impacts, employment etc) need to be considered and quantified. This requires the ability to effectively consider multi-goal objectives through the evaluation of alternative action outcomes. In this context, quantitative agricultural systems analysis via systems simulation models is an essential tool to provide objective information on which to base such decisions. In order to address issues of climate variability and change, these agricultural systems models require environmental input data – and specifically climate data – that reflects the current state of play in climate science. Statistical climate forecasts as well as forecasts based on coupled ocean/atmosphere models (GCMs) will play an increasingly important role in agricultural risk management.

Ramasamy Selvaraju1, Holger Meinke2 and James Hansen3

Climate variability is a major influence on agricultural production in smallholder farming systems of India. Smallholder farmers manage this climate variability only after the negative impacts are realized. The El-Niño/Southern Oscillation (ENSO) phenomenon explains some of this inter-annual rainfall variability. We suggest an integrated, interdisciplinary, participatory systems approach for the application of ENSO-based climate forecasts to vulnerable smallholder agriculture production systems in India. The overall aim of the approach is to demonstrate and deliver the benefits from climate forecasts for farmers and to provide operational support for seasonal climate prediction with in the target region. Our experiences demonstrate improved farm decision-making using climate forecasts combined with cropping system models. Simulated yields and gross margins helped to identify optimal farm decision scenarios conditioned on ENSO forecasts. The most valuable decision responses were associated with crop choice, sowing season and planting density. Although the potential aggregate benefit appears to be substantial, smallholder farmers face several challenges related to the uncertainty of current forecasts and complexity of agricultural systems. We suggest that, to benefit from seasonal climate forecasts, the decision capacity of the smallholder farmers need to be improved and greater emphasis should be placed on farmer involvement and a demand-driven participatory system analysis approach. The climate predictability needs to be improved further for wider application and to exploit potential benefit for smallholder risk management.

Marco Bindi1 and Mark Howden2

Human activities are affecting the composition of the atmosphere, influencing global and regional temperatures and rainfall and through these a large range of physical and biological processes. These changes appear likely to continue over the forthcoming century. As climate and atmospheric CO2 concentration are key factors in influencing plant production and other ecosystem processes such as decomposition, it is not surprising that changes in these will have consequences for the functioning of cropping systems. These consequences are likely to vary widely depending on the cropping system being investigated (i.e. cereals vs forage crops vs perennial horticulture), the region and the likely climate changes. For many cool-temperate systems, the prospect of global warming may bring new opportunities provided rainfall doesn’t decline substantially. For warm-temperate and tropical regions, the impacts may be significant and negative with increasing water stress, increasing problems associated with high-temperature conditions and a need for either substantial change in varieties and management activities or land-use change. There are a large number of adaptation options that may be explored to minimise negative impacts of climate changes and to take advantage of positive changes. These can be categorised as operating within different time-scales (i.e. short-term or long-term) or different spatial scales (i.e. farm-level to national policy level). We outline what some of these options may be at these different scales.

María E. Otegui1 and Gustavo A. Slafer2

On-farm grain yield of most grain crops has paralleled the improvement in grain yield potential, which has been mainly associated with an increase in the number of harvestable grains. A reduction in plant height (most cereal species) and tassel size (maize), with the concomitant improvement in assimilate availability for the growing spike, have been key traits for enhancing kernel number. The benefits of these traits, however, seem no longer useful for improving grain yield, and new molecular technologies are still far from giving a good explanation of the causal relationships between genes and the phenotype of complex traits like grain yield. In this paper we briefly reviewed (i) the importance of improving yield potential for further increasing actual yields in a range of conditions, and (ii) the significance of considering physiological attributes for achieving this goal. We finally discuss recent research on two developmental traits as tools for further raising yield potential in cereals. These are the particular extent of the stem elongation phase in wheat and the synchrony in the emergence of silks within ears in maize.

Thomas R. Sinclair

Legumes offer special characteristics that make them highly desirable as critical components of cropping systems. The key advantage of legumes is their ability to form symbioses with specific bacteria to fix atmospheric nitrogen (N2) into organic compounds for use by plants. As a result, soils on which legumes are grown do not normally need to be fertilized with N. Also, legumes tend to accumulate high concentrations of N in their tissues, which make the tissues valuable human food or animal feed. Many of the unique characteristics of legumes are associated with N2 fixation capability and the accumulation of high N concentrations in their tissues. Nitrogen fixation in all legumes is very sensitive to residual nitrate in the soil. While genetic variation in this trait has been identified, there has as of yet been no successful incorporation of nitrate tolerance into commercial cultivars. Also, N2 fixation in legumes that transport uriedes, e.g. soybean and cowpea, are extremely sensitive to soil drying. Recent studies with soybean have resulted in the identification of genotypes that have considerable N2 fixation tolerance to soil drying. High energy flux is necessary to sustain high N2 fixation rates and, consequently, legumes require phosphorus (P) in reasonably large amounts to sustain the energy flow pathways. Not surprisingly, several legume species have evolved especially effective methods to accumulate P from various P complexes in the soil that are unavailable to other species. Overall, legumes offer many traits that are highly desirable for improving many cropping systems.

Shaobing Peng1, Rebecca C. Laza1, Romeo M. Visperas1, Gurdev S. Khush2, Parminder Virk3 and Defeng Zhu4

The ideotype approach has been used in breeding programs at the International Rice Research Institute (IRRI) and in China to improve rice yield potential. First-generation new plant type (NPT) lines developed from tropical japonica at IRRI did not yield well due to limited biomass production and poor grain filling. Progress has been made in the second-generation NPT lines developed by crossing elite indica with improved tropical japonica. Several second-generation NPT lines outyielded the first-generation NPT lines and indica check varieties in both dry and wet seasons. China’s “super” rice breeding project has developed several F1 hybrid varieties using the combination of an ideotype approach and utilization of intersubspecific heterosis. These hybrid varieties produced grain yields of 12 t/ha in on-farm demonstration fields, 8-15% higher than the hybrid check varieties. The yield improvement was not due to increased crop duration so that cropping intensity will not be affected by adopting these new varieties in rice-based cropping systems. The success of China’s “super” hybrid rice was partially the result of assembling the good components of IRRI’s NPT design in addition to the utilization of intersubspecific heterosis. For example, both designs focused on large panicle size, reduced tillering capacity and improved lodging resistance. More importantly, improvement in plant type design was achieved in China “super” hybrid rice by emphasizing the top three leaves and the panicle position within a canopy in order to meet the demand of heavy panicles for large source supply. Success of “super” hybrid rice breeding in China and progress of NPT breeding at IRRI suggest that an ideotype approach is effective for breaking the yield ceiling of irrigated rice crop in rice-based cropping systems.

Elizabeth S. Dennis and W.J. Peacock

The Arabidopsis genome sequence was completed in 2000. This has led to a great increase in our understanding of the molecular basis of both plant development and the response to environmental stimuli. Having the genome sequence has enabled genomics approaches which aim to assign a function to each of the predicted 26,000 genes. Knockout mutations generated by insertional mutagenesis or gene silencing with RNAi methodology suggest a function for a gene if the mutants can be linked to a phenotype. Oligonucleotides corresponding to each of the predicted genes can be spotted on a microarray which can be used to determine the pattern of expression of each of the genes, again, suggesting a function. The knowledge of gene function is deepening our understanding of development in Arabidopsis, and importantly, it is enabling Arabidopsis to be a platform into similar levels of understanding in our major crop plants.

Yunbi Xu1 and Qifa Zhang

Rice has been serving as a model crop for cereals in genomics. The availability of complete genome sequences, together with various genomic resources fully developed for both rice and Arabidopsis, has revolutionized our understanding of genetic make-up of crop plants. Both macrocolinearity revealed by comparative mapping and microcolinearity revealed by sequence comparisons indicate that sequencing and functional analysis of rice genome will have great impact on other cereals. High-throughput capability, mutant libraries, and advanced transformation technique make functional genomics in rice and other cereals more manageable than ever. Sequences of rice genome and genes have been used to develop functional and biallelic markers that are more useful in genetic mapping and marker assisted selection. It is expected that an integrated database, which is for all rice-related information required for plant breeding and combined with other cereal databases, will be key to the utilization of all genomics resources for plant breeding.

Kim Hammond-Kosack3, Martin Urban, Thomas Baldwin, Arsalan Daudi, Jason Rudd, John Keon, John Lucas, Kerry Maguire, Dmitry Kornyukhin2, Hai-Chun Jing, Chris Bass and John Antoniw

Numerous phytopathogenic fungi and Oomycete species cause disease on crop plants. Over the past 17 years a combination of protein purification and forward and reverse genetics has lead to the identification of > 150 distinct pathogenicity and virulence genes required by pathogens to cause disease. Many conserved molecular mechanisms are now recognised that underpin the pathogenesis of very diverse species. In addition, > 20 pathogen effectors have been characterised which activate either non-host or race-specific resistance (R) gene mediated plant defence responses. Recently, full genome sequencing projects have been completed for eight phytopathogenic eukaryotic organisms and others are in progress. Through comparative genome analyses, the gene inventory and genome synteny of animal and plant pathogenic fungi and Oomycete species are being compared with each other and with other non-pathogenic organisms. This is providing exciting new information on the evolution of plant pathogens. For plant breeders, this wealth of molecular genetic information provides the opportunity to develop a suite of new approaches to attain durable disease control. For example, many pathogen targets have been revealed which potentially are accessible for intervention via plant cell derived products. Also, there is now the unprecedented capacity to monitor changes in plant pathogen populations resulting from the introduction of different resistant plant germplasms. A case study involving Fusarium graminearum and F. culmorum, which cause ear blight disease on wheat and other small grain cereals, is presented and illustrates how crop breeding can be assisted by molecular genetic information on the pathogen.

Mark Cooper, Dean Podlich and Oscar S. Smith

A plant breeder has to deal with multiple traits and many of these are genetically complex. The technologies that support plant breeding have progressed to a stage where there are now many options available to the applied breeder for the design of a breeding strategy. However, at this time the efficacies of many of the molecular breeding strategies that have been proposed for complex traits have not been empirically evaluated and compared to progress from conventional selection on phenotype. We seek a theoretical framework to better understand the power of phenotype-based (conventional) and molecular-based plant breeding strategies to change multiple complex traits by selection, and to study their relative strengths and weaknesses. For many traits high throughput technologies for studying DNA sequences have enabled us to move from studying phenotypes to the identification of candidate genomic regions and genes. To complement and focus our gene discovery capabilities we seek appropriate methods to develop gene-to-phenotype (GP) models that will lead to molecular-based strategies that are more efficient than the conventional pedigree-based breeding process. Advances in computer simulation, combined with large experimental data sets, provide the opportunity to consider the genetic architecture of traits on a continuum from simple to complex. We discuss the foundations of a suitable quantitative framework and apply this to examine aspects of response to selection. With this framework we can show that as the complexity of the genetic architecture of traits increases the opportunities for improving on phenotypic selection by molecular-enhanced strategies increase, but in parallel the requirements for development of adequate GP models become more challenging.

Stephen M. Welch1, Zhanshan Dong2, Judith L. Roe3

Flowering is a critical stage in plant development that initiates grain production and is vulnerable to stress. The genes controlling flowering time in the model plant Arabidopsis thaliana are reviewed. Previously, interactions between these genes were described by qualitative network diagrams. We present a generalized mathematical formalism that relates environmentally dependent transcription, RNA processing, translation, and protein-protein interaction rates to resultant phenotypes. We have developed models (reported elsewhere) based on this concept that simulate flowering times for novel A. thaliana genotype-environment combinations and critical short day lengths (CSDL) in rice (Oryza sativa ssp. japonica cv. Nipponbare). Here we show how CSDL phenotypes emerge from gene expression dynamics. Functionally different but homologous photoperiod measurement genes in rice and A. thaliana nevertheless yield similar results. Other technologies for interrelating genotypes, phenotypes, and the environment are crop simulation models and the theory of quantitative genetics (QG). Some potential synergies between genetic networking (GN) and these older approaches are discussed. Twelve contrasts are drawn between QG and GN revealing that both have equal contributions to make to an ideal theory. Such a theory is initiated by discussing epistasis, dominance, and additivity (all QG basics) in GN terms. Three or less genes can account for the first two but additivity is a complex property dependent on the structure and function of entire subnets. Finally, the utility of simple models is evidenced by 80 years of quantitative genetics and mathematical ecology.

Bruce Walsh

While animal breeders largely focus on improvement using additive genetic variance, inbreeding and asexual reproduction allow plant breeders to at least partially exploit non additive genetic variance as well. We briefly review various approaches used by breeders to exploit dominance and epistatic variance, discuss their constraints and limitations, and examine what (if anything) can be done to improve our ability to further use often untapped genetic variation.

François Tardieu, Matthieu Reymond, Bertrand Muller, Thierry Simonneau, Walid Sadok and Claude Welcker

The respective importance of the mechanisms which drive plant responses to environmental conditions are a function of climatic scenarios, with high year-to-year and site-to-site variabilities. Modelling is therefore an important tool for designing 'stress tolerant' plants. After reviewing mechanisms involved in the response of leaf growth to water deficit, we conclude that gene regulatory networks are not feasible for such complex systems. Leaf growth can be modelled via response curves to environmental conditions which are considered as 'meta-mechanisms' at a whole-plant degree of organisation. Response curves of leaf elongation rate to meristem temperature, water vapour pressure difference and soil water status were established in recombinant inbred lines (RILs) of maize in experiments carried out in the field or in the greenhouse. A QTL analysis was carried out on the slopes of these responses; most QTLs were specific for one response only. Each parameter of the ecophysiological model could then be computed as the sum of QTL effects, allowing calculation of parameters of new RILs, either virtual or existing. Leaf elongation rates of new RILs were simulated and were similar to measurements in a growth chamber experiment. This opens the way to the simulation of virtual genotypes, known only by their alleles, in any climatic scenario. Each genotype is therefore represented by a set of response parameters, valid in a large range of conditions and deduced from the alleles at QTLs. This approach, applied here to a relatively simple mechanism, might be extended to more complex plant modelling.

Graeme Hammer 1,2, Scott Chapman3, Erik van Oosterom1, Dean Podlich4.

New tools derived from advances in molecular biology have not been widely adopted in plant breeding because of the inability to connect information at gene level to the phenotype in a manner that is useful for selection. We explore whether a crop growth and development modelling framework can link phenotype complexity to underlying genetic systems in a way that strengthens molecular breeding strategies. We use gene-to-phenotype simulation studies on sorghum to consider the value to marker-assisted selection of intrinsically stable QTLs that might be generated by physiological dissection of complex traits. The consequences on grain yield of genetic variation in four key adaptive traits – phenology, osmotic adjustment, transpiration efficiency, and staygreen – were simulated for a diverse set of environments by placing the known extent of genetic variation in the context of the physiological determinants framework of a crop growth and development model. It was assumed that the three to five genes associated with each trait, had two alleles per locus acting in an additive manner. The effects on average simulated yield, generated by differing combinations of positive alleles for the traits incorporated, varied with environment type. The full matrix of simulated phenotypes, which consisted of 547 location-season combinations and 4235 genotypic expression states, was analysed for genetic and environmental effects. The analysis was conducted in stages with gradually increased understanding of gene-to-phenotype relationships, which would arise from physiological dissection and modelling. It was found that environmental characterisation and physiological knowledge helped to explain and unravel gene and environment context dependencies. We simulated a marker-assisted selection (MAS) breeding strategy based on the analyses of gene effects. When marker scores were allocated based on the contribution of gene effects to yield in a single environment, there was a wide divergence in rate of yield gain over all environments with breeding cycle depending on the environment chosen for the QTL analysis. It was suggested that knowledge resulting from trait physiology and modelling would overcome this dependency by identifying stable QTLs. The improved predictive power would increase the utility of the QTLs in MAS. Developing and implementing this gene-to-phenotype capability in crop improvement requires enhanced attention to phenotyping, ecophysiological modelling, and validation studies to test the stability of candidate QTLs.

Fred A. van Eeuwijk1, Marcos Malosetti1, Xinyou Yin2, Paul C. Struik2 and Piet Stam1

To study the performance of genotypes under different growing conditions, plant breeders evaluate their germplasm in multi-environment trials. These trials produce genotype by environment data. We present various statistical models for the analysis of such data that differ in the extent to which additional genetic, physiological and environmental information is incorporated into the model formulation. The simplest model in our exposition is the additive two-way analysis of variance model, without genotype by environment interaction and with parameters whose interpretation depends strongly on the set of included genotypes and environments. The most complicated model is a synthesis of a multiple quantitative trait locus model and an eco-physiological model to describe a collection of genotypic response curves. Between those extremes, we discuss linear-bilinear models, whose parameters can only indirectly be related to genetic and physiological information, and factorial regression models that allow direct incorporation of explicit genetic, physiological and environmental covariables on the levels of the genotypic and environmental factor. Factorial regression models are also very suitable for the modeling of QTL main effects and QTL by environment interaction. Our conclusion is that statistical and physiological models can fruitfully be combined for the study of genotype by environment interaction.

Michael Blakeney

This paper traces the history of the impact of intellectual property laws upon plant breeding and upon the genetic modification of plants. It concludes with an examination of the impact of these developments upon the international agricultural research environment and the food security debate.

Ronald L. Phillips1, Hei Leung2, and Ronald P. Cantrell2

Rice is a food staple throughout much of the world, especially in less developed countries.  Fortunately, rice has the lowest amount of DNA among the common cereals and has become a pivotal species for genomics investigations.  With the complete DNA sequence virtually at hand, the time has come to have a consortium to develop an understanding of the functional genomics of this important species.  With 50,000 or more genes predicted, the task ahead requires the development of many genetic resources to unravel the function and interaction of these genes and their relationship with important traits.  The DNA sequence coupled with full-length cDNAs, insertional and chemical-/radiation-induced mutants, and gene arrays represent resources for examining functional genomics questions.  An International Rice Functional Genomics Consortium has been established to share materials, integrate databases, elucidate gene function, and translate the information into benefits for society.

Judith Thompson, Michael Halewood, Jan Engels and Coosje Hoogendoorn

Plant genetic resources are one of the most important tools in agricultural research and development for the improvement of the productivity and sustainability of production systems, both in the developed and the developing world. There used to be plenty of diversity among crop varieties and their wild relatives, but this is rapidly disappearing, due to a trend towards uniformity in production systems and the disappearance of uncultivated areas which contain wild relatives. Fortunately there are now about 1500 genebanks or genebank collections in the world, in which a significant amount of the diversity is being conserved for future use. At the same time there is a growing awareness of the diversity that is still being grown in farmers fields, in particular in developing countries, and that concerted efforts have to be undertaken to conserve these genetic resources. However, while this diversity used to be available as a global public good, developments regarding intellectual property, plant variety rights and international agreements have made access and benefit sharing much more complicated and, thus, these developments affect the status of these genetic resources as public goods. In this paper we describe a range of developments that affect the value and the accessibility of plant genetic resources.

James B. Holland1

Molecular marker assisted selection (MAS) has been touted as a means to improve the efficiency and speed of plant selection programs. The most widespread use of MAS to date is to assist backcrossing of major genes into already proven, elite cultivars. Markers can aid selection for target alleles that are not easily assayed in individual plants, minimize linkage drag around the target gene, and reduce the number of generations required to recover a very high percentage of the recurrent parent genetic background. The use of MAS in forward-selection programs is less common and is mainly restricted to marker loci linked to major-effect genes with consistent linkage phase across numerous populations. MAS has not been widely used for the improvement of polygenic traits because quantitative trait loci (QTL) mapping techniques remain insufficiently precise and because QTL information cannot be easily extrapolated from mapping populations to other breeding populations. The accuracy of QTL mapping can be improved by increasing population sizes and the number of testing environments, but these same techniques also improve conventional phenotypic selection. Therefore, MAS for polygenic traits is mainly restricted to situations where phenotypic selection cannot be easily implemented (such as for traits that are difficult to phenotype on individual plants or in offseason nurseries). MAS will remain a specialized breeding tool until QTL mapping can be extended to estimation of breeding values across many diverse breeding crosses and subpopulations such as those that compose typical plant breeding programs.

William S. Niebur, J. Antoni Rafalski, Oscar S. Smith, Mark Cooper

The commercial grain yield of maize in the U.S. Corn Belt has undergone significant genetic improvement since the initiation of hybrid breeding in the first half of the 20th Century. Designing effective molecular enhanced breeding strategies that improve on the outcomes of the conventional pedigree breeding strategies is a challenge for commercial maize improvement programs today. Most of the traits of importance to the breeder are genetically complex and quantitative in nature. Genetically mapping these traits in elite breeding populations is difficult. Conventional mapping approaches in structured populations are often not relevant to the elite crosses of a maize breeder, are time consuming to create and even when successful usually only offer low levels of mapping resolution (ca. 10 to 20 cM). Therefore, considerable interest has emerged in the use of alternative methods for the mapping of quantitative traits. Genetic association mapping methods have been the subject of great interest in human genetics. More recently genetic association studies have been performed in crop plants, with some promising results. Much work still remains to develop association mapping methodology that is applicable to properties, such as pedigree relationships, among the elite populations of a maize breeder. We will discuss the utility of these approaches for mapping complex traits and issues for consideration in their application to breeding.

Donna J. Cahill 1 and Daria H. Schmidt 2

Marker Assisted Selection (MAS) has held promise for impacting, perhaps revolutionizing, plant breeding disciplines. There are examples of commercial breeding programs making use of MAS in product development as a tool in breeding schemes for many agriculturally important crops, including grain, oilseeds, vegetables, ornamentals, and tree crops. In most cases, levels of efficiency in selection at early generations and characterization in later generations are the tangible deliverables from MAS. Building the infrastructure of a high throughput MAS program is a costly and time consuming process, with vision and patience required. As a case study, markers have proven to be a useful tool in the development of disease-resistant soybean (Glycine max) varieties. The efficiency they bring to the breeding process is measured by the success in accumulating desired traits, particularly soybean cyst nematode resistance, in a larger percentage of candidate experimental lines throughout the breeding pipeline. This technology has been sufficiently streamlined to allow for high throughput data generation in a timely manner that supports "traditional" cultivar development. The improvements for sample turn-around and total data point capacity are continuing to make MAS a cost-effective tool in the breeding of high performing soybean cyst nematode (SCN) resistant varieties. MAS for soybean product development at Pioneer Hi-Bred has been used for almost 10 years and has significantly impacted early generation single plant selections, resulting in numerous successful commercial soybean varieties.

John Ohlrogge1, Vandana B Mhaske, Frederic Beisson, Sari Ruuska

The vegetable oils produced by soybean, palm, canola and other crops provide approximately 25% of the calories consumed by industrial nations. In addition to their dietary significance, vegetable oils are a major agricultural commodity, with worldwide production of 90 billion pounds, worth nearly $50 billion per year. This large market size and the fact that the fatty acid composition of vegetable oils influences both their physical properties and nutritional characteristics has attracted considerable interest toward modifying plant fatty acid production for both food and non-food uses. Many successes have already been achieved in altering the chain length and saturated/unsaturated fatty acid content of dietary plant oils by transgenic methods. Future efforts will lead to plant oils rich in omega-3 structures found in fish oils. Genomic approaches, including EST sequencing, microarrays and bioinformatics are now contributing greater understanding of the underlying metabolism of oilseeds and the regulatory networks that determine the quality and quantity of oils produced.

Elizabeth E. Hood

Plant production of biopharmaceuticals and bioindustrial proteins is a potentially viable industry with tremendous upside potential. Plants allow large amounts of biomass and can be easily and inexpensively produced, with seed based systems being the most economical. Significant technologies, including promoters with tissue-specific activity, and sub-cellular targeting sites that offer protein stability, have been successfully developed to address protein accumulation issues. Crop choices for production, whether for domestic or wild species, are based on many criteria including type of product, cost of production, and safety of the product. Production steps are numerous—from growing and harvesting the crop to transportation, storage, processing, extraction and in some cases protein purification. Examples of products and crop choices will be presented. Legal and regulatory issues also will enter into the decision-making process. The industry players must work together to solve a number of problems that are currently at issue, such as regulatory requirements and public acceptance. However, with attention to these details and good stewardship, the success of the industry is possible.

Oliver P. Peoples

Polyhydroxyalkanoates (PHAs) are a broad and versatile family of plastics, ranging in properties from rigid, strong and stiff to tough and highly elastomeric. They can be made as resins or aqueous dispersions with excellent film forming characteristics. Robust in use, yet biodegradable, PHAs offer a renewable and environmentally friendly alternative in many applications now served by synthetic plastics, including fibre, film, molded goods, extruded products, adhesives, and coatings. These materials can address unmet needs and ultimately replace a significant proportion of the 150 million tonnes of plastic produced today from petrochemical resources. PHAs are unique in the industrial biotechnology field in that they are produced as finished polymers in storage granule form as the result of known metabolic pathways inside living microbial cells. This has provided the basis to transfer these metabolic pathways into plants and develop an entirely new agricultural opportunity with markets solely in the industrial and energy sectors. Metabolix has developed a detailed biorefinery cost and engineering analysis using switchgrass (Panicum virgatum) which is being developed as an energy crop in the United States as a vehicle for very large-scale PHA manufacturing. Progress on advancing the production of PHAs in crop plants along with the overall environmental benefits of the switchgrass PHA biorefinery will be discussed.

Eduardo Blumwald1, Anil Grover2 and Allen G. Good3

Recent experimentation with transgenic plants has led to increased salinity tolerance, with emphasis on the areas of ion homeostasis, osmotic regulation and antioxidant protection. A case study of the major challenges and opportunities to improve stress tolerance in plants using salinity is presented. As different abiotic stresses are inter-related (e.g. salinity and osmotic stress), our ability to improve crop performance may well be determined by combining different, apparently unrelated approaches for introducing several stress tolerance mechanisms into specific crop plants.

Roberto Tuberosa and Silvio Salvi

Molecular markers, genomics and post-genomics platforms offer unprecedented opportunities to identify, select and clone genes influencing drought tolerance. The dissection of the genetic basis of quantitative traits into their single components, the so-called QTLs (Quantitative Trait Loci) provides a more direct access to valuable genetic diversity for important physiological processes that regulate the adaptive response to drought. This, in turn, enables us to deploy marker-assisted selection (MAS) for enhancing crops’ performance. However, despite the impressive progress in molecular techniques and the large number of QTLs described to influence yield in drought-stressed crops, the overall impact of MAS and other applications of genomics on the release of drought-tolerant cultivars has so far been marginal. QTL discovery should be viewed as the first step of a longer process aimed at identifying and isolating the underlying molecular polymorphism of the functional variation revealed through QTL analysis. The cloning of major QTLs will offer additional opportunities for a more effective exploitation of the allelic richness present in germplasm collections. A deeper integration of MAS with conventional breeding methodologies and other interdisciplinary approaches will enhance our capacity to improve drought tolerance.

H.R. Lafitte, A. Ismail, J. Bennett

Various abiotic stresses limit rice production in rainfed environments, which comprise about 45% of the global rice area. Important stresses include water deficit, submergence, salinity, and deficiencies of P and Zn. In recent years, advances in physiology, molecular biology, and genetics have greatly improved our understanding of how rice responds to these stresses and the basis of varietal differences in tolerance. Progress has relied on the application of rather specific phenotypic screens that allow the effects of stress to be distinguished from general differences in adaptation of diverse parents. QTLs have been identified that explain a considerable portion of observed variation, and in some cases, the genes underlying specific QTLs have been identified. Transformation has been used to assess the effects of altered expression of specific stress-related genes, allowing confirmation of the importance of particular metabolic pathways. Through expression profiling of many genes simultaneously, it has been possible to identify three types of stress-responsive gene networks: early signaling pathways, adaptive responses, and genes that reflect downstream results of damage. For crop improvement, the identification of useful allelic variation for genes in the second group may be the most promising approach. Once such genes or gene combinations are identified, either molecular approaches or trait-specific physiological screens can be used to search for these superior alleles. Marker-assisted backcrossing can then be applied to incorporate these alleles into agronomically superior germplasm.

Hei Leung1, Jianli Wu1, Bin Liu1, Masdiar Bustaman2, R. Sridhar3, Kuldeep Singh4, Ed Redona5, Vu Duc Quang6, Kangle Zheng7, Menchu Bernardo1, Guoliang Wang8, Jan Leach9, Il Ryong Choi1, and Casiana Vera Cruz1

Through the Asian Rice Biotechnology Network, marker-aided analyses of pathogens and host plant resistance have been practiced by several national breeding programs resulting in the production of elite or commercial lines with multiple disease resistance genes. A unique feature of ARBN is the continuing effort to capture new findings from host-pathogen interaction research and apply them in breeding. This network approach is essential for sharing resources and providing sustained training in the adoption of tools and genetic knowledge in individual breeding programs. Several studies have demonstrated the successful application of candidate genes selection for enhancing blast and bacterial blight resistance in breeding lines and varieties. Advances in genomic research will provide new approaches to determine the relationship between genetic variation, disease resistance phenotypes and performance in the field. Prospect for achieving sustainable disease control in Asia is good provided that breeding programs are enabled to access and apply tools to address local problems.

Ravi P. Singh1, Harindra M. William1, Julio Huerta-Espino2 and Garry Rosewarne1

The rust diseases of wheat pose a constant threat to sustainable wheat production and thus food security in Asia. If susceptible wheat cultivars are grown, approximately 60 and 40 million hectares could experience periodic epidemics of leaf rust and stripe rust, respectively. Avoiding major rust epidemics in the region is a complex challenge, given that fewer cultivars are being cultivated over large areas, that several of those cultivars are protected by the same resistance genes, and that there is free movement of new virulent races in most of west and south Asia. Monitoring the evolution and movement of new rust races and diversifying cultivars sown in the region based on genetic information could help reduce losses, provided newly susceptible cultivars are withdrawn quickly. Using race-specific resistance genes in combinations could enhance their longevity. Linked DNA markers show promise for achieving such combinations; however, a national and regional deployment strategy is necessary to achieve long-term success. The most promising long-term control strategy is to breed and deploy cultivars carrying durable resistance based on minor, slow rusting genes with additive effects. CIMMYT studies show that combining 4-5 such genes results in a high level of resistance, comparable to immunity. Traditional genetic and molecular mapping studies have demonstrated high genetic diversity for such minor genes, but significant investment is necessary to identify closely linked markers that could be used effectively in marker-assisted selection. Targeted incorporation of durable resistance genes into mega-cultivars grown in Asia by using a ‘single-backcross selected-bulk breeding scheme’ is being pursued at CIMMYT with encouraging results.

K. V. S. Reddy and Usha B. Zehr

The losses incurred due to pests and diseases have been a consistently reported feature. Changes in cropping patterns including the cultivation of high yielding varieties and hybrids have added to the problem in some areas. Plant breeding has been successful to some extent in keeping up with new and evolving diseases and pests. Innovation in agronomic practices, advent of chemicals for control, and more recently genetic engineering tools have been providing new opportunities for reduction of crop losses due to these biotic pressures. Insect control is even more important as many viral diseases are transmitted by insects. Molecular markers and other genomics information are allowing more precision in breeding for greater tolerance to diseases in many crops. India has commercialized genetically modified cotton which provides resistance to the bollworm complex of pests. Broad spectrum resistance is now possible with genetic engineering. Marker assisted breeding is being used in rice and other crops for disease resistance strategy. Still better understanding the mechanism of resistance for disease and pests, will allow better deployment of technologies for different pests and diseases.

Muffy Koch

Not all GM crops available for technology transfer are likely to have relevance for African growing conditions, but the only way to assess the effectiveness and appropriateness of GM planting material is to test it locally. This paper reports on the relevance of non-GM crop biotechnology and of some commercial GM crops to small farmer development in Africa. The impact of disease-free banana planting material in Kenya will be presented. Of the five GM crops approved for production in South Africa, two have shown production benefit for emerging and subsistence farmers: insect resistant cotton and insect resistant maize. A third crop, insect resistant potato, is in the testing stage, but already shows signs of providing socio-economic and development benefits for African farmers. This paper discusses the benefits and constraints of GM technology transfer to small scale African farmers and the future these crops hold for development in poor farming communities, for food security and for wealth creation.

Jikun Huang1, Ruifa Hu2, Carl Pray3, and Scott Rozelle4

This article provides an overview of China’ plant biotechnology development and its impacts on farmers. Our study shows that while Chinese policymakers have considered agricultural biotechnology as a strategically significant tool for improving national food security and raising agricultural productivity, they have been hesitant to approve the commercialisation of new genetically modified (GM) crops since the late 1990s. China now has several GM plant species such as rice, maize and soybean that are in the pipeline for commercialisation, but except for Bt cotton none have been approved for commercial release since 1997. In 2003, more than 5 million farmers adopted Bt cotton and nearly 60 percent of cotton area was planted with Bt cotton. Our survey data on yields and econometric analyses indicate that the adoption of Bt cotton increased output per hectare by nearly 10 percent and reduced pesticide use by 35 kg (or about 60 percent), which significantly improved the income of small farmers. We also provide evidence that farmers have less health problems because of reduced pesticide use. More importantly, our most recent survey shows that the performance of GM rice in the pre-production stage is impressive. Insect and disease resistant GM rice can reduce pesticide use per hectare by 17 kg (or nearly 80 percent). Our survey also provided evidence of a slight increase of yield from GM rice production. We conclude that plant biotechnology will significantly boost China’s agricultural productivity and there are lessons for other developing countries in their experience.

Greg Traxler

In 2003 North and South America (NSAm) accounted for more than 64 million ha, 94%, of total world area planted to genetically modified organisms (GMOs). Delivery has occurred almost entirely through the private sector and adoption has been rapid in areas where the crops addressed serious production constraints and where farmers had access to the new technologies. Four countries (USA, Argentina, Brazil and Canada), four crops (soybean, cotton, canola and maize) and two traits (insect resistance and herbicide tolerance) account for the vast majority of the global transgenic area. Colombia, Mexico, Honduras, Uruguay and Paraguay have also planted GMOs. The economic benefits of the diffusion of GMOs have been widely shared among farmers, industry, and consumers despite the fact that the products are patented. The GMOs have had a favorable impact on the environment by facilitating reduced pesticide use and the adoption of conservation tillage. This paper surveys the level and distribution of the economic impacts of GMOs in NSAm to date.

Tsakani Ngomane

Agriculture constitutes the backbone of most economies in developing countries, especially in Africa. However, benefits in the sector mostly accrue to industry and to the intensive farmers. The “transfer of technology” (ToT) paradigms introduced during the colonial era, failed to provide research and technology outputs that meet smallholder farmers’ needs. In various review reports and regional consultation meetings stakeholders identified extension-research as the weakest link to wealth creation and as the primary contributor to the widening gap between resource-endowed and resource poor farmers. In addition, successful smallholder farmer innovations, technologies and dissemination approaches are not well publicized.

Using the development perspective, this paper summarizes 1) the evolution of ToT and the history of extension services in developing countries, 2) the importance of research and extension linkages in fostering change, 3) two alternative extension paradigms and their track record - Farmer Field Schools and, Agricultural Knowledge and Information Systems, and 4) farmers’ perceptions of the impact of science and technology on rural livelihoods. Recommendations to narrow the gap between smallholder and intensive farmers as well as pro-poor extension strategies are discussed.

Jacqueline A Ashby12 and Nina Lilja13

Participatory research approaches that involve clients in the process of enquiry are widely practised today in many different branches of agriculture ranging from integrated pest management to applied biotechnology. This paper focuses on participatory plant breeding to show how participatory research increases benefits and is more effective at reaching women and the poor. Used in plant breeding, PR is seen to improve research efficiency and leads to more acceptable varieties thus accelerating adoption. This is probably the most compelling incentive for researchers to use this approach. Although often charaterized as expensive, PR also leads to changes in costs that do not lower breeding program cost benefit ratios and may improve these. The paper shows that a careful choice of research goals, targeting of environments and selection of user communities is required in order for PR to have an impact. Also a systematic understanding of different types of participation is needed to select appropriate PR techniques and tools. The paper concludes that PR or client-driven research when used appropriately and expertly, is a proven complement to conventional non-participatory research approaches.

Peter Hayman.

Decision support systems (DSS) have been a significant way that agricultural scientists seek to intervene and improve the way farmers manage their enterprises. Although there have always been some dissenting voices, until recently (early to mid 1990s) DSS were held as a promising means to transfer scientific information and farm management procedures to farmers. Despite relatively high levels of computer ownership, the use of DSS for routine decision making by farmers has been disappointing. The brief and unfolding history of DSS in Australian dryland farming systems provides an interesting case study of the challenges facing agricultural scientists intervening in the world of farm management decisions.

John K. Lynam

Increases in crop yield will be the principal path to meeting future world food needs. This paper reviews the history of the search for crop yield increases in the post-Green Revolution period within the CGIAR. The paper sets out a stage theory of increases in crop productivity, against which to understand the determinants of such increases under varying market and institutional conditions. The paper then reviews the experience with organizing crop management and varietal improvement research and in targeting such research to diverse farming systems and institutional settings around the globe. The changes in the organization of agricultural research is framed in regards to advances in the science versus an improved understanding in the conditions under which agricultural technology will be adopted by farmers. The paper concludes with reflections on the needs in organizing research to meet future increases in crop productivity.

M.M. Escalada and K.L. Heong1

A participatory planning process was applied in two resource management initiatives in Vietnam. The first case was a pilot project established in two districts of Long An province to evaluate the use of media materials to motivate farmers to experiment or test a simple rule: “insecticide spraying for leaf folder control in the first 40 days is not needed”. The second case was a research-extension initiative launched in Cantho province to motivate farmers to reduce seed rate and use of fertilizer and pesticides. The media campaign in Long An province resulted in a 53% reduction in insecticide use and no loss in production in the project sites, and the change eventually spread to more than a million rice farmers 3 years later. Leaf folder control perceptions, expressed as the belief index, changed from 11.25 to 7.62. The belief index is the sum of scale ratings of belief statements presented to respondents. A three-point Likert scale (1 for the preferred answer, 2 for indifference and 3 for the not preferred) was used to score components of belief about leaf folders. The study showed that mass media could effectively transfer some elements of knowledge-intensive pest management, especially simple non-site specific information designed to motivate. The case studies highlighted the need for processes that distill bits of information and develop them into knowledge that can be communicated and used by farmers to make resource management decisions. Some of the features found to be extremely useful in implementation are: developing high quality partnerships and building social capital, building project objectives within institutional objectives, using mechanisms to encourage participation, encouraging farmer participatory research (FPR) to facilitate farmers’ evaluation of heuristics, and developing a participatory communication strategy and materials for evaluation.

Greg Constable

This paper firstly illustrates the considerable changes which have occurred in the Australian cotton production system in the last 25 years. Changes in soil, water, insect, weed and disease management and cultivar development have been dramatic and together have produced a yield increase of 180% with better fibre quality. The change from a system heavily reliant on persistent pesticides and with exploitive soil and water practices to Integrated Crop Management (Pest, Weed, Disease and agronomy) has substantially improved sustainability. The use of crop rotation; development of disease resistant cultivars; and transgenic insect protection have been the three greatest single factors behind progress, although there is a genuine system package where no factor alone can explain the improvement. Research has played a role in all subject areas.

It has been estimated that breeding has contributed 45% to yield improvement, with soil and water management contributing 25%; insect management contributing 20%; and disease management contributing 10%. Performance indicators for improvements in fibre quality, disease resistance, water use efficiency; insecticide use and contamination are specified. Organisation is a feature of the cotton industry, with an overarching Australian Cotton Industry Council being comprised of research and extension bodies, an industry promotion body; seed and chemical retail representatives; and groups representing ginners, classers, shippers, merchants and spinners. Research organisation includes a Cooperative Research Centre which coordinates much of the research and extension activities.

There is not much in common between Australian cotton growers and smallholder farmers in developing countries, except that an organised industry structure helps research and extension of new technology. Farmers need to want to change and they have to be able to afford the change. With these criteria, farmers need help and advice from a familiar person to implement extension messages. All methods of information delivery from face-to-face, to written packages and electronic methods are available.

Warwick Easdown1 and Ann Starasts 2

The Internet will be of most use to cropping farmers when providers of agricultural information use it less like a library and more like an interactive field day. It is not its scarcity but the local contextualization of information that makes it valuable for farmers. The huge volume of information available on the Internet is of less value to farmers than the opportunities for interactivity with others that it provides to help make local sense of that information. There is a mismatch between current content aimed at farmers and the way that farmers make decisions.

The high social and economic costs of Internet access mean that it must complement and supplement traditional low cost media if it is to be most useful. A comparison is made of rural Australia and rural Uganda: the constraints on Internet services and the need for cross-promotion and integration with other media. In both cases a positive policy environment has been vital to the successful development of rural Internet services.

Farmers need good access, a supportive peer group, personalized training and online mentors to make best use of the Internet. Developing online support groups based on existing farmer groups is a good way to help individuals develop their skills in a safe environment and to find practical uses for the Internet. Organizations providing online information to farmers could greatly improve its relevance if they invested in online extension services to help farmers find and interpret their information and to facilitate the development of online farmer groups.

Achim Dobermann1, Simon Blackmore2, Simon E. Cook3, and Viacheslav I. Adamchuk4

Precision farming is a systems approach to managing soils and crops to reduce decision uncertainty through better understanding and management of spatial and temporal variability. Much research has been conducted to develop strategies for site-specific crop management in different agricultural systems, with mixed results. Applications in which the sole focus has been on variable rate technology for managing spatial variation at the sub-field level have often failed to deliver significant and consistent improvements in crop yields, profitability, input use efficiency, and environmental impact. More robust, dynamic, and integrated forms of site-specific management are currently being developed. They require better techniques for characterizing and understanding crop growth determinants at the spatial and temporal scales that are most relevant for decision-making. This level of detailed understanding pays most in high-value crops, where more precise management can improve both quantity and quality.

Peter Stone1 and Zvi Hochman2

Over the last 30 years, significant resources have been devoted to the development of computer-based decision support systems (DSS), usually in the belief that they were capturing, assimilating and delivering information that could help farmers to better manage their farms. The accumulated evidence suggests that this belief was largely misguided - most DSS have ‘failed’ in the agricultural market place. Despite this, many scientists continue to develop and attempt to deploy DSS that are intended to help farmers make management decisions. Here we examine aspects of the ‘success’ or ‘failure’ of three DSS with the aim of drawing from the experience some guidelines that may help in the development and deployment of future DSS. We don't see DSS as a lost cause, provided that scientists learn hard-won lessons from their collective achievements and failures. These include recognizing: (1) the need for comprehensive marketing information to inform the process of DSS conception and delivery rather than just the more usual autopsy; (2) that there are almost invariably other, perhaps more effective, methods for acquiring and transmitting the knowledge embodied in a DSS; (3) that what appear to be technical and quantitative management ‘problems’ often involve social, qualitative and subjective processes and ‘solutions’ that DSS are not well-equipped to consider; (4) that DSS are usually best accepted when they seek to enhance rather than replace farmers’ existing decision making processes, making those that help to understand ‘how things work’ generally better accepted than those that present ‘optimized’ solutions. Further lessons are examined.

Buenafe R. Abdon1 and Robert T. Raab2

Agriculture is of pre-eminent importance in the Asia Pacific region but is under threat from a number of sources. These include increased demand for food and fibre, complex new domestic and international economic and political forces and changing marketing regulations and requirements. Underlying all these is the rapidly deteriorating natural resource base upon which future productivity and farmer livelihoods depend. Knowledge and information are key requirements to enable farmers to deal with these challenges, particularly as new agricultural technologies are becoming more “knowledge intensive”. Reaching farmers with these prerequisites has been problematic in the past but new information and communication technologies – primarily the Internet – are showing considerable promise. While this approach for directly reaching farmers in developing countries is still in its infancy, ICTs are proving that they can reach “knowledge intermediaries” whose role is to bridge the local and global agricultural knowledge systems. While there are several initiatives at the global, regional, national and the local levels all across the globe, these are proving to be much less than what is required to make a real difference and capitalize on the potential. The donor community can do much to facilitate progress but must consider some fundamental changes in its priorities and how it operates. It must rethink its current faith in the private sector, target institutional support more rationally, develop and follow a clearer strategy and provide more substantial and sustained support for Internet-based initiatives that take advantage of the real potential of this approach.

Rasheed Sulaiman1 and Andy Hall2

Extension is clearly facing challenging times in Asia. This paper draws together experiences from across Asia to explore extension policy and the extension policy process. The paper argues that extension policy in Asia needs to tackle two major sets of issues. The first concerns the content of extension policy in view of the broader role extension need to play in the present context. The second issue concerns the nature of the policy process itself. Instead of prescribing reforms, the policy process should ideally facilitate continuous incremental change through experimentation, reflection and learning. Four cases of recent developments in extension policy and policy process are presented to illustrate the challenges involved in developing and implementing extension policy. The experiences indicate that reform processes only informed by prescriptions generated centrally or from outside are bound to fail. The message for extension policy in Asia is that the process of reform must be lead from within. The paper stress the need for undertaking an institutional analysis of historical and current approaches of implementing different extension approaches and developing capacity within the country on experimenting with different approaches and evaluating them. These learning based approaches should inform policy development. However the existing culture of extension organisations may prevent the emergence of learning based approaches to reinvent extension. Changing these cultures may yet be the biggest challenge of all for reforming extension.

Rashid Bajwa

This paper briefly reviews the present state of agricultural extension in Pakistan with respect to the role of public and private sectors, particularly from the perspective of small farmers. It argues that both sectors have strengths and weaknesses of their own. The public sector extension services do not reach the bulk of the small farmers due to poorly motivated staff, inadequate operational funds, lack of relevant technology, top-down planning, centralized management, and weak accountability systems. On the other hand, the private sector extension services are targeted at big farmers and are primarily triggered by a profit-maximisation motive. The paper then presents a unique model of partnership between a private sector concern, a non-profit (rural support programme), and farmers, and argues that similar models could be adopted to make agricultural extension services work to the benefit of small farmers.

Derek Byerlee

The recent evolution of agricultural research systems in developing countries is described, noting a change in focus from national public sector research organizations to one that emphasizes a diversified public-private system, in which clients, especially farmers, are key partners in financing, planning, implementing and monitoring research. Consistent with these changes, research planning, monitoring and evaluation has evolved from centrally-driven top-down approaches to give greater emphasis to decentralized and participatory approaches, in which client demands and satisfaction are key inputs. Although much progress has been made in reforms to enhance accountability and impacts of research, res systems still face major challenges in ensuring that demand-driven approaches provide coherent research programs consistent with national policy objectives, and in ensuring that they reflect the interests of the poor and are not captured by elites.

Steve Twomlow1 and Nina Lilja2

Evaluating the impacts of NRM research is essential to understand its contribution to increasing agricultural productivity and sustainability, reducing vulnerability, and ultimately alleviating poverty. A proper evaluation helps judge merit or worth, improve programs and generate knowledge. One indicator of a constructive evaluation is that it promotes learning and that the results are used to guide change. This paper suggests that a key to successful evaluation in NRM is in the mindset of the researcher. We discuss the contribution of four factors to a reflective learning process that is necessary in integrated NRM. They are: stakeholder participation, systems approach to evaluation, timing of the evaluation and an iterative approach to investigation.

Philip G Pardey1 and Julian M. Alston2

Worldwide, agricultural R&D is undergoing a sea change. Total funding is often now growing at much slower rates than in earlier decades, the nature and sources of support for research are diversifying with the private sector doing or funding much more of the research (at least in developed countries), and there are substantial shifts in the scientific basis for much of the biological research directed toward agriculture. At the same time the institutional, regulatory and intellectual property regimes that affect agricultural R&D are themselves undergoing rapid change. Efforts to reshape pubic policies that have long-term implications for scientific and technological capacity are underway, but progress has been uneven and in many cases uninformed by evidence of the likely (economic) effects of changes in the investment and institutional realities surrounding agricultural R&D.

J. RusikeP1P and J. P. Dimes

Smallholder crop management practices throughout sub-Saharan Africa still lag behind those of small-scale farmers in Asia and Latin America. During the past 50 years public and private sector investments in agricultural research, extension, and input and output markets have expanded. Starting in the late 1980s, 40 of the 47 African countries implemented economic policy reforms under structural adjustment programs to transfer responsibilities from public to private organizations, and use market forces to drive agricultural development. Globalization of input and output markets can allow African smallholders to catch up by tapping into production technologies and knowledge around the world. Yet the majority of smallholder farmers continue to use traditional and often unproductive crop production practices.

This paper summarizes recent developments and emerging trends in the organization of crop management research and development and technology delivery systems in African countries. The paper draws insights from the transaction costs and principal agent theories of the New Institutional Economics on the potential role of the private sector in inducing widespread adoption of improved crop management practices by smallholders. The paper applies the implications to case studies of targeting private sector-led development in Tanzania and Malawi and Zimbabwe in order to identify efficient incentive mechanisms for inducing widespread technological change where contract enforcement is difficult. The paper finds that there is a large public role to ensure that contract farming arrangements are conducted fairly and this, in turn, induces output market development, which pulls new technologies and facilitates adoption by farmers.

Jorge Gonzalez Montaner1

In this paper, we describe an example of integration of research and extension, combining private and public resources and activities in Argentina. This includes the general functioning of an association of farmers composed of 136 groups, Regional Consortiums for Agricultural Experimentation (CREA). CREA is distributed in 17 regions across Argentina, with a total of 1200 farmers and 150 consultants; collectively they are known as the Argentine Association of Consortia for Agricultural Experimentation, AACREA. It began 40 years ago inspired by a similar movement in France. We will discuss the case of one of the regions called Mar y Sierras that has developed particularly strong research and development activities involving public and private organizations. This region is situated in the SE of Buenos Aires (BA) Province between latitude 37 S - 39 S, with 5% of the total crop area (2.5 Mha) in that region under CREA groups and 70 % of this under no till. Wheat yield has shown an increase of 83 kg/ha/yr since 1975, rising to 5 t/ha over 60,000 ha in contrast with 3.5 t/ha for the farmers outside of CREA. Similar upward trends are evident in sunflower (44 kg/ha/yr since 1976), corn (148 kg/ha/yr since 1988) and soybean (58 kg/ha/yr since 1995) with a spectacular increase in area.

We shows how the relationship between farmers, private group consultants, private group scientists and state organizations can function to tackle various research and development issues inspired by questions from the farmers. Also we show how this region obtains funds for research and development and how the annual plan is built. A strong agricultural sector, confronted with weak public sector research, had promoted this effort by farmers to attract private and public scientists to work on agricultural systems. This has also involved strong relationships with the French, and research centers in the USA, Canada, and Australia. Dynamic, highly educated farmers and interest from young farmers is probably one of the most important success factors.

Ian G McClelland1, A Gartmann1, and H van Rees12

Farmer groups have made an important contribution to the prosperity of regional towns across Australia. Broadly speaking, they may be split into two types, those with the specific aim of increasing productivity and those with a broader focus of the welfare of the community as a whole. The Birchip Cropping Group (BCG) regards itself as one of the latter, as is reflected in its mission of “improving profit and viability of Mallee and Wimmera communities.”

The BCG was formed in 1992, the first of the farmer groups in the grains industry to do so. It is currently the largest in number of staff and in the breadth of its projects. There are now more than thirty groups around the country active in taking control of their own destiny. They undertake independent agronomic, economic and community research, provide training and identify future needs.

The agricultural community now accepts the farm group as having a local infrastructure, providing a means of communication and information exchange, and acting as a co-operative research partner and a pathway into the future for innovation and change. The members of different groups know of and mix with each other, share ideas and expertise, produce joint publications. They have developed a network that stimulates interest across Australia and has influence.

Farmer agronomic needs and interests have a significant profile as a result.

Much discussion has occurred about the sustainability of farm groups: whether they will maintain the current level of their impact on the way farmers obtain access to information, how the priorities of public sector research and extension could change and whether farmer groups will become the intermediary between funding bodies and public sector researchers.

Important ingredients of the sustainable success of farm groups include the presence of strong leadership, boundless energy and community support, encouragement of innovation and change, access to broad-based expertise and financial resources, and a commitment to clear achievable goals.

The financial viability of farm groups has been thus far derived largely from the support of the Grains Research and Development Corporation (GRDC), which has been the major investor since their inception. The prospect of their becoming economically self sufficient in the future is not high unless radical changes occur in the work undertaken and interests pursued.

Probably the greatest impact of farm groups has been to focus the efforts of researchers, industry and farmers in one direction, which has led to exchange of ideas, co-operation in solving problems and effective dissemination of new information and innovations.

Prabhu Pingali

Rapid economic and income growth and urbanization are leading to a dramatic shift of Asian diets away from staples and increasingly towards livestock and dairy products, vegetables and fruit, and fats and oils. This trend is reinforced by globalization leading to a convergence of world urban diets: one factor is the spread of supermarkets and acceptance of fast and convenience foods. Rice consumption per capita is falling while that of wheat products and high protein and energy foods, often of temperate origin, is increasing. Implications for Asian agriculture are substantial. Traditional rice-based systems will face pressure to move towards more diversified and commercialized production systems. The prospects for small farmers to benefit from these opportunities are discussed in the light of risk, land suitability and tenure, irrigation infrastructure, and labour constraints. Appropriate investments in crop research and policy reform, which can alleviate these barriers, are also discussed.

Kazutoshi Okuno

Rice is the staple food for most Asians. Breeding efforts at the national and international levels have resulted in high-yielding varieties with resistance/tolerance to biotic and abiotic constraints. Consequently Asia has enjoyed rice self-sufficiency in recent years. Now in some countries over-production of rice has occurred. For instance, in 1962 Japan had a per capita rice consumption of 118.3 kg and then this rapidly declined to about 60 kg in 2003. Imbalances between production and consumption in rice and other crops have promoted a paradigm shift of breeding objectives oriented from producers to consumers. Germplasm enhancement (pre-breeding) and breeding strategies now focus on a broad range of crop and food qualities, which are closely associated with industrial and processing properties and human health and nutrition. In particular, physiological functions of chemical compounds involved in crop products are being studied as a part of breeding programs. Diverse plant genetic resources and advances in plant genome research have contributed to successful breeding strategies to improve and manage crop and food quality. Recent progress in germplasm enhancement and breeding strategies for quality improvement of rice, wheat, soybean and sweet potato in Japan is discussed.

Neil Clark1 and Felicity Harrop2

This paper focuses on changes in production and farming demographics in Australia, it also provides some future trends. Australian farmers are recognised as the most efficient in the world. This is driven by having to farm oceans away from our markets, in an environment of fragile soils and an unforgiving climate. With relatively little farm support we have to be good at what we do to survive and grow. The area of land in Australia devoted to cropping reached new heights in 2001 at 24.5 million hectares. There has been an incredible increase in the area cropped during the nineties. This raises questions about our ability to maintain this growth and manage weed resistance and disease, production risk associated with high farm inputs, climate variability and price. Our cropping systems are dominated by cereal growing with increased production fuelled by a huge migration of those who ran mixed crop/livestock farms to grains industry farms. We are about to see this trend reversed. In addition, to remain globally competitive, we will have to transfer from a yield and “paddock” focus to a “whole farm” approach. We will have to embrace key performance indicators across the full range of profit drivers including water use efficiency, farm inputs, machinery, labour and financing costs. To achieve this we will need an expanded public and private extension service. We will need to provide access to better tertiary education, infield training and coaching. We will need to link all consultants and advisors to a nationally recognised accreditation program.

Michael Dunlop1 and Graham Turner2

This paper describes three very different scenarios for the future of agriculture in Australia. Each scenario has a mixture of social, economic and environmental benefits and costs. The scenarios serve to challenge preconceptions about the future and focus attention on long-term sustainability of agriculture. A range of lessons for the future development of Australian agriculture are drawn from the scenarios and discussed.

David Malinda and Rick Darling.

More than a century cultivating at the same depth and at different soil moisture contents has left most southern Australian soils compacted. Compaction reduces yield and economical viability of many farms. The South Australian Research and Development Institute (SARDI) established a long-term conservation tillage trial in 1978 and took us 16 years of tillage research to realise that poor water use efficiency in South Australian red-brown earth was mainly associated with subsoil problems. We also found out that the use of no-till without first removing compaction would take more than 15 years to satisfactorily repair compacted subsoil. In 1997, equipped with the knowledge of our long-term research results, we set up a field experiment next to the long-term trial to develop a new tillage regime to test the benefits of varying tillage depths to ameliorate compaction and increase the depth of soil exploitable by plant roots with the aim of increasing yield and yield quality. It took 6 years to develop such a tillage system capable of removing subsoil compaction and sustaining yield. This tillage system is simply called “Tillage Rotation” (TR) or progressive tillage. The TR system took only 4 years to reduce BD from 1.9 t/m3 to 1.34 t/m3 and with consistent economic returns for each year. The project produced further questions on the technology developed. Due to these emerging questions, the TR concept, developed with one type of seeding point was then tested using six other points in order to establish their effectiveness in removing compaction and increasing yield. Trials were set up at different sites with different soils. The experimental technique was also tested in commercial paddocks. The results show that TR has the potential to increase yield and yield quality if the soil has no severe chemical constraints. However, the magnitude of yield increase is dependent on both soil type and seeding points used.

K.H.M. Siddique1, K.L. Regan1,2 and M.J. Baker1,2

In recent years, ascochyta blight has caused widespread yield losses in chickpea in Australia. The Australian chickpea industry is largely based on desi chickpeas. However there is the potential to increase the area of production of kabuli chickpea up to 200,000 ha in Australia with the availability of disease resistant varieties. Kabuli chickpea crossbred lines and commercial varieties from ICARDA (Syria), AARI (Turkey) and Australia were screened for resistance to ascochyta blight and agronomic traits in Turkey during 1998 and 2001. More than 2000 breeding lines were screened and 335 superior lines were selected and introduced to Australia. Further agronomic and seed quality evaluation, disease screening and seed production were undertaken in Australia to fast track one or more of the, superior ascochyta resistant kabuli chickpea lines for release. It is anticipated that the first variety from this project will be commercially released in 2004-05.

Michael Robertson1, Don Gaydon1, Roy Latta2, Mark Peoples3 and Antony Swan3

Lucerne/crop companion cropping, whereby crops are direct drilled into an existing perennial pasture such as lucerne, is one way in which the out-of-season water use benefits of a perennial can be retained during the cropping phase. The risks and benefits associated with this new farming system need to be better defined via experimentation and simulation. There have been no previous tests of the ability of APSIM to simulate competition between a perennial and an annual crop. This paper reports the testing of APSIM against field measurements of companion farming systems made at Katanning, WA and Grogan, NSW. Long-term simulations are used to place experimental results into an historical perspective.

Colin Creighton1, Wayne Meyer1 and Shahbaz Khan2

Progress towards sustainability in irrigation for Australia is substantial. The prognosis for further improvement is extremely good, given the close link between science and practice and the widespread commitment to continuous improvement of public policy. This builds on the industry track record of rapid response through innovative science-based farm practices. This paper summarises the Australian irrigation industry, outlines how sustainability extends well beyond the farm and farmer control and concludes with some speculation on Australian irrigation futures as the irrigation industry meets the dual challenges of sustainability and productivity.

Kirsten Verburg, Warren J. Bond and Chris J. Smith

In southern Australia a fallow period provides an opportunity to store water for the subsequent crop. Experimental data are presented that show that fallow management, in particular that of weeds and residue cover, not only affects the amount of water stored or lost during the summer, but also has an effect on the loss of water past the root zone during the subsequent growing season. Model simulations capture these effects and a scenario analysis indicates that retaining residues past sowing increases the risk of deep water loss relatively rapidly. This suggests that managing weeds and residues according to seasonal conditions has the potential to balance the agronomic benefits and environmental impacts of water storage.

Mark Howden1 and Roger N. Jones2

We describe a systematic risk assessment of the combined effects of possible increases in atmospheric carbon dioxide concentrations and associated temperature increases and rainfall changes on the Australian wheat industry for the year 2070. The likely impacts of these three factors varied markedly among regions, with those in Western Australia having a high likelihood of significant yield reductions, but those in north-eastern Australia having a high likelihood of moderate increases in yield but also a small probability of substantial yield reductions. Nationally, whilst median yields are little changed (without adaptation) there is a significant risk to the industry as increases in crop value are limited (to about 10% or $0.4B p.a.) but potential losses are large (about 50% or $2B p.a.). Adaptation strategies of changing planting dates and varieties could be highly effective by offsetting the negative impacts of global change and enhancing positive aspects. The median benefit of these adaptations was about $225M p.a. but with a range of $100M to over $500M p.a. Identifying further adaptation strategies and building the capacity in the farming community to implement them will be a key pathway to deal with uncertain climate and atmospheric changes in the future.

Kristy B. Hobson1,2, Roger D. Armstrong1, M. Nicolas2 , David J. Connor2 and Michael A. Materne1

Soils with high concentrations of boron (B) were shown to be prevalent in the north and central Wimmera and southern Mallee region of Victoria. Pulses are generally considered more sensitive than cereals to abiotic stresses, including B toxicity, and the most viable approach is to develop B tolerant crop cultivars. Current Australian cultivars were found to be intolerant of high concentrations of soil B. B tolerance was, however, identified in lentil germplasm and subsequent research revealed that seedling tolerance persisted through to maturity and resulted in yield benefits. Under B toxicity, net photosynthesis is reduced as a result of a reduction in green leaf area, rather than by a decrease in photosynthetic rate of the remaining green leaf area. The incorporation of the boron tolerant genotypes identified in this study into backcrossing programs will allow breeders to produce cultivars that will expand lentil production areas.

Peter Thorburn, Heidi L. Horan and Jody S. Biggs

Sugarcane crop residues, known as trash, contain substantial amounts of nitrogen (N) and other nutrients. The availability of N in trash left in the field following harvest is complicated because most of the N cycles through the soil organic matter. To gain insights into the impacts of trash management on sugarcane production and the long-term fate of N contained in trash, a simulation study was conducted with the APSIM-Sugarcane cropping systems model. Long-term simulations were conducted for two different soil types combined with climatic data from three locations. Trash management and N fertiliser application rates were varied in the simulations. The simulation study showed that sugarcane yields have potential to respond positively to retention of trash in the field over the range of climates considered. However, achieving these higher potential yields will require that N applications not be reduced following the switch from trash burning to trash retention. This study also illustrates the potential negative, short-term impact of trash retention on sugarcane yields due to the immobilisation of N by the decomposing trash. The simulations also indicate that average environmental losses of N are likely to be greater where trash is retained and particular care should be exercised to avoid over-application of N in green cane trash blanket systems systems.

Michael A. Ewing1,2 and Felicity Flugge1

Integrated crop-livestock farming systems continue to dominate broadacre agriculture in southern and eastern Australia. A shift in the last decade to a more diversified production system based around an increased proportion of cropping is evidence of the flexibility of the farming system to respond to innovation and to economic signals. The nature and extent of changes has been regionally variable, depending on the current production potential of crop and pasture elements and suitability of emerging technologies.

The physical and financial stability of crop-livestock production systems arises from the complementary interactions between components of the production systems. This produces a whole-farm financial outcome that is buffered against economic fluctuations with similar profits generally achieved for a range of physical strategies. This allows producers to implement measured responses to a trend, making changes only when they are convinced the trend will persist.

Resurgence of livestock prices, combined with difficulties with weed management in all crop systems and the need to deal with sustainability challenges such as salinity and acidity increase the likelihood that pasture and livestock components of mixed systems will retain their importance. Long term financial viability of crop-livestock systems will depend on steady increases in productivity, through innovation in all components of the system.

Anthony Whitbread1 and Bob Clem2

Soil fertility decline in sub-tropical mixed farming areas may be arrested by legume based pasture leys. Ley pastures need to provide adequate returns to farmers from livestock production as well as improve soil fertility for subsequent cropping cycles. This study at Brian Pastures Research Station in southeast Queensland, Australia compared forage and animal production from eight tropical pastures. Lablab (Lablab purpureus) produced the most liveweight gain/ha with growth rates from 0.60 to 0.86 kg/head/day. Growth rates on other legumes varied from 0.39 to 0.79 kg/head/day and there were some differences in the duration of grazing. Liveweight gain/ha was similar for Clitoria ternatea and Macroptilium bracteatum and was higher than for Vigna trilobata, followed by Macrotyloma daltonii. On grass and grass-legume pastures, growth rates ranged from 0.39 to 0.71 kg/head/day with legume-based pasture producing gains of 30 to 70 kg/ha more than the grass only pasture over 5 years. The response of grain sorghum to the various periods of annual legumes and grasses were investigated using a no-till system. Two to four years of the tropical legumes M. daltonii and V. trilobata and lablab resulted in soil nitrate N (0-90 cm depth) ranging from 36 to 102 kg/ha compared with 5 to 11 kg/ha after grass only pastures. Grain sorghum produced in excess of 3000 kg/ha in the 4 crops following the removal of the legume pastures.

Anyou Liu1 and Clinton Revell2

Several annual pasture legumes were tested in five field trials in the southwest of Western Australia during 2003 to compare their potential as fodder crops (e.g. hay and silage). Species varied considerably in their potential as fodder crops and a strong interaction between species and sites was evident. However, some species, such as French serradella and crimson clover, showed wider adaptation than others. Balansa clover and Persian clover appeared to be exceptionally well adapted to the high rainfall and waterlogging prone areas. Some of the species including arrowleaf clover, crimson clover and serradella appeared to have potential for use in a mixture with a forage cereal crop. Some of these issues will be further examined as the project continues.

Andrew D. Moore, Libby Salmon and Hugh Dove

An exploratory simulation analysis is presented of four management options for using pasture, dual-purpose winter wheats and forage brassica in a lamb production system at two sites in south-eastern Australia (Canberra and Wagga Wagga). The GRAZPLAN process models were combined with a rule-based representation of management to produce a simulation model of the complex interactions within mixed cropping/grazing systems. At the Canberra site, allocation of 20% of land area to a winter wheat-fallow-pasture rotation resulted in an increase of $23/ha in whole-farm gross margin compared with a pasture-only system. The response at the Wagga Wagga site was smaller ($12/ha). At both sites, inclusion of a forage brassica in the rotation gave a further increase of about $30/ha in whole-farm gross margins but this was accompanied by increased year-to-year variability in gross margin, especially at Wagga Wagga. The inclusion of forage brassica also reduced deep drainage of water compared with a pasture-wheat system, though differences were small. The simulations suggest the need to explore the use of other livestock enterprises for utilising winter wheat forage, and have also highlighted areas in need of further research.

Ramakrishnan M. Nair1, Jake Howie1, Ross Ballard1, Rachel Hutton1, Nigel Charman1 and Chris Preston2

Strand medic (Medicago littoralis) provides the principle source of fixed nitrogen (N) in many neutral to alkaline sandy-loam soils, such as those that dominate the Eyre Peninsula region of South Australia. So well adapted is the species in these environments that it is often grown in near monoculture conditions in the ley phase of these farming systems. This paper reports the efforts made in the genetic improvement of strand medic for traits including herbicide tolerance, improved N2-fixation, tolerance to root-lesion nematode and resistance to powdery mildew disease. A sulfonylurea herbicide (SU) tolerant line (coded FEH-1) developed by EMS mutagenesis of the strand medic variety Herald, offers significant promise, especially for use in low rainfall regions with alkaline soils, where the breakdown of SU residues is reduced. The herbicide tolerance trait in FEH-1 appears to be controlled by a single dominant gene. Plant selections have also been made for ‘symbiotic promiscuity’ that will enable strand medic to form a greater proportion of optimal N2-fixing symbioses with the naturalised rhizobia that proliferate in most soils where the plant is grown. Selection and breeding for tolerance to the root-lesion nematode (Pratylenchus neglectus) and resistance to powdery mildew (Erysiphe trifolii) are also being undertaken in order to improve productivity.

Ann Hamblin

Official policy promotes the view that Australia must invest strongly in strategic and applied sciences to maintain competitive edge within an increasingly global economy, where knowledge creation and use are seen as the key to future economic prosperity. Nevertheless Australia’s small economy and research capacity mean that at best, Australia can never be more than a ‘fast follower’ in creating or acquiring new knowledge. This, plus the fact that over 70% of GDP is generated in the service sector, may explain why there is a credibility gap between rhetoric and actual proportion of government or private sector expenditure in R&D. Agricultural science is better supported by combined government and industry funding than most other sectors, and there is thus an expectation that this should lead to a more efficient and competitive agriculture sector than with those that are more reliant on government funding alone. While research supporting the supply side of agriculture performs well, those areas on the demand-side of the value chain are less well supported, and much Australian agricultural R&D remains conventional and emeshed in traditional organizational loyalties.

Doug Abrecht1, James Fisher2 and Mario D'Antuono2

We propose the concept of a “yield space” that represents the response of crop production to agronomic factors. The yield space can be thought of as a multidimensional polygon, with size defined by the magnitude of yield and shape determined by the response to agronomic treatments. The yield space concept was illustrated using simulated yield data for wheat at Merredin, Western Australia. Analysis of the size and shape of the yield space showed that the potential for managers to influence yield through agronomic practices and the factors of greatest importance varied from year to year. This concept is being explored further as a means of developing agronomic understanding and advice for dealing with seasonal variability.

Ingrid Christiansen1, Victor Callan2, Guy Roth3 and Michael Bange4

Managing a cotton crop is knowledge intensive and so effective knowledge management strategies are required for the crop to perform well. Recent research shows that cotton growers and consultants are experiential learners who actively seek information and experiences to develop their knowledge. Strategies are needed to aid experiential learning for assisting substantial changes in issues that cannot be easily “learnt by doing”. Knowledge services are moving towards partnerships between growers, consultants, research and extension. This paper describes the situation, challenges and opportunities that exist for improved knowledge systems in the cotton industry.

Grower groups
Extension staff

Evan William Ryan1, Lisa Day2, Margaret Evans3 and A Gartmann4

Crop scientists aim to facilitate improved crop management and practice change on farm. Practice change relates to how farmers alter their current practices to improve their economic, environmental and social sustainability within their industry. To achieve this, venues are needed where crop scientists, advisers, industry and farmers can interact. In Victoria, a key annual opportunity for this interaction is the BCG (Birchip Cropping Group) Grains Research Expo. This Expo is an opportunity for farmers to interact with researchers and industry to discuss ideas and innovative solutions to farmers’ issues. It is a forum for discussion and learning for both those presenting information and those attending. Planning, execution and interpretation of the Expo evaluation were undertaken jointly by the Department of Primary Industries (DPI) and the BCG to provide the right mixture of skills and resources. The evaluation consisted of a questionnaire and semi-structured interviews.

One hundred and eighty people paid to attend the Expo on the 10th of July 2003. Ninety-one questionnaires were returned and 14 semi-structured interviews were completed. Fifty seven percent of respondents were farmers - the main target audience. Farmer respondents valued discussion sessions (92%), hearing new ideas (86%), receiving up-to-date and relevant information (75%) and social interaction (75%). Respondents generally considered the Expo was well run and interesting, but a number of them had suggestions for improvement. The Expo provided a good opportunity for agricultural researchers to share their knowledge with and receive feedback from industry. A challenge for the future is to assess how effective the Expo has been in facilitating knowledge sharing between agricultural researchers and farmers and whether it has brought industry issues to the attention of agricultural researchers.

Frank H. D'Emden and Rick S. Llewellyn

Adoption of no-till sowing systems has increased rapidly in many Australian grain growing regions over the past decade. The extent of herbicide resistant weed populations has also increased over the same period. A survey of growers in the South and Western Australian cropping regions was conducted to characterise no-till adoption and determine growers’ expectations of the long-term effects of no-till systems. Trends in sowing system use are determined, as are growers’ perceptions of the long term effects of no-till on herbicide costs, herbicide resistance, glyphosate resistance and soil erosion. The results suggest a rapid expansion in the adoption of no-till sowing in South Australian cropping regions over the next five years, although growers expect increased herbicide costs in no-till systems and an increased risk of herbicide resistance. Herbicide resistance and/or weed control issues are the main reason given for reducing no-till use. A major research and extension challenge is the development of sustainable weed management strategies that are compatible with no-till systems.

Michael Dunlop1 and Graham Turner2

This paper describes three very different scenarios for the future of agriculture in Australia. Each scenario has a mixture of social, economic and environmental benefits and costs. The scenarios serve to challenge preconceptions about the future and focus attention on long-term sustainability of agriculture. A range of lessons for the future development of Australian agriculture are drawn from the scenarios and discussed.

James Walcott

Crop diversity is one indicator of the sustainability of cropping systems. An analysis of cropping intensity and crop diversity used concorded data from the Australian Bureau of Statistics to provide trends and spatial patterns over the Australian wheatbelt. Over the last 15 years cropping intensity and crop diversity generally increased, often in the same localities, but vary widely in spatial pattern and trend. Areas of concern for sustainability are those that have high cropping intensity and low crop diversity.

Wenjun Zhang, Yanhong Qi and Yali Liu

Rice feeds nearly 50% of the global population. Land expansion, environmental changes, and food security problem resulting from rice production influence the changes of global environment. With the estimated growth rates of 748,240 and 589,630 ha/yr, the rough rice areas would reach 172,848,000 ha and 152,105,000 ha for the world and Asia, respectively, by 2025. Rice production by 2025 would reach 845,099,000 t and 771,809,000 t with growth rates 9,790,950 and 8,926,580 t/yr for the world and Asia, respectively. Annual growth rate of global rice herbicide sale ($59.57 millions/yr) exceeds insecticide ($47.29 millions/yr) and fungicide ($41.43 millions/yr) sales. Global sales of herbicide, insecticide, and fungicide would reach 3,086, 2,764, and 2,175 millions of US dollars per year, respectively, by 2025. Intensification of rice production would cause unprecedented impacts. Advances in rice science and policy decisions are needed to manage the rice production and its biological and environmental impacts.

P.R. Kumar1 and S.K. Jha2

India is amongst the largest producer and consumer of vegetable oils. In the face of huge imports of edible oils by mid 1980s, the government made a concerted effort to make oilseeds more attractive to growers, through a combination of mission mode programmes. High prices of oils caused expansion of processing capacity and increase in oilseeds production by over 70 % in six years. India became almost self-sufficient in edible oil (up to 98%) and the imports of edible oil was reduced to 0.1 million tones in1992-93 from 1.5 million tones in 1986-87. Removal of all quantitative restrictions (QR) on imports and regulation through tariff in 1994 under WTO rules fundamentally changed the import regime of India’s edible oil and from 0.1 million tonnes in 1992-93 the country’s import has reached to 4.3 million tonnes in 2002-03. The corresponding export earnings however, have been much lower due to depressed prices in international market (due to quality consideration). There has been a shift away from oilseed cultivation in India due to the decline in relative profitability. The country’s demand for edible oils is expected to rise more than double from the current level in the next 12 years. India’s future self sufficiency under WTO is examined. Factors discussed include international oil prices and consequent impact on domestic availability and demand, importing of oilseeds instead of oil for local crushing, fiscal incentives for motivating the farmer to shift to oilseed cultivation; ICAR- led research initiatives for increasing the productivity of oilseeds, and agricultural reforms and modernization of oilseed industry to reach world standards.

J. Kumar1, N. Dhiman2, S.S. Yadav1, Jens Berger3, Neil C. Turner3,4 and Dhirendra Singh2

This study describes the effect of moisture stress on various agronomic traits in chickpea. In the present investigation, 50 genotypes representing four major classes of chickpea, viz. desi medium seeded, desi bold seeded, kabuli medium seeded and kabuli bold seeded types, were studied under rainfed and irrigated environments. The response of kabuli types to irrigation, in terms of pod number, seed and biological yield was far greater than in desi chickpeas. This study clearly revealed that moisture stress has differential effects on desi and kabuli chickpeas. Desi types appear to be better adapted to rainfed conditions, while kabulis are much more responsive to higher inputs. Mixing of the two gene pools may broaden the adaptability of both types of chickpea.

A.A. EL-Sayed1, R.A. Abo El-Enein1 , A.S. El-Gamal1, A.A. El-Sherbiny1, M.A. El-Moselhy1, M.A. Megahed1, A.A. El-Hag1, A.M.O. El-Bawab1, M.T. Abdelhamid1, K.A. Amer1, R.A. Rizk2, S. Grando3, M.A. Said1, H.A. Ashmawy1, S.I. Abaas1, M.Z. Shendy1 and M.I El-Hawary1

Giza 130 and Giza 131 are two six rowed spring type hull-less barley (Hordeum vulgare L.) varieties identified by the Egyptian/French Hull-Less Barley Project, Field Crops Research Institute at Giza, Egypt and released in October, 2001. They were selected for rainfed areas of Egypt as drought tolerant varieties to be used for the dual purposes of food and feed. Giza 130 has been selected from the crosses “Comp.cross” 229//Bco.Mr./DZ02391/3/Deir Alla 106 using the bulk method. Giza 131 from the cross CM67-B/CENTENO//CAM-B/3/ROW906.73/4/GLORIA-BAR/COME-B/5/FALCON-BAR/6/LINO using the pedigree method. The two varieties have been evaluated for four seasons in different environments. They outyielded the national check (hulled variety Giza 126) for both grain yield and straw yield. Both new varieties showed moderate resistance to leaf rust (Puccinia hordei) and powdery mildew (Erysiphe graminis hordei), and resistance to net blotch (Drechslera teres)and stripe disease (D.graminea).

O.P. Yadav1, Fran R. Bidinger2, C.T. Hash2 and Rachid Serraj2

New pearl millet (Pennisetum glaucum) cultivars for arid zone environments need to combine adaptation to drought with increased yield potential. We describe here results of three approaches viz., utilization of existing variation in landraces, genetic diversification of landraces and exploitation of heterosis in landrace-based hybrids, used to achieve this objective. Results demonstrate good exploitable differences among landraces for their response to both drought stressed and higher productivity environments. In the diversification study, the relative mean performance of landraces and elite composites showed a distinct crossover between drought and favourable crop seasons. Crosses between these two groups of material showed significant and positive heterosis for grain yield with magnitude of up to 33% over landrace parents. A few crosses showed consistent improvement over both landraces and elite parents. Exploitation of heterosis in landrace-based hybrids also proved to be a rapid and effective way to improve the production, while retaining critical adaptation of landraces to the arid zone environments. Development and performance of a commercial pearl millet variety CZP 9802, through selection within the landraces, are described.

Goodarz Najafian1, Akbar Ghandi2 and Hassan Abdi3

Considering the importance of seasonal drought and water shortages for irrigation, a trial aimed at identifying wheat varieties tolerant to terminal drought was performed. In this study 51 lines and varieties of bread wheat along with 3 check cultivars (Marvdasht, Cross of Alborz and Azar-2) were planted under late season water stress at three locations; Kermanshah, Isfahan and Varamin. These 51 entries were divided to 3 sets, which along with the above 3 checks included 20 genotypes in each group. These 3 experiments (WS1-WS3) were planted in a Randomised Complete Block (RCB) design with 4 replications. These trials depended on rainfall apart from some supplementary irrigation applied following the cessation of rainfall in May 2003. Every experiment was therefore exposed to water stress from the heading stage onward. Combined ANOVA showed significant effects for location, genotypes and G×E interaction, in all 3 experiments. Comparison of genotype means showed five of the entries had grain yields in excess of 6 t/ha in the WS1 set. The check varieties Marvdasht, Cross of Alborz and Azar-2, were significantly lower yielding than most of the test lines, and ranked 18, 19 and 20, respectively. In the case of the WS2 trial, two entries had grain yield above 6 t/ha, while in the WS3 trial five entries were the best performers for yield. A subset of entries from each experiment (7 genotypes from WS1; 5 entries from WS2; and 3 entries from WS3 ) were selected for further evaluation trials. While Marvdasht can yield up to 9 t/ha under full irrigation, it will yield < 5 t/ha when irrigation water is scarce. Accordingly, we suggest the growing of the more drought tolerant lines we have identified in this study could significantly reduce this gap.

M.S. Basu1 and P. C. Nautiyal2

Multi-location trials (MLT`s) were conducted to screen groundnut (Arachis hypogaea L.) germplasm for high water use efficiency (WUE). Specific leaf area (SLA) a surrogate of 13C/12C (Δ) was used to screen the germplasm for WUE. The multi-location data was analysed based on the model i.e. Pod yield = T x TE x HI, where T= transpiration, TE = transpiration efficiency, and HI = harvest index. The combined analysis of the multi-location trials demonstrated that high pod yield under deficit-water stress was associated with a combination of traits such as T, WUE, and HI, indicating these traits are not physiologically linked. A combined analysis of the MLT`s has indicated that G x E interactions for SLA/WUE traits is moderately high. Some genotypes, however; were stable over a range of environments. Physiological studies of the low and high SLA genotypes showed that low SLA types are capable of retaining more water (RWC) in the leaf under water-deficit situations than the high SLA genotypes. Genotypes found with high WUE are used in a trait based breeding programme as donor parents.

Parminder Virk1, Sant S. Virmani2, V. Lopena and R. Cabangon

Irrigated transplanted rice is a prolific user of water. According to one estimate it takes up to 3,000 liters of water to produce 1 kg of rice. However, due to looming water crisis we have to look for ways such that we increase water productivity in rice. We envisage that even a small savings of water due to a change in the current practices will translate into a significant bearing on reducing the total consumption of fresh water for rice farming.

Therefore, we undertook this study to identify rice varieties, both inbreds and hybrids, suitable for alternate wetting-and-drying (AWD) irrigation during the vegetative phase, saving around 17% of water, without any significant reduction in yield. In fact, we have observed a great deal of genetic variation for tolerance to water stress during the vegetative phase and have identified promising inbred and hybrid genotypes for further study to elucidate the underlying mechanisms. Our data suggest that 18 of the 31 inbreds bred for irrigated ecology did not experience any significant decline in yield due to AWD. Similarly, there was no significant yield decline in 3 of 7 hybrids tested. We have identified three hybrids and six inbreds which are water-efficient and produced 5.5 t/ha or more under AWD conditions with no significant yield loss as compared to conventional irrigated conditions.

P.S. Basu, Masood Ali and S.K. Chaturvedi

Six chickpea genotypes were grown under two distinct soil moisture (rainfed and irrigated) conditions. The relative water content (RWC) of leaves of these genotypes at podding stage decreased to mean value of about 55.7 % in rainfed and 76.5% in irrigated crop. Leaf growth rate and photochemical efficiency (quantum yield,Fv/Fm) of leaves pre-adapted to dark or light did not decrease significantly even RWC declined to about 55% due to water stress. The influence of water stress on steady state minimum fluorescence Fs at various irradiances was also non-significant. This suggested that non-stomatal components associated with photosynthesis were little affected by drought and high irradiance. None of the genotypes showed any significant decrease in the leaf elongation rate under drought. However , the effect of drought on other attributes such as total leaf and secondary branch numbers was prominent which invariably decreased under rainfed. The leaf number had significant association (r = 0.65**) with grain yield. The results indicated that photochemical efficiency could be relatively stable and less affected by drought in chickpea. This stability of photosynthetic components could be attributed by maintenance of positive leaf turgor under stress as a result of osmotic adjustment.

Gerald J. Seiler

The narrow genetic base of cultivated sunflower has been broadened by the infusion of genes from wild species, which continue to be a valuable source of desirable agronomic traits. Helianthus anomalus Blake is a wild annual species adapted to sandy dunes of the southwest USA. Helianthus deserticola Heiser is another wild annual species adapted to high desert areas of the same region. The adaptation of these species to harsh habitats makes them potential candidates for improving stress tolerance in the cultivated sunflower crop. Since seed of these species was not available in the USDA-ARS Sunflower Germplasm Collection, an exploration was undertaken in September, 2000 to collect populations for future research. Due to the extremely dry weather in 2000, only two populations of H. anomalus and one H. deserticola were collected. These collections are the first populations of these species added to the sunflower collection in over 20 years. Future research calls for introgression of the wild species into cultivated sunflower and evaluating the progeny for ecophysiological characteristics.

Zhengbin Zhang1, Ping Xu1 and Jizeng Jia2

Crop high water use efficiency (WUE) breeding will play an important role in the future. Much genetic diversity has been found in crop WUE especial in wheat, reviewed in this paper. Different WUE genes have been located by wheat aneuploids and detected by molecular markers in other crops; one WUE related gene has been cloned, and some genes associated with drought resistance (HVA1) and high photosynthesis (Asr1) transferred in wheat and maize. We believe that more genes controlling WUE could be precisely mapped and cloned, and more genes associated with drought resistance and photosynthesis and yield could be transferred into crops for improving WUE and yield in favourable and unfavourable environments.

Pervez H. Zaidi1, Ganesan Srinivasan2 and N.N. Singh1

Inadequate water is a major cause of crop yield losses particularly in the tropics. Uncertainties in weather due to global warming are expected to increase the occurrence of inadequate water availability. At CIMMYT, various approaches to improved drought tolerance in maize have been explored. About three decades of work on drought tolerance in maize has resulted in improved source populations and open-pollinated and hybrid products that perform well under drought stress. Results from recent studies show the usefulness of this germplasm under severe drought stress conditions. Furthermore, the improvement for mid-season drought tolerance appears to impart tolerance to various other stresses, such as low-N fertility. Under ICAR-CIMMYT collaborative program, a large amount of maize germplasm, including inbred lines from CIMMYT and the national program, were screened for excess moisture/waterlogging tolerance in India. Many promising tolerant lines were identified and further improved for developing excess moisture tolerant cultivars for waterlogging prone areas in India. The secondary traits such as anthesis-silking-interval (ASI), early and increased brace root development and high root porosity have been identified the traits associated with excess moisture tolerance in maize. Due to fairly high expression of the stress-adaptive traits under managed drought or excessive moisture stress conditions, they can be carefully selected and further improved. Since the maize is frequently exposed to both the extremes of water availability in many monsoonal areas in Asia, our major focus is to develop robust germplasm with improved performance across the regimes of water availability.

Rachid Serraj1, C.T. Hash1, Rattan S. Yadav2 and Fran R. Bidinger1

Pearl millet [Pennisetum glaucum (L.) R. Br.] is the staple cereal of the hottest, driest areas of the tropics where drought stress is a regular occurrence, making stress tolerance an essential attribute of new cultivars. Current breeding research has mapped several quantitative trait loci (QTL) for grain and stover yield under terminal drought stress conditions, and has evaluated these as possible selection criteria for improved stress tolerance. Initial evaluations, which were based on hybrids made with topcross pollinators composed of lines selected directly from the mapping population, indicated an advantage to the QTL-based topcross hybrids under terminal stress, which seemed to be related to particular plant phenotype which was similar to that of the tolerant parent of the mapping population. Subsequent evaluations were based on hybrids of NILs of the susceptible parent of the mapping population, which were bred by marker-assisted backcrossing of the putative drought tolerant QTL into these lines. Several of these lines had a significant positive general combining ability for grain yield under terminal stress and out yielded the hybrids made on the original recurrent parent in both unrelieved terminal tress and in gradient stress evaluations.

James E. Specht1

The response of soybean biomass and seed yield to variable seasonal water is linear. Discerning the genetic basis of water use efficiency on a seed yield basis (i.e., WUEy, but termed yield beta in this report) has long been a key research objective. Yield beta data have been collected on five RIL mapping populations of 250-300 members each, but RIL marker-genotyping is incomplete in three. A few yield beta QTLs have been detected to date, but their map positions have coincided with QTLs governing genotypic mean yield, and/or with genes governing plant growth habit and maturity. A carbon isotopic composition (δ13C) estimation of transpiration efficiency (TE), conducted in two populations, identified a strong δ13C QTL, but its map position was coincident with that of the growth habit gene. In all five populations, the yield of a genotype in a water-abundant environment was highly correlated with its yield in a water-scarce environment, which is expected when genotypic yield beta and mean yield are governed in a coupled manner by either linked or pleiotropic QTLs, as seems to be the case. If so, then genetic yield advances in water-abundant environments are expected to generate concomitant yield advances in water-scarce environments (though to a lesser degree). Thus, genetic yield improvement for rainfall-variable soybean production areas (i.e., Midwestern USA), where extremes in water-abundance and water-scarcity are equally probable, is probably best attained by elevating the slope of the yield-to-water response (i.e., WUEy), while concurrently limiting the potential for such elevation to cause a downward slippage of the low end of the response slope.

John T. Christopher1, Andrew K. Borrell2, A.M. Manschadi3, Graeme Hammer3 and Scott Chapman4

A novel strategy linking physiology with plant breeding, molecular biology and computer simulation modelling is outlined here which aims to enhance selection of high yielding wheats with superior performance under conditions of water scarcity for the northern, subtropical, winter cereals region of Australia. In previous research, a source of high yield and performance under dry conditions for the target region was identified in a drought resistant parent. A large population of fixed lines for molecular genetic studies has been developed using the drought resistant line and widely grown current Australian variety. A preliminary study comparing the parent varieties was conducted in the winter of 2003. The two varieties were similar in many aspects of phenology, morphology and physiology. However, several important traits were identified that likely contribute to higher grain mass and yield of the drought resistant parent, including differences in the number and dry mass of tillers and spikes during development and the ability of drought resistant line to retain green leaves longer during grain filling.

Walter Zegada-Lizarazu and Morio Iijima

Deep root penetration may help millet species to exploit soil water more effectively and therefore overcome drought stress. The aim of this study was to evaluate interspecific differences in water uptake abilities by the deep roots of millet species, which can penetrate a hard pan layer. Six millet species were grown in tubes, which consisted of three parts. Top loose soil, middle hard pan layer, and bottom loose wet soil. A vaseline layer prevented water movement between the hard pan and bottom layer. Soil moisture was adjusted to well-watered and drought conditions in the top and hard pan layer, while the bottom layer was always kept wet. Drought imposed in the top two layers at the end of the heading stage reduced the photosynthetic rates in common millet and foxtail millet, but did not in the other four species (pearl millet, barnyard millet, finger millet, Job’s tears). The root penetration in the four species was not decreased by the hard pan layer, and their root water extraction efficiency in deep roots was increased significantly by drought. Although roots in common millet were able to effectively penetrate the hard pan layer, root water extraction efficiency in deep roots was not significantly increased. In contrast, roots in foxtail millet could not effectively penetrate the hard pan layer. Interspecific differences in both the root penetration ability through the hard pan layer and the deep root water uptake efficiency were clearly demonstrated indicating these traits offer effective drought stress avoidance mechanisms.

Alan Cruickshank1, Arnaud Dowkiw12, Graeme Wright1, NageswaraRao C. Rachaputi1 and Shyam Nigam3

The paper presents results from a case study on genetic enhancement of drought resistance in peanut using combined physiological and breeding methods. Peanut genotypes with high levels of components of a resource capture model, transpiration (T), transpiration efficiency (TE) and harvest index (HI), were used as parents in a hybridisation program. F2-derived families of peanuts from 4 crosses were subjected to trait-based among family index selection in the F3 and F4. In order to calculate the selection index, estimates of harvest index, transpiration efficiency and transpiration were obtained. Heritability estimates for these traits were estimated using 3 different bases i.e. broad-sense heritability on an F3 row basis, broad-sense heritability on an F4 family mean basis using variance components and standard unit heritability estimates using correlation among generations.

The heritability estimates varied significantly between crosses and traits depending on levels of genetic variation in parents. In some cases the variation seems to be caused by errors in sampling method.

Kernel yield (KY) generally had the best correlations between F3 and F4 (maximum 0.65), HI and TE were intermediate and correlations for T were very poor (one cross in one environment 0.56 the remainder not significant).

Consideration of these differences in heritability and the costs of sampling lead to the proposal that a simpler index based on KY and TE may be a useful compromise for selection of superior drought performance in peanut. Use of an index including TE would prevent selection for decreasing TE when selecting for KY, where there are casual negative associations between TE and the other two components.

R Shrestha1, 2, K.H.M. Siddique1, David W. Turner2 and Neil C. Turner1, 3

Lentil (Lens culinaris M.) is one of the major grain legumes in Nepal whose seed yield is low and unpredictable as it is grown under limited soil moisture conditions during the winter months. However, there may be a potential to increase lentil yields by utilizing germplasm that is adapted to rainfed conditions and residual soil moisture from the preceding crop. Nineteen diverse lentil genotypes and a locally adapted grasspea (Lathyrus sativus) were evaluated for phenology, growth, yield and yield components at a mid-hill site in Nepal during 2001/02. Lentil genotypes showed significant variation in morphology, root characteristics, seed yield, yield components and disease susceptibility, although there was little soil moisture stress in the post-flowering period during the above season.

S.S. Yadav1, J. Kumar1, Neil C. Turner2, F.J. Muehlbauer3, E.J. Knights4, Bob Redden5, David McNeil5 and Jens Berger6

Investigations were undertaken with two major objectives, viz. to explore opportunities for improving adaptation of large-seeded kabuli chickpea for drought-prone environment, and to identify extra-large-seeded kabuli chickpea genotypes for cultivation in dry areas. To develop the segregating populations, three sets of cross combinations were formulated, viz. 1. extra-large-seeded wilt resistant kabuli variety BG 1073 was crossed with extra large-seeded kabuli varieties, 2. variety BG 1073 was crossed with large-seeded varieties, and 3. variety BG 1073 was crossed with medium large seeded kabuli varieties. The segregating populations, viz. F2-F6, were advanced under moisture stress environments in multiple sick-plots. Advanced yield testing was also carried out in rainfed conditions to evaluate the relative performance of the newly developed superior genotypes from 2000 to 2003. The relative seed yield of the new extra-large-seeded genotypes, when compared with the new large-seeded, the medium-seeded genotypes and the extra-large-seeded exotic and local control varieties, showed significant superiority and adaptation under water-limited environments. Under rainfed conditions, the new extra-large-seeded genotypes also showed significant superiority in respect of number of branches, number of pods and biomass production over all the extra large seeded control lines. The findings clearly indicated that the seed yield, along with number of branches, number of pods, and biomass, of new extra large seeded lines increased simultaneously and played a crucial role in the improvement of drought tolerance because these three traits were very poor in the extra-bold-seeded control lines. These three traits may have improved due to new recombinations of the gene pool during the hybridization and selection strategy adopted in the segregating populations. Based on these findings it was concluded that the poor adaptation to drought prone environments of the extra-large-seeded kabuli types could be genetically enhanced if strategic selection of parents and systematic approaches are adopted during hybridization and generation advancement. It was also concluded that agronomic traits such as the number of branches, number of pods, total biomass production and medium-early maturity played a crucial role in the drought stress tolerance in chickpea.

Cristine Hall1 and B.P. Naidu1,2

Fifteen genotypes of lablab (Lablab purpureus L.), including commercial cultivars, cultivated and wild type accessions, and bred lines were evaluated for drought resistance in a controlled environment pot experiment. Drought resistance was not related to whether a genotype is annual or perennial. One of 2 commercial cultivars, 4 of 8 cultivated accessions, 1 of 3 wild accessions and 2 of 2 bred lines were measured as drought resistant after a prolonged period of withholding water. This study demonstrated that there is a high level of variation for drought resistance within the lablab genotypes and that with the extensive germplasm available, genotypes with the desirable characteristic of drought resistance could be selected to enhance forage lablab breeding programs that already focus on high yield and perenniality.

Claude Welcker1, Jean-Marcel Ribaut2, Bertrand Muller1 and François Tardieu1

Several maize lines selected by CIMMYT can maintain growth of reproductive organs under water limited conditions, a key mechanism for grain production under drought. The objective of this work was to test whether these lines also maintain leaf growth under water deficit. Leaf elongation rate of six tropical maize lines, parents of segregating populations contrasting for silk growth maintenance under drought stress, were analysed via response curves to temperature, evaporative demand and soil water deficit controlled in growth chamber and greenhouse experiments. Large differences were observed in the responses of studied lines, with a tendency that lines with a maintained anthesis-silking interval under water deficit also maintained leaf elongation. Relationships between adaptation traits within this material suggest that evaluation of derived recombinant inbred lines might allow testing co-segregation of key adaptive mechanisms to water-limited environments.

Prabawardani Saraswati 1, Mark Johnston2, Ross Coventry1 and Joseph Holtum1

Pot experiments were conducted to screen fifteen sweet potato cultivars for drought tolerance. Two levels of water regimes were applied, control (maintained by regular watering at or close to field capacity) and water stressed plants (saturated then allowed to dry progressively to permanent wilting point). Plant biomass, main stem length, internode diameter, internode length, leaf number and area, and root weight all decreased in response to the water stress. Leaf water potential decreased significantly when water supply was withheld, however leaf water potential was not statistically different among cultivars in both control and water stressed treatments. The cultivar Lole showed more strongly developed drought resistant characters than all the other cultivars.

C. C. Holbrook, B. Z. Guo, D. M. Wilson, and C. K. Kvien.

Peanuts become contaminated with aflatoxins when subjected to prolonged periods of heat and drought stress. The objective of this research was to evaluate the effect of drought tolerance on preharvest aflatoxin contamination (PAC). Two drought-tolerant genotypes (PI 145681 and Tifton 8) and an intolerant genotype (PI 196754) were evaluated in two studies using rain-protected shelters in Tifton, Georgia, USA. Drought and heat stress conditions were imposed for the 40 d preceding harvest. The drought-intolerant genotype had greater preharvest aflatoxin contamination than Florunner, the check cultivar. Both drought-tolerant genotypes had less preharvest aflatoxin contamination than Florunner in these tests. We are using drought-tolerance as an indirect selection technique to develop peanut cultivars that are less susceptible to preharvest aflatoxin contamination This has resulted in late generation breeding lines that have high relative yield and low relative aflatoxin contamination when subjected to late season heat and drought stress.

Jong Gun Won, Jang Soo Choi and Seung Phil Lee

To reduce water requirement and improve water productivity by water-saving irrigation techniques a field study was carried out with three water management treatments: very shallow intermittent irrigation (VSII, 2cm), shallow intermittent irrigation (SII, 4cm) and traditional deep water irrigation (DWI, 10cm) for two years. The total water input was 527, 654 and 777 mm in VSII, SII and DWI, respectively. Rice growth and grain yield in the three treatments were not significantly different. As the water input decreased the water-productivity (the grain yield per unit volume of water) increased. The water use efficiency, (ratio of evapotranspiration to total water input) when compared with DWI increased by 44% in VSII and 26% in SII. In the lodging characteristics, as the irrigation depth decreased the breaking weight and lodging resistance increased and more roots were deeper in the paddy soil. Due to the increase of chalky rice, the percentage of head rice decreased and the content of protein was higher in DWI, suggesting deterioration in the palatability of cooked rice. The water-saving in VSII was 32% and 16% in SII compared to typical deep water irrigation in Korea.

M. Tsubo1, Shu Fukai1, Jayampathi Basnayake1, To Phuc Tuong2, Bas A.M. Bouman2 and Dome Harnpichitvitaya3

Quantifying water losses in paddy fields assists estimation of water availability in rainfed lowland rice ecosystem. There is, however, no definite method for determining the water losses, and little information is available on water balance in different toposequence positions of a sloped rainfed lowland. Therefore, the aim of this work was to quantify percolation and the lateral water flow with special reference to the toposequential variation. Data used for the analysis was collected in Laos and northeast Thailand. Percolation and water tables were measured on a daily basis. The percolator is a steel cylindrical tube with a lid to prevent water loss from evapotranspiration. The water table meter is a short PVC tube for determination of perched water table and a long PVC tube for groundwater table, and the side is perforated with 5-mm diameter holes at 20-mm distance. Percolation rate was determined using linear regression analysis of cumulative percolation. Assuming that the total amount of evaporation and transpiration was equivalent to potential evapotranspiration, the lateral water flow was estimated using the water balance equation. Our results are in agreement with the previously reported findings, and the methodology of estimating water balance components appears reasonably acceptable. With regard to the toposequential variation, the higher position in the topoesquence, the greater potential of the water losses because of higher percolation and lateral flow rates.

Riaz A. Mann1, Waqar A. Jehangir2 and I. Masih2

Wheat and rice are the major food staples for more than 15 million people in Pakistan. The projected demand for the next 25 years will fall short of the supplies by nearly 20 m tons. In order to grow more quality food from marginal/degraded lands and diminishing water resources, the productivity of rice-wheat system must be improved and sustained to make it more viable and eco-friendly. Thus, field experiments were conducted to assess the impact of alternative crop establishment techniques on water productivity of rice-wheat crops. The results revealed that the direct seeding of rice saved 25% water compared to conventional method (transplanted puddled rice). The average water productivity of rice ranged from 0.27 to 0.32 Kg/m3 among the treatments, direct seeding indicating higher water productivity over conventional rice. Significant gains in producing more rice with less water through direct seeding and bed planting were hindered by lower yields mainly due to higher weed infestation. Zero tillage wheat gave better land (4.3 t/ha) and water productivity (1.6 Kg/m3) compared to conventional method, whereas bed planted wheat needs further efforts to improve land and water productivities. Thus, resource conservation tillage technology provides a tool for improving and sustaining water productivity of rice-wheat system, helping with food security and poverty alleviation in Pakistan in the next few decades.

Jose Mathew, K. Mohanasarida and O.N. Resmi

This study addresses the water scarcity issue in dry seeded lowland rice in humid tropics through a three-pronged approach compatible with the unique ecology of the production system. The first evaluated seed priming to ameliorate moisture stress in the early upland phase. The phytotonic effect of imidacloprid was reported for the first time in the study. The second developed a low cost and easily adaptable method of concurrent growing of green manure crops susceptible to water logging, and its subsequent incorporation. Finally, weed infestation, which increases the severity of moisture stress, was effectively controlled by biological suppression through concurrent growing of green manure crops as well as by the use of complimentary pre emergent herbicides.

Siva Sivapalan1, K. Yin Chan2 and Nicholas Addison3

High water turbidity levels affect the successful establishment of rice seedlings. A range of anionic polyacrylamides (PAM) were tested for their effect on turbidity, infiltration, germination and crop growth. Different PAM products had varying ability to reduce water turbidity. PAM at the rate of 5 kg/ha combined with gypsum at the rate of 25 kg/ha reduced turbidity below threshold levels. PAM used alone or with gypsum did not have any significant effect on infiltration through the treated soils. On the other hand, these treatments had a positive effect on the germination of soybean seeds. Plant growth rate was also improved by these treatments.

B.W. Dunn1,2, S.K. Mathews1, H.G. Beecher1,2, J.A. Thompson2,3 and E. Humphreys2,4

The performance of conventional ponded rice grown on a flat layout was compared with rice grown on 1.84 m raised beds with flood, furrow and sub-surface drip irrigation at Coleambally, NSW. The traditional flat flooded treatment achieved the highest grain yield of 12.7 t/ha, followed by the Bed.ponded treatment (10.2 t/ha). The furrow irrigated bed treatment yielded 9.4 t/ha and the Drip treatment the lowest (8.3 t/ha). Grain yield from all bed treatments was reduced due to the wide furrows (0.8 m between edge rows on adjacent beds), which were not planted to rice.

Rice crop water use was significantly different between the layout/irrigation treatments. The Flat and Bed.ponded treatments had similar irrigation water use (mean of 18.4 ML/ha) while the Furrow treatment used 17.2 ML/ha and the Drip 15.1 ML/ha. Water use efficiency (WUE) of the Flat treatment (0.68 t/ML) was higher than the raised bed treatments, which were all similar (mean 0.55 t/ML). The delay in physiological maturity (11 days) of the bed treatments, particularly at high N rates could cause planting delays when growing a winter crop immediately after the rice crop. The increase in length of growing season for the bed treatments also increased the period of irrigation, thus reducing the potential for water savings.

Anita Boling1, Bas A.M. Bouman1, To Phuc Tuong1, Sigit Y. Jatmiko2, Maddala V.R. Murty1, Hendrika H. VanLaar3 and Herman van Keulen3

The typical rainfed cropping system in Central Java includes a dry-seeded rice crop grown from November to February (gogorancah), followed by a transplanted rice crop from March to June (walik jerami). This study assessed the climatic and agrohydrologic constraints to rice production and explored management strategies to increase the yield and yield stability of the double-rice cropping system using the crop growth simulation model ORYZA2000. The model was parameterized and evaluated using eight seasons of field experiments from 1995 to 2000 in Jakenan Experiment Station. The root mean square error between simulated and measured grain yields is considered low (10-20%). Simulation of potential and rainfed rice yield was carried out on a 15-d planting interval for the period 1977-2000. The average simulated potential yield of walik jerami rice was higher than that of gogorancah rice, indicating that radiation and temperature are not determinants of the observed relatively low yields of walik jerami rice. Simulated rainfed yields of walik jerami crops declined sharply if planted later than early March. Deep tillage, additional N fertilizer, and supplemental irrigation increased the yields of rainfed walik jerami crops. The results highlight the importance of timely planting and management to increase rice yields and yield stability in the area.

C. Venkata Reddy1, R.K.Malik2 and Yadav Ashok3

In large parts of India and in many South Asian countries, rice is traditionally being grown by transplanting in puddled fields. Puddling reduces water losses through percolation besides being very effective in controlling weeds. But it has resulted in reduced soil fertility and increased soil compaction. Therefore, the present experiment was conducted to study the feasibility of other planting techniques. It was carried out in a farmer’s field in Haryana in India during kharif 2002 and 2003. The study examined 3 factors – Variety (HKR 126 and IR 64), Tillage (Puddled and Zero tilled) and seeding method (Transplanted and Broadcast of sprouted seed). The grain yield of HKR 126 (6.24 t/ha) was significantly higher than IR 64 (5.75 t/ha). The higher yield in HKR 126 was attributed to more effective tillers and, depending on year, more filled grain and larger grain weight. Overall, Transplanting produced significantly higher yields (6.54 t/ha) than Broadcasting sprouted seed (5.44 t/ha). However, Tillage had no significant effect (Puddled 6.00 t/ha and Zero tilled 5.99 t/ha). Although the Transplanted treatments had fewer tillers/m2 (300) than Broadcast (332), it produced a higher yield because it had more grains in the panicle (148 compared with 122) and larger grains (27 g compared with 25g).

Waqar A. Jehangir1, Hugh Turral2 and I. Masih1

The sustainable productivity of rice wheat system is under threat due to growing water scarcity. More and more groundwater resources are being exploited. One of the major future challenges for agriculture is to produce more food with less water. Therefore, system performance should be evaluated in terms of water use efficiency and water productivity along with the land productivity. This paper studied the water use efficiency and productivity in rice-wheat zone of Punjab, Pakistan. The performances of different rice establishment techniques were evaluated. The results show that canal water shortages were acute; therefore, about 3/4 of the crop demand is met through groundwater exploitation. The water use efficiency of the system was low as the water productivity of gross inflow for rice was only 0.27 kg/m3. The irrigation water productivity for direct seeding method for rice on flat field was estimated as 0.41 kg/m3 and the corresponding value for conventional method was 0.34 kg/m3. The irrigation water productivity for wheat was estimated as, 2.0 kg/m3 and could be improved further by meeting the full crop demand through better irrigation and groundwater pumpage strategies. The adoption of innovations in the fields of crop physiology, agricultural practices, agricultural engineering and resource conservation technologies could play a leading role in sustaining and enhancing the productivity of rice-wheat systems.

Anil Prashar1, S. Thaman1, A. Nayyar1, E. Humphreys2, S.S. Dhillon1, Yadvinder Singh1, P.R. Gajri1, Jagadish Timsina2 and D.J. Smith2

The performance of wheat on flat and bed layouts was compared on three soil types (sandy loam, loam and reclaimed sodic loam) in Punjab, India during the winter of 2002/3. Mid-season conditions were unusually foggy and cool and the crops virtually stopped growing during the month prior to anthesis. On the sandy loam total biomass and grain yield were significantly lower on the beds (4.3 t ha-1) than on the flats (4.8 t ha-1), but were similar on the beds and flats on the two loams. The lower yields on the beds on the sandy loam appeared to be due to failure of the crop to tiller as a result of water deficit stress during early crop growth. The recommended practice of delaying the first irrigation until 3-4 weeks after sowing may need to be revised to 2-3 weeks after sowing for wheat on beds on sandy loam soils.

M.Ilias. Hossain1, Craig Meisner2, J.M. Duxbury3, J.G. Lauren3, M.M. Rahman4, M.M. Meer5 and M.H. Rashid6

The combined effects of tillage options, nitrogen management and levels on wheat yield (Triticum aestivum L.) as a winter crop on raised beds has increased productivity in the temperate world but has not been investigated in lesser developed countries, like Bangladesh. Therefore, a study was conducted during 3 wheat seasons at the Regional Wheat Research Center experimental field in Rajshahi NW Bangladesh, to compare the effects of tillage options, nitrogen levels and management strategies on wheat. In a strip-split plot design, two tillage systems were tested: manually prepared, permanent bed (PB) and conventionally tilled on the flat (CTF). Within each tillage system, two nitrogen management practices were used: broadcast, (BC) and furrow placement (FP) between wheat rows. Three N levels (50, 100 and 150% of recommended N) representing 60, 120 and 180 kg N/ha were used. PB increased wheat yield by 18% when compared with CTF. Predictably, wheat yields responded to N fertilizer rates in all years over all treatments. There were no statistical differences between the two nitrogen managements in 2 out of 3 years, i.e. BC and FP. Using raised beds at 150% N rate, yield was statistically higher in all years. Using raised beds at 50% N rate, yield was statistically equal to 150% conventionally tilled in all years. The data indicate that by using raised beds compared to conventional tillage, nitrogen uptake and efficiency can be increased. The maximum N uptake by the grain and straw was recorded in PB where the highest dose of N was applied. Permanent bed tillage systems also showed substantial water saving (32%) over the CTF treatments. Thus, in warmer areas where water resources are often limited and nutrient uptake and efficiencies are low, the use of raised beds in a permanent bed cropping system would be a distinct advantage.

S.C. Tripathi, A.D. Mongia, D.S. Chauhan, R.K. Sharma, A.S. Kharub, R.S. Chhokar and Jag Shoran

A field study of eight crop sequences was done at the Directorate of Wheat Research, Karnal during 2001-2003 with the objective to diversify/intensify the rice-wheat system for higher productivity and profitability. Rice, berseem and sorghum were grown by conventional flat planting whereas other crops were grown on raised bed planting. The experiment was conducted in randomized block design with four replications. Combined analysis of three years showed that diversification/interruption of rice -wheat system, once in three years, always enhanced the net return, when all crops (except rice) were grown on raised bed in a system approach. Inclusion of oilseed or pulses once in three years or intensification by growing vegetable pea in between rice and wheat or green gram after wheat showed higher return and sustainable value index (SVI) as compared to conventional rice-wheat system. Maximum SVI and benefit cost ratio was recorded in pigeon pea-wheat-rice-wheat-rice-wheat (CS8) crop sequence whereas maximum net return (Rs 60952/ha/year) was in rice-mustard-greengram-rice-wheat-greengram-rice-wheat-greengram crop sequence. Growing of berseem crop in the rotation reduced weed population in subsequent wheat cycle. Diversification and/or intensification options enhanced the protein content of wheat grain in subsequent crop cycle.

Ambrocio R. Castañeda, Bas A.M. Bouman, Shaobing Peng and Romeo M. Visperas

Rice grows and produces best under flooded condition but large amount of water is needed to satisfy puddling during land preparation and maintenance of standing paddy water depths throughout its growth period. Hence, reducing water use through an aerobic system of rice production that eliminates puddling and maintenance of ponded water in paddies is necessary to mitigate the potential occurrence of water scarcity. In 2001-02, a field experiment on aerobic rice was conducted at the International Rice Research Institute (IRRI) to evaluate the potential of aerobic rice in the tropics to mitigate a looming water crisis. Under aerobic conditions, the soil was dry-plowed and flush-irrigated when the soil moisture tensions reached –30 to –50 kPa during the crop growth stage. Compared to flooded conditions, the soil was puddled during the land preparation and a paddy water depths of 2-10 cm were maintained during the crop growth stage. Aerobic rice saved 73% of irrigation water for land preparation and 56% during the crop growth stage. Moreover, it effectively used rainfall during the wet season. Aerobic rice yields were lower by an average of 28% in the dry season and 20% lower in wet season. Magat (a tropical lowland hybrid) and Apo (a traditional upland inbred) showed the highest yield potential between 5-6 t/ha under aerobic conditions. Further experiments in medium textured soil and breeding of varieties better suited to aerobic conditions are needed.

Sarath P. Nissanka1 and Thilak Bandara2

Productivity of System of Rice Intensification (SRI) method was evaluated with conventional rice farming systems in Sri Lanka. An experiment was carried out in the dry zone region during 2002 (Oct)/2003 (March) Maha season and a popular rice variety B.G. 358 (3.5 months duration) was used. Four treatments namely; SRI (T1; one plant per hill with 25 cm x 25 cm spacing), conventional transplanting (T2; three plants per hill with 15 cm x 15 cm spacing), conventional broadcasting (T3; 100 kg seeds/ha) and high density broadcasting (T4; 300 kg seeds/ha) were arranged in a randomized complete block design with four replication. Growth parameters and dry matter distribution in every two weeks intervals and yield components and grain yield at maturity were measured.

G.N. Atlin, M. Laza, M. Amante, and H.R. Lafitte

Aerobic rice varieties are high-yield upland varieties distinguished from traditional upland rices adapted to low-input, subsistence-oriented management by their improved lodging resistance and higher harvest index. In the Asian tropics, aerobic varieties are usually medium-statured indica cultivars that are moderately drought-tolerant. Aerobic varieties may be useful where irrigated lowland production systems are failing due to water shortage, and in management intensification for drought-prone rainfed upland and lowland cropping systems. Little information is available on the yield potential, agronomic features, and hydrological adaptation of tropical Asian aerobic rice varieties. Improved and traditional varieties were therefore evaluated in multi-year irrigated lowland, non-stressed upland, and water-stressed upland environments at IRRI. Aerobic cultivars yielded 3.89 t ha-1 in favorable upland environments, outperforming improved upland and irrigated varieties by 100 and 30%, respectively. Aerobic cultivars are of intermediate height under favorable upland conditions and maintain HI of nearly 0.4, or about one-third higher than other cultivar types. Traditional upland cultivars, which are tall, lodging-prone, and have low HI, are not suitable for aerobic systems with yield targets of 2 t ha-1 or more. Aerobic rice cultivars offer a new approach to increasing productivity and reducing risk in Asian rainfed rice systems.

Yonglu Tang, Jiaguo Zheng, Gang Huang and Jinquan Du

Throughout the formal experiments at selected locations and comparison trials conducted in the same fields from 1993 to 1997, the technique of permanent-bed-planting with double zero tillage for rice and wheat (PBDZ) was investigated. The aim was to determine the influence on the yield of rice and wheat and the pattern of production trends, to determine the factors increasing yield for both rice and wheat and to evaluate economic benefits. The results show that the PBDZ can significantly increase rice and wheat yield. Compared with the traditional cropping technique (TCT), wheat yield increased by 6.7%~9.7%, and rice yield by 5.1~6.7%. The yield increase for wheat was more than for rice, and the wheat yield showed an increasing trend over years, while the rice yield increase showed a gradual declining pattern. The substance cost of PBDZ was reduced by 1290 Yuan/ha compared to TCT, while labor cost was reduced by 645 Yuan/ha. In addition to the yield and income increase of 847 Yuan/ha, the annual saving in costs and the increase in income all together amount to 2782 Yuan/ha, i.e. 76% increase over the traditional practice. The increase in yield of rice and wheat with the PBDZ technique can be accounted for by changes in pedology, agronomy and physiological ecology of the new cropping technique.

Yumiko San-oh, Daisaku Yoshita, Taiichiro Ookawa and Tadashi Hirasawa1

A planting pattern in which each hill contains one rice plant (planting pattern I) results in a higher yield of dry matter, especially during the reproductive stage, than a planting pattern in which each hill contains three plants (planting pattern III). Root system development, resistance to water transport, and afternoon depression in photosynthesis were compared between plants in planting patterns I and III. The number of crown roots and root length density per stem were significantly larger in plants in planting pattern I when compared to those in planting pattern III. In the ripening stage, the resistance to water transport and the afternoon depression in photosynthesis tended to be smaller in plants in planting pattern I. The larger capacity of water uptake and the smaller afternoon depression of photosynthesis may contribute to the larger yield of dry matter from plants in planting pattern I compared to plants in planting pattern III.

Jin Jian 1, Wang Guanghua 1 and Liu Xiaobing 1,2

Heilongjiang province is a low rainfall province in NE China. Phosphorus nutrient is an important factor improving the tolerance ability to water stress in soybean (Glycine max L.Merrill). We tested the root morphological characteristics root mass, root length and root surface area. These were greater at high applied P fertilizer rate than with either the absence of fertilizer P or at low P rates when water deficit occurred at R1 or R4 stage. P nutrient improved root traits to enhance tolerance of water deficit during reproductive growth, with less yield reduction at high applied P.

Neelam Yadav and Vijay K Yadav

The influence of water stress, simulated whitegrub and real whitegrub damage on water relation parameters and stress-induced biochemicals under various soil moisture levels in groundnut was studied. A novel method of simulating the white grub damage was developed by cutting the roots vertically by 25%, 50% and 75% at 40 days after sowing (DAS) in one set and by cutting the roots horizontally 30, 20 and 10 cm from the top soil surface at 30 and 60 DAS in other set to obtain an indication how the feeding activity of the insect affects growth of the plant. Cutting of roots reduced relative water content (RWC) significantly (4.18-8.53 %) to the levels almost equivalent to that in water-stressed plants (8.63 %). Proline content in plants with simulated white grub damage was elevated by 31.25-78.12 % and in plants under water stress by 56.25 % as compared to the control. When whitegrub larvae were introduced at 40 DAS, the plants showed markedly reduced relative water content, increased transpiration rate and proline level but no change in peroxidase level. RWC and peroxidase activity did not change while transpiration rate and proline content increased significantly in plants when whitegrub larvae were introduced at 60 DAS. In general, the plant physiological effects of both simulated white grub damage and the root damage caused by H. consanguinea larvae feeding appear to mirror closely the effects of water stress.

Jean-Louis Durand1, Thierry Bariac2, Mia Victoria Gonzalez Dugo1, Marc Ghesquière3, Patricia Richard2 and Philippe Biron2.

Screening in plant breeding nurseries for depth of water extraction or rooting depth is hardly possible using standard techniques of soil moisture measurements. A new methodology based on the discrimination of 18O in soil water is proposed. It consists in measuring the natural gradient in 18O which generates in soil following several days of evaporation, and the δ18O of the water extracted from the plant. The study compares the actual plant δ18O and the value computed combining neutron probe and soil δ18O measurements. The study shows that, provided the plant sample is appropriate, there is consistency between the plant δ18O and the soil water δ18O actually extracted. Tested here on forage grasses, the method can be easily used for any crop.

Janjira Puntase1, Chuckree Senthong1, Sawit Meechoui2 and Keith T. Ingram3

Aspergillus flavus populations appear to be greater on roots and pods of drought-susceptible peanut genotypes than on roots and pods of drought-resistant genotypes. Root exudates may provide growth substrate to promote A. flavus population increase. The objective of this research was to ascertain the relationship between root exudates, development of A. flavus population, water deficit and aflatoxin resistance. The experiment was conducted at Lampang Agricultural Research and Training Center and Chiang Mai University during 2002-2003. Four peanut genotypes; 419CC, 511CC, Luhua 11 and Tainan 9 were grown in a hydroponic system with half-Hoagland’s solution. Poly-ethylene glycol was used to impose water deficit. Root exudates were measured by HPLC. Root systems were analyzed for root length, using a flatbed scanner and WinRhizo software. The effect of root exudates on A. flavus population growth was observed. Water deficit promoted more exudation of sucrose but not glucose or fructose. No sucrose was found in the drought-resistant genotype (511CC) under normal condition, whereas under water deficit, drought-susceptible genotype (419CC) tended to excrete more sucrose compared with the drought-resistant genotype (511CC).

M. Yusuf Ali1, Selim Ahmed2, Chris Johansen3, D. Harris4 and J.V.D.K. KumarRao5

Root traits of six different crops grown rainfed in the post-rainy season in the High Barind Tract of Bangladesh were investigated for the purpose of identifying alternative crops to diversify the rainfed rice-chickpea cropping system. In general, crop yield was related to rooting ability below 30 cm soil depth. In the 2000-01 season, roots of barley, mustard and chickpea penetrated deepest, to 90-105 cm, whereas in 2001-02 roots of linseed penetrated deepest, to 120-135 cm. Barley developed the highest root length density (RLD) at depth (30-90 cm) in 2000-01, a growing season devoid of rainfall. Chickpea, mustard and linseed, in that order, had the next highest RLD at depth. In 2001-02, linseed and chickpea produced greater RLD at depth (30-105 cm), followed by barley. Lentil had least RLD with depth and the crop could not set seed in either year due to drought stress. Wheat had intermediate RLD, between lentil and other crops, and produced yields well below its potential had it been irrigated. Barley had the smallest root diameter but mustard had the thickest roots. The large variation in root traits between seasons was attributable to the different rainfall patterns experienced and bulk density characteristics of the soil profile at different locations. Economics of cultivation of barley, linseed and mustard were favorable when compared with chickpea, even if they were not as remunerative as chickpea. These three crops could be considered as alternatives to rotate with chickpea in the High Barind Tract, to mitigate against build-up of pests and diseases of chickpea. It is suggested that more suitable genotypes of these crops should be sought, ones having grater rooting ability at depth and hence adaptation to rainfed cropping in the High Barind Tract.

Liusheng Duan, Xiaoli Tian, Yi Zhang, Zuoshun Tang, Zhixi Zhai and Zhongpei He

This paper studied the effects of Mepiquat Chloride (DPC) on initiation and development of lateral roots of cotton seedlings, using the upland cotton (Gossypium hirsutum L.) cultivars Zhongmianshuo 16 and Zhongmianshuo 29 as experiment materials. Seedlings were cultured on glass boards after seeds were soaked with 400 mg/L DPC solution for 12 hours. DPC increased the number of lateral roots and root primordia, and the length of the segment where lateral roots and root primordia initiated. It was shown that DPC promoted both the initiation of primordia and their development to lateral roots in an experiment of lateral root removal. Under the stress of low temperature, the initiation of lateral roots was also significantly promoted by DPC. The levels of endogenous Auxin, Zeatin and Zeatin riboside in the middle segment of primary root were all increased by DPC, which might be the key reason for lateral root induction.

Tina Botwright and Len Wade

Around a third of arable land in Western Australia is in the low rainfall zone and grain yield of wheat in this zone averages 1 t/ha. Clay duplex soils and those compacted by heavy farm machinery restrict water infiltration and root penetration as roots cannot grow through soil pores narrower than their diameter, and are instead deflected and thicken. Although there is little to no information on genetic diversity in root traits in Australian wheat cultivars, there has been success in selecting for root traits beneficial to drought avoidance and hardpan penetration in rice, using a glasshouse technique where a synthetic wax-layer was used to simulate a hardpan. A glasshouse experiment was conducted to validate this method for wheat by comparing root biomass and plant water use in four wheat cultivars in drought or well-watered conditions, with or without a hardpan. Water use with a hardpan differed among treatments and the four wheat cultivars. Halberd and V18 used more soil water in total and had the fastest rate of water use when grown without a hardpan, but ran out of water several days before pots with a hardpan, compared to Cranbrook and CM18. Total water uptake was similar in V18 and Halberd, yet the rate of water uptake per unit root mass was greater in V18, with a smaller root DM. The technique will be used to evaluate a wider range of wheat cultivars and breeding lines for root penetration of hardpans and water-use under drought, but requires further validation to ensure that the identified traits are effective against real hardpans in the field.

Katashi Kubo1, Yutaka Jitsuyama1, Kazuto Iwama1, Nobuyoshi Watanabe2, Akira Yanagisawa3, Ismahane Elouafi4 and Miloudi M. Nachit4

The presence of semi-dwarf (Rht) genes in wheat may limit ability of roots to penetrate hardpans. This was tested by growing Rht and tall (rht) wheats in 15cm pots of vermiculite in which a thin paraffin:Vaseline (PV) disc had been inserted to simulate a hardpan at 10cm. Number of roots penetrating the PV disc (RNPV) and the total root number per plant (TRN) were measured at 8 wks after sowing. A root penetration (RP) index was calculated as RNPV/TRN. ‘Jennah Khetifa’ (rht type) had greater RNPV and RP index than ‘Cham 1’ (Rht type). But among 110 RILs derived from these parents, there was no association between shoot height and either RNPV, TRN or RP index. Other comparisons between near-isogenic wheats with and without Rht genes also showed no effect of Rht on RNPV, TRN or RP index. We conclude that RP ability of wheat is not affected by the presence of Rht genes.

Stephen P. Milroy, Senthold Asseng and Michael L. Poole

A field study has been initiated to examine the potential yield of wheat on the deep sands of the northern sandplain landscape of the Western Australian wheat belt and what constraints are limiting growers’ capacity to achieve such yields. In the first year’s experiment, there was no difference in the root distribution of canola and wheat and no indication that the contrasting root systems responded differently either in terms of rooting or water extraction. Simulation analysis suggested that high nitrogen application rates could overcome the impact of compaction in this system. The relative importance of restriction to water and nitrogen uptake by compaction in these soil types needs to be explored.

Ryosuke Tajima1, Shigenori Morita2 and Jun Abe3

The dynamics of the elongation growth of roots in peanut plants (Arachis hypogaea L.) was investigated from viewpoints of developmental morphology. Peanut plants were grown in root boxes and the roots were traced every two days until 55 days after sowing. The frame of the whole root system was defined by the taproot and some of the 1st-order lateral roots emerged from basal part of taproot that elongated long and formed 2nd-order lateral roots. In the time course of elongation rate of whole root system, two peaks appeared during the observed period. In the interval period between the two growth peaks, emergence and elongation of 1st-order lateral roots were synchronically suppressed with declined elongation of taproot. In cases where the axis of taproot stopped elongation completely, existing 1st-order lateral roots grew vigorously and compensated the lost growth of the taproot. Therefore, there is close relation and interaction between the tap root elongation and the development of lateral roots in peanut root system.

Zvi Hochman1, Merv Probert2 and Neal P. Dalgliesh1

A simulation model was used to develop hypotheses about the impacts of sodicity and salinity on wheat crops, runoff and drainage in Australia’s northern cropping region. Based on the hypothesis that subsoil constraints reduce crop yield by restricting their roots’ access to soil moisture and nutrients, a range of levels of subsoil constraints was simulated by progressively restricting plant available water capacity of a typical Grey Vertosol at four locations representing the range of rainfall distributions in the region. While predicted impacts of subsoil constraints were highly variable from year to year, 100 year means showed that these impacts on yield, drainage and runoff were greater when pre-season soil moisture was high. Impacts were similar at all sites while their absolute values were proportional to average annual rainfall and summer dominance.

Ian Broad1 and Graeme Hammer1,2

Wide and ‘skip row’ row configurations have been used as a means to improve yield reliability in grain sorghum production. However, there has been little effort put to design of these systems in relation to optimal combinations of root system characteristics and row configuration, largely because little is known about root system characteristics. The studies reported here aimed to determine the potential extent of root system exploration in skip row systems. Field experiments were conducted under rain-out shelters and the extent of water extraction and root system growth measured. One experiment was conducted using widely-spaced twin rows grown in the soil. The other experiment involved the use of specially constructed large root observation chambers for single plants. It was found that the potential extent of root system exploration in sorghum was beyond 2m from the planted rows using conventional hybrids and that root exploration continued during grain filling. Preliminary data suggested that the extent of water extraction throughout this region depended on root length density and the balance between demand for, and supply of, water. The results to date suggest that simultaneous genetic and management manipulation of wide row production systems might lead to more effective and reliable production in specific environments. Further study of variation in root-shoot dynamics and root system characteristics is required to exploit possible opportunities.

Yash Dang1, Richard Routley2, Michael McDonald3, Ram Dalal4, Vanessa Alsemgeest2 and Denis Orange1

Relative performance of a range of winter crop species on soils with various combinations of subsoil constraints was determined in eight field experiments. Drained Upper Limit (DUL) and Crop Lower Limits (CLL) were determined using soakage ponds and rainfall exclusions. CLL varied between crops such that mean plant available water capacity (PAWC) for various crops at the sites examined were: bread wheat cv. Baxter, 164 mm; durum wheat cv. Yallaroi, 125 mm; barley cv. Mackay, 156 mm; chickpea cv. Jimbour, 141 mm; and canola cv. Hyola 43, 190 mm. Threshold levels for the effect of subsoil constraints on CLL were calculated using a two-step regression; firstly accounting for the effect of soil texture on CLL, and secondly, analysing relationships between residuals of CLL and subsoil constraints of salinity and sodicity. Significant, positive relationships between residuals of CLL and electrical conductivity (ECse), exchangeable sodium percentage (ESP) and chloride concentration (Cl) were obtained. Durum wheat was more sensitive to subsoil salinity as compared to barley and bread wheat. Chickpea was found to be most sensitive to sodicity.

Jianhua Zhang1 and Jianchang Yang2

Water use efficiency (WUE), if defined as the biomass accumulation over water consumed, may be a highly inherited characteristics of a specific genotype. In practice, WUE can also be enhanced by less irrigation, particularly via stomatal regulation. However, such enhancement is largely a trade-off between lower biomass production and higher WUE. We have presented a case here that WUE may be enhanced through an improved harvest index. Harvest index has been shown as a variable factor in crop production, especially in cases where whole plant senescence of rice and wheat is unfavourably delayed. Such delayed senescence can delay the remobilisation of pre-stored carbon reserves in the straw and results in lower harvest index. A controlled soil drying, i.e. moderate drying such that overnight rehydration of plants is still possible, should enhance whole plant senescence and therefore improve the remobilisation of pre-stored carbon reserve. The gains from the improved harvest may outweigh any possible biomass loss due to shortened photosynthetic period in grain filling, such as the cases with high N nutrition, lodging-resistant cultivars that stay green for too long, and hybrid cultivars with excessive heterosis.

Diane Rowland1, Paul Blankenship1, Naveen Puppala2, John Beasley3, Mark Burow4, Dan Gorbet5, David Jordan6, Hassan Melouk7, Charles Simpson8 and Jim Bostick9

The ability of a peanut variety to use water efficiently can spell the difference between high yields or a failed crop when water is limited. Because of this, high water-use efficiency (WUE), or the ratio of yield to water use, may now become a priority in many peanut breeding programs. To support such a breeding effort effort, we examined the variation in WUE (as measured by carbon isotope composition) as well as two leaf characteristics, specific leaf area and chlorophyll content, of up to 19 varieties in six U.S. peanut producing areas: Georgia, Florida, North Carolina, Texas, Oklahoma, and New Mexico. We found significant variation among sites and among varieties grown at single sites in all three characteristics, indicating these traits were under genetic control but had the potential for genotype by environment interactions.

M. John Foulkes1, Vinesh Verma2, Roger Sylvester-Bradley3, Richard Weightman3 and John W Snape2

The association of three target traits for drought resistance (early flowering, high accumulation of stem water soluble carbohydrate (WSC) reserves and high green flag-leaf area (GFLA) persistence) with yield performance under drought was analyzed utilizing a doubled-haploid (DH) population derived from a cross between Beaver and Soissons. The aims were to: (i) quantify associations between target traits and yield response to drought and (ii) search for quantitative trait loci (QTLs) for drought-resistance traits. Flowering had neutral effects on drought resistance, suggesting there may be a trade-off between water-saving behaviour in the shorter pre-flowering period with early flowering and a reduced capacity to access water associated with the production of a smaller rooting system. The value of large stem soluble carbohydrate reserves for drought resistance could not be confirmed in the UK environment. Stem WSC was positively associated with grain yield under both irrigation and drought. An effect of major significance for this trait was related to the 1R arm of chromosome 1BL/1RS. The genetic trait which showed the clearest correlation with yield performance under drought was green flag-leaf area persistence. The coincidence of QTL for senescence on chromosomes 2D and 2B under drought-stressed and optimal environments, respectively, indicate a complex genetic mechanism controlling expression of this trait involving the remobilization of resources from the source to the sink during senescence.

Fernanda Dreccer, Francis Ogbonnaya, Gabriela Borgognone and Jayne Wilson

We evaluated the shoot and root growth performance of primary synthetic wheats compared to commercial bread wheat cultivars during early vegetative stages. Variation in total biomass and leaf area at the 5-6 leaf stage was present in primary synthetics, with many lines producing significantly more than the bread wheat cultivars. In the primary synthetics, higher seed weight and relative growth rate were associated with higher growth rate. Their net assimilation rate was on average higher than that of the bread wheats and was accompanied by thicker leaves. Primary synthetic wheats and bread wheat cultivars did not differ in the root shoot ratio. Thus, genotypes with higher total biomass had higher root mass, often accompanied by longer root length. In summary, in the primary synthetics there are lines with high above and below ground growth that could be useful in developing germplasm for drought-prone environments. Additionally, the roots of primary synthetic wheats tended to be thicker than those of bread wheat cultivars. The adaptive significance of this characteristic is yet to be explored.

Martha Lazaridou1 and S.D. Koutroubas2

Drought is one of the major factors limiting yield under Mediterranean conditions. This investigation was conducted at Drama in Macedonia of Greece, in 2002, to evaluate the effects of drought on plant water use efficiency at various phenological stages of berseem clover (Trifollium alexandrinum L.). Drought conditions were imposed by irrigation with half quantity of water needed to reach field capacity. Measurements of the above ground dry biomass, leaf area and transpiration rate were made at early vegetative, vegetative, bud, early flower and full flower stages. Growth rate, plant transpiration and plant water use efficiency were calculated at each stage. Growth rate of plants under drought was lower compared to that of irrigated ones. This resulted in a reduction of the above ground dry biomass to one third of irrigated plants (2.3 vs 6.8 g/plant). Leaf area and transpiration rate were also lower in plants under drought than under irrigation. Results indicated that berseem clover reduced substantially the plant water losses by decreasing the transpiration rate and the leaf area. However, it reduced less the yield, resulting in higher values of plant water use efficiency. The highest value of plant water use efficiency under drought was obtained at the beginning of the flower stage.

Michihiko Fujii, Chika Andoh and Seiji Ishihara

In Africa, as population increase is severe, increase of crop production is a major problem. Recently to solve the problem, NERICA (New Rice for Africa) was developed in West Africa by the cross between African rice (Oryza glaberrima Steud.) and Asian rice (Oryza sativa L.). In this study, eight rice cultivars including two parents of NERICA, six NERICA lines and two millet species (common millet and Italian millet) were grown in field under drought condition, and physiological measurements were made. Stomatal conductance was measured by porometer, and soil water contents at individual depths were measured by TDR (Time domain reflectometry) method as water uptake characteristics. Some NERICA lines showed high dry weight and yield under drought condition among the rice cultivars and lines tested, though there were line differences in NERICA. Including all rice cultivars and lines tested, dry weight at harvest under drought condition was correlated with stomata conductance (r= 0.638**), and cultivars and lines that maintained high growth showed high stomata conductance. In Asian rice (O. sativa L.), dry weight at harvest was closely correlated with soil water content at harvest (r= -0.953*), and cultivars and lines that maintained high growth showed high water uptake. On the other hand, correlation between dry weight and soil water content was not significant in NERICA lines (r=0.106). It became clear that there are some lines in NERICA that show high growth with low uptake of water and they seem to be appropriate for long periods of cultivation in drought condition.

K. J. Boote

Imma Farré1, José María Faci2

Growing drought tolerant crops can save water in regions where irrigation water is limited. A field experiment was conducted on a loam soil (Typic Xerofluvent) in Northeast Spain to compare the responses of maize (Zea mays L.) and sorghum (Sorghum bicolor L. Moench) to irrigation deficit. Soil water status, crop development, biomass and yield were measured in a sprinkler line-source experiment. Crop water uptake, phenology, total above-ground biomass and yield were markedly affected by the irrigation treatments in both crops. Maize was superior to sorghum under well irrigated conditions, but sorghum outyielded maize under moderate or severe water deficits. Sorghum had a greater ability to extract water from deeper soil layers. Its higher yield under irrigation deficit was achieved by a higher above-ground biomass and a higher harvest index. Sorghum was more efficient than maize in the use of irrigation water under limiting water conditions. The results indicated that sorghum could be an alternative to maize under limited water conditions in the semi-arid conditions of Northeast Spain.

Xi-Ping Deng1, Lun Shan1, Sui-Qi Zhang 2, Shinobu I Nanaga 3 and Neil C. Turner4

Increasing crop water use efficiency (WUE) and drought tolerance by genetic improvement and physiological regulation may be one means to achieve highly efficient use of water. In this paper we discuss the molecular mechanisms, physiological principles, strategies and future perspectives of plant biological water-saving and highlight some approaches of plant biological water-saving which could contribute not only new water-saving techniques but also scientific base for application of water-saving project.

Christopher J. Lambrides1, Scott Chapman2 and Ray Shorter3

Plants incorporate isotopes of carbon into their tissue at different rates because of discrimination against 13C relative to 12C during photosynthesis. This difference in discrimination has been negatively correlated with transpiration efficiency (TE) in many C3 species and so, carbon isotope discrimination (Δ) of leaf tissues has been proposed as a potential tool for selecting genotypes with improved performance under water limited conditions. The relationship between Δ and TE in sunflower has been described previously using diverse genotypes, but this relationship has not been investigated with material selected from a segregating population. In this study, the TE of twenty recombinant inbred lines from a population (HAR4 x SA52) segregating for Δ was evaluated in a rainout shelter experiment. A strong negative genetic correlation between TE and Δ was observed (rg = -0.58), confirming previous studies of sunflower with unrelated lines. In addition, TE was strongly correlated to plant height at the final harvest (rg = 0.64) and TDW (rg = 0.58), and moderately correlated to SLW (rg = 0.46) and SPAD (rg = 0.21) but not leaf number (rg = 0.02). Estimates of narrow sense heritability of TE and Δ were very high (0.82 and 0.77, respectively) suggesting that selection for these traits could occur in early generations of segregating populations. Grain yield evaluations under field conditions of hybrids contrasting for Δ showed that low Δ (high TE) hybrids had a yield advantage between 22-35% in dry environments where the yield was less than 2t/ha. While this level of yield advantage may not be realized in commercial breeding programs, computer simulations suggest that 10-15% yield improvements may be possible. Low Δ material selected from the population HAR4 x SA52 has been distributed to private seed companies for further evaluation.

Masoud Sinaki Jafar 1, Ghorban Nourmohammadi2 Abbas Maleki3

Water stress restricts crops yields in the arid and semiarid zones of the world. Water stress is associated with low available water as well as with osmotic effects associated with salinity. Plants adapt to water deficits by many different mechanisms including changes in morphology, altered patterns of development as well as a range of physiological and biochemical processes. A number of these adaptive responses are associated with the accumulation of osmolytes like sugars and proline. Two experiments were conducted with forage sorghum (Sorghum bicolor cv. Speedfeed) to examine the response to water stress during germination and seedling growth and the response in some of these traits. In the first experiment seeds were germinated in Petri dishes at 12 levels of water stress (-0.1, -0.2, -0.3, -0.4, -0.5, -0.6, -0.7, -0.8, -0.9, -1, -1.1, -1.2, MPa) which were generated using solutions of PEG 6000 at different concentrations. Water deficit decreased the percent and speed of seed germination, length of shoot and weight of the plants. Seedling root growth was less sensitive to osmotic stress than shoot growth. In the second experiment the effects of 4 periods of water deficit (3, 6, 9 and 12 day) on the growth of 15 day-old seedlings were examined. Water potential, relative water content, root and shoot growth declined with the severity of the water deficit. Chlorophyll concentration decreased but carotene concentration increased with water stress, as did total soluble sugars and proline concentration of the plants.

B. Kamkar1, M. Kafi2 and M. Nassiri Mahallati3

A green house experiment was conducted to determine the effects of different salinity levels(control,100,200,and 300 mol/M3) and different periods of salinity exposure(from 2-leaf stage to first node , 2-leaf stage to the end of pollination, and from 2-leaf stage to the end of growth season )was studied on wheat(Triticum aestivum,cv.Falat) yield components by path coefficient analysis method. Path coefficients indicated that grain yield/spike was a function of grain number/spike primarily and mean grain weight in second instance. The main effect on level of salinity was on floret abortion, and subsequently grain/spike and grain weight. Grain yield/spike reduced by increasing of salinity level and salt exposure duration. Also, the effect of grain number reduction on yield was not reduced by compensatory effect on mean grain weight. Reduction of total photosynthesis production by some factors as leaf number, area and area duration reduction, and reduction of photosynthesis rate resulted in source limitations and reduction in grain/spike occurred in response to source limitation. Therefore, it seems that if salinity stress can be avoided in special developmental period of wheat (that potential seed number and fertile florets will be determined), damage to reproductive sinks will be decreased. This can help growers to use some approaches such as the use of high and low quality irrigation water either in combination or as separate applications, with any considerable reduction of yield.

E. Nabizadeh1, H. Heidari Sharifabad2, E. Majidi Heravan3 and G. Nourmohammadi4

Plants that are exposed to environmental stresses, especially water deficit, can respond by altering the osmotic potential of the cells. To study the effects of changes in osmotic potential, the response to water deficit in 8 doubled-haploid lines of wheat was compared with 2 commercial lines (Azar2 and Zarrin). Plants were grown at 100%, 75%, 50% or 25% of soil field capacity. The doubled haploid lines were chosen on the basis of their tolerance to water stress in previous studies. The results showed that decreasing the soil available water caused the leaf water potential and RWC to decrease. The smallest decreases in RWC and water potential under restricted moisture were observed in the lines Azar2 and DH15 and the greatest decreases were observed in the lines Zarrin and DH36. The decrease in plant water potential and RWC was associated with an increase in the concentration of proline and soluble carbohydrates, but these accumulated at different rates between the genotypes. The genotypes considered tolerant to water stress accumulated more soluble sugars as the RWC fell compared to less tolerant genotypes. The highest accumulation of soluble carbohydrates occurred in the line Azar2 and the least belonged to the doubled-haploid DH36.

Y. Gan1,4, J. Wang2, S.V. Angadi3 and C.L. McDonald1

A study was conducted to determine the effect of short periods of high temperature and water stress on pod production, seed set and yield of chickpea. ‘Myles’ desi and ‘CDC-Xena’ kabuli chickpea were grown in growth chambers under 20/16°C day/night temperatures (as check). High (35/16°C) and low (28/16°C) temperature stress was imposed for 10 d during flower and pod development. Simultaneously, high (plants remained at 50% available water) and low (at 90% available water) water stress was also imposed. Plants stressed at 35/16°C during flowering produced 53% fewer fertile pods on the mainstem and 22% fewer pods on the branches than those kept at 20/16°C. Nearly 90% of the pods formed during stress were infertile. Due to high temperature stress, kabuli crop filled 58% of the pods formed and decreased seeds pod-1 by 26% from the check. Consequently, desi chickpea seed yield decreased by 54% when stressed during pod development and 33% when stressed during flowering. Kabuli chickpea seed yield decreased by 50% when stressed during pod formation and 44% when stressed during flowering. In semiarid northern Great Plains, shortening the stress period during reproductive development may increase the yield potential of chickpea.

Yoshiyuki Ohashi, Nobuhiro Nakayama, Hirofumi Saneoka and Kounosuke Fujita

The responses of photosynthetic gas exchange, chlorophyll fluorescence, and stem diameter were studied in two cultivars of soybean during water stress and recovery. Photosynthetic rate (Pn), stomatal conductance (gs) and transpiration rate (E) were significantly reduced by water stress, while the intercellular CO2 concentration (Ci) was slightly changed. The maximum photochemical efficiency of PSII (Fv/Fm) and apparent photosynthetic electron transport rate (ETR) were also not altered by water stress in Tanbakuro. Pn, gs, E in cultivar Tanbakurio recovered nearly to the levels of the control plants after rewatering, while cultivar Tamanishiki did not recover during the 24 hours after rewatering. Water stress induced daytime shrinkage and reduced night-time expansion of stem. The plant stem diameter of plants reduced with the initiation of photoperiod and expanded during the night.

Masahiko Tamaki1, Tomio Itani2 and Katsu Imai3

The effects of water supply and light intensity on the growth of spring wheat (Triticum aestivum L.) were studied under carefully controlled conditions. The leaf water potential (LWP) was measured from 5 to 40 d after the initiation of water supply treatments (DAIT). The LWP decreased as DAIT progressed. At higher photosynthetic photon flux densities (PPFDs), the LWP decreased as the water supply decreased. The water supply rate had little impact on tiller initiation and survival under low PPFD. As the PPFD increased, however, tillering responded sharply to water supply. Differences in tiller numbers were mainly due to differences in the number of subtillers from T0, Tl and T2 primary tillers. The water supply rate did not affect plant growth significantly under low PPFD. lncreased PPFD resulted in increased plant growth, except for leaf numbers per main stem, as water supply rate increased. Thus, there was a highly significant interaction of water supply and light intensity on the growth of spring wheat.

Motohiko Kondo1, Osamu Ideta1, Edward Barlaan2, Tokio Imbe1, Sumio Itoh3, Paquito P. Pablico4, Darryl V. Aragones4, Ruth Agbisit4 and D. Brar4

Genotypic and environmental (soil water regime and N level) variations in δ13C in plant were investigated in relation to the gas exchange, transpiration efficiency (A/T), and biomass production in rice (O. sativa L. and O. glaberrima Steud.) genotypes. In addition, genetic control of δ13C was studied by QTL analysis using RIL derived from IR69093-41-3-2 and IR 72. The results showed that genotype factor was more dominant for variation in δ13C than in total biomass. Genotypic ranking in δ 13C was consistent across environments because of small genotype x environment interactions. Japonica genotypes tended to have higher δ13C than indica genotypes in O.sativa. Genotypes of O.glaberrima showed similar ranges of δ13C to indica genotypes. Higher soil water content significantly decreased δ13C. There was a positive correlation between δ13C and A/T among genotypes within water regimes. Genotypic variation in δ13C was associated mainly with variation in stomatal conductance under all soil water regimes and with photosynthetic capacity in late growth stages under aerobic soil conditions. The correlation between biomass and δ13C was not clear in aerobic soils, whereas it was negative in submerged soils in some cases, which indicated that the significance of lower or higher δ13C for improving biomass productivity may differ under different soil water regimes. QTLs inferring to δ13C were detected mainly on chromosome 1, 4, 8, 9, and 12 although the effects of these QTLs were relatively small, indicating that genetic control of δ13C was relatively complex.

Hemmatollah Pirdashti 1, Zinolabedin Tahmasebi Sarvestani 1, Ghorbanali Nematzadeh 2 and A. Ismail3

Water stress affects plant growth and development and ultimately, reduces grain yield of irrigated lowland rice. A field experiment was conducted during 2001-2003 to evaluate the effect of water stress on the yield and yield components of four rice cultivars commonly grown in Mazandaran province, Iran. The cultivars used were Tarom, Khazar, Fajr and Nemat. The different water stress conditions were water stress during vegetative, flowering and grain filling stages and well-watered was the control. Water stress at vegetative stage significantly reduced plant height of all cultivars. Water stress at flowering stage had a greater grain yield reduction than water stress at other times. The reduction of grain yield largely resulted from the reduction in fertile panicle and filled grain percentage. Water deficit during vegetative, flowering and grain filling stages reduced mean grain yield by 21%, 50% and 21% on average in comparison to control respectively. The yield advantage of two semidwaf varieties, Fajr and Nemat, were not maintained under drought stress.

Madhiyazhagan Ramadoss1, Colin J. Birch1, Peter S. Carberry2 and Michael Robertson2

Water stress-associated with high temperature is often considered to be a limiting factor in maize production in dry land regions. A field study was undertaken with two sowing dates and two row spacings to obtain different levels of water stress and incident temperature during crop growth in a deep Vertisol in south eastern-Queensland, Australia. The maize crop sown in October experienced extremely high air temperatures (41 o C) over several days at the time of anthesis (silking). Lower grain yield and associated grain numbers and harvest index were recorded in the October sowing compared to the later December sowing date, while soil water in both sowings and configurations was relatively low at anthesis (25-35% PAWC). The results from this study suggest that high air temperature (>38 oC) compounded by water stress occurring at the same time decrease kernel set under dry land environments.

C.P. Gunasekera1, 2, L.D. Martin1, R.J. French3, 4 and K.H.M. Siddique4

Indian mustard has been identified as a potential and profitable alternative oilseed crop in Australia. Recent field studies at several sites in the low rainfall grain belt of WA suggest that mustard has superior adaptation to canola in the short season environments of southwestern Australia. The responses of selected mustard and canola genotypes to varying levels of post-flowering water stress was studied at Merredin. Detailed morphological and physiological measurements suggest that dry matter production of mustard was higher than canola under severe water stress. This was related to their superior osmotic adjustment and leaf water potential. Poor ability of mustard to convert its dry matter into seed yield (low harvest index) was related to the lower seed yield in mustard when compared to canola under post-flowering water stress. Future breeding effort in mustard should be directed to improving its harvest index through modification of its morphology and yield components.

Hide Omae1, Ashok Kumar1,2, Yoshinobu Egawa3, Koichi Kashiwaba1 and Mariko Shono1

Water consumption and growth of two cultivars of Snap Bean (Phaseolus vulgaris L.) were measured under three temperature regimes in a glasshouse. at Ishigaki, Okinawa, Japan. ‘Haibushi’, a heat-tolerant cultivar and ‘Kentucky Wonder’, heat-sensitive cultivar, were grown under low (24/20°C, day/night), normal (27/23°C), and high (31/27°C) temperature. ‘Haibushi’ consumed more water than ‘Kentucky Wonder’ at low and normal temperature, while both consumed similar amounts of water at high temperature during the day and night time. ‘Kentucky Wonder’ showed changes in shoot extension depending on temperature. The shoots of ‘Kentucky Wonder’ extended more under normal than low temperature, and extension was reduced under high temperatures. ‘Haibushi’, on the contrary, maintained a consistent low shoot growth at various temperatures. This temperature-independent shoot growth may cause higher water consumption and contribute to heat tolerance.

Liusheng Duan, Zhaohu Li, Caihong Guan, Zhixi Zhai and Zhongpei He

The experiment was conducted with winter wheat (Triticum aestivum L.) cv. Jingdong 6 in PVC pots and under rainproof conditions in Beijing from 2000 to 2002. It was shown that the distribution of 3H2O in roots and flag leaf, characteristics of vascular bundle in primary roots and the internode below the spike, roots validity, transpiration rate and stomatal impedance of flag leaf were changed by water stress after flowering. The treatment of foliage spraying at early jointing stage using 450 g/hm2 HK, a plant growth regulator containing 3.3% Paclobutrazol and 16.7% Mepiquat Chloride as active components, were proved to release and compensate the harmful effects of water stress. Both the area of vascular bundle in primary roots and internode below ear were increased by HK, while the roots validity and the ability of water absorbing and transporting were promoted. In flag leaf, stomatal impedance was changed to maintain the transpiration rate and the water use efficiency of single wheat plant was higher. The rate and ratio of 14C-assimilates exporting from flag leaf were increased by the chemical regulation.

Ian C. Dodd1, Andrei A. Belimov2, Wagdy Y. Sobeih1, Vera I. Safronova2, Donald Grierson3 and William J. Davies1

The plant hormone ethylene is generally inhibitory to shoot and root growth. We tested two independent strategies to overcome ethylene-mediated growth inhibition when plants are grown in drying soil. Antisense suppression of plant ethylene synthesis was trialled to overcome the inhibition of tomato (Lycopersicon esculentum Mill.) leaf expansion. Rhizosphere bacteria containing the enzyme ACC deaminase (to decrease plant levels of the ethylene precursor ACC (1-aminocyclo-propane carboxylic acid)) were trialled to overcome the inhibition of pea (Pisum sativum L.) root growth. Two pea genotypes (cv. Sparkle and its E2(sym5) mutant) were grown at two levels of soil moisture in pots containing the plant growth-promoting rhizobacterium Variovorax paradoxus 5C-2. The bacterium stimulated root biomass by 20-25% irrespective of soil moisture regime, and whole plant biomass was stimulated also by 25% in plants grown in drying soil. Isogenic wild-type (WT) and ACO1AS genotypes of tomato were grown at two different soil moisture regimes. The ACO1AS genotype has decreased ACC oxidase activity and is thus less able to convert ACC to ethylene. Leaves of WT and ACO1AS plants elongated at the same rate under well-watered conditions. When plants were exposed to drying soil, both genotypes dried the soil to a similar extent but ACO1AS leaves had a 10% higher growth rate than WT leaves. The significance of these responses to plant yield are under investigation.

Simone Graeff1, Zhongxue Fan and Wilhelm Claupein1

Availability of water is one of the most limiting factors in crop production. Current technologies for measuring plant water status are limited. Considering plant and irrigation management it is essential to discriminate between water stress and various other possible biotic and abiotic stress factors.

A greenhouse study was conducted to determine specific reflectance wavelength ranges responsive to water stress in wheat. Pot experiments were carried out in Mitscherlich pots on a sandy loam over 10 weeks. Reflectance of wheat plants grown under five different water treatments ranging from 65 % field capacity to 26 % field capacity was determined once a week from the beginning of the 4th leaf stage until the 6th leaf stage. Reflectance measurements were performed at the 4th leaf of wheat plants with a digital camera under controlled light conditions. Reflectance was measured in different wavelength ranges in the visible and infrared spectra using various long-pass filters. Reflectance of wheat leaves changed significantly 9 d after induction of water stress at a leaf water content < 75 %. Reflectance patterns of 510780 nm, 5161300 nm, 5401300 nm were found most suitable to identify water deficiency regardless of the sampling date or growth stage. Reflectance pattern of water deficient plants were significantly different from those of other plant stresses. The results indicated that reflectance measurements may serve as a rapid, non-destructive approach to discriminate water stress from other biotic and abiotic stresses.

Mingcai Zhang, Liusheng Duan, Zhixi Zhai, Jianming Li, Xiaoli Tian, Baomin Wang, Zhongpei He and Zhaohu Li

The effects of PGRs, including benzyladenine (6-BA), uniconazole (S3307), brassinolide (Br), and abscisic acid (ABA), on leaf water potential (Ψleaf), chlorophyll (Chl), photosynthetic rate (Pn), PSⅡ photochemical efficiency (FV/FM) and seed yield of soybean (Glycine max Merr.), cv. Keng 5, were studied under water deficit. PGRs were foliar applied at R1 of 50, 100, 0.1 and 50 mg L-1 for 6-BA, S3307, Br and ABA, respectively. Two levels of soil moisture (–0.02 and –0.06 MPa for well-watered and water-deficit, respectively) were applied at R3. The results indicated that water deficit decreased biomass of stems and leaves, and induced yield loss significantly. PGRs treatments increased soybean yields both under well-watered and water deficit conditions, expect 6-BA under water deficit. However, the yields of PGR treatments under water deficit were still lower than that of the well-watered control. PGRs increased roots and nodule biomasses under both water conditions, except nodule biomass of 6-BA under water deficit condition. ABA and Br treatments increased stems and leaves biomass under well-watered condition. Water deficit significantly decreased Ψleaf, Chl, Pn, and FV/FM. Under water stress condition, PGRs treatments significantly increased water potential and FV/FM, and improved Chl (expect 6-BA) and Pn (except S3307 and Br) compared to the control. Under well-watered condition, PGRs treatments did not affectΨleaf, Ch1 and FV/FM in our experiments, but increased Pn. It was concluded that PGRs treatments minimized the yield loss coursed by water deficit.

PGR treatments increased soybean yields, roots and nodules biomasses both under well-watered and water deficit conditions compared with the control at the same water levels, expect 6-BA under water deficit. ABA and Br treatments increased stems and leaves biomass under well-watered conditions. Water deficit significantly decreased Ψleaf, Chl, Pn, FV/FM, resulted in significant yield loss. Under water stress condition, PGRs treatments significantly increased water potential and FV/FM, and improved Chl (expect 6-BA) and Pn (except S3307 and Br) compared to the control. Under well-watered conditions, PGR treatments did not affectΨleaf, Ch1 and FV/FM, but increased Pn. It was concluded that PGR treatments minimized the yield loss caused by water deficit.

Dawoud Habibi1, Masoud Mashdi Akbar Boojar2, Ali Mahmoudi1, Mohammad Reza Ardakani1 and Daryoush Taleghani3

In order to study the role of antioxidant enzymes superoxide dismutase (SOD), catalze (CAT) and glutathion peroxidase (GPX) in the drought resistance of five sunflower varieties an experiment was carried out under drought and control conditions. Results showed that the activity of these enzymes were significantly different between control and stress treatments. Results also showed there were no significant differences among varieties in the level of these enzymes. There was no relationship between drought resistance as measured by grain yield and the content of glutathion peroxidase, catalaze and superoxide dismutase among varieties. There was also no significant relationship among varieties between seed germination susceptibility to stress imposed by mannitol and antioxidant enzymes measured in the field. Therefore, selection for drought resistance by evaluation of SOD, GPX and CAT in these varieties was impossible.

Richard D. Johnson, Fred L. Allen and Carl E. Sams

The objective of this study was to evaluate the combinations of leaflet orientation and root morphology traits in soybean on water use characteristics. Three soybean varieties were chosen: USG 5601T, PI 416.937 and Williams 82 which differ in leaflet orientation and root morphology. Non-grafted plants of each variety, self grafts and reciprocal combinations of scion and rootstocks were made among the three varieties. Water use of each plant was measured on several successive days via a Dynamax Flow 32 Sap Flow Monitor™ when the plants were in the R5 stage of growth. USG 5601T (high leaflet orientation, normal root morphology) improved water use efficiency when used as a scion across the different rootstocks. The low leaflet orienting, fibrous root accession, PI 416.937 decreased water use efficiency when used as a scion across rootstocks, to produce the same seed yield. The intermediate leaflet orienting line, Williams 82 increased water use efficiency when grafted on the PI 416.938 rootstock but decreased water use efficiency when used as a scion on the USG 5601T rootstock. This study provides further evidence of the role of leaflet orientation in water use efficiency and a possible drought tolerance trait in soybeans. The high leaflet orientation phenotype had equal water use efficiencies when grafted onto the fibrous or the normal rootstocks. There was abundant soil moisture through the 2003 growing season in Knoxville. It is not known whether the fibrous root trait would have been beneficial during a moisture stress season.

S. Robin1. R. Manimaran1, R. Pushpa1, P. Jeyaprakash2, S. Mahendran3, H.R. Lafitte4 and G.N. Atlin4

Moisture stress occurring in the reproductive stage of the rice crop is often considered as the most devastating factor limiting production. Genetic analysis of reproductive stage moisture stress tolerance was the subject of this study. Results from the earlier mapping populations and germplasm screening revealed that phenology difference in the test entries can influence the performance of lines under natural moisture stress conditions. Hence, a drought tolerant landrace known for its long-term adaptation in the target drought prone ecosystem was crossed with a high yielding variety of same phenology, IR64 to develop sets of near flowering lines through recombination breeding. The population comprising 214 lines differed significantly in grain yield under stress. Three subsets of lines with three ranges of heading days viz., 59-64, 65-70 and 71-76 were constituted. Within individual subsets no correlation existed between heading days and grain yield under stress though within the range, grain yield exhibited a normal distribution. These subsets of lines similar in duration are subjected for further analysis on molecular dissection of physiology of reproductive stage stress tolerance.

Jason Brand and Tony Leonforte

Field trials were sown in 2003 to investigate the effect of seed source, seed size and frost damage on emergence and grain yield. Only the frost damaged seed source resulted in a significant reduction in emergence and grain yield. However, if seeding rates for this treatment were increased so that plant emergence was optimum for Kaspa it could be expected that grain yields would be similar to other treatments. This research also confirmed previous studies that seed size has little effect on grain yield and highlighted that provided optimum plant densities are reached grain yield will be unaffected.

Mohammad Reza Jahansooz 1, Isa Yunusa2 and David Coventry3

In dryland regions such as the cereal zone of South Australia, the most limiting biophysical resource is water. Field experiments were conducted to quantify the use of soil-water and production of biomass in sole crops and crop mixtures in a study designed to evaluate the efficiency of intercropping in the use of this natural resource. Water-use and water use efficiency (ratio of biomass to water-use) for sole wheat were greater than for sole chickpea, but were similar for sole wheat and mixture. The land equivalent ratio showed no advantage or disadvantage of intercropping over sole crops. However, the water in the soil with the mixture was greater than the sole wheat. The presence of legumes in the mixture probably increased the N pool of the soil and might enhance the growth of the current and subsequent crops in an environment where the soil is poor in nutrient content.

Renick Peries1, Bruce Wightman1, Chris Bluett1 and Abdur Rab2

The area under broad acre raised bed crops in southern Victoria has increased from 300ha in 1997 to 35,000ha in 2003. The enhanced crop yield on raised beds compared to traditional ‘flat’ cropping results from better drainage and differences in soil structure below the depth of tillage resulting in an improvement in the plant available water (PAW) capacity. These differences in soil physical properties assist crops to survive the extreme weather events and achieve yield stability across years.

Yoichiro Kato1, Satoshi Hayashi2, Akihiko Kamoshita3, Jun Abe4, Kentaro Urasaki5 and Junko Yamagishi6

Rice production in uplands has a low yield due to limited water availability, but it has a great potential to saving water. Field experiments were conducted to compare grain yield (GY) in flooded lowland (FL) and in uplands with three water regimes (rainfed [RU], irrigated [IU] and water deficit during panicle formation stage [WD]) in Japan from 2001 to 2003 by using three cultivars (Yumeno-hatamochi [YHM]; Lemont [LMT]; Nipponbare [NPB]). GY of NPB in RU equalled that in FL (only 6% reduction) in 2003, when it amply rained before heading, which suggested that it was possible to achieve high yield in favourable upland conditions as in lowlands in temperate climate conditions. In 2002 with less frequent rainfall, GY in RU was 21% less than GY in 2003. Among uplands in 2003, GY in IU was 9% higher than in RU, while that in WD was 37% lower than in RU. There was genotype by water regime interaction in GY, with NPB yielding highest in FL and LMT yielding highest in all upland conditions. These results suggested that the amount of water supply greatly affected GY in uplands and there were large potential for cultivar improvement adapted to both water deficit and favourable upland conditions.

H.O. Ogindo and Sue Walker

Seasonal water content fluctuation within the effective rooting depth was monitored during the growing season for an additive maize-bean intercrop (IMB), sole maize (SM) and sole bean (SB). Comparisons were made at progressive depths of extraction 0-300 mm; 300-600mm and 600-900 mm respectively. These enabled the understanding of water extraction behavior of the cropping systems within the topsoil, which is normally influenced substantially by soil evaporation under semi-arid conditions. The additive intercrop had almost similar seasonal extraction pattern as the sole crops. This was against expectation given its higher plant density. It was concluded that the early and larger canopy modified the microclimate, reducing the soil water used as surface evaporation and increasing the overall efficiency of the system. During both 2000/01 and 2001/02 seasons the water extraction limits (DUL-CLL) were determined. The potential extractable water by the cropping systems were: 121 mm (IMB), 114 mm (SM) and 103 mm (SB). These differences reflected the atmospheric demand for water, soil profile and cropping system characteristics. An examination of the seasonal soil water extraction for the 0-900 mm profile depth among the systems showed minor differences. Layerwise examination showed that the cropping systems water extraction was influenced by factors imposed upon it by the nature of both the above and below ground growth as well as competition for soil water resource.

NageswaraRao C. Rachaputi, Graeme Wright, Stephen Krosch and Jeff Tatnell

Aflatoxin contamination in peanuts is a major food safety issue world-wide and costs the Australian peanut industry (processors and growers) between $5-10M p.a. via analytical costs and associated sorting losses. This paper describes an aflatoxin monitoring and management strategy developed by researchers from the QDPI&F at Kingaroy to minimise pre-harvest aflatoxin contamination in rainfed peanuts grown over 11 peanut farms in the Burnett District of Queensland during the 2000-01season, which was rated as one of the most severe aflatoxin risk seasons. According to industry statistics, 60% of commercial loads tested positive for aflatoxin contamination while there was substantial reduction in aflatoxin from farms that adopted the aflatoxin minimisation program implemented by QDPI&F (only 22% of loads positive)

Mike T.F. Wong1 and Senthold Asseng2

A recommendation of precision agriculture to lift profits and minimise the off-site impact of farming, is to zone paddocks into areas of similar soil properties and thus similar yield potential and to implement more site-specific management. One problem sometime faced during zoning is ambiguity due to climate variability, which leads to temporal variability in both yield and the yield classification membership of each zone. In extreme cases, a zone may fall in the high yielding class in one year and in the low yielding class in another. These fluctuations are sometime observed even with the relatively short history of yield mapping in Western Australia. Lack of longer-term yield mapping data is currently a shortcoming and prevents us from determining with reasonable confidence the probability of membership of a zone to a particular yield classification. We used crop simulation in the APSIM framework to overcome this problem and to account for the effect of climate variability on yield performance. The simulations reproduced wheat yield classification measured in the last few years well and showed that temporal variations in both yield and in zone classification would occur in all zones due to interactions between seasonal rainfall, soil moisture retention properties and fertiliser use. In spite of these fluctuations, some zones are more likely to perform well whereas others are more likely to perform poorly based on likely conditions during crop growth. Our findings suggest that the concept of assigning a probability of membership of a zone to a yield classification may be more appropriate than assigning definite classifications to these zones. This property is well suited to fuzzy classification, which assigns a degree of membership to a zone rather than a rigid membership. Actual zone classification for a particular year can be determined when the actual conditions for wheat growth are known.

Nick Wachsmann1, Rob Norton1, David Jochinke1 and Sue Knights2

Two field experiments were undertaken in the Victorian Wimmera to assess the effect of sowing time on the development, growth and yield of safflower (Carthamus tinctorius). The sites had different amounts of stored soil water at sowing. For the latitude at which the experiments were conducted and cultivar Sironaria, the mean thermal duration of 713 °Cd8 predicted the flowering date of all observations with a standard deviation of 2.8 d, even though flowering dates were 22 – 24 d earlier in the warmer season in 2000, compared to 2001. Yield declined at a rate of ~0.04 t/ha (5%) for each week that sowing was delayed after mid July at the drier site. On the wetter site, yields were similar for the July, August and September sowings (mean = 4.18 t/ha), but declined to 3.41 t/ha as the delay continued into October. The main yield component affected by delayed sowing was capitula number, suggesting that some of the yield loss could be overcome by increasing seeding rates for later sowings.

Sukartono1, Jaikirat S. Gill2, Mansur Ma'shum1, I.G.M. Kusnarta1, Mahrup1, Blair McKenzie2,3 and Judy Tisdall2

In semi-arid tropics, unreliable water supplied from the erratic rainfall restricts production of the primary rice crop (Oryza sativa), and of secondary crops grown in rotation with rice. Various secondary crops grown under a range of new land and water management systems were compared with secondary crops grown under the conventional system (gogorancah) on Vertisols in two different climatic regions. At each site, the yield of soybean (Glycine max) grown after rice on permanent raised beds with or without tillage was not significantly different from that with gogorancah (flat land with tillage), or on flat land with no tillage (mean 1.3 t/ha in 2002; 1.6 t/ha in 2003). In 2003, chilli (Capsicum frurescens) after onion on permanent raised beds gave the highest economic revenue of Rp. 7.3 x 106/ha (Site 1 - Wakan) and Rp. 4.3 x 106/ha (Site 2 - Kawo); followed by intercropped tomato-mungbean (Lycopersicon esculentum-Vigna radiata) after intercropped maize-soybean (Zea mays-Glycine max) on wavy raised beds with Rp. 4.03 x 106/ha (Site 1) and Rp. 3.6 x 106/ha (Site 2). The lowest financial return of less than Rp. 1.5 x 106 /ha was from soybean (Glycine max) on each system. Thus, on rainfed Vertisols of Southern Lombok, at current prices, the secondary crops of chilli on permanent raised beds without tillage, or intercropped tomato-mungbean on wavy raised beds without tillage, could successfully replace soybean on the conventional gogorancah.

David Jochinke1, Nick Wachsmann1, Rob Norton1 and Sue Knights2

The effect of four sowing rates on the growth and yield of safflower (Carthamus tinctorius) was investigated at two sites in the Victorian Wimmera. One site was rainfed (RF), whilst the other pre-watered (PW) prior to sowing. By the start of branching, increasing sowing rate between 9 and 35 kg/ha had improved biomass production by about threefold at both sites. Individual plants subsequently compensated for low sowing rates by growing larger. This resulted in the biomass at maturity (mean; RF = 7.1, PW = 17.3 t DM/ha) and number of capitula/m2 (mean; RF = 196/m2, PW = 353/m2) being similar for all treatments within each site, although there were substantial differences between the two sites. Seed number per capitulum (13.4 to 6.7) and seed mass (28.6 to 24.2 mg) generally declined with increasing sowing rate at the drier site (RF) and total seed yield declined accordingly from 0.70 (9 kg/ha) to 0.36 t/ha (35 kg/ha). Sowing rate had a smaller relative effect on seed number per capitulum (35.1 to 28.3) and no significant effect on seed mass (mean = 38.7 mg) at the wetter site (PW). The seed yield of all treatments was similar at this site (mean = 4.3 t/ha).

John Sturgess1, Giles Butler3 and Kym McIntyre2

Final grain yield and associated grain quality are influenced by field plant population of commercial barley crops. Anecdotally, commercial plant populations range from 0.5 to 1.0 million plants per hectare, and are often at the lower end of the range, limiting potential yield and having a negative effect on grain quality. In 2002 and 2003 replicated barley yield and grain quality trials with different plant populations were conducted in Southern Queensland and Northern New South Wales, with different plant populations. Each trial had six entries of released or soon to be released barley cultivars, planted at targeted field plant populations of 0.4, 0.8, 1.2, 1.6, and 2.0 million plants per hectare. Grain quality parameters measured were plump grain, screenings and protein. The different plant populations had a significant effect on yield, protein, plump grain and screenings. Further trials are being planned for 2004 to clarify this response with regard to specific barley cultivars.

Jeremy Whish1

In recent years many sorghum producers in the more marginal (<600 mm annual rainfall) cropping areas of Qld and NNSW have utilised skip row configurations in an attempt to improve yield reliability and reduce sorghum production risk. But will this work in the long run? Under what conditions is the use of a skip row configuration the optimal choice?

This paper describes long-term simulations conducted on soils of different water holding capacities (PAWC) and with 3 different initial starting water conditions. The results show an interaction exists between starting water conditions and soil (PAWC) that suggests crops grown on soils with a low water holding capacity benefit from the use of skip configurations.

Mobin-ud-Din Ahmad1, Ilyas Masih2 and Hugh Turral1

Joe Jacobs, Graeme Ward and Frank McKenzie

A study determined the effect of rate of dairy effluent application on dry matter (DM) yield, nutritive characteristics and mineral content of a perennial pasture following harvesting for silage. Rates of effluent applied were 0, 15, 30, 45, 60 and 75 mm/ha. The effluent applied contained high levels of potassium (K) (445 kg/ML) and sodium (Na) (508 kg/ML) and moderate levels of nitrogen (N) (155 kg/ML). With effluent, DM yields at the first grazing where higher (P<0.05) than the control treatment (0 mm/ha). When effluent was applied at rates of 60 and 75 mm/ha, DM yields were higher (P<0.05) than for all other effluent treatments. At the second grazing, effluent treatments of 30mm/ha and above resulted in higher (P<0.05) DM yields than the control treatment. Pasture crude protein (CP) was higher (P<0.05) at the first grazing where effluent had been applied at rates of 30 mm/ha and higher, whilst by the second grazing this effect was only apparent at rates of 60 and 75 mm/ha. The concentration of K at the first grazing was higher (P<0.05) when effluent was applied, whilst both phosphorus and Na concentration were higher (P<0.05) at application rates of 30 mm/ha or higher.

This study indicates the potential to use dairy effluent to increase pasture DM yield during late spring and summer in dryland areas of southern Victoria. Further research is required to determine the impacts of long term dairy effluent use on pasture composition and environmental factors such as soil structure.

Mark N. Callow and Sarah J. Kenma

This study evaluated the water use efficiency (WUE) of milk and forage production from a range of temperate and tropical forages on 5 dairy farmlets and a small field plot study located at Mutdapilly Research Station in south east Queensland. The feedbase had a greater affect on the WUE of milk production than the volume of irrigation and rainfall received. For instance, the high irrigation, high quality temperate pasture based (M4) farmlet received an additional 36% volume of water when compared to the crop based feedlot (M5) farmlet, though milk production from forage was 30% less. This difference in efficiency occurred in part from the superior WUE of the irrigated maize (Zea mays) summer crop with 3.4 t DM/ML and lucerne (Medicago sativa) winter crop with 2 t DM/ML, and the increased efficiency of herbage utilisation from the conservation of crops compared with grazing of pastures. The raingrown (M1) farmlet’s WUE of milk production was relatively high, however forage production was limited and consequently milk yield was comparatively low. The range in herbage WUE associated with forage species was consistent between the farmlet and small plot studies. Farmers are challenged with striking a balance between selecting forage types that optimise WUE and those that increase diet quality.

Alister Lawson, Kerry Greenwood and Kevin Kelly

We have recently commenced a 3-year experiment to determine the water use efficiency of annual and perennial forage systems used in the irrigated dairy industry in northern Victoria. The forage systems will be grazed and/or mown for hay, using best management practices recommended for local farmers. The forages are perennial ryegrass (Lolium perenne) and white clover (Trifolium repens), tall fescue (Festuca arundinacea) and white clover, lucerne (Medicago sativa), Persian clover (Trifolium resupinatum) and Italian ryegrass (Lolium multiflorum), subterranean clover (Trifolium subterraneum) and Italian ryegrass, and a double crop system of oats (Avena sativa) and millet (Echinochloa crusgalli). All six treatments will be flood irrigated. The seventh forage treatment is subterranean clover and Italian ryegrass under spray irrigation. Measurements will include dry matter removed by grazing or haymaking, forage quality (energy, protein and fibre contents), irrigation water applied, run off, and water content of the soil profile before and after irrigation. The data will be used to compare the production, water use and water use efficiency of the forage systems. Comparison of water use with crop water requirements predicted from weather data will enable validation of crop factors for northern Victoria.

Daryoush. F Taleghani1, Ghasem Tohidlou1, Javad Gohari1, Davood Habibi2, Yaghob Sadeghian1 and Mahmood Mesbah1

Water is the most important factor in agriculture in Iran. Surface Irrigation system (SIS) is used in most crops such as sugar beet. Irrigation Efficiency (IE) has been estimated about %30 and it is too low in Comparison with other systems. This study was carried out to improve IE in SIS in sugar beet crop during 1999-2001 in sugar beet seed Institute (SBSI) of Karaj – Iran. Six plant spacing & irrigation methods investigated as follow:
1-Single rows 60cm spacing, all furrows irrigated (SR 60 A) (check).
2-Single rows 60cm spacing, every other furrow irrigated (SR60 E).
3-Single rows 50cm spacing, all furrows irrigated (SR 50 A)
4-Single rows 50cm spacing, every other furrows irrigated (SR 50 E).
5-Double rows 100cm distance between furrows and row spacing 60 x 40cm (DR 100).
6-Double rows 90cm distance between furrows and row spacing 50 x 40cm (DR 90).

The results indicated sugar yield (8.17 t/ha) and water productivity (682 g/m3) in treatment No.6. In this treatment water consumption was about 12000 m3/ha. The lowest water productivity (530 g/m3) belonged to treatment No.1 (check), whereas sugar yield and water consumption were 7.4 t/ha and 14000 m3/ha, respectively.

Anna Rita Rivelli1, Rossella Albrizio2, Stella Lovelli1 and Michele Perniola1.

The effect of water deficit on muskmelon and pepper leaf water potential, gas exchange and water use efficiency was evaluated. Both species were submitted to three watering treatments in open field conditions: irrigation only at transplanting (the control), irrigation at transplanting and fruit-setting, and full irrigation restoring 100% maximum crop evapotranspiration (ETc). Leaf water potential (ψl) in pepper markedly decreased with increasing evaporative demand during the day and it was lower in the stressed than in well-watered plants. In contrast, muskmelon maintained a near constant ψl from 10:00 h to 16:00 h both in stressed and in well-watered plants. Muskmelon exhibited greater net assimilation and leaf water use efficiency than pepper. With varying air vapour pressure deficit, stomatal conductance of muskmelon markedly changed while it varied slightly in pepper. Above-ground total dry biomass was much higher in muskmelon than in pepper and total biomass water use efficiency in muskmelon was about 2-fold higher than in pepper (on average 1.6 and 0.82 kg m-3, respectively), demonstrating a greater efficiency of the former in using water.

Joe Jacobs, Graeme Ward and Frank McKenzie

A study determined the effect of different irrigation strategies on dry matter (DM) yield, water use efficiency (WUE) and marginal water use efficiency (MWUE) of perennial ryegrass (Matrix), millet and two forage brassicas (Hunter and PG545). Irrigation treatments were dryland control (A), irrigated to 100% (B) and 50% (C) of estimated requirements each week and 50% (D) of estimated requirements every second week.. At each irrigation level, nitrogen (N) was applied at either 50 or 100 kg N/ha after each grazing. Irrigation treatments were imposed from early November until late March.

Where species were fully irrigated (B) there were higher (P<0.05) DM yields than for the dryland treatment (A). For the ryegrass and two brassica species there were also higher (P<0.05) DM yields when irrigated at 50% of requirements on a weekly basis (C). Application of N at the higher rate also led to higher (P<0.05) DM yields. Total WUE was higher (P<0.05) for the dryland treatment (A) than for the fully irrigated treatment (B) for all forages. For dryland treatments (A), millet had a higher (P<0.05) WUE than all other species. Application of N at the higher rate also improved (P<0.05) WUE for all species. The MWUE were similar for all irrigation treatments across all forages.

The forages used in this study all responded to irrigation, with the degree of response dependent upon volume of water applied. Further work is required to define the optimal irrigation strategies to maximise DM yield and WUE.

Joe Jacobs, Graeme Ward and Frank McKenzie

The effect of dairy effluent application rates on dry matter (DM) yield, nutritive characteristics and mineral content of millet was determined. Effluent rates were 0 (A), 15 (B), 30 (C), 45 (D), 60 (E) and 75 (F) mm/ha. The second pond effluent contained high levels of potassium (K) (445 kg/ML) and sodium (Na) (508 kg/ML) and moderate levels of nitrogen (N) (155 kg/ML). Treatments C, D, E and F increased (P<0.05) DM yield at the first grazing compared to the zero application rate (A). By the second grazing, DM yield of A was lower (P<0.05) than treatments D, E and F. Apart from the lowest rate of effluent application (B), all other levels led to an increase (P<0.05) in total DM yield compared to the control (A).

Michele Rinaldi and Alessandro Vittorio Vonella

Southern Italy is an important area for sugar beet cultivation. The aim of this research is to measure the capability of sugar beet to convert water in dry matter and sucrose when subjected to two experimental factors: sowing date - autumn (October-December) and spring (March) - and irrigation regime - optimal and reduced (respectively with 100 and 60 % of actual evapotranspiration). Data sets from three experiments of spring sowing and three of autumn sowing were used to calculate water use efficiency of dry matter (WUEdm, plant dry matter yield at harvest vs. seasonal water use ratio) and of sucrose (WUEsuc, sucrose yield vs. seasonal water use ratio).

The results indicated comparable WUEdm values for sowing dates and irrigation regimes (on average, 3.08 g of dry matter per kg-1 of water used). A better WUEsuc was observed in the autumn sugar beet (1.23 vs. 0.88 g of sucrose per kg-1 of used water) for a root sugar content higher than in the spring sowing. WUEdm and WUEsuc results related to the length of crop cycle expressed in growth degree days and mainly to the length of the period from full cover canopy to harvest, when root dry matter and sucrose accumulation is maximum. The results showed a certain stability of WUEdm and a superiority of WUEsuc of autumnal sown beet.

Richard J Martin1, Derek R Wilson1, Peter D Jamieson1, Peter J Stone2, Jeff B Reid3 and Richard N Gillespie1.

Farmers need to know when to irrigate, how much water to put on, and the yield penalty if the crop is not irrigated. To develop answers to these questions we use a simple model developed 30 years ago that relates crop yield to maximum potential soil moisture deficit (MPSMD). MPSMD is calculated from potential evapotranspiration, rainfall and irrigation data. To calibrate the model for different crops, we use a rainshelter that covers the experiment automatically when it rains. Crops grown in the rainshelter have included wheat, oats, sweet corn, carrots, peas and white clover for seed production. Six to twelve irrigation treatments, based on timing or intensity of drought, were set up in each of the experimental crops. Total or economic yield of all the crops tested, with the exception of white clover seed, decreased linearly as the MPSMD increased, regardless of the timing of drought. The slope of the regression line between yield and MPSMD is the yield loss with increasing deficit. In some crops, very small deficits caused problems through excessive vegetative growth. The information from these experiments has enabled clear irrigation scheduling information to be given to growers. It has also been included in computerized decision support systems being developed for arable and vegetable farmers in New Zealand.

Pu Wang, Yaping Wei, Hui Ju and Danxi. Zhou

Water scarcity makes it imperative to develop water-saving irrigation systems on the North China Plain. A field experiment was carried out for winter wheat to evaluate the effects of single irrigations at different times on the crop canopy development, yield and WUE. Four irrigation times/treatments are adopted: zero irrigating (I0), irrigating at regreening (post winter) (I1), shooting (tillering) (I2) and booting stage (I3). Irrigating at regreening stage produced a shady canopy architecture with many ineffective tillers and large leaf area, which led to more water consumption and low photosynthesis after anthesis. Thus the yield and WUE was comparatively low. Comparing with I1, irrigating at booting stage resulted in water deficit in the early growth stage of winter wheat. This brought about a canopy architecture with appropriate effective tiller number, small leaf area, short basal and long upper internodes, which was helpful to light interception and reduced water consumption in the early stages. These characteristics improved the photosynthesis and dry matter production after anthesis. Finally the yield, WUE, and harvest index were significantly increased. The performance of winter wheat irrigated at shooting stage was between that of other two irrigated treatments. The results showed that canopy architecture of winter wheat could be changed by controlled irrigation time. Late irrigation could save water and obtain high yield through modifying canopy architecture to achieve high photosynthetic rate and low water consumption. Booting stage was the optimal time to irrigate with a single irrigation in this area.

Graeme Wright1, Andrew Robson1 and Greg Mills1

Remote sensing imagery of irrigated peanut crops using simple airborne digital video camera systems offers growers and consultants a cost effective technique for the assessment of ‘spatial’ variability in crop performance. Images of near infra-red reflectance taken from irrigated peanut crops (pivots) in southern Queensland showed major variability arising from crop stress, which was most likely a result of poor irrigation distribution and/or poor water infiltration. Near infra-red reflectance from peanut crops taken at approximately 4 to 6 weeks prior to harvest was also shown to be highly correlated with final pod yield, and offers a potential yield forecasting technique for growers and industry. The close association also allows an assessment of the magnitude of the yield deficit resulting from spatial variability (or ‘yield gap’).This provides growers and consultants with a useful method to calculate the economic impact of reducing the ‘yield gap’ in their own fields and has potential to be utilised as a strategic tool for identifying problems and improving various aspects of crop management.

Simon C. White and Steven R. Raine

Irrigation water restrictions in the cotton industry have increased the focus on improving water use efficiency. Regulated deficit irrigation (RDI) has been found to improve the water use of efficiency of cotton under drip irrigation. Partial rootzone drying (PRD) has been commercially implemented in grapevines and found to increase the water use efficiency for a variety of crops. This paper investigates the potential to improve cotton water use efficiency using RDI and PRD strategies applied with lateral move machines. A range of RDI treatments (71 % - 100 % evapotranspiration replaced) and a PRD and non-PRD treatment were applied to a crop of Sicot 180 during the 2002/2003 cotton season. No yield reduction was found between the fully irrigated and the 50% RDI treatment that received 1.05 ML/ha less water. Crop WUE was found to increase from 0.94 bales/ha to 1.17 bales/ha as the irrigation water applied was reduced from 100% to 79 % of evapotranspiration replacement. No difference in physiological growth and yield was found due to the implementation of the PRD treatment. Further work is required to confirm the RDI results, further explore the application of PRD strategies using these machines, and to more fully understand the physiological response of cotton to imposed soil moisture deficits applied either by volume (RDI) or space (PRD).

Kang-Ho Jung1, Wontae Kim2, Seung-Oh Hur3 and Sangeon Ha4

A shortage in soil moisture for crops prevents plants from growing normally. Moreso, lack of moisture suppresses nutrient availability. On the other hand, excessive nutrients make water more scarce. Thereby, water and nutrients should be managed mutually to minimize yield reduction under drought conditions.

This research aimed to find out the response of red pepper to fertilizer, and to improve nutrient management to increase yield production under several soil moisture deficit conditions. Irrigation started at three soil matric potential levels, -30, -50, and -80 kPa in 2002 and at four soil matric potential levels, -30, -50, -100, and -150 kPa, in 2003. The amount of fertilizer applied was at four levels: recommended fertilization with soil test (RFST), 50% of RFST, 150% of RFST, and no-fertilization. Yield at -30 kpa-irrigation and 150% RFST plot was the largest, and it was regarded as 100 at yield index. At -30 kPa-irrigation, yield increased linearly with fertilization amount. At -50 kPa-irrigation, yield was largest at RFST. Yield index at -80 kPa-irrigation was lower than 70 at no-fertilization but increased to 85 at RFST. Fertilization did not contribute to increasing yield under irrigation condition below -100 kPa. The RFST fertilization for red pepper in Korea was useful at higher than -100 kPa soil moisture potential. However, fertilizer application needed to be reduced at lower water than -100 kPa.

Kurt Thelen, Mark Bernards and Michael Staton

Five irrigation schedules based on soybean growth stage and soil water deficit were evaluated. Soybean varieties responded similarly to the irrigation treatments, i.e., the variety x irrigation treatment interaction was not significant (p=0.05). Average yields were equal between the full season, flowering (R1-R2), and pod elongation (R3-R4) treatment timings, at about 3025 kg/ha. Waiting until seed fill (R5-R6) to begin irrigating cost approximately 335 kg/ha in yield (2690 kg/ha), and plots that were not irrigated (except to keep soil moisture above the 75% soil water deficit level) produced yields of only 1950 kg/ha. Yields averaged across all five irrigation treatments of seven of the varieties were equal, 2755 to 2950 kg/ha. Soybean aphids were present in large numbers between late July and mid-August. Although the trend showed higher aphid populations in irrigated plots, there was not a statistical difference between irrigation treatments. Based on three years of data, it appears that maximizing soybean yield in the Northcentral Corn Belt is dependent on maintaining adequate soil moisture beginning at full bloom (R2) or beginning pod (R3), provided that the soil water deficit (SWD) does not exceed 75% prior to that growth stage.

Joung-Du Shin, Jong-Sik Lee, Won-II Kim, Goo-Bok Jung, GunYeob Kim, Jin-Ho Kim and Sun-Gang Yun

This study was carried out to determine the suitable irrigation period and to assess the proper fertilization level with irrigation of alternative water during transplanting season in rice paddy for drought periods. Irrigation periods of alternative water as the discharge water from the municipal wastewater treatment (DMWT) were 10, 20, 30 days and continuous irrigation during rice cultivation after transplanting. Also, fertilization was applied with 3 levels such as amount of fertilization after soil test (FAST), 50% of fertilization after soil test (FAST50%) and non-fertilization (Non). It was observed that plant growth and yield characteristics at 20 days of alternative irrigation period with application of FAST50% were relatively similar to the control. For the surface water quality, it appeared that ECi and SAR values of DMWT irrigation were twofold higher than those of groundwater irrigation regardless of fertilization levels. According to the irrigation periods, there were not significantly difference between 10 and 20 days, but ECi and SAR values of surface water were highest at 30 day irrigation periods during initial rice growing stages. Overall, it might be considered that there is the possibility of irrigating DMWT with application of FAST 50% for 20 days of drought periods at rice transplanting season. Furthermore, efficiency rate of alternative irrigation water for 20 days of drought period was 32.7% relative to the total annual irrigation water for rice cultivation.

Joung-Du Shin, Sang-Won Park1, Won-II Kim, Jong-Sik Lee, Goo-Bok Jung and Sun-Gang Yun

This experiment was conducted to investigate the available alternative irrigation waters for drought periods in the agricultural land. The treatments were consisted with the discharge water from industrial wastewater treatment plant (DIWT), the discharge water from municipal wastewater treatment plant (DMWT) and ground water as the control. In the chemical compositions of alternative water resources, it appeared that concentrations of the Ni2+ and SAR in DIWT and CODcr concentration in DMWT were over the reuse criteria of other countries for agricultural irrigation. SAR value in soil is increased with prolonging the irrigation periods at head forming stage, but not significantly difference except for 30days of irrigation period at harvesting time for DIWT. However, it was not significantly difference along with irrigation periods through the growth stages for DMWT as compared to that of the groundwater. However, ECe value in upper layer soil (0-15cm) irrigated with DIWT was over twofold less than its DMWT except for 10 days of irrigation period. For the Ni2+ concentration in upper layer soil irrigated with DIWT, it was increased with prolonging the irrigation period at head forming stage, but dramatically decreased and almost constant in all the treatments at harvesting time. Therefore, it might be concluded that there was potentially suitable to irrigate the discharge water from municipal wastewater treatment plant for 20days of drought periods with cultivating the Chinese cabbage.

Rose Roche1,2, Michael Bange1, Stephen P. Milroy3, Grant Roberts1 and Greg Constable1

There is strong interest in the Australian cotton industry to develop systems that reduce the time to maturity (i.e. shortening the time between planting and harvest), which can lead to savings in irrigation water and late season insect pest spray costs. However, there is generally a trade off in seeking earlier maturity in that for each day that maturity is brought forward, there is a yield loss (0.6 to 1.0 bales/ha per week). This paper presents results of ongoing studies which aim to integrate different approaches to reduce the time to cotton crop maturity and increase efficiency of resource use (eg. water). Three field experiments were conducted over two seasons to assess the impact of maturity and yield of varieties differing in their crop maturity grown in systems with different sowing times, row configurations and irrigation management. Across the two seasons there was no consistent effect of variety, plant population and sowing time on lint yield or maturity. Delaying sowing time had the greatest effect on maturity (15 d shorter), without penalising yield.

Ravinder Kaur and Rashmi Malik

A field scale, user-friendly Decision Support System (DSS) named IMPASSE (IMPact Assessment & management of Saline/ Sodic Environments) has been developed for assessing impacts of conjunctive water use practices on soil salinization and crop yield reductions. Such tools provide a time-efficient and cost-effective means for maintaining sustainable agriculture. The DSS has been extensively tested and validated on 11 fields in 6 villages of Gurgaon district and on controlled experimental fields in Sampla experimental station of Karnal district in Haryana (India). The average relative wheat yield reductions due to salinity, under various saline water-irrigation treatments, could be realistically simulated by the DSS. Proposed DSS based long-term (2001-2010) impact assessment of existing (cyclic) and 8-alternate (cyclic and blending) conjunctive water use strategies, in a test farmer’s field, suggested that cyclic mode was superior to the blending mode of irrigation during both Paddy and Wheat growing seasons. It further suggested that a change in the conjunctive water use plan for the Wheat growing season was associated with minimum additional demand for fresh water supplies, reduced root zone salinizations/ sodifications and 3-4% higher long term returns to the test farmer.

Ghasem Tohidloo1, Saeed Ghalebi2, Daryoush Taleghani3, Seyed Yaghoob Sadeghian3 and Mohammad Ali Chegini3

A line-source sprinkler irrigation trial was carried out to study water use efficiency (WUE), photochemical efficiency of photo system II (PEPS II), yield and quality of two different sugar beet varieties (IC1 and 9597*7233) at a site with clay-loamy soil and low rainfall (semi-arid area, about 250 mm rainfall annually) in Kraj-Iran, 2001-02. Irrigation water was applied when 50% of soil available water was used by plants from the soil to a depth of 60 Cm closed to the sprinkler line. 4 irrigation treatments were considered on the basis of water distribution form from sprinkler line between sugar beet rows. Water content in soil was measured by a time domain reflectometer (TDR).

WUE increased significantly with decreasing water consumption but no difference was found between the varieties. Root and shoot weight, sugar content and yield, and PEPS II were varied significantly among irrigation treatments.

Saeed Zehtab-Salmasi1, Aziz Javanshir1, Reza Omidbaigi2, Houshang Alyari1 and Kazem Ghassemi-Golezani1

Field and greenhouse experiments were carried out in order to determine the effects of water supply and sowing date on water use efficiency of anise ( Pimpinella anisum L.) at the agricultural research station of Tabriz university in Iran. The results indicated that WUE of dry matter production decreased, while WUE of essential oil production was not affected by the amount of soil available water in a greenhouse trial. It was concluded from the field study that for higher grain and essential oil production, and for efficient use of water, anise must be sown early in the spring (April 4 to 16) in Tabriz. Water deficit during stem elongation and umbel appearance reduced WUE in producing dry matter and essential oil, but irrigation disruption during grain filling period had no significant effect on WUE of anise.

Aly I.N. Abdel-Aal1 and Mohamed M. Moukhtar2

In the new virgin area in the extreme part of the southern Nile Valley of Egypt it is very important to establish agriculture free from pollution. The aim is to study a suitable land and water resource management plan for crop production under local climatic conditions. The study was conducted during summer 2001 and 2002; the design involves water application treatments (I1: Water Requirements (WR)+20%, I2: WR+10%, I3: WR only, I4: WR -10% and I5: WR - 20%. The soil texture varies from sandy to sandy loam; with many rock fragments and gravel differing in shape, size and colour evident on the soil surface and through the whole profile. The soil taxonomy could be classified as Typic xerofluvants, sand loam mixed, Hyper thermic. Plant height, pods numbers, weight of plants and seed weight of soybean was highly significantly related to irrigation water applied. The highest yield was obtained with the highest amount of applied irrigation water.

Mohamed M.Moukhtar1, El-Sayed El-Hadidy2, and Mohamed .A.B.El-Shewikh3

Drainage problems in northeastern parts of Egypt are associated with low-lying areas, clay to heavy clay soils with low permeability, saline to saline-sodic soils, shallow and salty ground water, often under artesian pressure. This study examines crop production as affected by drainage in conjunction with subsoiling types to maximize crop production and prevent soil deterioration. The field trial was three-drain spacing treatments, 15 m., 30 m. and 60 metres in conjunction with parallel or net subsoiling. The successively cultivated crops were wheat, sorghum, and clover.

Wheat plant height, number of tillers and dry weight of plant were significantly increased with decreasing drainage spacing, and subsoiling method was highly significant. The net (cross hatched subsoiling) treatments are more effective than parallel treatments. Total yield of wheat also increased with decreasing drain spacing and subsoilng treatments. Sorghum plant height, dry matter and yield show a highly significant increase with decreasing drain spacing and subsoiling type treatments. The best treatment is net subsoiling combined with 15 m drain spacing. Clover fresh or dry weights at second or third cut are increased with decreasing drain spacing treatments increases with net subsoiling treatments.

Steve Orloff1, D.H. Putnam2, Blaine Hanson3 and Harry Carlson4

Alfalfa (Medicago sativa) uses approximately 18.7% of California’s agricultural water, a larger percentage than any other single crop. Reduced water availability for agriculture is probable in the coming years, driven by urbanization and environmental demands. Therefore, examination of deficit irrigation strategies is warranted. More information is needed to determine the most profitable irrigation strategy to produce alfalfa with inadequate water supplies. Large-scale field trials were established in the Klamath Basin (California and southern Oregon) and the Sacramento Valley in 2003 to evaluate the effects of early-season irrigation cut-off (deficit irrigation) on yield, forage quality, stand persistence and economics. Results of these field trials showed severe yield loss when irrigation was halted in summer in some cases, but only slight losses in yield in other cases. There appeared to be little to no stand loss in these trials, but it was too early to make an accurate assessment. However, stand losses have been observed in other trials, particularly in the low desert. Research in this area is ongoing. Preliminary results suggest that the concept of temporary voluntary water transfers from alfalfa may have merit. The desirability of this practice from a grower’s perspective will depend largely upon economic incentives and the potential for such strategies to sustain long-term alfalfa production on farms.

Shahryar Sasani 1, Mohammad Reza Jahansooz 2 and Ali Ahmadi 3

Water limitation, water stress and so deficit irrigation are common phenomena in the Middle East. Although pearl millet has been known as an important subsistence cereal for dry areas of the semi-arid tropical regions, nowadays it is cultivated across a wide range of environments ranging from extremely stressful to favourable. To assess the effect of deficit irrigation on water-use efficiency, yield, yield components and forage quality of pearl millet at different growth stages, a field experiment was conducted on Research Farm of Karaj Agriculture Faculty of Tehran University in 2002. The irrigation intervals (weekly irrigation interval, 11-day irrigation interval and 15-day irrigation interval) were assigned to the main plots and irrigation volumes (Control (equal to calculated water requirement), moderate water stress (75% of water requirement) and severe water stress (50% of water requirement)) were assigned to the sub-plots. The crop was cut three times during the growth cycle. Leaf and stem characteristics (biomass, digestible dry matter, crude protein, water-soluble carbohydrates, acid detergent fiber, ash, digestible crude protein, and metabolism energy) were measured separately, other characteristics measured were water-use efficiency, plant height and forage yield. The F.A.O. Penman-Monteith equation was used for estimating crop water requirement and Near Infrared Spectroscopy (NIR) was used to estimate the quality parameters. The results showed that irrigation intervals had significant effects on total protein and digestible crude protein; on the other hand irrigation volume had significant effects on yield, plant height, water-use efficiency, metabolism energy, digestible crude protein, digestible dry matter, crude protein, water soluble carbohydrates, acid detergent fiber and biomass. It can be concluded that irrigating with 75% of the estimated water requirements of pearl millet, the quantity and most of the qualitative traits of dry forage does not change, and water-use efficiency increases with higher levels of water stress.

Z. Tahmasebi Sarvestani, S.A.M. Modarres Sanavy and A. Roohi

In order to evaluate the yield and yield components of different dryland wheat genotypes under supplemental irrigation at different growth stages and to determine the best phonological stage for supplemental irrigation, an experiment was conducted in 1998-1999 at Ghamloo research station in Kurdistan province of Iran. A split plot design With four replications, five main plots and six sub plots were applied. Main plot treatments were consisted of five treatments including no irrigation treatment (control), irrigation at planting, flowering, milking and planting + milking stages. Sub plot treatments were consisted of six dryland wheat genotypes such as sardari, sabalan, and four superior lines. Results showed that irrigation at planting plus milking stages produced the highest yield compare to irrigation at milking stage. Among genotypes sabalan genotype with average yield of 2213 kg/ha produced the highest and sardari genotype with 1502 kg/ha had the lowest grain yield. In general supplemental irrigation caused an increment of 36 percent yield of sabalan genotype.

Garry J. O'Leary1, Vincent Grinter2 and Ivan Mock3

We measured the increased error in mapping the apparent electrical conductivity (ECa) with increasing transect spacing from 10 to 150 m at six 15-100 ha sites across the Murray Mallee. Punctual (point) Kriging was used on a 5x5 m common grid for all sites at each transect spacing using a local spherical variogram model determined from the software package Vesper (University of Sydney). Mean paddock standard errors were regressed against transect spacing and linear models were derived. These errors (ECa, dS/m) were converted to drainage error (mm) by using previously measured drainage - ECa functions from Lysimeter studies at Walpeup. The cost of error was calculated by assuming that error in drainage would result in a significant loss (in water use or more correctly transpiration) at one standard deviation. The drainage loss was then derived by applying a production efficiency loss at a particular gross margin. The optimal transect spacing was determined from marginal cost analysis and varied from around 30 to 60 m depending upon the variance of ECa and the production capability of the field.

Garry J. O'Leary1 and Mark G. O'Connell2

The use of naturally occurring chloride in the soil to estimate long-term average deep drainage rates is a useful tool where annual drainage rates are low. In environments, such as the temperate semi-arid zones, directly measuring deep drainage is problematic because the errors of measurement are close to the annual drainage rates. We report changes in soil chloride for an 11-year period starting from 1990 under a long-term rainfed cropping rotation experiment at the Mallee Research Station, Walpeup, Australia. Over the 11-year period, the cumulative net drainage at the sampling depth of 9 m for the fallow-wheat rotation was 54 ±25 mm/yr compared with 1.3 ±23 mm/yr for the pasture-fallow-wheat (PFW) and –1.8 ±36 mm/yr for the pasture-wheat (PW) rotation. There was a tendency for a small upward movement of water in the upper parts of the profile, but below the nominal root zone depth of 1 m. The work corroborates the earlier findings that fallow every second year at this site causes significantly more drainage than a PW rotation. What is interesting is that the PW had a small net upward movement over the same period. The PFW rotation had a slightly positive drainage term at 9 m but clearly it was upward for much of the upper profile. It seems that a fallow every third year at this site over the 11 years did not contribute greatly to deep drainage, indeed the differences between PFW and PW in the original analysis of 11 mm/yr are considered manageable.

Charles K.K. Gachene1 and Joseph G. Mureithi2

Gully control and reclamation activities using low-cost measures were carried out in early March 2001 at Gatanga division, Kenya. The study area was selected on the basis of previous work carried out in farmers fields by the Legume Research Network Project (LRNP). The project’s main objective is to introduce green manure legume species that perform well in different agro ecological zones of Kenya mainly for the purpose of soil fertility improvement and erosion control in smallhold farms. Area studied is characterized by a mean annual rainfall of about 1100 mm with a bimodal distribution, deep red soils, steep slopes and intensive landuse.

Joung-Du Shin, Jong-Sik Lee, Won-II Kim, Sang-Won Park1, Goo-Bok Jung, Yong-Sun Jhang and Dong-Sig Oh

This experiment was conducted to evaluate the nutrient loss and to assess the eutrophication into small stream by rainstorm in a steep cornfield during cultivation season. The crop cultivated was a silage corn (DW5969), and the experimental plots were divided into two parts that were 10 and 18% of slope degrees. The amount of Total-N and Total-P loss was calculated by analysis of surface run-off water quality, and investigated the effect of eutrophication to small stream as a part of life cycle assessment (LCA) methodology application. Total surface run-off ratio was not significantly different with slope degrees, but amount of T-N and T-P losses at 18% of slope degree were high as 5.96 kg/ha and 0.65 kg/ha as relative to 10% of slope degree, respectively. For the eutrophication to the small stream, it shown that PO4 equivalence and Eco-indicator value at 18% of slope degree were greater as much 6.11 kg/ha and 0.81 as compared to the slope angle 10%, respectively. Therefore, it was appeared that each effect of nutrient losses, eutrophication and Eco-indicator value was enhanced according with higher slope degree.

Yvette Oliver1, Ted Lefroy1, Richard Stirzaker2 and Christine Davies3.

This project examined the factors that influence the trade-off between crop yield and recharge control to develop design guidelines for medium to low rainfall agroforestry. Twenty one tree-crop interfaces in the Western Australian wheatbelt and in southern New South Wales were surveyed over two years to determine the relative importance of environmental factors and system characteristics on this trade-off. The factors most strongly correlated with reduced yield loss were water gaining sites (access to perched water tables, run-on water or ground water), aspect and heavier soils. The factors most strongly correlated with the area of cropped land protected against recharge were lighter soils types and trees greater than ten years old.

Enli Wang, Hamish Cresswell, Zahra Paydar and John Gallant

A 1-D farming systems simulator (APSIM) was coupled with a catchment hydrological framework (FLUSH) to simulate water balance on a topographic sequence in two sub-catchments in Simmons Creek, NSW. The impact of alternative land use options including continuous cropping, rotations, perennial lucerne and forestry were simulated using historical weather data. With annual crops, the valley floor land units were predicted to receive 187 mm/year of extra water in addition to annual rainfall in one year out of 10, and in excess of 94 mm/year in one year in four. In this valley floor position predicted drainage averages around 110 mm/year under annual crops and pastures whereas permanent tree cover or perennial lucerne reduces drainage by up to 99%. Introducing lucerne into a crop rotation reduces drainage by 11%, 67% and 35% on the uphill, slope and valley units respectively. Planting trees on a specific land unit has little impact on the quantities of water predicted to run on to lower units as surface or shallow sub-surface flow. The more significant hydrological impact is on reduction in deep drainage on the units where trees are planted. The work indicates opportunities for the use of lucerne or trees in specific locations where positive hydrological benefits are disproportionately large given the areas taken out of crop production.

Seung-Oh Hur, Won-Tae Kim, Kang-Ho Jung and Sang-Keon Ha

This study was carried out to assess the effect of soil texture and crops on soil erosion and nutrient loss during rainfall. Although rainfall was frequently received for four month from April to September, yet soil erosion occurred only on bare soil, with runoff rate of about 36.9%. This was because selection of crops with high ground cover prevented the occurrence of bare soil surface. Nutrients loss from bare soil was two times bigger than soil covered with crops, resulting in higher nutrient contamination of rivers or streams. The total nutrients loss of peanut on loam (L) and clay loam (CL) soil was similar with that of maize except for sandy loam (SL) soil with peanut. Therefore, cultivating peanut on SL soil will be in a better position than cultivating maize in the side of nutrients conservation and pollution decrease in river. But, the aspect of nutrients loss in L or CL soil showed similar trends. Consequently, crop cultivation having high ground cover during rainfall can be great agricultural practices resulting in decreasing runoff, soil and nutrient loss.

Julianne Lilley1, Merv Probert2 and John Kirkegaard1

The APSIM simulation model was tested against comprehensive field data from a 13-year crop sequence study following a grass/legume pasture at Harden in southern NSW. Soil water balance was simulated using a multi-layer, cascading approach (SOILWAT2 module) and wheat, canola and legume crops were simulated using WHEAT, CANOLA and CHICKPEA modules, while fallow weeds were simulated using the WEED module. Average annual rainfall over the period was 625mm (range 340-823). Simulated soil water content closely matched the measured data (generally 1-2 times per year), providing confidence to consider the drainage component of the simulation. Average annual drainage + runoff was predicted to be 75mm, or 12% of annual rainfall. Annual drainage ranged from 0 – 207 mm, with an average of 51 mm/year. There was no relationship between annual rainfall and drainage (r2=0.16). For example in 1992, 1993 and 1994 rainfall was 801, 823 and 424 mm and drainage was 0, 207 and 0 mm, respectively. In this study, significant drainage generally occurred in years where the profile was full in autumn, and subsequent growing season rainfall was above average. Most drainage occurred in the months July to September. Further, simulations indicate that if weeds had been completely controlled during the summer fallow, average drainage would have increased to 79 mm/year with a maximum of 251mm in 1993. This level of drainage may warrant changes to future management to reduce drainage, given salinity concerns in the Jugiong subcatchment.

Partap S. Thakur and Vaishnu Dutt

Four medicinal plant species namely, Ocimum sanctum, Spilanthes acmella, Tagetes minuta and Withania somnifera have been grown successfully as intercrops between the rows of Populus hybrid, a commercial timber tree species. The presence of tree canopies did not influence growth and yield of economically important organs of medicinal plant species although some adverse effect of tree species was evident in plants growing nearer to the tree rows. Growth parameters like plant height, branch number, leaf area and leaf area index; yield attributes namely herbage yield and production efficiency per unit area were slightly less when medicinal plant species were grown in combination with tree species in comparison to sole cropping. The standing tree biomass (timber wood) ensured additional income from the system (medicinal plants + trees). Physiological parameters of medicinal plants were affected only in plants up to 1m distance from tree rows. The presence of trees resulted in reduced light transmission to the plants nearer to the tree lines. Photosynthetic rate was comparatively less in plants of all the four medicinal plant species growing immediately beneath tree canopies, however, rate increased with the increase in distance from tree trunk. Out of the four tree spacings i.e. 8x3, 6x4, 5x5 and 4x6 m; Populus planted at 8x3 m and 6x4 m proved to be the best tree spacings for no or little adverse effect on the production efficiency of medicinal plant species. The total income from diversified system (medicinal plant species + Populus) was substantially higher than monocropping of medicinal plants.

A.A. Jaradat1, D.W. Archer1, J. Johnson1, S. VanKempen1, S. Wagner1 and J. Eklund1

Research is needed to identify cropping systems that simultaneously improve economic viability of farms and decrease reliance on external inputs while improving the natural resource base. The objective of this research was to map initial soil and crop yield variability and quantify patterns of spatial yield variability in response to increased crop diversity and contrasting management practices. All phases of 2- and a 4-yr crop rotation were established in 2002 on 192 geo-referenced plots. Three factors (F1, F2 and F3) explained 49.2% of total variation in 42 soil variables. Total yield in 2002 and 2003 were negatively correlated (r=-0.37) and yield variance in 2003 was 79% of its initial value in 2002. In 2003 system x tillage accounted for 52% of total variance in corn yield, system x tillage x fertility accounted for 33% of total variance in soybean yield and fertility accounted for 40% of variance in wheat yield. Crop-specific three latent variables were found among system, tillage, fertility, ECa, D, F1, F2 and F3 and accounted for 69.0, 63.0 and 66.0% of total variance in corn, soybeans and wheat, respectively. When grain yield was regressed on these latent variables, the R2 were 0.84, 0.68 and 0.47 for corn, soybean and wheat, respectively. Multiple regression analysis indicated that 2-3 sub-samplings and growth monitoring, especially past the 200 Julian date, and a final sub-sample at harvest generated adequate data (R2=0.75-0.83) to create a detailed spatio-temporal map of the experimental site, plant development and crop yield in a single cropping season.

U.R. Sangakkara1, P. Stamp2, A. Soldati2, P.S.D.R. Bandaranayake1 and K.B. Attanayake1

Depleted soil organic matter and weeds are significant problems of smallholder tropical highland farming systems. As improved fallows in Africa have helped overcome these problems, field studies were carried out in Sri Lanka, to evaluate the effect of two popular fallow crops, which are also used as green manures, on weed management, growth and yields of a succeeding maize crop, using a natural fallow for comparison. Crotolaria and Tithonia added 250% and 160% more biomass to the soil at the end of the fallow, in comparison to the natural fallow. These fallows also had less weeds. While establishment of the succeeding maize crop was not affected by the improved fallows, they increased biomass, stover and most importantly seed yields (30% in Tithonia and 27% in Crotolaria fallow plots) when compared to the natural fallow. In comparison to the natural fallow, weed populations were also reduced in maize planted in improved fallow plots (42% and 54% in Crotolaria and Tithonia plots). The study has demonstrated significant benefits of using improved fallows in seasons when crops cannot be grown due to drought in the smallholder highland cropping systems of tropical humid Asian regions.

James Krall1, David Baltensperger2, David Koch3, Drew Lyon2, Jerry Nachtman1, Glen Frickel2, Jack T. Cecil1, Jim Margheim2, Eric Nielsen2 and Jeffery Flake3

An assessment of the number and status of alternative crops that are under research and development by the Universities of Wyoming and Nebraska for southeastern Wyoming and the Nebraska Panhandle was undertaken. Thirty-six crops are identified for the region, which is characterized as having limited precipitation (370 to 420 mm/yr), and a short growing season (124 days). Most (21) are broadleaf crops. A similar number (22) are cool season prospects. Importantly, fifteen are alternative crops that producers should know how to grow, that have an established market, but that may not fit current economics. The remaining 21 crops require more research to further develop production packages and/or markets. The two universities are currently collaborating through their respective regional research and extension centers to help make this happen.

J. Hoffmann1 and Jörg Michael Greef1

Problems and requirements regarding indicators are discussed for species diversity (wildlife species) in agricultural landscapes. A mosaic indicator approach has been developed, which takes into consideration the various natural site conditions and different historical development of the landscapes. Landscape-typical key species, e.g. several bird species, are regarded as indicators of the ecological situation of the area. Their ecological needs and requirements are the basis of measures to be taken for improving their habitat conditions.

Andrew D. Moore, Libby Salmon and Hugh Dove

An exploratory simulation analysis is presented of four management options for using pasture, dual-purpose winter wheats and forage brassica in a lamb production system at two sites in south-eastern Australia (Canberra and Wagga Wagga). The GRAZPLAN process models were combined with a rule-based representation of management to produce a simulation model of the complex interactions within mixed cropping/grazing systems. At the Canberra site, allocation of 20% of land area to a winter wheat-fallow-pasture rotation resulted in an increase of $23/ha in whole-farm gross margin compared with a pasture-only system. The response at the Wagga Wagga site was smaller ($12/ha). At both sites, inclusion of a forage brassica in the rotation gave a further increase of about $30/ha in whole-farm gross margins but this was accompanied by increased year-to-year variability in gross margin, especially at Wagga Wagga. The inclusion of forage brassica also reduced deep drainage of water compared with a pasture-wheat system, though differences were small. The simulations suggest the need to explore the use of other livestock enterprises for utilising winter wheat forage, and have also highlighted areas in need of further research.

Walter Kelman, Hugh Dove and Libby Salmon

We determined the impact on soil water content and on livestock production, of including a spring-sown hybrid forage brassica crop, as a prelude to incorporating winter wheat into a mixed cropping/grazing system. Lambs grazed 0.2ha plots of forage brassica for 33 days near Canberra, in the High Rainfall Zone of south-eastern Australia. Weight gains were rapid (294 g/day) and the system provided 2141 grazing days/ha and 637 kg lamb gain/ha. Net of the variable costs of the brassica crop production, the value of the weight gain produced while grazing the brassica was $843/ha. Depletion of soil water was markedly higher under the forage brassica crop than in adjacent fallow plots, however, the estimated potential value of this in terms of the likely yield loss from a subsequent winter wheat crop was much less ($384/ha) than the value of livestock production. While this suggests that there would be value in including a forage brassica within a pasture/winter wheat rotation, computer simulation of the system on a whole-farm basis is needed to quantify the long-term consequences and price sensitivities of introducing a forage brassica into a mixed cropping/grazing system.

P. Tixier1, E. Malezieux2, M. Dorel1and J. Wery3

Monospecific banana (Musa spp., AAA group, cv. Cavendish Grande Naine) based cropping systems may be very detrimental to the environment. In these agrosystems, there is a high risk of pesticide pollution of surface and ground water, especially in the insular tropical conditions of the French West Indies. A specific model called SIMBA was built to assess these risks and help design more sustainable cropping systems. SIMBA simulates banana cropping systems through several crop cycles. It includes sub-models that simulate soil structure, water balance, root nematode populations, yield and economic outputs. Agri-environmental indicators linked to the model enable environmental impact assessment. The model has been implemented in Guadeloupe and will be useful for drawing up practical guidelines for farmers, and virtual testing of agro-technological innovations or field management strategies.

Nenita E. Dela Cruz1, Edwin C Villar2, Fe L Porciuncula1, Edgar A Orden1, Pablito Paulo C Pinto2, Rodolfo V Antalan2 and Sonny N Domingo2

Lack of assured irrigation in rainfed environments forces farmers to fit agricultural activities with the changing seasons. Optimum productivity in farm operations under this scenario is difficult if not impossible to achieve. Research to solve agricultural problems like this needs immediate attention. A systems approach has more opportunities to be applied when dealing with smallhold farmers. Crop productivity was significantly improved as a consequence of crop intensification, which likewise improved animal productivity that ultimately increased farm family income. The inclusion of feed-feed crop in the cropping system contributed to the sustainability of crop-animal integration and ensured more regular cash flow in the farm. Farm family income was significantly increased by 146 percent after the integration. Nutrient cycling was improved wherein manure produced was used as fertilizer for forage production and by the inclusion of food feed legumes in the system.

Dean Holzworth and Neil Huth

The Agricultural Production Systems Simulator (APSIM) has long been used in the simulation of discrete management units within production systems. Recent developments now allow for the inclusion of multiple instances of the point-based modelling capability within a single simulation. This allows the user to explore the behaviour of management systems where individual land units can be influenced by other points in space. This paper provides three hypothetical case studies to illustrate both the need for such a capability, and the possibilities provided by the developments to the APSIM framework.

Octavio P. Caviglia1,2 and Víctor O. Sadras3

Wheat-soybean double crop is the main element of cropping intensification in the southeastern pampas of Argentina. The long-term impact of including double cropping in the entire crop sequence is unknown. Locally calibrated DSSAT models and climatic records (30 years) were used to estimate the yield of crop sequences combining wheat, soybean and maize. Annual glucose yield averaged between 5.9 and 8.7 t ha-1. Intensification, quantified with the intensification sequence index (ISI; #crop per year) increased the average annual yield and its coefficient of variation. Annual glucose yield increased from 10 to 28% with increasing intensification sequence index (ISI = # crops per year). In parallel with the increase in yield, greater ISI resulted in higher coefficients of variation. Broader comparisons indicated both wheat-maize and double cropped wheat/soybean-maize could lead to highest annual yield. Lowest yields were obtained with wheat-soybean and double cropped wheat/soybean-soybean. Simulations highlighted the contributions of wheat to stability and of maize to productivity of cropping systems in the southern Pampas.

Víctor O. Sadras and David K. Roget

In the semiarid Mallee region of southern Australia, risk management is largely based on a conservative, low input approach with substantial opportunity costs (missing the benefits of wet seasons) and low yield per unit available water. We combined field and modelling experiments to evaluate an intensive, flexible cropping approach based on (i) an opportunistic combination of crops, including wheat, canola, and grain legumes, and (ii) a close matching of nitrogen input to soil and seasonal conditions. In a four-year field trial established on a coarse textured soil, an intensive cropping approach doubled gross margin and halved its coefficient of variation in relation to current practice. Modelling experiments (a) confirmed the long-term economic benefits of the intensive cropping approach tested in the field, (b) highlighted its neutral or slightly beneficial impact on nitrogen leaching and deep drainage, and (c) unveiled a key trade-off whereby water-use efficiency can be increased at the expense of nitrogen-use efficiency; this is consistent with the theoretical expectation that plant growth is maximized when all resources are equally limiting. The approach to intensification in this research provides a platform to improve production and profit, and to reduce its seasonal variation with neutral or slightly positive effects on environmentally relevant processes.

Damian Heenan1 and K. Yin Chan2

In a long term rotation trial, production from canola and wheat following either canola, wheat, sub-clover or lucerne/sub-clover at Wagga Wagga, New South Wales was studied over seven seasons. Annual rainfall varied considerably (375 mm to 688 mm) over the period 1996 to 2002.

Mean establishment of canola following sub-clover was similar to lucerne/sub-clover (90 cf 86 plants/m2). However, the seasonal variation in establishment was considerable (39 to 150 plants/m2). Consistently higher (0.1-0.81 t/ha) canola grain yields were produced following sub-clover rather than lucerne/sub-clover. Over-all, similar oil% and grain protein were recorded after lucerne/sub-clover and sub – clover though seasonal differences did occur.

Though wheat as a second crop received 50 kg N/ha as urea, higher (mean 0.32 t/ha) wheat yields and grain protein (mean 0.6%) were obtained when wheat was the first crop after pasture compared to a second wheat crop. When wheat was the second crop and receiving 50 kg N/ha as urea, there was no difference in wheat grain yields following either canola or wheat with stubble burnt. However, grain protein was usually higher after lucerne/sub-clover - canola (mean 13.7%) compared to both lucerne/sub/clover - wheat (mean 13.0%) and sub-clover – canola (mean 13.1%).

Ali Farhoodi, Murray Unkovich and Marisa Bartolome

We evaluate low rainfall (<350mm annual rainfall) agriculture in southern Australia and strategies for incorporating non-cereal crops into these regions. Less than 5% of farmers in the SE Australian Mallee grow pulses and oilseeds. Desktop studies suggest that in many locations with <350mm annual rainfall it is unlikely that yields of ≥1 t/ha can be achieved with grain legumes or oilseeds in most years. Furthermore, an examination of seasonal longevity /suitability (using precipitation/evaporation ratios) and the probability of clear seasonal breaks (Σ 25mm rain/3days from April 1) indicates that growing season length and probability of a clear sowing opportunity do not favour non-cereal crops. We are thus investigating novel options to assist in the integration of non-cereal crops in the region. These include dry sowing, reducing input costs, growing multipurpose crops (grain/forage/graze) to reduce the reliance on cash grain yields, and the use of crop mixtures to increase rotational benefits to following cereal crops. A successful grazing enterprise would be key to capitalising on such an approach. Gross income and gross margin probabilities will also be used to determine which crops and rotations are more likely to be provide a return on investment across the region. Such systems might be suited to variable, low rainfall climates and help overcome barriers to adoption of non-cereal cash crops in low rainfall agriculture.

Wen Chen1, Yu-Ying Shen2, Michael Robertson3, Merv Probert3, Bill Bellotti1 and Zhi-Biao Nan2

The objective of this paper is to evaluate the performance of the APSIM model in simulating crop growth and soil water for different cropping systems in China. The APSIM was parameterised and tested using data collected from two dryland field experiments being conducted on the well-fertilized Heilu soil of the Gansu Loess Plateau. In bare fallow and continuous lucerne treatments, soil water and lucerne biomass were well simulated. In a maize-wheat-soybean (M-W-S) rotation with crop stubble either being removed or retained, crop biomass and grain yield were well simulated. Soil water was generally well simulated in the M-W-S rotation without stubble retention except for the periods near harvest of the maize and wheat crops; where stubble was retained, the over-prediction continued through the soybean phase. Simulated water balance components suggest that water use efficiency could be improved if lucerne, summer and early maturity crops were integrated with winter wheat cropping.

APSIM shows promise for simulating soil water balance, crop growth and grain yield for different cropping systems in Gansu, China. By using long-term climatic data, the model offers opportunities for evaluating climatic risk associated with changing from ‘current’ to ‘new’ cropping systems.

Shaun Lisson1, Neil MacLeod1, Cam McDonald1, Andrew Ash1, Bruce Pengelly1, Lisa Brennan1, John Gross2, Jeff Corfield2, Sania Saenong4, Tanda Panjaitan3, Rusnadi Padjung6 , Lalu Wirajaswadi3, Yusuf Sutaryono5, Rahmat Rahman4 and Syamsu Bahar5

Many forages suitable for improving livestock production in mixed crop-livestock systems in the tropics have been identified, however their adoption has been limited, even when participatory research has been used. Before farmers will introduce new forages into their farming system an important prerequisite is that the change will be considered profitable, will have an acceptable level of risk and will not interfere with food security. This paper describes a farming systems research approach that investigates the benefits of new forages to improve cattle production in mixed crop-livestock systems of Indonesia, and quantifies these benefits in bio-physical and economic terms.

N.V. Elias1, Richard J. Martin1, J.F. Holland1, Peter Hayman1, Michael Robertson2, J. Gordon1 and S. Belfield3

The aim of this four-year study is to understand, and where possible overcome, constraints to the adoption of broadleaf crops in north-western NSW, with a focus on chickpea, faba bean and canola. A survey of 131 growers and advisers identified the major constraints to adoption of these crops as the risk of disease and concern about broadleaf weed management. A benchmarking study was also carried out in 2003 of growers in the study region already growing the 3 focus crops. It is anticipated that this data will be used to aid growers in decision making. For chickpea crops in 2003 the variables most associated with yield were plant available water (r2=0.51); stubble cover (r2=0.58) and nodulation (r2=0.56). Frosts occurring late in the season were also particularly detrimental to some crops in the north-west region.

A.S. Kamel, Sahar A. Serif and Sahar T. Ibrahim

Two intensive experiments were carried out in Toshky region in upper Egypt to adapt two crop rotations to cover most of the year under torrid, arid and hyperthermic conditions of this region. First rotation was cotton followed by tomato intercropped with sorghum. The second rotation was sugar beet followed by cotton. Both rotations proved success, particularly, when new agro-techniques were used when raising these crops to avoid sharp waves of heat which frequently occurred coupled with windy storms or the very cold nights in winter or in the short spring. The results obtained from the first rotation (cotton- tomato) revealed that mechanically transplanted cotton yielded more than the direct seeding method. When raising the second crop, heat tolerant variety of tomato was used to avoid heat waves, which frequently occurred during summer. Tomato intercropped with grain sorghum as the shade crop yielded more than pure stand tomato, with little loss of sorghum yield. The Land Equivalent Ratio of the tomato-sorghum intercrop ranged from 2.58 to 2.99. In the second rotation, sugar beet was followed by cotton grown in a multi-seasonal system. Transplanting gave higher number of dual roots in sugar beet than direct seeding, but tuber yields were not significantly different. Late summer planting of cotton resulted in high yield, but the yield was depressed when planting was delayed to July.

Nageswara V Rao 1, Piara Singh1, D Balaguravaiah.2, J. P. Dimes1 and Peter S. Carberry 3

Peanut monocropping is the predominant rainfed system in semi-arid Anantapur region (Andhra Pradesh), India, where low rainfall and lighter alfisols support shorter length of crop growing season (105-135 days). To investigate how to minimize frequently occurring crop failures, we analyzed constraints and opportunities existing with peanut production systems following a systems simulation approach using APSIM. The three peanut systems were simulated using historical weather data at Anantapur (1962 to 1999) and included sole peanut, peanut/medium duration (MD) pigeonpea intercrop and peanut/short duration (SD) pigeonpea intercrop. Our analyses indicated peanut/SD pigeonpea intercrop system would minimize crop failure and record higher productivity by escaping water stress conditions in 7 of 31 crop seasons, when sole peanut or peanut/MD pigeonpea intercrop systems failed. Simulated SD pigeonpea yields were higher than MD pigeonpea yields in 19 crop seasons and showed a potential for >1.5 t ha-1 yields with peanut/ SD pigeonpea system in most of the good rainfall seasons. To further evaluate cropping systems options identified by systems simulation approach, verification demonstrations on peanut/ short duration pigeonpea intercrop system were planned with farmers’ participation during 2000-2002 crop seasons.

Nageswara V Rao1, Piara Singh1, Y. Padmalatha2, T. J. Rego1, J. P. Dimes1 and Peter S. Carberry 3

Through systems simulation we identified peanut/short duration (SD) pigeonpea intercrop systems as the most suitable system for rainfed Anantapur region. Farmers’ participated field trials were conducted during 2000-2002 seasons to determine the adoptability of this system for this region. During these seasons, peanut yields were higher with sole peanut although system productivity was consistently higher with peanut/SD pigeonpea systems based on total grain productivity and LER. SD pigeonpea yields were higher compared to medium duration (MD) pigeonpea in the intercrop systems. Adoption of peanut/short duration pigeonpea system by farmers in the neighboring villages during the third cropping season (2002), and better productivity in a severe drought year (2003) benefited farmers. Tools and methodologies employed in this study may well be utilized for similar situations in the SAT.

We planned to have two geographically distant locations that are 40km apart, to encompass varying soil profiles of 30, 60, and 90 cm depth to typically represent Anantapur region (District map). Three soil depths (30, 60, 90 cm) were available in Krishnamreddipally, but in another village, Pampanur, only 30 and 60 cm profiles were available. Soil profiles of 90 cm were selected from Akuthotapally village to have same number of replication of soil types. Twenty four farmers volunteered to conduct field demonstrations from these three villages.

Dhananjay Singh1, Vanessa Alsemgeest1, David Cooper1, Richard Routley1 and Peter Sale2

A multi-phase legume-wheat cropping system experiment is being carried out in the semi-arid district of Roma, in southwest Queensland, Australia. The split-plot design used 2 rates of phosphorus (P) fertilizer (10 and 40 kg P/ha), applied at 10-15 cm depth, as main plots, and 4 forage legume treatments, sown in mid February 2003, as subplots. The legumes were lucerne (Medicago sativa), butterfly pea (Clitoria ternatea), burgundy bean (Macroptilium bracteatum), lablab (Lablab purpureus), together with a summer-fallow control. Spring wheat (Triticum aestivum cv. Kennedy) was sown into the legume stubble in early May and was harvested in early October. Soils were sampled during the legume and wheat phases, and analysed for available P and nitrate-N, and water content. Significant P x Legume interactions (P<0.05) occurred for legume shoot biomass, and for wheat grain yield. The annual summer forage legume lablab produced the highest shoot dry matter yield of 6.2 t/ha after 2.5 months growth with 40 kg P/ha, production that was significantly greater (P<0.05) than the 5.0 t/ha produced with 10 kg P/ha. The following wheat crop yielded 2.7 t grain/ha from the high P lablab, butterfly pea and fallow combinations, a yield that was significantly greater than wheat after lucerne. The annual forage legume-wheat system was able to use much of the summer rainfall water for biomass production. The system was able to maintain continuous surface cover and minimised weed growth in the wheat crop. Valuing the legume shoot biomass as hay or as a ration for cattle live-weight gain indicated that the legume-wheat system, particularly lablab-wheat, can be very profitable.

Jeffrey Evans1, Edwin Wolfe2, Mun Yun-Guk3, Ri Yong-Jo4 and Kim Tong-Ryul3

Over the last decade in the Democratic Peoples Republic of Korea (DPRK), the yields of the staple crops rice and maize declined to less than half of their known potential (8 t/ha). Insufficient application of fertiliser, soil erosion (maize) and extreme climatic events (drought, flooding, high winds) were responsible, at least in part, for the decline. Current production is constrained by low soil fertility and tenuous domestic supplies of fertiliser, particularly nitrogen. Even when supplemented with international donations, the supply of nitrogen fertiliser is inadequate to achieve food self-sufficiency. In an effort to produce sustainable, higher yielding crops, we are seeking to introduce legumes into rice and maize cropping systems to produce nitrogen, organic matter and soil stabilisation benefits to soils in the DPRK. To avoid competing with staple grains during the late May to September (summer) growing season, the legume phase ideally will be based on green manure legumes that are sown in autumn, survive winter temperatures as low as -20oC and grow productively in spring. After severe winters, it may be necessary to re-establish the legume phase post-winter. In 2002, over 400 legumes of diverse genera and species, mostly sourced from cold climate regions, were established in hill plots at Pyongyang, DPRK. There were 2 sowing dates prior to winter and 2 sowing dates post winter. In this preliminary investigation, all legumes were grown with adequate mineral fertiliser. On the basis of observations in spring for apparent winter survival, biomass and ground cover, 25 accessions were rated as potentially promising/highly promising for autumn sowing and 42 for post-winter sowing.

Anyou Liu1, Richard Snowball2, Clinton Revell2 and Bradley Nutt2

Twenty six lines and varieties from 19 different species of annual pasture legumes were compared in a field trial near Brookton, Western Australia, in 2003 for their potential to be used as fodder crops. Characters considered included visual growth score, biomass production early and late in the season, flowering time, the ability to maintain green late in the season and tolerance to water stress. Although a dry season restricted herbage production, most new lines included in the trial failed to reach the production levels of the commercialised lines used as controls. French serradella (cv Cadiz), crimson clover (cv Caprera), and some lines from T. dasyurum, T. hirtum, and T. purpureum were amongst the best performing lines. Simple correlations showed that early vigour as indicated by a visual score and early biomass production was closely related to biomass production late in the season. However, time of flowering, water stress tolerance and the ability to maintain greenness late in the season showed little relationship with biomass production under the conditions experienced at the site.

Joseph G. Mureithi1, Josephat M. Kiama1, Charles K.K. Gachene2 and Francis M. Gitahi1

Purple vetch was evaluated as a green manure legume for the production of Irish potato (Solanum tuberosum) in four growing seasons from 2001 to 2002 in Matanya, Central Rift, Kenya. The legume was compared with the recommended fertilizer for Irish potato production in the area, which is di-ammonium phosphate (DAP) fertilizer applied at the rate of 80 kg N and 90 kg P/ha. The farmers’ practice for growing Irish potato is intercropping the potato between maize rows spaced 75 cm apart and a few farmers (<10%) apply farm yard manure at the recommended rate of 5.5 t/ha. This practice was also including in the study treatments. As expected the fertilizer treatment gave significantly (P<0.01) higher tuber yields than the intercropping treatment but it was not better than the green manure treatment. The mean annual tuber yield for the two years was 27.2 t/ha for fertilizer treatment, 23.4 t/ha for the legume green manure and only 13.0 t/ha for the farmer practise. Economic analysis showed that intercropping treatment gave a higher gross margin than the other treatments because maize grain fetched a higher price than potato tubers. However, total variable costs were lowest for green manure treatment, which made it an attractive option for farmers who normally do not have much money to purchase inputs like fertilizers and farm yard manure at the beginning of the season.

Sui-Kwong Yau1, John Ryan2, Mustafa Pala2, Mussa Nimah1 and Adel Nassar3

A cereal monoculture is potentially unsustainable. The objectives of this study were: (1) to find whether the common vetch-barley rotation is profitable, and (2) to test whether cumin and safflower are suitable crops for rotation with barley. The study was conducted for two seasons (2001-02 and 2002-03) as a part of a larger 2-course (i.e., 2-year) rotation trial that was set up in 1994-95 in the Bekaa Valley of Lebanon under rainfed conditions at the Agricultural Research and Educational Center. There was no significant rotation effect on barley seed and straw yield. Vetch gave a higher seed yield than cumin and safflower. Vetch also gave a higher straw yield than the other three crops. Thus its rotation with barley led to the highest overall dry-matter yield. Common vetch, cumin and safflower left higher soil moisture than barley at 25 cm depth. Despite the higher cost of production, the vetch-barley rotation gave the highest net revenue, followed by the cumin-barley rotation. The higher dry-matter yield and net revenue of the vetch-barley rotation showed clearly that farmers in the Bekaa should be encouraged to adopt such a rotation and abandon barley monoculture. Cumin and safflower may be useful crops to break barley monoculture, but further evaluation is needed.

Giovanni Pacucci, Carlo Troccoli and Beniamino Leoni

Under Mediterranean conditions, the amount and seasonal incidence of rainfall play important roles in determining the response of wheat to carryover effects from the previous crop and to the rate of nitrogen (N) fertilization. The purpose of the present research was to evaluate the possibility of growing durum wheat in an agricultural system that is characterized by reduced inputs of fertiliser nitrogen and minimum tillage. In one growing season (1999-2000), we assessed the effects on wheat yield and grain characteristics of: (i) the previous crop (vetch and wheat), (ii) the nitrogen fertilizer level (0, 45 and 90 kg/ha –1), and (iii) the genotype (10 were compared). Low rainfall reduced the grain yield, which ranged between 1.22 and 3.50 t/ha. The previous crop did not significantly affect the wheat grain yield, but after vetch an average 5% yield increase was observed. After wheat, the grain yield did not show any significant difference between the three N levels, while after vetch the grain yield increased significantly (+ 20.6%) with 45 kg/ha of N and remained constant with 90 kg/ha of N. On average, the cultivars Ciccio (2.40 t/ha) and Colosseo (2.28 t/ha) were the highest yielding genotypes. However, with some genotypes, significant interactions occurred with both the previous crop and nitrogen fertilization. For example, the genotype Rubiu Cixireddu showed a 45% yield increase after the vetch crop, followed by the cv Ciccio with +24%. The nitrogen fertilisation also influenced the genotypes in different ways. Yellow berry, hectolitre weight and kernel weight varied mainly with the genotypes.

Ramakrishnan M. Nair1, Jake Howie1, Ross Ballard1, Rachel Hutton1, Nigel Charman1 and Chris Preston2

Strand medic (Medicago littoralis) provides the principle source of fixed nitrogen (N) in many neutral to alkaline sandy-loam soils, such as those that dominate the Eyre Peninsula region of South Australia. So well adapted is the species in these environments that it is often grown in near monoculture conditions in the ley phase of these farming systems. This paper reports the efforts made in the genetic improvement of strand medic for traits including herbicide tolerance, improved N2-fixation, tolerance to root-lesion nematode and resistance to powdery mildew disease. A sulfonylurea herbicide (SU) tolerant line (coded FEH-1) developed by EMS mutagenesis of the strand medic variety Herald, offers significant promise, especially for use in low rainfall regions with alkaline soils, where the breakdown of SU residues is reduced. The herbicide tolerance trait in FEH-1 appears to be controlled by a single dominant gene. Plant selections have also been made for ‘symbiotic promiscuity’ that will enable strand medic to form a greater proportion of optimal N2-fixing symbioses with the naturalised rhizobia that proliferate in most soils where the plant is grown. Selection and breeding for tolerance to the root-lesion nematode (Pratylenchus neglectus) and resistance to powdery mildew (Erysiphe trifolii) are also being undertaken in order to improve productivity.

Beda Bahadur Rokaya1

This study was carried out with the objectives of improving soil fertility and enhancing the productivity of upland rice in Nepal, by identifying both higher yielding land races of upland rice and summer legumes that could be grown as an intercrop in the upland rice production systems. Local landraces of legumes and upland rice were collected from the mid-hills and tar (river basin) areas of Nepal. These land races were evaluated and selected for agronomic characters that are suitable for the intercropping production system. Intercropping experiments using the selected land races of upland rice and legumes were conducted over 3 years (1999/00-2001/02) at on-station and on-farm sites in the far-western mid-hills of Nepal. The upland rice (Oryza sativa L.)-Damari, soybean (Glycine max L.)-Sathiya and black gram (Vigna mungo L.)-Maintada local exhibited the best performance in the intercropping system. The land equivalent ratios (LER – the ratio of total yield from intercropping with that of sole crop yield) were found to be 1.89 and 1.82 for upland rice intercropped with black gram (Maintada local) in the ratio (rice:legume rows) of 3:2 and 4:2. A LER value of 1.65 was obtained from upland rice and soybean (Sathiya) grown as a 3:2 intercrop. Considering the soil fertility status of the experimental sites, fertility trends indicated an immediate increase in available phosphorus after fertilization as well as favourable trends in total nitrogen and organic matter. The investigation has indicated that the continuous inclusion of legumes may have a positive impact on soil fertility, resulting in the sustainable productivity of upland rice.

Senthold Asseng1, Imma Farré2, Michael Robertson3 and Perry Dolling4

To explore the impact of narrow-leafed lupins in rotation with wheat in Western Australia, the simulation model APSIM was employed to analyse nitrate nitrogen (NO3 N) leaching and wheat productivity in a range of lupin-wheat rotations on contrasting soil types, using long-term historical weather records from two rainfall locations. The simulated impact of lupins on wheat profitability and N leaching differed somewhat from that expected from agronomic experience. Soils with low plant available water-holding capacity did not necessarily leach more N than soils with higher plant available water-holding capacity, due to differences in organic material and mineralisation. N leaching in some years at a low rainfall location (with less average deep drainage) was as high as at a high rainfall location. When the proportion of lupins in rotation with wheat was increased, wheat yields increased as well as the financial returns from the wheat crops. However, returns from including lupins in rotation were reduced under high additional N fertiliser input to the wheat crop at a low rainfall location and in low rainfall seasons. To maximise benefits from lupins in rotation with wheat, the proportion of lupins in the rotation and N management need to be site and soil specific. Seasonal variability, in particular the combination of seasons in a sequence of years, will add a large level of uncertainty to the management of wheat-lupin rotations.

K.K. Ayisi1, PNZ Mpangane1 and Anthony Whitbread2

The smallholder cropping system in the Limpopo Province of South Africa is characterised by predominantly maize monoculture, low external input and poor soil fertility, particularly, nitrogen and phosphorous. Intercropping cereal and legume species is usually proposed to enhance nitrogen nutrition in the system. Alternate row intercropping studies of maize and four distinct cowpea cultivars were conducted during the 1998/99 and 1999/2000 growing seasons at two sites to determine the effect of the system on grain yield of the component crops, and symbiotic activities of the legume. Differences in maize grain yield were only observed at Syferkuil in 1999/00. With the exception of one cultivar where lower intercrop yield was recorded, seed yield of the cowpea cultivars were similar in the sole and intercrop systems. The amount of nitrogen fixed by the legumes ranged from 0 to 217 kg N ha-1 over the two seasons and on average, fixation was higher in the intercropped cowpea than the sole crops, except in 1999/00 at Syferkuil.

P.R.S. Rao1, K.N. Rao1, S. Sridhara2, M. Byregowda3, B.C. Shankarlingappa3, Holger Meinke4, Peter DeVoil4 and Sulochana Gadgil1

We have investigated the option of pigeonpea in place of peanut over rainfed tracts of semi-arid parts of southern India by analysis of the simulations with a crop model, APSIM At present, pigeonpea is cultivated as an intercrop with peanut and the yields are not high enough for economic viability. We have shown that the low yields are a consequence of late planting, which is adopted because it is fits in with the major crop peanut. The model results indicate that pigeonpea, when sown early, is an economically viable option to peanut.

M.G. Thwala and E.M. Ossom1

Intercropping involves growing two or more crops on the same land, and in the same season. In Swaziland, peasant farmers commonly intercrop maize (Zea mays L.) with sugar bean (Phaseolus vulgaris L.), but do not intercrop groundnut (Arachis hypogaea L.) with maize because there is a lack of knowledge regarding which crop combinations are most beneficial. Maize was grown as a monocrop and in association with sugar bean and groundnut, to determine the effects of crop combination on the agronomic characteristics of the associated crops. Pure maize gave the highest yield (6298 kg/ha); the maize-groundnut combination yielded 6146 kg/ha of maize, and the maize-sugar bean mixture gave 5806 kg/ha of maize. Pure groundnut yielded significantly (P<0.05) higher (840 kg/ha) than intercropped groundnut (419 kg/ha). Crop competition was probably responsible for observed reduced yields. The maize-groundnut mixture provided the best weed control. To simultaneously obtain the three benefits of higher maize yields, higher total crop yields/ha and effective weed suppression, the maize-groundnut intercrop is recommended.

K. Yin Chan1 and Damian Heenan2

In Australia, stubble burning and excessive tillage are the two major processes responsible for decline of soil organic carbon levels in the cropping soils and the resulting soil degradation problems. However, the relative importance of the two in controlling the soil organic carbon (soc) level and the long term impact on soil health/productivity are not known. The effects of wheat stubble burning as practised by farmers in south eastern Australia were evaluated in two agronomic trials in southern New South Wales. Three tillage passes under conventional tillage practice led to far greater loss than stubble burning. Loss of soil organic carbon attributed to stubble burning was 1.75 C t/ha (0-10cm) in the 19 years trial, equivalent to 23 % that the total loss. In the 5 years trial, no change in soc due to stubble burning was detectable. Changes in soil quality due to stubble burning included reduction in macroaggregate stability, increases in pH and exchangeable K. Averaged over 19 years, higher wheat yield of 0.15 t/ha was also observed under stubble burning. Research to identify conditions of stubble burning when soc loss is minimised is needed.

Zinta Gaile

Demonstration of growing possibilities of corn for energy dense silage in Latvian conditions, marginal for corn growing, as well as timing of planting and harvesting as important management considerations, - have been a matter of great concern for qualitative dairy and livestock forage making. The aim of this study was to show the possibility to obtain high and good quality forage from corn in Latvian conditions, growing early maturity hybrids in meteorologically diverse growing seasons, and to point out importance of planting and harvesting time as determinant factors for high good quality yield. During 2000 to 2003 a total of 18 hybrids were evaluated in RSF “Vecauce” (latitude: N 56° 28′, longitude: E 22° 53′). Two planting times for one standard hybrid and three harvesting times (by sampling) for 3 hybrids were evaluated in addition. Quite good average dry matter (DM) yield was obtained every year (11.54 – 15.85 t ha-1), but average DM content at harvest varied from 23.63 to 35.87 %. Substantial influence of meteorological conditions, mainly air temperature and in connection with this – corn heat units, on DM yield and quality were found. Year as a factor has the main effect on DM yield and DM content of whole corn plant at harvest (p<0.01). Planting time influences DM yield, but even more so, quality indices such as content of DM and corn-cob density in the whole plant DM yield. Mainly delay of harvesting time within September improves such important silage characteristics as DM content (increases), NDF and ADF content of whole plant DM (decreases), and energy density measured as net energy for lactation (NEL, increases).

Brian L Duggan1 and Megan H. Ryan2

Colonisation by arbuscular mycorrhizal fungi (AMF) was assessed on cotton grown during the dry season on soil that had no previous history of fertiliser application or cropping in the Ord River Irrigation Area (ORIA) of northern Western Australia. Colonisation by AMF was low (<11% of root length) 17 days after sowing in the first year cotton was grown while in the second year colonisation improved dramatically (>62% in phosphorus-fertilised plots). However, second year crops that had received no phosphorus fertiliser in either year displayed lower colonisation levels (25%). As the response of cotton dry matter and node development to application of phosphorus fertiliser was the same in both years, irrespective of AMF colonisation being negligible or high, it appeared the fungi were not playing a major role in crop nutrition or growth at time of sampling. Colonisation levels also did not differ between Bt transgenic and conventional plants.

Heping Zhang, Neil C. Turner and Michael L. Poole

An experiment was carried out from 2001-2003 at Kojonup in the high rainfall zone (HRZ) of southwestern Australia to examine crop yield potentials and constraints to achieving these potentials. Subsurface waterlogging early in the growing season reduced ear number which was identified as a major constraint to crop production. Ear numbers were found to be the major contributor to yield differences and therefore it is important to maintain higher ear numbers for high yields in the HRZ.

Shane Broad1, Shaun Lisson2 and Neville Mendham3

A field trial in Tasmania was established in September 2003 to examine the practicality and benefits of strip cropping three vegetables, namely onions, broccoli and potatoes. Yield and disease data suggest that growing broccoli in close association with potatoes has the potential to increase the average harvested weight of broccoli by 16g per plant, while reducing the incidence of white blister rust (Albugo candida). Potato yield and disease incidence was not significantly affected by strip cropping, while the onion yield was significantly higher in the monoculture compared to strip cropping.

Sebastian Ulrich, Bodo Hofman and Olaf Christen

The effects of differences in the fertilization on soil organic matter and soil physical properties were measured in the long-term field experiment “eternal rye” (Halle, Germany), which has been started in 1878. The trial is one of the oldest agricultural field experiments still continued in recent times.

The unfertilized control in the continuous rye treatment showed the lowest total C content of 1.13 percent in the layer 0-6 cm depth, 1.13 percent in 12-26 cm and 0.49 percent in 32-38 cm. A long term annual mineral fertilization with 60 kg/ha nitrogen, 24 kg/ha phosphorus and 75 kg/ ha potassium increased the total carbon content to 1.33 percent in the first two layers sampled. An annual amount of 12 t/ha of farmyard manure (FYM) increased the total carbon content to 1.63 % in the first two and to 0.78 % in the third layer. These differences in the total carbon content caused profound differences in soil physical properties. The field capacity in all three layers was highest in the FYM-treatment and lowest in the unfertilized treatments, with the mineral fertilizer treatment showing intermediate results. Besides the important macropores larger than 10 μm differed according to the fertilizer treatments. Additionally the pneumatic and hydraulic conductivity was affected by the differences in the long term fertilizer treatments. The conclusion from our results is that for the interpretation of soil functions in long term field experiments changes of soil physical properties have to be considered as an additional explanation for differences in crop yields.

Glen Frickel1, David Baltensperger1, Jim Margheim1 and Eric Nielsen1

Research is being conducted to determine the feasibility of producing canaryseed (Phalaris canariensis) in the Central High Plains area of the United States. Work is being coordinated by the staff of the University of Nebraska Panhandle Research and Extension Center located at Scottsbluff, Nebraska. Canaryseed is grown in the cooler regions of North America and may be suited to the local climate. There are a limited number of crops that grow well in this area and another cropping possibility would benefit the local economies. Canaryseed is commonly included in birdseed mixtures, and would fit in this region where local markets for birdseed are well developed. Several common components of birdseed are locally produced and packaged. These include sunflower seeds and proso millet. The packaging facilities have a need for more product. Several years of experience demonstrate that this crop can be grown here under irrigation. Preliminary results show that a row spacing of 15 cm produces more seed than 30 cm spacing and that planting rates of 20 to 30 kg/ha are optimal for grain production.

Melanie Bradley1, 2, Michael Robertson1, Alan House1, Perry Poulton3 and Clyde Wild2

The potential for integrating native brigalow (Acacia harpophylla F. Muell. Mimosaceae) vegetation with dryland cropping systems is being investigated in the Tara Shire, southern Queensland. Of particular interest is regrowth brigalow, a key means for landscape revegetation following broadscale land clearing last century. Integration of brigalow vegetation and cropping can result in competition for water, light and nutrients between trees and crops, and potentially, a reduction in agricultural production. Competition dynamics must be assessed to understand the trade-offs involved with brigalow-cropping integration and to guide sustainable landscape management. Extent of the brigalow-crop competition zone, i.e. the horizontal distance over which crop production is reduced, has been measured at four sites where regrowth and remnant brigalow are adjacent to wheat. Evaluated on the basis of grain yield, the competition zone ranged from 19 m for 3 year old regrowth (3YRG), to 44 m for remnant brigalow > 70 years old (> 70YRM). When expressed as a ratio of tree height, the competition zone ranged from 4 tree heights for > 70YRM to 13 tree heights for 3YRG. The tree heights results suggest that in a relative sense, regrowth brigalow produces a larger competition zone compared to remnant brigalow. Further collection of field data as well as simulation modelling will allow for investigation of the impact of land use history and seasonal conditions on brigalow-crop competition. The overall aim is to develop a simple spreadsheet model that will allow farmers to explore different brigalow-cropping scenarios and their associated economic and ecological trade-offs.

Adam Dellwo1,2, Rob Norton1, Nick Wachsmann1 and David Jochinke1

Four field experiments were undertaken in south western Victoria to compare safflower yield with wheat, canola, mustard and linseed. The sites differed on the amount of stored soil moisture and where the highest stored water was available safflower performed the best, although wheat consistently provided the highest grain yields across all sites. Based on typical crop costs and prices, wheat had the highest gross margin at three of the four sites, with canola usually the second most profitable crop. Safflower showed the lowest returns of the crops on the two central Wimmera rain-fed sites. However, where there was significant rainfall or the soil profile approach field capacity, the returns from safflower approached or exceeded the returns from wheat and canola. Breakeven yield for safflower was estimated at 0.54 t/ha, and across the four sites, safflower produced positive gross margins on three occasions. When the areas were re-sown to wheat in the subsequent year, there were no differences in wheat yield attributable to biotic or abiotic effects associated with the prior crops. Wheat re-cropped in 2001 on the 2000 crop comparisons yielded 2.2 t/ha at one site and 4.4 t/ha at the other. In 2002, all the wheat sown on areas cropped in 2001 failed due to drought, although where the land was fallowed, wheat yields averaged 1.2 t/ha.

Ibrahima Diédhiou and Malaïny Diatta

A study was conducted to ascertain farmers’ perceptions of trees in the agricultural landscape of the Sudanian zone of Médina Yoro Foulah in Senegal. Survey results indicate that trees play a central role in the agricultural production system through social (production of food, fodder and drugs), economic (wood production and income generation), agronomic and ecological (soil conservation) functions. Farmers’ preference of tree species is dictated by the roles the species plays but generally the typical ranking in decreasing order is: fodder production > food production >high quality wood>soil fertility maintenance> medicinal>income generation. Farmers are averse to trees with negative or competitive effects on crop production and those with superficial rooting systems (which makes land preparation harder). Constraints to increasing and/or stabilization of tree numbers in the landscape mainly include recurrent wild fires and termites. Based on kept or planted species and on farmer preferences, a list of six priority species with significant potential to spark strong interest among farmers was established.

Stephen Guy and Ying Wu

Conservation tillage is needed in the Palouse region located in Idaho, Washington, and Oregon of the Pacific Northwest, USA. Crops of winter wheat need residue on the soil surface from previous crops to deter erosion. Previous studies evaluated wheat response to previous crops, crop residue levels over time, but have not addressed differences for variety response between tillage systems. A replicated tillage comparison trial was started in 2000 and is ongoing near Genesee, Idaho, USA with varieties of winter wheat, spring wheat, spring barley, and pea within tillage treatments. Other soil and biological differences between the tillage are also studied. Yields of cereals are generally similar between the tillage treatments, but when problems occur with weed control, rodent feeding, stand establishment, and other factors, the no-till (NT) treatment usually suffers more impact. Generally cereal test weight, seed size, and kernel plumpness are higher in NT, but crop biomass, yield, protein, and plant height are lower in NT. Most varieties and environments did not show an interaction with tillage, but in some cases certain varieties did perform better. The winter wheat variety ‘Rod’ was the highest yielding in NT both years, but not in conventional till. It appears that some varieties are not suited to NT and give consistently poor results. It may be easier to identify varieties that are not adapted to NT than to find varieties that are superior in NT.

Isaiah I.C. Wakindiki1 and M. Ben-Hur2

Smallholder farmers in many arid and semi-arid regions use wide spaced trashlines to control runoff and erosion. The objective of this work was to study the effects of close spaced trashlines on runoff, erosion and crop yield in a cowpea - maize rotation. Big trashlines, small trashlines, and control (without trashlines) were evaluated in 12 runoff plots constructed at 10% slope in a semi-arid area in Kenya, during five consecutive rainy seasons. Big trashlines reduced runoff and soil loss about two-fold and three-fold respectively and increased crop biomass yield two-fold compared to the control treatment. In the small trashlines treatment runoff, soil loss and crop biomass yield were about half that in big trashlines. The seasonal biomass increased linearly and significantly (P ≤ 0.01) with increasing water infiltration. As more water infiltrated, more water was available for crop production, and the higher was the yield. However, the scatter of the points around this regression line was relatively high, which was probably because the distribution of rainfall amounts and rainstorm frequency influenced the crop yield.

Chandra Reddy1, Ermson Nyakatawa1 and David Mays1

Disposal of poultry waste created by the burgeoning poultry industry in the SE USA is becoming a major environmental concern. Its use in agriculture has been limited to pasturelands and rice deltas. In order to develop a meaningful use for poultry litter in crop production, we designed a long-term study (1996-2002) evaluating its effects on soil quality and cotton (Gossypium hirsutum, L.) production in conjunction with different tillage treatments (conventional till, mulch till, and no-till) and cropping systems on a Decatur silt loam in north Alabama. The experiment was conducted in 1997 and 1998 and 2000 and 2001. Nitrogen was applied to cotton through poultry litter or ammonium nitrate. Cotton was rotated with corn (Zea mays L.) in 1999 and 2002 without any nitrogen application. Cotton was either fallowed in winter or sequenced with rye (Secale cereale L.) to generate additional crop residues for the conservation tillage treatments. Winter rye increased cotton lint yields by 222 to 365 kg/ha under no-tillage over the study period. Cotton lint yields under no-tillage with poultry litter as the nitrogen source were 200 to 436 kg/ha greater than those under conventional tillage with ammonium nitrate as the nitrogen source. Poultry litter application in conjunction with no-tillage and winter rye cover crop is a sound management practice for cotton production in the southeastern USA.

Jan Rücknagel1, Bodo Hofman2 and Olaf Christen2

Economic pressure and environmental legislation forces farmers to adopt conservation tillage systems. The yield decrease, however, is often quite substantial, which limits acceptance by the farmers. In a study conducted in eastern Germany the effects of long-term tillage treatments (1984 – 2001) with a mouldboard plough vs. a cultivator treatment were compared. Measurements included a number of soil properties as well as grain yield of winter barley. The soil physical properties of the uppermost layer of the top soil improved in the cultivator treatment compared with the plough treatment. Soil from the top layer sampled (0-6 cm) in the cultivator treatment showed an increase in total organic carbon and a slightly lower bulk density as well as an increase in the available water content compared with the soil from the plough treatment. Relevant differences were also detected in the 12-25 cm layer. Though the bulk density in the cultivator treatment was higher compared with the plough treatment, the hydraulic conductivity was not significantly affected, which indicates the continuity of the macropores. The differences in the deepest soil layer sampled (25-35 cm) were negligible. With the exception of the harvest years 1999 and 2000 no significant differences in the grain yield between the two tillage treatments were observed, which is in our opinion due to the long crop rotation used in this experiment.

M.A. Ghazavi

Some experiments were conducted to select a soil preparation method for potatoes. The energy input requirement of a high speed disk plough (Yule and Roddy 1994; Ghazavi 1997) was compared with that of a mouldboard plough and also the effects of each implement on the soil were investigated. Then, these implements were used in the preparation of a potato seedbed for final evaluation. The energy input was measured using a 3-point linkage dynamometer with on-board data acquisition system. Soil physical changes were measured including soil aggregate analysis, cone penetrometer resistance, bulk density, surface relief and soil moisture content before and after cultivation. The comparison of total energy requirements between the two tillage tools, showed a higher requirement for the mouldboard plough than for the high speed disk plough. The field experiments concluded that an overall improvement of about 40 % in output (ha/hr) could be obtained when using the improved disk plough compared with a conventional plough. The aggregate analysis of the cultivated layer revealed that the performance of the two machines were largely similar, and no significant differences were seen in potato production rates during two years of field experiments, indicating no disadvantage from using an alternative to the mouldboard plough.

Marc Corbeels1,2, Eric Scopel1,2, Alexandre Cardoso2, Jean-Marie Douzet1, Marcos Siqueira Neto3 and Martial Bernoux4

Direct seeding mulch-based cropping (DMC) systems have largely been adopted over the last 10 to 15 years in the Cerrado region of Brazil as a means to combat soil degradation. Continuous cropping and the absence of soil tillage under DMC favour the sequestration of C in soils. The objective of this study was to assess the soil C sequestration potential of the DMC systems in the Cerrados based on data from a chronosequence and simulation of soil C dynamics using the G’DAY plant-soil model that includes the CENTURY decomposition submodel. Soil C sequestration rate derived from linear regression of all soil C contents measured on a DMC chronosequence between age 0 and 12 in the upper 0-20 cm topsoil layer was 0.83 Mg/ha/yr. The corresponding change in soil total N was +79 kg/ha/yr. Model results indicate that C is lost at rates of about 1.25 Mg/ha/yr from the 0-40 cm soil layer after conversion of native vegetation to soybean or maize monocropping under conventional tillage for 30 years. In contrast, DMC systems with pearl millet as cover crop were adequate to maintain high soil C levels as under the native vegetation. This was largely attributed to the high net primary productivity (NPP) and relatively small removal of NPP as harvest. Gains in modeled C under DMC were sustained by increased N input and/or decreased N losses.

Mike Collins

The lack of a clear economic driver is hindering the development of better residue management methods. However, recent published data from a Western Australian long-term trial shows a 10% yield improvement from retaining residue compared to burning, with a no-till seeding system. A survey researching growers’ views and practices and fieldwork investigating residue manager efficacy and spread straw evenness are reported.

Jiaguo Zheng, Xianjun Lu, Xinlu Jiang, and Yonglu Tang

The System of Rice Intensification (SRI) is a new technique for rice culture. The main features of this system are: transplanting of young seedlings singly in a square pattern with wide spacing, using organic fertilizers and hand weeding, and keeping the paddy soil moist during the vegetative growth phase. Significant phenotypic changes occur in plant structure and function and in yield and yield components under SRI cultivation. The production increases can be notable. However, there are some constraints to adoption of the presently recommended set of practices, e.g., a small number of plants may not be suitable for the low solar radiation condition. Experiments over 2 years are reported in which SRI is modified according to the agro-ecological conditions in Sichuan, with variations in the transplanting pattern, plant leaf-age and density, etc. The following modifications were tested: transplanting 3 separated seedlings in one hill in a triangular pattern with the leaf age extended to 3-4; application of herbicide before transplanting; mulching the spaces between plants with straw; adding chemical fertilizers to promote plant growth vigorously when needed; making shallow furrows before transplanting in the zero-till fields, and applying the alternate-wetting-and-drying method for water management with mid-season drainage to inhibit tillering. With these modifications, grain yield exceeded 12 t/ha, 46% greater than in control using field comparison.

Lucien N Diby1, 2, Robert Carsky3, Ayémou Assa1, Tié B Tra4, Olivier Girardin2 and Emmanuel Frossard5

The influence of soil properties on yam growth and tuber production is discussed. Two species were grown with or without fertilization in two agro-ecological zones (forest and savannah) in Ivory Coast. Leaf area index (LAI), and dry matter (DM) accumulation and partitioning among plant parts were measured during plant growth. These data were tested against a model describing the growth of D. alata. DM production of all plant parts of D. alata was always higher than those of D. cayenensis-rotundata for all sampling dates and for both zones. This was explained by the higher LAI of D. alata which intercepted a higher amount of radiation. Fertilizer application increased DM production of both species in the savannah site only. A good agreement between measured and simulated DM was noticed only for D. alata in the forest zone site, and for all other treatments in both sites the DM pattern was similar and with overestimations. The overestimations were attributed to the differences in soil fertility (e.g. higher pH, higher clay and organic matter in forest) between zones and to genetic differences between species.

Ling-Hoak Ooi and Heriansyah

Malaysia has banned open burning of old oil palm biomass at replanting. The most widely adopted zero burn techniques of replanting oil palms in Malaysia currently are the “chipped and windrow” and “under-planting” methods. These methods resulted in very high breeding of Oryctes rhinoceros, which has become the most serious pest in immature and young mature palms in Malaysia currently. Three new no-burn methods of clearing old oil palms for replanting whereby almost the entire palms are pulverized into fine pieces of less than 0.1g dry weight each and spread widely over the entire field and the root mass dug up at felling are reported. More than 50% of the pulverized palm biomass decomposed at 24 weeks after pulverization, which increased to 80% by the 56th week. All the three methods have good potential in reducing the breeding of Oryctes rhinoceros beetle. They also have good potential in reducing the rat and Ganoderma boninense disease problems. In addition, the new clearing methods reduced the fallow period, facilitated replanting and the subsequent field upkeep work, improved the utilisation of nutrients released by the decomposing palm biomass by the newly replanted palms. The methods of clearing old oil palms for replanting are environmentally less polluting and also improve the sustainability of oil palm plantations.

Soon-Kwon Kim1, Kwang-Soo Lee2, Hyung-Jai Han2, Park Kim2, Hyung-Wook Kim1, Joon-Soo Lee1, Young-Hwan Kim1, Kyung-Geun Jo1 and Hwang-Gi Min3

Malnutrition and food shortage issues in North Korea are the center of the world concern. Flood, hail and drought hit NK during the early and mid-1990s. Economic hardship has trigged the problems. Since 1998, the first author visited NK 27 times (238 days). The International Corn Foundation project on “Super-corn development” that started in 1998 has taken two prolonged tasks: immediate increase of corn (Zea mays L.) production and development of new corn cultivars. The outcomes of the project for six years include: sustainable corn production system development with soybean intercropping, considerable increase of the purity of F1 hybrids, and selection of 25 outstanding new hybrids from different ecologies. An average of 0.5 million tons of more grains are additionally produced annually since 2001. In addition, this project has promoted science based agriculture in the country and introduced a new term, “Seed Revolution”. The project has increased not only corn production, but also developed sustainable and ecology specific crop promotion technologies as well as promoting dialogues with South Korea and adopting of an incentive system.

Khan-Kiang Kee

When oil palms are replanted at about 20-25 years old, the biomass of the palm trunk alone comprised nearly 70 t dry matter/ha representing an enormous pool of nutrients that could be recycled. Nitrogen and K are the two most abundant nutrients in oil palm trunks, accumulated at 190 kg and 770 kg/ha, respectively. Concentrations of the nutrients are highest in the upper, and lowest at the basal, segment of the trunk. Results from a field experiment to determine the rate of palm trunk decomposition and nutrient release indicated that decomposition was most rapid in the upper, followed by the mid and basal, trunk segments. Only 57 and 37% of the initial total trunk dry weight could be recovered after six and 12 months respectively. Very little of the N, P, Ca and Mg stored in the palm trunk are released in the first 12 months after felling presumably due to nutrient immobilization by the microbial fauna and flora population involved in decomposition. Net release of these nutrients occurred mainly after the 12th month of felling. In contrast, K was rapidly “released” and leached out as cellular disintegration occur after felling. Over a period of 18 months nearly 80% (> 600 kg K/ha) of the K in the palm trunks was released. Although some of the nutrients may be retained by the soil, the standard practice of planting a fast growing legume cover crop soon after felling of the old palms will mitigate against potential nutrient losses by reducing surface soil erosion and nutrient immobilization.

U.R. Sangakkara, K.B. Attanayake, J.N. Gajanayake, and P.S.D.R. Bandaranayake

Cassava and sweet potatoes are popular tropical tuber crops, grown under marginal conditions in smallholder systems. Thus potential yields of these crops are not realized due to the suboptimal management practices. Mulching is an easy and useful method inducing benefits to most tropical crops. The impact of three types of plant materials used as mulches (rice straw, grass and leaves of a legume tree Gliricidia) on growth and yields of cassava and sweet potato was determined under field conditions. Mulching increased growth and yields of both species when compared to that of non mulched plants. However legume leaves, which has a lower C: N ratio increased vegetative growth of both species when compared to plants mulched with rice straw or grass. The type of mulch did not affect yield components and tuber yield of sweet potato, and tuber yields were increased by 41%. The impact of mulches on cassava was greater (54%) than in non-mulched plants. The rice straw (or grass) mulch, which has a higher C: N ratio enhanced tuber yields by 24% when compared to the legume leaf mulch in this long-term tuber crop. The usefulness of mulches for increasing yields and the benefits of slow decomposing mulches on cassava was observed under rainfed conditions.

Jaquie Mitchell, Shu Fukai and Jayampathi Basnayake

The mean grain yield of 81 direct seeded (DS) and 91 transplanted (TP) environments that were conducted as part of 3 ACIAR projects over 11 years, from 1992-2002, in Laos, Thailand and Cambodia were examined. The average yield of TP rice was 6% greater than DS rice. A subset of 27 pairs of DS and TP environments was examined and results indicated a significant positive correlation between the DS and TP establishment methods for mean grain yield with only a 3% difference in overall performance. The performance of 3 genotypes in 3 locations in Laos in 1996 was also examined. Results indicated a highly significant positive correlation between the performance of genotypes in DS and TP experiments in which TP rice had a 30% yield advantage over DS rice. This particular experiment highlights the need for good management practices when DS establishment methods are utilised. Results of this paper indicate that DS and TP rice will produce a similar yield for a given environment provided that they are grown utilising good management practices.

K.J. Goh1, P.S. Chew1,2 and K.C. Teoh1,3

Oil palm is mainly grown on infertile soils in Southeast Asia with large amount of fertilizer input to sustain growth and production. The objectives of this paper are to examine the effects of soil and fertilization on the growth and biomass allocation of oil palm in relation to its N productivity, and to determine the critical plant N concentration for optimal growth of oil palm. Results from five long-term oil palm fertilizer response trials on Oxisols and Inceptisols indicated that vegetative growth and biomass allocation were consistent with the concepts of N productivity and resource optimisation, respectively. Plant N productivity at 0.08 kg dry weight/g N/year was higher on the more fertile Inceptisols due to better N uptake and larger storage of excess N in the stem. Their critical plant N concentration was also higher at 8.3 g N/kg dry weight compared with 7.1 g N/kg dry weight in Oxisols. Oil palm under N limiting conditions tended to allocate less biomass to the stem resulting in higher relative growth rate. Higher leaf N concentration reduced root:shoot ratio in Oxisols but had no effect in Inceptisols. The roots seemed insensitive to external soil N availability and maintained their internal N concentrations fairly well. These results could be included in future models of growth and N nutrition of oil palm to better predict its N requirement and N-use efficiency for sustainable production.

Truyen N Quach 1, Hanh T.M. Nguyen 1, Andrew T. James 2 and Long D Tran 1, Thang Q Ngo1 and Truong T Tran1

Five soybean genotypes differing in growth duration (TN12 and M103 as early, and CM60, 95389 and MSBR20 as late maturity types) were sown on three different dates (July 12, July 27 and August 11 2002) to investigate the effects of genotype and sowing time on growth of soybean in rainfed mountain region of Northern Vietnam. Biomass and growth duration of early maturing genotypes were similar for three sowing dates, while late maturing ones had higher biomass and shorter growth duration for the 2 later sowing dates. Grain yield was not different for the three sowing dates but differed among genotypes. CM60 produced the highest yield of 2.4 t/ha. M103 and TN12 produced 1.67 and 1.6 t/ha while 95389 and MSBR20 yielded 1.47 and 1.29 t/ha, respectively. The results suggest that soybean could be sown from early July to early August in variable cropping systems and CM60 was the most promising variety for the region.

Jiayou Zhong1,2,3, Huib Hengsdijk1, Herman van Keulen1,2, Qinghua Shi3 and Xiaoming Zhao3

Jiangxi Province, a typical humid subtropical region, is one of the major rice producing areas in China, with more than 85% of its arable area under rice-based cropping systems. Major problems and developments in current systems include: (1) low economic returns of rice production, (2) small farm sizes, (3) decreasing agricultural area due to urbanization, (4) high inputs of labor, fertilizers and biocides, (5) the use of large quantities of irrigation water in the production of late season rice, (6) declining agricultural labor force, (7) increasing demand for a more luxurious and diversified diet which meets food safety standards. Current rice-based farming systems need to change to be able to deal with these problems and to respond to new developments. This paper describes a generic methodology to explore options for rice-based farming systems taking into account various possibly conflicting goals of stakeholders in rural land use of Jiangxi. It consists of four major parts: (1) identification of objectives, (2) quantification of input-output combinations for production activities, (3) an interactive multiple goal linear programming model, and (4) analysis of results. Key to this approach is the quantification of input-output combinations of alternative production activities, which are categorized into three types: (1) rice-based crop rotations, (2) mixed crop-animal systems, and (3) rice-duck coexisting system. The described method can be used in other land use studies exploring options at farming systems level.

Anil Prashar1, S. Thaman1, E. Humphreys2, Yadvinder Singh1, A. Nayyar1, P.R. Gajri, S.S. Dhillon and Jagadish Timsina2

Transplanted and direct seeded rice on fresh and permanent beds (TRB, DSRB) were compared with puddled transplanted rice (PTR) on sandy loam and loam soils in Punjab, India. The treatments were irrigated daily (CF or “continuous flooding” of flats and furrows) or 2d after the floodwater had disappeared. The furrows in DSRB-CF on the loam drained within 8-10 h, while they remained shallow flooded on the sandy loam. Highest grain yield occurred in PTR-CF, followed in order by PTR-2d, TRB-2d and DSRB-2d on both soils. Yields of TRB on the sandy loam were reduced due to nematode infestation, while yields of DSRB were reduced due to severe Fe deficiency, except for DSRB-CF on the sandy loam. DSRB also required 2-4 hand weedings to supplement herbicide application, while TRB required 1-2 weedings. On these soils, successful production of DSRB may require early Fe sprays prior to the appearance of Fe deficiency symptoms, measures to control nematodes, and early irrigation to germinate weeds followed by herbicide application prior to sowing,

Abdul Rahman Abu Bakar1, M.A. Ghazali2, and Abu Hasan Daud3

A research on the mechanization of fertilizer and pesticide application in non-flooded rice was conducted in the Muda area in the state of Kedah in Malaysia. The soil cone index values were higher, and the insect infestation was lesser, in non-flooded rice compared to the flooded rice. Boom-cum-spot sprayer and fertilizer broadcaster, attached to the 45-hp tractor, fitted with narrow steel wheels, were appropriate machines for crop care and maintenance, in non-flooded rice cultivation. The width of the narrow steel wheel should preferably be lesser than 10 cm, so that the width of the tracts made in the non-flooded rice field can be small. This narrow steel wheel tractor mounted with applicators can be used during the rice growing period, but only until the heading stage. An area of 7 hectare per day can be sprayed by the boom sprayer, while the inverted cone shaped fertilizer broadcaster can broadcast an area of 6 hectares per day. The soil should have a cone index value of above 3.0 kg/cm2 at 25 cm depth. These results have significant implications for moving towards mechanization of fertilizer and pesticide applications in non-flooded rice in Malaysia.

Jagadish Timsina1, Himanshu Pathak2, E. Humphreys1, Doug Godwin3, Bijay Singh4, A.K. Shukla5 and Upendra Singh6

Observations from rice field experiments at three sites in northwest India (New Delhi, Ludhiana and Modipuram) were used to calibrate and validate the recently released version 4.0 of CERES Rice. The model performed satisfactorily in terms of grain yield and N uptake when compared against data from field experiments with a range of water and N management treatments across the three locations (root mean square of 0.82 Mg ha-1 and 8.5 kg ha-1 for grain yield and N uptake, respectively and d-stat of 0.94 for both traits). The model was used to analyse the gaps between potential and actual yields at the three locations. Potential yields ranged from 10.0 to 10.8 Mg ha-1 across the three locations, compared with research station yields of 6.2 to 7.8 Mg ha-1 and farmer average yields of 3.3 to 5.6 Mg ha-1. The results suggest that there is plenty of scope to increase farmers’ yields by improving crop management.

Nguyen Ngoc De11, Vo Tong Xuan2, M. Zainul Abedin3 and Ma. Romilee Bool

Upland crops like maize, groundnut, casaba melon, and water melon were introduced with partial irrigation into the traditional ‘rice- rice-fallow’ pattern in the rainfed coastal areas of Tra Vinh Province, Mekong Delta, Vietnam to increase farm productivity through crop diversification and to improve the household income of resource-poor farmers. Farmers used to get an average net return of 4.2 million VND (~US$ 260) from the traditional rainfed pattern but with the introduction of upland crops, net benefits increased greatly depending on the crops grown. After two rice crops, each of a modern variety (MV), net returns per ha from the pattern with maize, groundnut, casaba melon, and water melon were US$ 197, US$ 360, US$ 555, and US$ 986, respectively. In contrast, net returns per ha from the pattern involving MV followed by traditional rice (TR) and those crops were US$ 345, US$ 423, US$ 252, and US$ 527, respectively. Farmers benefited from higher farm productivity and seasonal crop diversity from the improvement brought by the introduction of new cropping pattern. Incorporation of additional crops also generated opportunity to diversify sources of income and created employment opportunities directly or indirectly for the otherwise poor farming communities. Marketing of the new farm products and availability of capital are expected to be major issues in the expansion of the new cropping pattern.

Santosh kumar Nayak 1 and Pawan Kumar Singh 2

Seven species of Azolla, A. caroliniana, A. filiculoides, A. mexicana, A . rubra, A. microphylla, A. nilotica and A. pinnata, were cultivated in Khurda, Orissa ( 84°W to 85°E Long. and 19° to 20° N Lat.). Multi-branched tiny water fern Azolla sps. were grown in 4mx2m sized plots. The plots with Azolla were left for mat and sporocarp formation in January to March (2000-2002). At 30, 45, 60 and 75 days after inoculation (DAI), sporocarp count was made to record average per cent of sporocarp bearing plants and average number of plants giving 100 megasporocarps. The post harvest operations like collection, separation, up-gradation, cleaning, drying and storage management of megasporocarps were also carried out. The mature and full sized megasporocarps of A. caroliniana, A. mexicana, A. microphylla, A.nilotica, and A. pinnata were incubated in paddy soils with varied pH. The soil samples were collected from various places/states of India. Under Khurda condition, 5 species (A. caroliniana, A. mexicana, A. microphylla, A. nilotica and A. pinnata) produced a good number of sporocarps (52-76%) in prolonged mat–forming situation, but 2 other species (A. filiculoides and A. rubra) didn’t produce any sporocarps. Soils of Thottapallikari, Kerala (pH, 4.3) and soils of Karnal, Haryana (pH, 8.3) were not suitable for emergence of plantlets from megasporocarps, whereas soil pH 6.1 to 7.6 of different States such as Orissa, West Bengal and Andhra Pradesh were favourable for emergence and establishment of young seedlings of Azolla.

Estela Pasuquin1, Brenda Tubana1, Jessica Bertheloot1 and Tanguy Lafarge1, 2

Appropriate crop management in rice is required for newly selected genotypes to match with their growth potential. In irrigated areas, transplanting is the most widely accepted method to obtain high yield. Even though the nursery management, and particularly seedling age at transplanting, is expected to have a great impact on plant growth through potential seedling competition in the nursery, research on its adaptation to the characteristics of promising genotypes has not gained much focus. The impact of early transplanting on rice growth and grain yield of four contrasted genotypes, including hybrid, new plant type and improved inbred line, was compared in the wet and dry growing seasons in IRRI, Philippines. Seedlings were grown in seedling trays and wet-bed nurseries at 3000 seeds m-2 and were transplanted 7, 14 and 21 days after sowing at 25 pl m-2. Late transplanting delayed tiller emergence by 15 days for all genotypes in all the studied situations through a delay in main tiller leaf emergence observed before transplanting. Leaf emergence started again as soon as the seedling was transplanted. Early transplanting then induced higher tiller production and higher plant shoot dry matter accumulation at early stage. Compared to later transplanting, early transplanting generated a significant positive effect on grain yield, up to 10% of hybrids and IR72 when seedlings were transplanted at 7 days, and up to 78% of the new plant type when seedlings were transplanted at 14 days. Early transplanting appears to be a relevant practice to improve yield in irrigated rice.

Hisashi Kitagawa1, Hiroyuki Shiratsuchi1 and Akio Ogura2

Recently, ‘Long-mat Seedling Culture System’ (Long-mat System: LS), a new technique for raising rice seedlings hydroponically for modified machine planting was developed aiming at higher efficiency and labor saving in rice production. Because the seedlings raised by LS were partially damaged at the time of machine transplanting, optimal seeding rate for LS was expected to be higher than that by conventional soil-seedbed system (SS). Therefore, the effect of different seeding rate on the growth rate and quality of the seedlings for LS and SS were examined. When LS system at the seeding rate of 200g was compared with the SS system at the conventional seeding rate of 130g, there was no inferiority in the growth and quality of seedlings and also no difference in the growth rate after the transplanting. Therefore adopting higher seedling rate (200g) for LS is recommended.

Salina P. Banu1, J.M. Duxbury2, J.G. Lauren3, Craig Meisner4 and Rafiqul Islam5

High quality seed is the key to successful agriculture. Survey results have shown that 64% of Bangladeshi farmers use their own wheat seed year after year, or 26% purchase from other farmers in local markets. Only 10% of the seed is purchased from governments’ seed suppliers. As a result, poor seed quality is a significant factor affecting wheat productivity at the farm level in Bangladesh. To quantify farmers’ seed quality, wheat seeds were collected from the same 44 farms in the Chuadanga region of southwestern Bangladesh during sowing and after harvest. Seed germination was compared between the standard blotter test and a soil assay on farmers’ representative soil at Wheat Research Center, Bangladesh Agricultural Research Institute, Gazipur. Results indicated that the soil assay is an easy and accurate way for farmers to evaluate seed quality under their conditions. Good to best quality seed (>81% germination) during sowing in first week of December was 68% by the soil assay and 93% by the blotter test. After harvest in May, seeds from all farms germinated by blotter test, but only 9% of farmer seeds had >81% germination by soil assay. Infection of Bipolaris sorokiniana was found on harvested seed from 80% of the farms after storage in October. This and other seed-borne fungus demand for seed treatment to increase wheat production in Bangladesh.

Sarath P. Nissanka1, A. Ananda Coomaraswamy2 and C.K. Seneviratne3

An investigation was carried out on the impact of aging of pruning cycle on productivity parameters of two popular tea clones of TRI-2025 and DT-1 grown in higher altitudes (>900 m amsl) of Sri Lanka. Different ages in the pruning cycles considered were 1st, 2nd, 3rd, and 4th years after pruning. Shoot extension rate, thermal time requirement for shoot appearance, active and banji (shoots with retarded growth) shoots, leaf photosynthesis, leaf area distribution and black-tea yield were measured. The thermal requirement for an axillary bud to become pluckable shoot was 370 day degrees for DT-1 while it was 350 for TRI-2025. Shoot extension rate was highest at the first year of the pruning cycle for both clones. Active shoot density decreased with age, with the corresponding increase in banji shoot density. Leaf photosynthesis rate was similar and was highest for both clones during the first year and then decreasing the rates subsequently. Leaf area index increased up to 2nd year in TRI-2025 and up to 3rd year in DT-1 after pruning and reduced thereafter. Yield increased after pruning, and reached to a maximum at 2nd year for TRI-2025 and at 2nd and 3rd year for DT-1 after pruning. Thereafter, gradual decline in yield was observed for both clones. However, the productivity of TRI-2025 was greater across all years from pruning compared to DT-1. This may be attributed to the production of higher percentage of shoots per unit area, faster shoot growth, and larger shoot sizes with greater inter-nodal length compared to DT-1. Light skiffing at the 5th year after pruning enhanced the productivity by 42%.

Mahrup1, Andrew K. Borrell2, Mansur Ma’shum1, I.G.M. Kusnarta1, Sukartono1, Judy Tisdall3 and Jaikirat S. Gill3

Rice (Oryza sativa) grown on rainfed Vertisols in the semi-arid tropics of southern Lombok, Eastern Indonesia, is usually flooded in the short wet season, creating a considerable demand for water. However, rice crops and secondary crops frequently suffer from water stress as the soil dries after rainfall. Four systems of soil management for rice were studied at Wakan and Kawo, with average annual rainfalls of 984 mm and 1665 mm respectively. The objective was to improve water use efficiency (grain yield/m3 water consumed). The four systems were unflooded permanent raised beds with tillage (RMT) or without tillage (RNT), and flooded flat land with tillage (FMT, the conventional system, gogorancah), or without tillage (FNT). Water was kept at 0.10 m depth in the furrows (RMT, RNT) or at 0.05 m depth above flat land (FMT, FNT). Excess water was collected in a dam (embung), and used when necessary to keep the water at the desired depth. Compared with FMT, RNT reduced crop water requirement for rice by 50% at Wakan and by 44% at Kawo. Water use efficiency in RNT was increased by 90% (Wakan), and by 56% (Kawo), compared with that in FMT. There were no differences between treatments in the yield of rice at Site 2 (4.5 t/ha), but at Site 1 yield was better in FMT or FNT (4.2 t/ha) than RMT or RNT (2.8 t/ha). Hence, on rainfed Vertisols of Southern Lombok, rice grown on permanent raised beds, with or without tillage, could successfully replace rice grown under the conventional flooded system with tillage on flat land (gogorancah), where the rainfall is higher. The extra water saved with permanent raised beds could be used to irrigate secondary crops.

I.G.M. Kusnarta1, Judy Tisdall2, Sukartono1, Mahrup1, Mansur Ma’shum1, Jaikirat S. Gill2 and Don VanCooten3

Root distribution and yield of crops depend on the physical properties of soil, which in turn depend on soil management. The root distribution, shoot:root ratio and yield of rice (Oryza sativa) under four soil management treatments within two years on a rainfed Vertisol in Southern Lombok, Indonesia (annual rainfall 700 mm to 1300 mm) were studied during the 2002/2003 wet season. The treatments were rice, grown on: a) raised beds with no tillage, not flooded (M1), b) raised beds with tillage, not flooded (M2), c) flat land with no tillage, flooded (M3), and d) flat land with tillage, flooded (M4, the conventional system gogorancah). In each treatment, the root distribution varied with depth, with fewer roots at 15 to 20 cm depth than higher in the profile. There were no significant differences in concentration of roots between treatments at each depth. The shoot:root ratio was at least 3.2 in treatments with tillage (M2, M4), and was no more than 2.6 in treatments without tillage (M1, M3). In this climate with low rainfall, the yield of rice was not related to root distribution, but was higher in the conventional flooded system M4 (6.0 t/ha), than the yield on unflooded raised beds (M1, M2, mean 5.0 t/ha). Further study is needed on Vertisols in this semi-arid climate to determine the long-term effects of unflooded raised beds on root distribution and crop performance of wet-season crops and of secondary crops.

A.S.M.H.M. Talukder1, Craig Meisner2, M.J. Kabir3, A.B.S. Hossain4 and M Harun-ur-Rshid5

Present rice–wheat systems in Bangladesh to meet up the food security of an expanding population are threatened by productivity decline, scarcity of resources, and environmental factors. Raised bed agriculture is widely used in developed countries to improve system productivity. Straw retention can be a potential source for improving soil health and crop productivity. The consequences of straw removal on productivity and profitability of rice-wheat systems have not previously been documented in Bangladesh. A 3-yr study was conducted at the Wheat Research Centre, Dinajpur, Bangladesh to compare the effects of 4 N levels (0, 50, 100 and 150% of recommended) and 3 straw management (straw removal of all crops, 50% and 100% straw retention of all crops) in wheat-maize-monsoon rice cropping systems on permanent raised beds. Compared with straw removal, the 50% straw retention with 100% N significantly increased grain yield (by 32%) in maize, with no statistical difference with 150% N plus 100% straw retention. The subsequent rice yields were also increased significantly by 33% with 100% N compared to straw removal and was not significantly different from 50% or 100% straw retention with 50% or 150% recommended N. In wheat, the highest grain yield was recorded from 50% straw retention plus 150% N, which was 26% higher than straw removed plots. In 100% straw retention with 150%N treatment, the yield was negatively affected and in 50% N plus 50% straw retention treatment the profit was maximized. Weed pressure was also reduced with straw retention. Results reveal considerable benefits of straw retention of crops with the use of 50-100% recommended N in terms of yield and economic benefit.

James Ernest1 and Jane O'Sullivan2

A novel agroforestry system using the leguminous tree Gliricidia sepium (Gliricidia) as improved fallow and live stake for yam (Dioscorea spp.) is being evaluated in several locations in Papua New Guinea. The trees are established from pole cuttings directly into degraded grasslands, 8-12 months before planting yam. Gliricidia poles are planted on a 2 x 2 m grid, each tree supporting four yam vines. Data from four trial sites harvested in 2003 showed no difference in yield attributable to staking system, while NPK fertilizer increased yield by 50% (from 18.6 to 27.9 t/ha) on two Bogia District sites, but not on two Markham Valley sites. While positive responses attributable to nutrients contributed by Gliricidia leaf mulch are not yet evident, these preliminary results indicate that, when regularly pruned, the trees do not compete to the detriment of the crop, and can reduce management inputs for weeding and staking. The system may alleviate many of the problems associated with shortened fallows, including weed intensity, decline in soil nutrient availability and organic matter content, and shortage of staking materials. Further benefits to farmers include softer soil texture, and shading of workers at planting and harvest. The trials are continuing to evaluate medium-term impacts on soil and crop. Further long term experiments are needed to assess the system fully.

Mohinder Singh. Kadian1, Sarath Ilangantileke1, Moeen Ud Din2 and Nasrat Wassimi2

Afghanistan has ideal conditions for potato production. The present national average yield of 16.8 t/ha could be increased to 25 t/ha if farmers obtain good quality seed. There is no formal or informal seed system existing in the country. In 2002, the International Potato Center (CIP) initiated a project on the production, multiplication and diffusion of good quality informal seed to increase potato production. In all 94 farmers and 118 extension workers were trained by CIP on improved agro-techniques for good quality informal seed production. Good quality seed of existing varieties Kufri Chandramukhi, Kufri Lauvkar, Cardinal and Desiree were imported from India and Pakistan and given to 41 farmers in Nanghar province. CIP, for the first time introduced a seed potato production system in the autumn season of 2002. Farmers in this province normally produce potato in the early spring season and therefore were not keen on planting potato in autumn. After one season however, farmers were convinced of the possibility to produce high quality seed potatoes in autumn. Seed produced by farmers in Nanghar province in autumn was stored in Jalalabad. In March, the seed was transported to Kabul and distributed to 53 farmers of Wardak, Kabul and Bamyan provinces in Afghanistan. The average tuber yield of 49 farmers for the three varieties ranged between 21.7 to 33.5 t/ha. The farmers obtained higher yields and therefore higher incomes by planting good quality seed and adopting improved production techniques. The availability of good quality informal seed at affordable prices to poor farmers is therefore expected to increase national potato productivity.

Lal P. Amgain1 and Jagadish Timsina2

The Institute of Agriculture and Animal Sciences (IAAS) has been conducting research on a range of field crops in the central Terai region of Nepal for over 25 years. A review of published and unpublished results of crop research at IAAS was undertaken to identify the nature of the research effort over the past 25 years, and to determine yield gaps and identify future research priorities. On-station research has included 14 crop types, however the main research effort has been on wheat followed by rice, but with some focus also on maize, potatoes, oilseeds, and legumes, and with a small amount of cropping and farming systems research. The main research themes were varietal performance and breeding (especially wheat), crop, soil and water management, weed management (especially in rice) and insect pest and disease management. Potential yields of rice, maize and wheat were 5.5, 4.4, and 5.0 t/ha, respectively, higher than research station yields (3.4, 3.3 and 3.5 t/ha, respectively) and farmers’ yields (2.7, 1.8, and 1.9 t/ha, respectively) in Chitwan. The results suggest that there is great scope to raise yields of all cereals in farmers’ fields, more so for wheat and maize than for rice. Improved agronomical research on rice varieties and crop and soil management are required to reduce the yield gap for rice, while adoption of recommended technologies by farmers would help reduce the wheat yield gap. For soybean, lentil, and potato, the gap between potential and farmer yields is much larger than the other yield gaps, suggesting large scope for increase in yields in farmers’ fields through both improved management and improved varieties. Innovative and new research on eco-region suited variety identification, improved crop and soil management, improved water and N management, agro-meteorology and crop modelling are suggested as priorities for future research to increase productivity and reduce yield gaps of major field crops in the Chitwan district of Nepal.

Kesang Lachungpa

Sikkim has a total area of 7,096 km2 with only 11% of land suitable for agriculture. About 80% of the farms are small and marginal (0.2 to 0.4 ha) with fragmented land holdings. Mandarin is the most important commercial fruit of Sikkim and is never grown alone but always intercropped throughout the year. These intercrops are grown in such a way so as to take maximum advantage of the space in between the fruit trees. Leguminous crops and ginger were found to be most beneficial in terms of economic returns. Due to its geographical location and biodiversity the existing mandarin agri/horti system is ecologically sustainable and provides farmers with their household food needs and cash income for family welfare.

Guangdi Li and Mark Conyers

Wheat and weed dry matter at anthesis and harvest, were monitored over 4 years, 1999-2002. Two pasture/crop rotation systems, each with lime and without lime application, were used, annual pasture/crop rotation (AP/C, 2-year rotation) versus perennial pasture/crop rotation (PP/C, 6-year rotation). The pasture in AP/C was subterranean clover dominated pastures with voluntary grass weeds whereas pasture in PP/C was a mixed sward of perennial ryegrass and subterranean clover with voluntary grass weeds. The crop in AP/C was wheat whereas crops in PP/C were triticale, lupins and wheat. However, only the wheat crop and its relationship with weeds are discussed in this paper. Lime significantly increased dry matter of wheat and suppressed weed dry matter at anthesis and harvest. The grain yield on the limed treatments was 3.1 t/ha whereas on the nil lime treatments it was 1.3 t/ha. There were strong negative relationships between wheat and weed DM at anthesis and harvest. Liming could be used to increase wheat grain yield and suppress weeds on highly acidic soils in high rainfall zones.

Bhagirath S. Chauhan1, Gurjeet S. Gill1, Chris Preston2 and Glenn McDonald2

In the growing season of 2003, a field study was undertaken to investigate the effects of tillage systems on the vertical distribution, recruitment pattern and persistence of Lolium rigidum Gaudin (annual ryegrass) seed-bank. The tillage systems comprised low soil disturbance discs (Day-Break and K-Hart), intermediate narrow openers (16 mm Harrington knife point) and high disturbance Ribbon seeder (178 mm wide point). Assessment of vertical distribution of weed seeds after the sowing operation showed that in the case of the disc systems most (76%) of L. rigidum seed remained on the soil surface. In contrast, the surface seed-bank was considerably lower in the Harrington knife point (42%) and the Ribbon seeder (11%) systems. In the Ribbon seeder, about 80% of the seeds were found in the 1-5 cm soil layer, which is optimal seed placement for rapid germination. This difference between the tillage systems in the vertical distribution of seeds may have been responsible for the slower and lower final recruitment of L. rigidum seeds in the two disc systems. The persistence of L. rigidum seed however, was extremely high but unaffected by the tillage system. Irrespective of the tillage system, about 50% of L. rigidum seed carried-over from one growing season to the next, which is much greater than previously reported. The soil at this study site was non-wetting in nature and this may have been responsible for the unusually high persistence of the seed-bank of this species. Further research is needed to investigate the effects of non-wetting soils on the ecology and management of weed species.

U.R. Sangakkara1, Sarath P. Nissanka1, B. Marambe1, K. Hurle2 and B. Rubin3

Weeds are a significant problem in rice culture, and increasing use of herbicides in the developing countries do pose problems of herbicide resistance. A study was undertaken to determine herbicide use patterns, weeds and the possible existence of resistance in the prominent weeds to the most popular herbicides used in two agroclimatic zones of Sri Lanka. The rice farmers could be categorized into non, suboptimal, optimal and excessive users of herbicides based on rates. The weed populations were greater in the dry season and grasses were predominant. The most common species were Echinochloa spp., Ischaemum rugosum, Leptochloa chinensis, Cyperus spp (sedges) and few broadleaved species. Selected populations of E. crus-galli and I. rugosum showed some resistance to Propanil and Nominee (bispyribac sodium), respectively, by assays determining seedling death, while there was no evidence of resistance in E. colona. Further research to examine the potential for herbicide resistance in rice fields with increasing use of herbicides is warranted.

Craig M. Alford1, Stephen D. Miller1 and Jack T. Cecil1

Maize, sugarbeet, and dry bean are the primary row crops grown in Wyoming, usually in 76 cm rows. A substantial amount of research has been conducted in the mid-west; showing yields of crops can be increased when they are grown in narrow rows (< 76 cm). In addition to improving yields narrow rows may also allow crops to be more competitive with weeds. Row spacing trials were established in maize, sugarbeet and dry bean at Torrington Wyoming under sprinkler irrigated conditions. Crops were grown in 38, 56 and 76 cm rows. Light interception readings were taken throughout the growing season and end of season weed biomass and crop yield were determined. Growing crops in narrow rows reduced weed biomass, and light interception by the crop was increased, especially early in the season. Sugarbeet yields were increased when grown in narrow rows, while row spacing had no impact on maize or dry bean yields.

Stephen D. Miller1, Robert Wilson2, Philip Westra3, Andrew Kniss1 and Craig M. Alford1

The commercialization of numerous glyphosate tolerant crop varieties could potentially allow farmers in the Central High Plains to grow a three, four or five – crop rotation utilizing only glyphosate as the sole weed management tactic. Plots were established under irrigation at Torrington, Wyoming; Scottsbluff, Nebraska; and Ft. Collins, Colorado in 1998 to determine if glyphosate use pattern in glyphosate tolerant crops influences weed control by placing selection pressure on weed species, alters weed population dynamics, or leads to development of glyphosate resistant weeds. After six years there was no evidence that any species has developed resistance to glyphosate. However, at all three sites common lambsquarters (Chenopodium album) populations have increased in the treatments receiving 0.4 kg/ha of glyphosate. Rotating glyphosate with conventional herbicides was no more effective in slowing this population increase than the use of glyphosate at 0.8 kg/ha.

B.S Alabi1, Albert O. Ayeni2 and Akinola A Agboola3

The economic assessment of manual and chemical methods for controlling thorny mimosa (Mimosa invisa) in cassava established at 10,000 plants/ha was investigated at the Institute of Agricultural Research and Training, Ibadan, Nigeria (7° 22.5’ N, 3° 50.5’E), a humid tropical environment. Six weeding regimes were compared with an unweeded control. Removal at 4, 7, and 11 weeks after planting (WAP) consistently gave the highest net benefit and marginal rate of return. In a herbicide trial, net benefit and marginal rate of return was highest when thorny mimosa was hand-weeded in cassava. Only atrazine [6-chloro-N-ethyl-1-methylethyl)–1,3,5-trianzine-2,4-diamine] + metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy–1-methylethyl)acetamide] at 0.82 + 1.68 kg/ha had net benefit and marginal rate of return that were close to hand-weeding.
Abreviation: N = Nigerian currency, Naira. In 1995 to 1996 1$ = N80. In 1996 to 1997 1$ = N84.

Jairo A Palta1, Mingtan T. Liao1, 2 and Ian R.P. Fillery1

Early vigour, and deep and fast root growth are desirable characteristics for wheat (Triticum aestivum L.) grown on the deep sandy soils of the Mediterranean climatic region of Western Australia, where large quantities of NO3 are moved rapidly down the soil profile before nitrogen uptake is possible. The difference between the vigour wheat lines, Vigor 18 and B18, and Janz, a current commercial cultivar widely adapted in Western Australia, on the growth and proliferation of roots was compared.. Plants were grown in a glasshouse in glass-walled boxes filled to a depth of 1 m with sandy soil, collected from a field site, and under non-limiting water and nutritional conditions. Root length, root number and distribution along the soil profile were non-destructively measured at 48 h intervals by a mapping technique. Shoot and root biomass and nitrogen uptake were measured destructively at stem elongation. Maximum rooting depth of the vigour wheat lines was not different to that of Janz. The vigour wheat lines branched earlier and considerably more prolifically in the top 0.7 m of the soil profile, resulting in higher root number, higher root length density and presumably improved the capture of nitrogen before it moved down the soil profile. Cumulative root length of the vigour wheat lines from the 1-leaf stage to stem elongation was 83% higher than that of Janz.

Abdel O. Mesbah1 and Stephen D. Miller2

Two field experiments were conducted from 2001 to 2003 at the Powell Research and Extension Center, Wyoming to evaluate wild oat (Avena fatua L.) control and malt barley (Hordeum vulgare L.) response to fenoxaprop and tralkoxydim applied alone or in combination with several broadleaf herbicides. Excellent control was achieved with tralkoxydim applied alone or in combination with broadleaf herbicides to wild oat at the 1 to 3 leaf stage. The addition of ammonium sulfate enhanced wild oat control by 5 to 7%. There was no significant difference between two tralkoxydim formulations and no injury to barley was registered with any of the treatments. Compared to the weedy check, barley yields were 0.95 to 1.47 t/ha higher in treated plots. Excellent wild oat control was achieved with fenoxaprop alone or in combination with broadleaf herbicides; however, barley injury ranged from 3 to 17%. Tank mixing fenoxaprop with broadleaf herbicides, especially MCPA, enhanced its safety. Barley yield with fenoxaprop was closely related to the degree of injury.

Seyed V. Eslami1, Gurjeet S. Gill1, Bill Bellotti1 and Glenn McDonald2

The effects of various densities of wild radish (Raphanus raphanistrum L.) and wheat on the growth and reproductive output of each other were investigated in a field trial at Roseworthy, South Australia in 2003. The experiment was established as a factorial combination of wheat (0, 100, 200 and 400 plants/m2) and wild radish (0, 15, 30 and 60 plants/m2) densities. The presence of wild radish in wheat reduced shoot dry matter and grain yield of wheat with the magnitude of this reduction dependent on weed density. The variation in wheat grain yield was largely related to the changes in the density of wheat ears. Increasing the density of wheat substantially reduced the adverse effects of wild radish on wheat. As crop density increased, weed dry matter and pod production per unit area decreased. Wild radish pod weight/m2 was negatively correlated with wheat density (r = -0.70, P < 0.01) and wheat grain yield (r = -0.81, P < 0.01). This indicated that higher densities of wheat were able to suppress pod production of this weed species. From a practical view point, this study shows that increased wheat density in the range of 200-300 wheat plants/m2 can reduce wild radish pod production and may also give some reduction in crop yield loss. The data collected will be used to develop a simulation module based on the APSIM platform.

Chanya Maneechote1, Sansanee Jamjod2 and Benjavan Rerkasem2

Wild rice (Oryza rufipogon Griff.) a close relative of cultivated rice, O. sativa L., is a noxious weed in rice fields of central Thailand. After a few years of infestation, the wild rice seed bank builds up rapidly. Invasion in some fields was so severe that the crop was abandoned. To slow down this process, ACCase-inhibiting herbicides (quizalofop-p-tefuryl, fenoxaprop-p-ethyl and profoxydim) were tested under glasshouse and field conditions. In the glasshouse experiment, quizalofop-p-tefuryl at a rate of 50 g a.i./ha effectively induced sterility, i.e. empty seeds, when applied at either flowering or booting stages. Fertile wild rice seeds were reduced by 50% compared to untreated plants. In the field experiment, yield loss could be prevented by herbicide treatments. Quizalofop-p-tefuryl at the rate of 50 g a.i./ha gave higher grain yield than the other treatments. ACCase inhibiting herbicide not only prevented yield loss but it may also help in slowing down the seed bank build up in the field.

S.O.S. Akinyemi1, Josephine O. Makinde2, Isaac O.O. Aiyelaagbe3, Folasade M. Tairu1 and Olayinka. O. Falohun1

The effects of five different weed control methods (hoe weeding, chemical weeding, intercrop with pumpkin [Yellow var.], pumpkin [White var.] and groundnut intercrop) on the growth and yield of papaya (Carica papaya cv. ‘Sunrise solo’) were compared on an alfisols in Ibadan Southwestern Nigeria. No weed control method significantly (P>0.05) influenced plant height and stem diameter of papaya. Days to 50% flowering were lowest under chemical weeding. Weed dry matter (WDM) was lowest under chemical weeding. Chemical weed control reduced weed density by 79, 49 and 70% at 5, 9 and 12 months after planting (MAP), respectively, when compared with hoe weeding. Papaya fruit number per plant was highest in the last quarter of both the first and second year. While the white pumpkin gave the highest fruit yield among the intercrops, chemical weed control gave the highest fruit yield (first and second year harvests) and revenue among all the strategies.

Stevan Z. Knezevic1, Sean P. Evans2 and Mike Mainz2

With the widespread use of glyphosate resistant crops two common questions related to a weed control program have emerged: (1) when is the most appropriate time for a postemergence weed control operation and (2) what is the cost of a delayed weed control operation? The first question was addressed using the concept of critical period for weed control. Our field studies determined the effects of three N rates in corn and three row spacings in soybean on the critical time for weed removal. Critical period for weed control in corn ranged from V1-V11, V3-V10, V4-V9 and V6-V9 for N-rates of 0, 60, 120 and 240 kg/ha, respectively. The study in soybean suggested that the critical time for weed removal coincided with V3, V2 and V1 for soybean row spacing of 19, 38 and 76 cm, respectively. The second question was addressed by pooling yield loss data across locations and years from both studies and related to the extrapolated crop growth stage at the time of weed removal for both corn and soybean. A yield penalty of 2% for every crop leaf stage of delayed weed control past the critical time for weed removal is proposed as a reasonable prediction rule with moderate to heavy weed infestations in corn and soybean as the cost of delaying weed control. Full version of this paper was published in the Crop Management Journal online:

E. Zand1 and H. Rahimian Mashhadi2

Genetic improvement of ecophysiological traits of Iranian winter wheat cultivars released during the last 50 years was studied during 1998 and 1999 growing seasons in Mashhad, NE of Iran. The results showed a significant yield difference among old and new cultivars. In both years a significant positive correlation was found between yield and harvest index (r = 0.65 and 0.93 for 1998 and 1999, respectively). New cultivars showed advantages over old cultivars for some yield components and growth indices (e.g., leaf area index and crop growth rate) and had higher resource capture ability by means of radiation and nitrogen use efficiency. Path analysis showed that about 89% of grain yield variation could be explained by harvest index, crop biomass, internode length, and number of fertile florets per spikelet. New wheat cultivars were better competitors with wild oats than old cultivars. An increasing trend in yielding ability of wheat cultivars was observed in the presence of wild oat with a higher competition index in new cultivars. It seems that competitive ability of wheat cultivars was mainly related to their leaf area index, height at which maximum leaf area occurred, and leaf area at the end of tillering. In all cultivars grain yield decreased with increasing sowing density above the optimal level but this was not significant. It was concluded that during the last 50 years Iranian wheat cultivars have been improved for higher grain yield and better inter-specific competitive ability. Intra-specific competition ability of cultivars, however, has not undergone significant change.

Jan Grenz1, A.M. Manschadi2, Peter DeVoil2, Holger Meinke2 and Joachim Sauerborn1

Legume production in the Mediterranean countries suffers considerable damage from infestation with the parasitic weed Orobanche crenata. Characteristics of O. crenata infestation include host specificity, complex host-parasite interaction and a persistent soil seed bank. Hence durable control of the parasite can only be achieved through a combination of control approaches in an integrated strategy. The time-consuming evaluation of potential control strategies may be accelerated by use of an ecophysiological model of host-parasite interactions. A mechanistic modelling capability for simulating the interaction between host plants and parasites has been implemented within the Agricultural Production Systems Simulator (APSIM) and parameterised for the association faba bean - O. crenata.

Wen-xiong Lin1,2, Hua-qin He1,2, Li-hua Shen2, Xiang-xu Chen1, Yuqing Ke1, Yu-chun Guo2 and Hai-bin He2

Proteomic analysis was used to investigate the changing pattern of protein synthesis in allelopathic rice exposed to the stress from barnyard grass. Four differentially expressed proteins, 3-hydroxy-3-methylglutaryl-coA reductase 3 (HMGR3), phenylalanine ammonia-lase (PAL), thioredoxin-m and peroxidase precursor, which are related to the pathways of isoterpenoid and phenylpropanoid biosynthesis in the plant defence response, were detected by MALDI-TOF/MS analysis. The findings support the emerging concept that terpenoid and phenolic compounds are the allelochemicals against weeds.The proteomic approach in the discovery of genes and pathways conferring allelopathy is discussed.

B.S Alabi1, A.A Osobu1, Josephine O. Makinde2, O.F Owolade2, E.A Makinde1 and Albert O. Ayeni3

Tillage is being considered as a method to reduce weed infestation and improve the efficacy of applied herbicides in Nigeria. A field experiment was conducted to investigate the influence of tillage methods (conventional, manually formed ridges, no-till) and herbicides on weed control and the performance of tomato at the Institute of Agricultural Research and Training, Ibadan in 2002 and 2003. Weed biomass was higher in no-tillage than in conventional tillage. Conventional tillage gave the highest marketable fruit yield of tomato followed by manually formed ridges. No-tillage had the lowest yield. Metolachlor+ metobromuron at 2.5 kg.ha-1 a.i., and pendimethalin at 2.0 kg.ha-1 a.i., produced yields that were comparable with hand weeding. The levels of tillage tried did not increase the efficacy of the herbicides.

U.R. Bishnoi and R.S. Payyavula

The use of plant activators to reduce severity of diseases in many crops has been reported. Therefore, the effect of two plant activators, Messenger® and Actigard™ was tested on three tomato (Lycopersicon esculentum Mill) cultivars (Mountain Pride, Floralina and Florida-47) and two canola (Brassica napus L.) cultivars, (Flint and 188-20B). Results showed that in tomato, Messenger® and Actigard™ decreased early leaf blight (Alternaria solani) severity from 8-12% and increased tomato yield from 10-13% in comparison to control. Response to activators varied among cultivars. In canola, effect of both activators on crop maturity and severity of blackleg (Leptosphaeria maculans) disease infection was non-significant. The activators significantly increased plant height with application of Messenger® at a rate of 567.0 g/ha. The use of Actigard™ at a rate of 53.2 g/ha resulted in an increase of 7.2% and 8.6% in number of pods/plant and 9.7% and 7.2% in seed yield, in resistant and susceptible canola cultivar respectively.

Gilberto Omar Tomm1, Hadley Randal Kutcher2, Edson Clodoveu Picinini1 and Beatriz Donida3

Field pea fits well in the grain production systems of southern Brazil, where two crops are produced annually, and has the potential to contribute to increased diversification and sustainability of the cropping systems. Foliar diseases are the main limiting factor to field pea production in this region and disease control is essential to maintain field pea productivity in this humid environment. The objective of this study was to search for suitable fungicides to reduce disease severity, particularly of Ascochyta blight and anthracnose.

Our study demonstrated that fungicide application effectively reduced disease severity and maintained yield and quality. A single application of a combination of active ingredients (pyraclostrobin and epoxiconazole) appeared to result in a synergy that proved to be the most effective treatment evaluated. Therefore, use of fungicides with other integrated disease management practices, such as early seeding and cultivar choice, should help to maintain yield and quality of field pea in southern Brazil.

Ben Fleet 1,2, David Coventry 2 and Darren Koopman.2

A field experiment was conducted in 2001 to determine the interaction between Ascochyta blight intensity and sowing arrangement with chickpea under 3 fungicide regimes. The experiment was a 3 x 2 factorial (row spacing x seeding rate) design with strips (fungicide treatments). The experiment found wider row spacing did reduce the disease intensity, but was limited to treatments with the higher seeding rate. Whilst the reduction in disease due to agronomic management was small when compared to yield benefits obtained from fungicide use (eg. yield increases of 300%), the benefits were significant and important in overall crop management.

Burcin Dilci1, Gerhard Rühl1, Andreas Bramm1 and Frank Hoeppner1

High oleic sunflower production shows an increasing trend worldwide. Although Germany has a high demand for this sunflower type, its production is variable as inappropriate agronomic practices cause yield instability. An integrated project was established in Germany to expand the production area through better agronomic practices and through breeding early maturing cultivars. Commercially available resistance inducing product BION® (Syngenta), controlled uptake long term ammonium nutrition (CULTAN) methods and their combinations were applied in different dosages and at different growth stages against Sclerotinia sclerotiorum (white rot) and Botrytis cinerea (grey mould). The results indicate that in certain varities BION® can lead to a significant decrease in disease development. CULTAN fertilization did not result in a significant improvement of plant health, but caused an increase in fungal infection rate in 2002.

Jason Scott1, Olufemi Akinsanmi1, Vivek Mitter1,2, Steven Simpfendorfer3, Ruth Dill-Macky4 and Sukumar Chakraborty1

Crown rot affected wheat crops in northern New South Wales and southern Queensland were surveyed during the 2001 and 2003 growing seasons. Sixteen species of Fusarium were isolated from crowns and basal stem nodes displaying crown rot symptoms. Fusarium pseudograminearum was the predominant crown rot pathogen isolated, followed by F. crookwellense, F. graminearum and F. avenaceum, respectively. A greater proportion of isolates from crowns were F. pseudograminearum than were isolates from stem nodes, while F. graminearum preferentially infected stem nodes relative to crowns. Future work will determine the genetic basis of specificity among the principal crown rot pathogens and the evolutionary mechanisms influencing their population structure.

Jean-Noël Aubertot1, Xavier Pinochet2, Raymond Reau3 and Thierry Doré

Phoma stem canker is a major world-wide disease of oilseed rape. Genetic and chemical control methods have not succeeded in completely containing the disease. However, the combination of cultural with genetic and chemical controls may provide a efficient method to contain the disease. To define integrated strategies, a simulation model is needed due to the numerous interactions between cultural practices, the pathosystem and the environment. This paper presents the process chart of SimCanker, a Simulator of Crown Canker development. The aim of this model, which is still being developed, is to simulate the effects of cultural practices on crown canker development and yield loss to help in defining integrated cultural practices to control the disease. The cultural practices taken into account are the sowing date, crop density, the application of a fungicide at autumn, the susceptibility of the cultivar, and nitrogen management within the cropping system. The model works at the field scale during the whole cultural cycle. The parameterisation and the evaluation of two sub-models are presented. SimCanker will be used in the definition of Integrated Pest Management strategies for oilseed rape crops, in association to a crop model and other sub-models representing the effects of cultural practices on the development of other pests.

M. Elahi Baksh1, M. Alamin Siddique2, Craig Meisner3, J.M. Duxbury4 and J.G. Lauren4

Soil borne pathogens and nematodes cause every year heavy yield losses in rice in tropical countries like Bangladesh. Soil solarization can control soil borne diseases and nematodes. This technique showed potential to produced higher rice yields. A survey was conducted in Dinajpur district during 2001 to study the effect of soil solarization on rice yields and profitability and to document farmers’ reactions on this technology. Results showed that transplanted monsoon rice yield increased up to 36% after using solarization to raise seedlings. Farmers received an additional gross return of about Tk. 10,276/ha by investing only Tk 941/ha extra cost for solarization. Farmers overall opinion about this technology was very high. They claimed it was very easy to do, low costing and helped to increase their livelihood through increased rice productivity and ultimately their household food security.

Vijay K Yadav and Neelam Yadav

Behavioural study of whitegrub beetles of Holotrichia consanguinea showed Azadirachta indica, Prosopis cinerarium and Ziziphus jujubeas its preferred host trees. Hexane was identified as the best solvent for extracting attractant chemicals from the host tree leaves and A indica and P cinerarium as the most preferred host trees for H consanguinea. Chemical volatiles were isolated from the two most preferred host trees of H consanguinea by trapping in Tenax followed by elution in hexane and also by non-destructive extraction in hexane. Bioassay in wind tunnel showed that GLVs trapped in Tenax attracted more beetles than the extracts and that Azadirachta indica (Neem) appeared better source of attractant chemical (kairomone) than Prosopis cinnerarium (Khejri). Fractionated of green leaf volatiles by a reverse phase HPLC using gradient mobile phase of acetonitrile and water showed presence of a number of chemical components. Chemical component(s) present in fractions eluted between RT 1-2 min from green leaf volatiles of A indica and P cinnerarium were most active in attracting the beetles. The chemical present in the most active fraction of GLV attracting the beetles was identified as isomers of hexenyl acetate by GC-MS.

Tara D Sutherland 1, Irene Horne, Robyn J Russell and John G Oakeshott.

Chemical pesticides will continue to be a major part of agricultural systems throughout the world in the foreseeable future. However, a growing concern about the non-target toxicity of these chemicals has led to requirements for effective pesticide remediation technologies in a range of industries and applications. Many of these applications require rapid action and therefore traditional remediation strategies are inadequate. This has led to an interest in the use of formulated enzymes rather than live bacteria as bioremediation agents. This process known as Enzymatic bioremediation is particularly suited to situations where rapid remediation is needed, ranging from minutes to a few hours. CSIRO Entomology is involved in an initiative with Orica Australia Ltd and Horticulture Australia Limited to isolate and develop enzymes for treatment of pesticide-contaminated waste waters from agricultural production and processing industries. Water quality regulations, particularly in Australia, are becoming increasingly stringent necessitating efficient and affordable treatment strategies. This paper describes progress by CSIRO on the isolation and development of enzymes that detoxify pesticides containing ester bonds, including organophosphates, carbamates and synthetic pyrethroids. These compounds comprise the major insecticides that are most problematic with respect to residue issues and in fact account for the majority of insecticide sales both in Australia and world-wide.

S.C. Tripathi1, K.D. Sayre2 and J.N. Kaul3

Ten spring wheat (Triticum aestivum L.) genotypes (4 Indian and 6 Mexican) were evaluated at 180 and 300 k g N/ha application at CIMMYT (Centro Internacional de Mejoramiento de Maiz y Trigo), near Ciudad Obregon, Sonora, Mexico during 1997-1998 and 1998-1999 for their yield potential, N concentration in grain and straw and their relationships. From pooled analysis, effect of N rates on biomass, yield and yield attributing characters was non-significant whereas genotypic effects on the above mentioned characters as well as on grain N concentration, uptake, nitrogen harvest index and utilization efficiency were significant. From combined analysis across years, grain yield and harvest index (HI) ranged from 7.81 t/ha (Pavon 76) to 9.13 t/ha (Baviacora 92) and from 39.5 % (Pastor) to 45.1 % (Baviacora 92), respectively. The range of grain N concentration, uptake and nitrogen utilization efficiency ( NUE) was from 1.99 % (Baviacora 92) to 2.23 % (Rayon 89), from 147.6 kg/ha (Pastor) to 169.5 kg/ha (UP 2338), and from 29.8 kg grain/kg N uptake (Pavon 76) to 35.6 kg grain/kg N uptake (Baviacora 92), respectively. The grain yield correlated positively with HI (r = 0.66), NHI (r = 0.62), grain N uptake (r = 0.77) and negatively with N concentration in grain (r = -0.68) and straw (r = -0.64). The correlation between HI and NHI was highly positive (r = 0.89), which suggested that enhancing these two indices could lead to higher grain yield and protein content. Therefore, these two indices should be given more emphasis for enhancing yield potential of spring wheat genotypes.

Vethaiya T. Balasubramanian

Over 90% of the global rice is produced in Asia, using 93% of the total fertilizer N allocated for the crop. Efficient N use is critical to provide food security for the growing population and protect the environment. Three strategies are discussed for efficient N use in irrigated rice in Asia.

Kounosuke Fujita1a, K. Lei1, Hirofumi Saneoka1, R.E.A. Moghaieb 1 and P.K. Mohapatra2

Tomato (Lycopersicon esculentum) plants were grown hydroponically inside the green house of Hiroshima university, Japan. At the first fruiting stage, N was withdrawn from the rooting medium for a period of 19 days and its effect on photosynthesis, partitioning of both 13C and 15N, N contents of various organs and changes in stem and fruit diameter of the plant was studied in order to identify the mechanism of resource management on the parts of the plant at low N. Compared to the control, N-deficiency treatment decreased biomass growth of all organs. The treatment depressed leaf photosynthesis within a few days and the decrease in stem diameter was detected after a lag period of about 11 days, however there was no clear impairment of fruit diameter. The circadian rhythm in fluctuations of diameter was less manifested in the fruits compared to the stem. N-deficiency induced daytime shrinkage and reduced night expansion of fruit. It is concluded that nitrogen deficiency reduces source activity more severely than sink activity, and results in limiting fruit production without restriction of fruit expansion.

Mohammad Lotfollahi

From the importance and quantity point of view, the cereals, in particular wheat, has the highest level of consumption in the world, and provides about 40 percent of the nutritional energy worldwide, especially in the developing countries. The implementation of this project, which is for the enhancement of yield and quality of wheat, as well as the optimal utilization of chemical fertilizers and performance of the animal manure to the point of reaching sustainable agriculture, defines the objective of this research project. This research has been determining the individual and combined effects of chemical and animal manure on the quantitative and qualitative performance of the bread wheat, advanced type Mahdavi (M-70-12). In this long term experiment, 3 rates of animal manure (0,15,30) tons per hectare and four chemical fertilizer compounds (N0P0K0 , N120P45K50 , N180P90K75 , N240P135K100) were applied in a factorial arrangement of complete randomized blocks (R.C.B.D), consisting of 12 treatments, with 3 replications, amounting to 36 plots. The results of the third year of this project indicated that the highest yield belonged to a treatment in which 30 tons of animal manure combined with 180 kg nitrogen, 90 kg phosphorus and 75 kg of potassium. When compared to a treatment in which the chemical fertilizer was used without any animal manure, an increase of 1520 kg was achieved. The maximum grain protein concentration (14.3%) pertained to a treatment in which 15 tons of animal manure, along with N180P90K75, was used, but in general protein concentration difference were small. The results generally show the importance of simultaneous use of chemical fertilizers and animal manure.

Yu-Ying Shen1, Chong-Yue Gao1, Zhi-Biao Nan1, Bill Bellotti2, Wen Chen2, Ya-Li Zou1, Murray Unkovich2, Michael Robertson3 and Merv Probert3

A field experiment was conducted from 2001 to 2003 to determine the yield and N-content response of winter wheat after 4 years of lucerne in the Gansu Loess Plateau. Fallow lengths had no effects on the sequent wheat yield in 2002 and 2003 ( p> 0.05). Fertilizer application significant increased winter wheat yield after lucerne removal. With N application, grain yields (3.71 t/ha for short fallow, 4.43 t/ha for long fallow) and straw yields (7.11 t/ha for short fallow, 8.17 t/ha for long fallow) were higher than those without N (3.15 t/ha or 3.33 t/ha grain for short or long fallow, 5.85 t/ha or 5.19 t /ha straw for short or long fallow). Neither fallow length nor N application had significant effects on nitrogen content of grain or straw for the first winter wheat (P>0.05).For the second wheat crop, N application did not increased straw yield but significantly improved grain yield (P<0.05). However previous fallow length and N application had significant effect on N content of grain for the second winter wheat,. N content of straw under short fallow or long fallow with N application was 68% or 24% higher than that without N application.

Yadvinder Singh, Jaswinder Singh Bains and Bijay Singh

General fertilizer N recommendation for rice does not take into account site-to-site variation in N supply capacity of soils to meet crop N demand. Leaf colour chart (LCC) is an ideal tool to optimize N use irrespective of soil N supply and source of N applied. It will help farmers realize high yields and achieve high N-use efficiency in rice. Several field experiments were conducted to evaluate need-based fertilizer N management in transplanted rice by using LCC in Punjab, India during ‘kharif’ season for three years (2000 to 2002). Application of N with LCC using a critical value of 4 produced rice grain yields, which were on a par with recommended N applied in three equal splits in the three years. There was no effect of applying 20 kg N ha-1 compared with no fertilizer N applied at the time of transplanting on grain yield and N uptake of rice. On average, application of fertilizer N to rice using LCC 4 resulted in a saving of 26% fertilizer N as compared with the recommended practice of applying 120 kg N ha-1. Agronomic efficiency and recovery efficiency of fertilizer N were higher when N was applied using LCC 4 as compared to the recommended practice of applying 120 kg N ha-1 in three equal split doses on all soils.

Bijay Singh, Anshujit Virk and Yadvinder Singh

Mineralization potential (N0), an estimate of soil organic N that is susceptible to mineralization in infinite time was estimated in 18 samples of soil under rice-wheat system collected from different agroclimatic regions in northwestern India. N0 ranged from 21.5 to 61.1 mg N/kg soil and was significantly related to organic C and clay content of the soils. A quick (q) reaction was almost completed during 0 to 4 weeks, whereas a slow (s) reaction continued untill the end of incubation period. When 3 soils differing in texture and organic C content were amended with different organic materials, the highest and the lowest values of both N0s and N0q were observed for Sesbania aculeata green manure (GM) and wheat straw, respectively. Unlike when applied freshly, the organic amendments did not influence mineralization potential as per their C/N ratio. Amending the soil with different organic manures for 5 or more years enhanced N0 in the order: farmyard manure (FYM)> GM> poultry manure> press mud (waste from sugar industry). FYM enhanced the mineralization potential to a greater extent than GM (highest N0 when applied freshly). Application of wide C:N ratio crop residues year after year may increase organic C content of the soil, but not necessarily the potentially mineralizable N. Soil amended with crop residues for 8 years recorded N0q values even less than those for unamended control. When both rice and wheat were amended with crop residues, no rapidly mineralizable fraction of N could be found in the soil.

Areum Chun1, Ho Jin Lee2

This study was conducted to investigate absorption and partition of nitrogen for improvement in efficiency of nitrogen. This experiment was carried out with two cultivars, Hwasungbyeo and Dasanbyeo (semi-dwarf) in paddy field. The levels of N treatments were 60, 120, 180 kg N per ha. Microplots (0.81m2) were established for 15N labeled fertilizer application. Nitrogen utilization differences between the two cultivars were associated with total nitrogen uptake and partitioning after heading. The ability to absorb soil nitrogen through the grain filling period contributed to the increased yield of Dasanbyeo.

Laurence Rossato, Carine Noquet, Philippe Malagoli and Alain Ourry

Oilseed rape (Brassica napus L.) is commonly grown for oil or bio-fuel production, while the seed residues can be used for animal feed. It can also be grown as a catch crop because of its efficiency in extracting mineral N from the soil profile. However, the N harvest index is usually low, due in part to a low ability to remobilize N from leaves and to the fall of N-rich leaves which allows a significant amount of N to return to the environment. In order to understand how N filling of pods occurs, experiments were undertaken to quantify N flows within the plant by 15N labelling. N uptake capacity decreased at flowering to a non significant level during pod filling. However, large amounts of endogenous N were transferred from the leaves to the stems and to taproots which acted as a buffering storage compartment later used to supply the reproductive tissues. About 15% of the total N cycling through the plant was lost through leaf fall and 48%, nearly all of which had been remobilized from vegetative tissues, was finally recovered in the mature pods. A 23 k Da polypeptide, accumulated in the taproots during flowering and later fully hydrolyzed to sustain grain filling, has been characterized as a vegetative storage protein (VSP). A mechanistic N uptake model based on the functioning of NO3- transport system has also been proposed. The overall results are discussed in relation to plant strategies which optimize N cycling to reproductive sinks by means of buffering vegetative tissues such as stems and taproots.

Klaus Sieling1, Henning Kage1 and Olaf Christen2

In 1990/91-1998/99, different N treatments including slurry and mineral N fertilization were tested on a pseudogleyic sandy loam (Luvisol) in NW Germany. Simple N balance of the plots varied between –710 kg N/ha and +1,490 kg N/ha. In 1999/2000 –2001/02, unfertilized wheat crops were grown to investigate the residual effects of the former N fertilization on N mineralization and crop growth and grain yield. Grain yield decreased from 692 g/m2 in 2000 to 357 g/m2 in 2002 and N uptake by the grain and straw from 109 kg N/ha in 2000 to 59 kg N/ha in 2002. Wheat recovered less than 3 % of the differences in the N balance in the 3 years.

Samuel Y.C. Essah1, David G. Holm1 and Jorge A. Delgado2

Nitrogen (N) rate and seed piece spacing are important economic considerations in the production of potatoes (Solanum tuberosum L.). The optimum spacing and N rate vary with cultivar, geographic location, and intended market. Studies were designed to determine the influence of N rate and seed spacing on yield, tuber size distribution, and quality of two red potato cultivars, CO93037-6R and Sangre. In the seed piece spacing experiment, seed tubers were planted 15.0, 22.5, 30.0, or 37.5 cm apart. In the N rate study nitrogen was applied at 90, 157, 224, or 291 kg/ha. Total yield, tuber size distribution, external and internal defects were determined. Seed spacing did not influence total yield in either cultivar, but size distribution shifted from a predominance of small tubers (<5 cm diameter) at the narrowest (15 cm) spacing to a predominance of large tubers (>5 cm diameter and >284g) at the widest (37.5 cm) spacing. Even though seed spacing did not influence marketable (5 to 10 cm diameter) yield, fewer external and internal defects were observed when seed tubers of CO93037-6R and Sangre were planted at 15 and 30 cm apart, respectively. N rate did not influence total yield in Sangre, but higher total yields were produced in CO93037-6R at lower N (90 to 157 kg/ha) rates. Even though N rate did not influence marketable size tubers, fewer external and internal defects were observed when N was applied at 90 kg/ha in Sangre. Application of N at 157 kg/ha produced higher marketable size tubers with lower percent external and internal defects in CO93037-6R. Percent external defects showed some promise as a predictor of optimum seed piece spacing and N application rate.

Christian Witt1, 2, Julie Mae Cabrera-Pasuquin2 and Randall G. Mutters3

A leaf color chart (LCC) offers substantial opportunities for farmers to detect plant nitrogen (N) demand in real time for efficient fertilizer use and high rice yields. There are several LCCs available for irrigated rice, but colors and color ranges vary greatly among charts. A systematic analysis using a Minolta CM 3700-d spectrophotometer showed a tight relationship between leaf color measured by spectral reflectance (SR) and leaf N content in a two-season field experiment with ten rice varieties grown at three different N levels in the Philippines in 2001. Based on actual SR measurements performed on rice leaves, criteria and target patterns of SR were established for the evaluation of five existing leaf color charts. Color panels were subjected to reflectance measurements, which confirmed the visual observation that color charts vary greatly in color, color ranges, and consistencies in color among panels of each chart. Despite technical limitations in achieving a perfect match between leaf and plastic color, the LCCs developed by the University of California Cooperative Extension (UCCE) and the International Rice Research Institute (IRRI) in collaboration with UCCE met the established criteria reasonably well. The two charts have consistent reflectance patterns among their color panels and appear to successfully capture the relevant color range observed for rice varieties commonly grown in California (UCCE) and Asia (IRRI). The leaf color charts of UCCE and IRRI are currently tested and evaluated by rice growers.

M.M. Rahman, Takahisa Amano, H. Inoue and Y. Matsumoto

This study was established in the long-term experimental plots of Kyoto University Farm at Takatsuki, Japan. Double cropping systems including rice (cv. Hinohikari)-fallow, rice-broad bean (Vicia faba L.), rice-hairy vetch (Vicia villosa Roth), and rice-naked barley (Hordeum vulgare Nudum) and 15N-labeled fertilizers at rates 0, 40, 80 and 120 kg ha-1 were tested. The legumes broad bean and hairy vetch produced 3350 to 10820 kg aboveground biomass ha-1, accumulated 131 to 352 kg N ha-1 of which 41 to 78 % was derived from N2 fixation (% Ndfa). Legume residues significantly increased rice yield and recovery of 15N-labeled fertilizer (% of N applied). Recoveries of 15N-labeled fertilizer were 80, 76, 74 and 72 % in rice-broad bean, rice-hairy vetch, rice-naked barley and rice-fallow systems, respectively.. The greater performance of rice-broad bean systems was reflected in greater N fixation. The effects of combined application of unlabeled legumes and labeled fertilizer on N losses are lower than those obtained with a single application of labeled fertilizer N. Results show that legumes N can supply a substantial proportion of the N requirements of wetland rice.

Andreas Bramm, Frank Höppner, Jörg Michael Greef, Gerhard Rühl and Burcin Dilci

The effects of various cropping intensities on yield and product quality were investigated for a crop rotation of six fields with winter wheat, silage maize, winter rye, potatoes, winter barley and sugar beet between 1997 and 2001. The intensity levels studied were; (1) nitrogen supplied as cattle slurry with conventional plant protection and sowing intensity, (2) conventional mineral fertilizer, other activities as in 1, (3) mineral nitrogen reduced by 25 % and reduced pesticide use and (4) mineral nitrogen reduced by 40 %, herbicides only allowed, and sowing density reduced by 20 %. With the exception of potato cultivation, the lowest yields were obtained in intensity level 1. The crop cultivations were specifically effected by reduced production intensities. For all three grain crops, the yield reductions in fields with organic nitrogen fertilisation compared with mineral fertiliser supply were proportionally higher than in those with root crops. The yields of intensity level 3 did not differ significantly from those of level 2, with the exception of winter wheat and winter barley. In the intensity level 4, higher yields were obtained for grain crops and sugar beet than in level 1. Potato yields were positive with organic fertilisation. With regard to product quality, reduced nitrogen fertilisation decreased protein contents in all grain crops and maize in the sequence, level 2 > level 3 > level 4 > level 1. For this reason considerable loss of quality with regard to baking (wheat and rye) and fodder quality (barley, maize) were observed for levels 3, 4 and 1. High nitrogen supply reduced carbohydrate contents in sugar beets, silage maize and potatoes A comparison of the productivity of the four intensity levels based on dry matter production showed that the highest economically usable annual dry matter yields were obtained with intensity level 2. Significantly lower productivity was observed in levels 4 and 1..

Ho Jin Lee1, Seung-Hun Lee2 and Ji Hoon Chung3

This experiment was conducted to investigate the variation of nitrogen use efficiency, nitrogen uptake efficiency, physiological utilization efficiency and their relationships with growth characteristics of rice cultivars. Variation in nitrogen use efficiency of rice cultivars was very low (44.09 to 51.91), but there were a high variation in nitrogen uptake efficiency (0.51 to 0.90), and physiological utilization efficiency (51.71 to 94.26). On average, nitrogen use efficiency of the 28 rice cultivars was 47.74, nitrogen uptake efficiency was 0.71, and physiological utilization efficiency was 68.76. Nitrogen uptake efficiency was positively correlated with plant dry matter (0.842**), leaf area index (0.761**), and leaf nitrogen content (0.599**). Therefore, the dry matter weight of rice plant was more important than leaf area index and leaf nitrogen content for characterizing nitrogen uptake efficiency, and the rice cultivars with high nitrogen uptake efficiency had higher chlorophyll meter value.

J.F. Angus1, Rob Norton2, J.F. Pedler2 and C.N. Walker3

Much of the dryland cereals in southern Australia grow in semi-arid regions where the subsoils are highly alkaline and contain high levels of salinity, sodicity and boron. The severity of the limitations that these impose on crops varies across the landscape, both between and within paddocks. The levels of salinity, boron and sodicity are positively correlated and tend to increase with depth in the soil, typically reaching levels that confine the roots of cereal crops to the top 40-90 cm. Areas with the shallowest rooting zones have limited amounts of available soil water, leading to low cereal yields and poor responses to N fertiliser. A possible strategy to maximise yield is to concentrate N fertiliser on the parts of the landscape with the least subsoil limitations. To test this hypothesis, we applied ~10m-wide strips of urea along the length (~1km) of eight cereal paddocks. The yield response to N were measured and related to apparent electrical conductivity (ECa), measured by electromagnetic induction (EM) surveys. In five of the paddocks the average yield response to N decreased with increasing ECa, falling from 20 kg grain /kg N where ECa was zero, to no response where ECa =136 mS m-1. Of the other paddocks, responses in one were masked by frost damage, in another by soil-water depletion on soils of low ECa by previous high-yielding crops, and in the last by large N responses by barley on a paddock with low ECa. The results offer a strategy to increase cereal yield by concentrating N on the most responsive parts of the landscape identified by EM surveys.

Narelle Hill1, Nathan Moyes2, Ron McTaggart3, Walter K. Anderson3 and Ray Tugwell1

Timing nitrogen (N) according to soil and weather conditions can give a 60% lift to wheat yields. In 2003, waterlogging reduced N uptake in Calingiri wheat during crop growth at Cranbrook. Our trial results suggest that timing of N application was critical and should be more dependent upon rainfall and waterlogging. These results need confirmation at other sites and seasons but the probability of waterlogging and the expectation of specific grain quality and final grain yield will all influence future strategies. It is likely that some N will be required to ensure adequate plant numbers and tillers. To avoid substantial losses of N and profits, our results suggest that subsequent applications should be determined at least in part, according to major rainfall and waterlogging to replace N lost and to maximise final wheat grain yield. For maximum crop returns, farmers are urged to determine the waterlogging probability of their cropping land by using dipwells. Further confirmation of this strategy will be sought in 2004 with large scale trials throughout the high rainfall, cropping zone.

Samuel G. L. Kleemann, Gurjeet S. Gill, and David Coventry

In the 2000 and 2001 growing seasons, field experiments evaluating the effects of N-fertilizer rate and placement on establishment, growth and grain yield of wheat were undertaken at Roseworthy, South Australia. Wheat seedling establishment was significantly reduced in 2000 (85%) and 2001 (67%) when high rates of N-fertilizer were placed with the seed. However, toxicity was mostly (2000) or partially (2001) avoided when high rates of N-fertilizer were either banded below or to the side of the seed providing adequate separation between seed and fertiliser. In 2000, there was evidence of high N uptake when banded N increased dry matter (DM) production, however there were no corresponding grain yield or protein benefits. In the 2001 season, there were small N-fertilizer responses in grain yield and protein. However, irrespective of N placement, the crop did not benefit from amounts of N input potentially put in the canopy. From a practical view this study has shown that one-off applications of N-fertilizer, although safer when banded did not necessarily position the crop for higher yields and or protein.

Field studies were conducted over three years on a clay loam (CL) and a fine sandy loam (FSL) soil near Brandon, Canada to evaluate effects of increasing rates of side-banded UAN and urea, with and without the urease inhibitor N-(n-butyl)thiophosphoric triamide (NBPT) on seedling damage, seed yield and seed quality of canola. Seedling damage occurred with side-banded urea and UAN on the CL soil. In contrast, rainfall after seeding on the FSL soil in two of the three years limited seedling damage. Seedling damage was similar with urea and UAN and was reduced with application of NBPT. Seed yield increased with application of urea or UAN in spite of the reduced stand density, but was not significantly affected by the use of NBPT when averaged over the three years of the study. However, when analysed separately, NBPT increased seed yield on the CL soil in two of three years. Seed quality generally declined with N application and with increasing seedling damage. Oil content decreased and glucosinolate content increased with N application. Oil content was higher with urea than UAN and increased with the use of NBPT. Glucosinolate content on the CL soil was lower with urea than UAN and decreased with the use of NBPT. Seedling damage from excess seed-placed N can lead to reductions in canola seed yield and quality, while the urease inhibitor NBPT can reduce damage, potentially improving yield and quality.

Ashok Alva1, Javier Marcos2, Claudio O. Stöckle3, Vangimalla Reddy4 and Dennis Timlin4

Application of the CROPSYST-SIMPOTATO model was evaluated for potato production systems in the Pacific Northwest of the United States. Model predictions showed that unaccounted N at the end of the crop growth varied from 102 to 170 kg/ha in the year 2001, and were much greater in the year 2002. Further studies are needed to validate the fate of this unaccounted N. Results also demonstrated the use of model predictions to assess N transport and losses under different water and N management practices. Therefore, the model simulation can be used to predict the fate and transport of N under different N and water management options. This information is useful to optimize the rate and timing of N and water applications to support the maximum production, while minimizing the negative effects of N losses.

U.R. Sangakkara1, P. Stamp2, A. Soldati2 and M Liedgens2

The impact of two tropical green manures, Crotolaria juncea and Tithonia diversifolia on root growth of two important food crops, maize and mungbean, having fibrous and tap root systems respectively was evaluated. Soils incorporated with the two green manures for three years were used for the study along with a control with no green manures, with and without inorganic fertilizers. Green manures, especially Tithonia stimulated root growth of both species and fertilizers increased this effect. In maize, green manures and fertilizers promoted the development of seminal and nodal roots. In mungbean, both the tap root and lateral roots were stimulated by green manures and fertilizers, highlighting the potential of green manures in promoting extensive roots for better crop establishment.

Abdul Rahman Abu Bakar1, Rohani Yon2, Saad Abdullah3, Aini Zakaria4, Othman Omar5, Zulkifli Malik6, Sariam Othman7 and Azmiman8

A single crop rice area covering 8.6 ha in Kampong Ewa, Langkawi, Malaysia, is currently being progressively converted into organic rice farming, commencing last main season rice crop in 2003. Among initial steps taken were to fence-up the area to disallow any interference of chemical usage from outside, reconsolidated small plots into bigger area, used independent unpolluted water source, improved land leveling and water management, practiced transplanting method and introduced rice-fish culture. Future plans for the area and issues and challenges in organic rice farming in Malaysia are also discussed in this paper.

Guixin Pu1, Mike Bell1, Glenn Barry2, Peter Want1 and Teresa Cokley2

Land application of biosolids can help to improve declined soil fertility and soil health in intensive agricultural systems. Understanding the fate of the nitrogen (N) applied is the key to take advantages of such application and minimise the possible side effects. A study was carried out to investigate the effects of land application of aerobically and anaerobically digested biosolids at the Nitrogen Limited Biosolids Rate on plant growth and the mineralisation of the applied N in biosolids in a red feresol soil planted with maize in subtropical Australia. Plant maximum biomass production and grain yields were significantly higher from the biosolids treated plots (14.2-14.9 t/ha for maximum biomass production and 8.3-8.9 t/ha for grain yields) than from the unfertilised and fertilised plots (10.6-12.6 t/ha for maximum biomass production and 6.8-7.2 t/ha for grain yields). Six weeks after application, ammonium N in biosolids treated plots (478 kg/ha for aerobically and 408 kg/ha for anaerobically digested biosolids) accounted for more than half of the applied organic N (632 kg/ha for aerobically and 730 kg/ha for anaerobically digested biosolids), suggesting that significant amount of the applied N could be lost through volatilisation. The total mineralised N recovered from the plant and the top 1200 mm soil profile was 21% for aerobically and 30% for anaerobically digested biosolids. No leaching of the mineralised N was found below the top 1200 mm soil profile.

Kelly L. Kopp1 and Karl Guillard2

Decomposition rates and N release patterns of turfgrass clippings from lawns are not well understood. Litter bags containing clippings were inserted into the thatch layer of a cool-season turf. The experiment was arranged as a 2 × 4 factorial in a randomized complete block design with three replicates. Treatments included four rates of N fertilizer (0, 98, 196, and 392 kg N ha-1 yr-1) and two clipping treatments (returned vs. removed). Litter bags were removed periodically over the growing season and samples were analyzed for biomass, N and C concentrations, and C:N ratio on an ash-free basis. Percentage N loss from the clippings after 16 weeks ranged from 88% to 93% at the 0 and 392 kg N ha-1 rates, respectively, and from 86% to 94% when clippings were removed (CRM) or returned (CRT), respectively. Percentage C loss from the clippings ranged from 94% to 95% at the 0 and 392 kg N ha-1 rates, respectively, and from 92% to 96% with CRM and CRT, respectively. Cumulative N release was similar across N fertilization rates, (ranging from 131 g N kg-1 to 135 g N kg-1 tissue) but was higher for CRT (151 g N kg-1 tissue) than for CRM (128 g N kg-1 tissue). Grass clippings decomposed rapidly and released N quickly when returned to the turf thatch layer. This indicates the potential for reduced N fertilization when clippings are returned. Such rapid decomposition also suggests that the contribution of grass clippings to thatch development is negligible.

Yong-Hwan Lee, Sang-Min Lee, Yun-Jeong Lee and Du-Hoi Choi

Organic farming, which is responsible for material circulation in agricultural ecosystem and crop production with a minimal environmental load, has played a crucial role from two points of view i.e. ecological protection and agricultural production. Since no chemical fertilizers and minimal inputs are allowed in organic farming, nutrients for the crop production are mostly supplied with organic fertilizer such as compost containing different organic materials. Therefore, the management of soil fertility in organic farming should be differentiated with other conventional farming. For this purpose the soil chemical and physical properties and crop productivity were determined on organically managed rice paddy soil to manage soil fertility in a proper way for long-term rice cultivation. Organic materials used were compost, rice straw, and hairy vetch and compared with conventional farming. K and Ca contents of soil were increased by application of organic materials compared to those of conventional farming while P content in soil was decreased in organic farming with application of compost and hairy vetch. Crop productivity was higher in application of hairy vetch compared to those of compost or rice straw. In conclusion, organic farming was more beneficial for the improvement of soil properties and the use of hairy vetch as green manure was more effective than compost or rice straw for the maintenance of crop yield and enhancement of soil properties.

Janet S. Hartin1, Steven B. Ries2, Stephen.T.Cockerham2 and Victor A. Gibeault3

The California Integrated Waste Management Act mandated a 50% diversion of landfill wastes by the year 2000, based on 1990 levels. Grass clippings comprise approximately 50% of yard trimmings deposited in California landfills, and yard trimmings are the largest single component of California’s municipal waste. Recycling greenwaste into composted soil amendments for use in turfgrass plantings could improve turfgrass quality and significantly reduce landfill deposits. In this study, three rates of composted greenwaste (0.24, 0.39 and 0.49 m3 m-3 ) were incorporated into the top 10 cm of a sandy loam soil. Arizona common bermudagrass (Cyonodon dactylon L) was seeded 2 wk subsequent. Sports traffic was mimicked using a modified Brinkman simulator over three seasons. Soil amended with composted greenwaste resulted in higher turfgrass visual quality ratings and greater infiltration rates and total plant biomass than unamended soil. The highest overall visual quality ratings occurred in plots receiving no traffic and the greatest volumes of compost. Infiltration rates were highest in the 0.49 m3 m-3 treatment receiving no traffic and lowest in plots receiving traffic. Total plant biomass levels resulting from the 0.49 m3 m-3 treatment receiving traffic were not significantly lower than the.25 m3 m-3 no traffic treatment. Plots receiving no amendment and traffic produced the lowest biomass of all treatments. The highest volume of amendment applied did not reduce visual quality, biomass production or infiltration rates, potentially increasing the market for greenwaste compost as a turfgrass soil amendment and leading to greater landfill diversion.

P.L. Matthew, Colin J. Birch and P.G. Saffigna

The use of high biochemical oxygen demand (BOD) organic waste on farming land offers two resource recovery opportunities, first nutrient for plant production and secondly organic matter for soil health. One such waste, dunder from yeast production was tested for its impact on irrigated lucerne hay production. A randomised complete block trial with five treatments (0, 8, 24, 48, 96 L dunder m-2) and three replications was used to test the impact of dunder on total dry matter production. The trial showed that the lower rates of 8 and 24 L m-2 of dunder was not significantly different to the control (0) while the high rates of 48 and 96 L m-2 significantly reduced total dry matter. This was significant as it identified limits to dunder application rate. However, more importantly, the trial showed that site characteristics and agronomic management had greater impact than the dunder alone on the plant production. In this trial a sodium hazard not related to the dunder significantly added to the reduction of dry matter. The results show that the assessment of dunder and other similar wastes for land application must include both the direct and indirect site related consequences of application to agricultural land.

P.L. Matthew, Colin J. Birch and P.G. Saffigna

The disposal of waste to agricultural land requires a systematic and transparent assessment procedure to ensure environmental and production sustainability. A hybrid model of risk assessment used in the general risk, environmental management and the mining industries was developed and tested using the waste from a yeast factory. The model is systematic and cybernetic and develops a succession of decisions that have the capacity to focus the environmental and agronomic considerations down to individual crops, land and management systems. The process directly links environmental risk assessment and development of management plans to agronomic development of the use waste products.

Brad A. Silver1, Colin J. Birch2, Tom Cowan2 and P.L. Matthew2

Five rates (0, 28.0, 65.4, 83.7 and 111.7 mm) of dairy effluent were applied through irrigation to tropical grass pasture during the wet season on the Atherton Tablelands in the Far North of Queensland, Australia. Irrigation water was applied to the treatments in inverse proportion to the effluent for equivalent total water application. Pastures were harvested on a three weekly basis, dry matter yield determined and sub samples analysed for N concentration (%), and Nitrogen yield (kg ha-1) calculated. Lysimeters installed in the high effluent treatment and the no effluent treatment measured leachate volume to 50 cm. Samples of leachate were analysed for nitrogen concentration and loss below 50 cm calculated. There was no significant difference in pasture yield and nitrogen yield among treatments. Loss of nitrogen through leachate was substantial in both the high effluent treatment and the zero effluent treatment.

R.J.K. Myers1, G.M. Heinrich2 and J. Rusike2

We report on farmer-participatory testing of strategies to increase manure use on crops to improve food sufficiency in communal farming lands of semi-arid southern Zimbabwe. In seeking to overcome farmers’ reluctance to use kraal manure, we tested cattle and goat manure, and methods of preparation (composted in heaps, heaps covered with soil, and in pits) on farmers’ fields in Tsholotsho and Gwanda South. Most methods increased yields, and farmers assessed them as practical and effective. Modelling with APSIM helped promote engagement with farmers. Despite drought and economic conditions, the combination of three research approaches – on-farm participatory trials, modelling, and farmer surveys – has resulted in adoption of manure application, and opportunities for further adoption. While male-headed households tended to adopt fertilizer use, female-headed households accepted FYM. To help farmers invest, extension agents need to escape from ideal recommendations, and offer soil fertility improving technologies.

Ke-ru Wang 1, Shao-kun Li1,2, Lian-pu Cao1

The field experiments were carried out to investigate the dynamics and models of N,P and K absorption for the cotton plants with a lint of 3000kg/ha in Xinjiang. The main results were as follows: contents of N in leaves, squares and bolls, in particular in the leaves of fruit-bearing shoot were higher in high-yield cotton than in CK. Content of P2O5 in squares and bolls and that of K2O in stems were higher in high-yield cotton than in CK during the whole growing period. The accumulations of N, P2O5 and K2O in cotton plant could be described by a logistic curve equation. The most rapid nutrient uptake occurred at about the 90 d for N, 92 d for P2O5 and 85 d for K2O after emergence, respectively. Total nutrient accumulation of N, P2O5 and K2O were 385.8 kg/ha, 244.7 kg/ha and K2O 340.3 kg/ha, respectively. Approximately 12.5kg N, 8.0 kg P2O5 and 11.1kg K2O concentration in leaf and stem per 100 kg lint were needed to produce 3000 kg/ha in Xinjiang.

LanBin Guo1,2, Michael J. Halliday1,2 and Roger M Gifford1,2

Soil carbon stocks may decrease or increase following land use change (LUC) from one ecosystem to another. Several factors may influence such gain or loss of soil carbon and we hypothesise that the species growing before and after the transition is one such factor. A 1-year pot experiment was designed to test the above hypothesis in a glasshouse independent of soil disturbance and other management effects of LUC. Two grass species (Themeda triandra and Austradanthonia racemosa) and two tree species (Pinus radiata and Eucalyptus globulus) were sown in pots. Half of the grass pots were defoliated monthly to test for any cutting effect. Themeda growing in topsoil from a pine plantation forest significantly increased soil carbon, but Austrodanthonia did not. Cutting the grass only eased Themeda’s effect on soil carbon. Pine seedlings reduced soil carbon, especially when grown in top soil from a native pasture, but the Eucalyptus seedlings did not. The soil carbon reduction under Pinus was due to Pinus trees contributing much less new carbon to the soil than old carbon was released from the soil. We conclude that choice of species involved in afforestation and deforestation projects can influence the potential net soil CO2 storage or emission after LUC.

Yoshifumi Tamura1,2, Abdón Siles2 and Eddy Ajhuacho2

Rice has been cultivated in Colonial San Juan, Bolivia, without the use of fertilizers for more than 40 years. However, yields have gradually declined and farmers have now begun to utilize fertilizers. An effective strategy might be to apply fertilizer according to the nutrient content of the soil and the nutritional requirements of the crop. To investigate this theory, we used the ‘balanced nutritional’ method to calculate the required amounts of fertilizer. The target yield for the rice grains was set at 8 t/ha and five experimental plots were created: a control, which received no fertilizers; G8, which received the required amount of fertilizer for a yield of 8 t/ha; G10, which received the required amount of fertilizer for 10 t/ha; G12, which received the required amount of fertilizer for 12 t/ha; and GA, which received the average amount of fertilizer applied by the farmers. The resulting yields were 7.5 (control), 8.6 (G8), 8.4 (G10), 8.8 (G12) and 8.7 (GA) t/ha. The yield obtained in plot G8 was similar to the target (8 t/ha) and excess fertilizer increased vegetative growth only. Therefore, the balanced nutritional method was effective in determining the appropriate quantity of fertilizer for rice plants. In addition, we compared the performance of three types of nitrogenous fertilizer (urea, ammonium sulfate and ammonium nitrate) on growth and yield. Urea had the highest nitrogen efficiency and should therefore be the fertilizer of choice for the cultivation of paddy rice in developing countries.

Susanna Muurinen 1 and Pirjo Peltonen-Sainio 1

Nitrogen is one of the most important nutrients in crop production, even thought crops can make use of only 30-50% of the applied nitrogen fertilizer. The loss of nitrogen causes environmental pollution as well as economic losses. Therefore, cereal cultivars with more efficient nitrogen use are of special interest in Finland as cereal production covers some 50% of the cultivated area. The objective of this study was to determine genotypic differences for traits characterizing nitrogen use efficiency (NUE). Three spring barley cultivars (landrace and two modern cultivars) were studied in MTT, Jokioinen in clay soil without (N0) and with 90 kg N ha-1 (N90) fertilizer. The plant samples were collected at four growth stages during the growing period and samples were divided to main shoots and tillers. The nitrogen content was analysed with Leco and calculations of NUE were made based on differences in fertilizers treatments (N0-N90). According to our results from three years there were no significant differences in NUE between modern varieties and landrace.

Marie Melteras1, Jane O’Sullivan2, Colin Asher2 and Vincent Lebot1

Soils from seven sites in Vanuatu were evaluated by nutrient omission pot trials to identify deficiencies of plant-available nutrients. Results from these trials were compared with relevant soil test results, namely nitrate nitrogen, available phosphorus (NaHCO3 and H2SO4 extractants), exchangeable potassium and extractable sulfur. Except for sulfur and H2SO4-extractable P, the correlations between soil test value and plant response were poor, and all soil tests incorrectly assigned at least one of the seven soils to the "deficient" or "adequate" categories. In the case of sulfur, increasing the critical value to about 20 mg/kg would have improved the predictive power of the test.

Ho Jin Lee1, C. H. Yi1, Seung-Hun Lee1 and Ji Hoon Chung1

Precision agriculture is a developing technique that can modify the current agricultural production system dramatically. Variable rate fertilization by applying the optimum amount of fertilizer can reduce fertilizer use and environmental pollution. The rice cultivar for this experiment was Oryza sativa L. cv. Haepyeongbyeo. Three paddy fields were divided into control and variable rate treatment (VRT) plots and grid sampling was conducted with each of thirty 10m×10m cells. The amount of basal fertilizer, and topdressing at tillering stage, in each cell was based on soil chemical analysis, and the amount of topdressing at panicle initiation stage in each cell based on plant leaf area index and chlorophyll meter value. There was no yield decrease by reduced fertilizer, and variation of yield was decreased by the effect of variable rate fertilization. According to experimental results, variable rate fertilization of paddy rice was effective at reducing fertilizer without yield decrease. It also decreased variations in growth and yield.

Lene K. Christensen1 and Rasmus N. Jørgensen2

Discrimination of a nutrient stress condition is the essential step prior to estimating the actual nutrient status using remote sensing. This research introduces a new methodology able to discriminate amongst non-stressed barley plants and N, P, and K deficiency symptoms spectrally using just three narrow reflection bands utilising both the spectral and spatial dimension simultaneously. Nine spectral measurements were carried out on each plant using the directed sampling technique. The measuring regions were spatially located at the tip, middle and base of the three last fully developed leaves. This design generated a four-dimensional data set consisting of the specific plant, the spectral dimension, the plant leaf position, and the position on the leaf. The barley plants were grown under controlled conditions, certifying the establishment of the three target deficiency symptoms (N, P and K and the non-stressed control). Three measurement occasions were carried out at three early growth stages within a time window of two weeks. Based on the results from the four dimensional multiway partial least square regression models (N-PLS) using the full spectral range (450-1000 nm) for discrimination four central wavelengths were identified as essential in the spectral discrimination modelling. The 2 nm wide reflectance bands (R) identified and used in the discrimination model were R450, R700 and R810. These three wavebands correspond to earlier findings on leaf pigment and leaf structural quantification.

Hiroyuki Daimon, Kazue Nobuta, Masamichi Ohe, Jiro Harada and Toshinobu Morikawa

To evaluate plant growth and phosphorus (P) uptake of two green-manure legumes, Sesbania cannabina and Crotalaria juncea, a pot experiment under different P conditions was conducted. Dry weight and P content of S. cannabina were not affected by the rate of applied P. On the other hand, applying P at the rate of 8.0 g/pot significantly increased the P content of C. juncea at 50 days after sowing. The difference in P content between the two species was larger at lower P supplies (3.2 and 4.0 g/pot). The rhizobial strain of S. cannabina, U9709-SC, showed high solubilization of tricalcium phosphate in the medium accompanied by a lowering of the medium pH, but the strain of C. juncea, USDA-3024, did not show this ability. A contribution of P to a succeeding crop by incorporation of these legumes would be expected as a result of P recycling.

Mingtan T. Liao1,2, Peter Hocking1,2, Bei Dong1,2, Emmanuel Delhaize1,2 and Peter R. Ryan1,2

A glasshouse pot trial was conducted to screen for P-uptake efficiency in 18 cereal genotypes by growing plants on two soils with high total P content but low plant available P. Genotypic variation in plant growth and P uptake were apparent in both soils at two harvests made at 21 and 35 days after sowing. A significant P fertilizer response was observed on both soils. Total P uptake by the genotypes was closely correlated with shoot biomass, suggesting that shoot biomass may be a reliable parameter to select for P-uptake efficiency in short-term pot bioassays. This variation may provide opportunities for developing molecular markers for wheat breeding programs to improve P-uptake efficiency in wheat.

Delphine Luquet1, Bao Gui Zhang2, Michael Dingkuhn1 and Amandine Dexet1

Plant morphogenesis is subject to environmental influence. The underlying control mechanisms are of great interest for crop improvement. A phytotron study on Nippon Bare rice seedlings was conducted to analyze the effects of P deficiency on plant organogenesis (tiller and leaf appearance, root apex number) and allometric relationships (root/shoot weight ratio, specific leaf area (SLA) and specific root length (SRL), leaf blade/sheath length ratio). The results confirmed that the main effect of P deficiency is a reduction of shoot growth to the benefit of the root system. This phenomenon, apparently caused by a reduction in leaf elongation rate without changing final leaf size, explains other changes in morphogenesis, such as longer phyllochron (because leaves take longer to expand) and lower tillering rate (because tillering is largely under trophic control). Allometric parameters such as SLA, SLR, root apex number per unit length and leaf blade/sheath length ratios remained stable. Further studies on the genetic control of phenotypic plasticity are suggested.

J.D. Hull and P.M. Martin

Research was conducted to establish critical soil phosphate (P) and tissue P levels for the maintenance of creeping bent putting greens on sand based rootzone media. Three sands ranging in P buffering capacity (PBC0.3) (Ozanne and Shaw, 1967) from 20 to 87 ml/g and three commercially available creeping bent varieties (Lofts L-93, Penn G-2, and SR1020) were used. Mitschelich type response curves were fitted to results. Soil P sufficiency ranges (Bray 2) at 90% relative yield (RY) were between 6.4 and 13.6 mg/kg. Tissue sufficiency ranges at 90%RY were between 3.47 and 3.88 mg/kg.

Ilze Skudra and Andris Skudra

Mineral nutrition is one of the most important factors affecting plant processes. The aim of the experiments was to test one of the main macronutrients, phosphorus (P), for its effect on wheat yield, and to determine the biological need for P at defined periods of plant growth. The studies were conducted as a field trial at the Experimental Station of Latvia University of Agriculture for two years with four winter wheat varieties with different nitrogen applications. P2O5 concentration was determined at the three Zadoks Growth Stages (32, 51, and 69). P concentration in the three plant parts: leaves, stems and ears was also determined at these growth stages. Leaf P2O5 concentration from the middle of stem elongation until late flowering decreased by 0.8 % for no-nitrogen variant and 0.1 % for N120 variant. Stem P2O5 concentration changed by 1.0 % for the N0 variant and by 1.5 % for the N120 variant between ZGS-32 and ZGS-69. Close correlation was found between P concentration in wheat leaves and P concentration in soil at depth 0-20 cm and 20-40 cm at ZGS 51. P concentration in leaves at ZGS 51 was negatively correlated with grain yield. There was a negative correlation between grain yield and soil P concentration.

Maarten Hens and Peter Hocking

A glasshouse experiment was conducted to evaluate the break-crop benefits of chickpea, faba bean, white lupin, canola and wheat to the phosphorus (P) nutrition and growth of following canola plants. Three soils (Berthong, BT; Grenfell, GF; and Robertson, RB) were labelled with 33P to quantify the size of the soil P pools accessed by the species using 33P isotopic dilution (L values), and to evaluate the role of P in the break-crop effect. Growth and P uptake of canola and wheat were in the order BT>GF>RB, reflecting soil P availability. In contrast, the 3 legumes had better growth and P uptake than canola or wheat on the low-P soils (RB, GF). Overall, the L values showed that white lupin accessed a larger pool of soil P than faba bean, chickpea, wheat and canola. Canola growth was lowest after wheat and canola on all soils. On RB, faba bean had the greatest P break-crop effect and chickpea had no effect. On GF and BT, all the legumes increased the growth and P uptake of the following canola. The unexpected large break-crop effect of faba bean may be due to uptake by the following crop of mineralised P from faba bean root residues.

B.M. Frischke1, R.E. Holloway1, M.J. McLaughlin2 and E. Lombi2

More than 1 million hectares of South Australia’s cereal production area consists of highly calcareous alkaline soils. Despite decades of applied fertiliser phosphorus (P), productivity in some of these areas has not increased. Six years of trial work on Eyre Peninsula using fluid fertilisers as an alternative to high-analysis granular fertilisers such as MAP and DAP, have shown wheat yields can be increased through improved P availability by 15%-23% over a range of seasons.

Anthony Whitbread1, Philip Mushayi2 and Stephen Waddington3

The variation in response to the application of fertilizer N in smallholder agriculture is related strongly to temporal and spatial variability in soil moisture, soil fertility and crop management history. Smallholder farmers in many parts of sub-Saharan Africa create fertility gradients across landscapes through their management of limited nutrient and organic residue resources. Using a previously published dataset described in Mushayi (2001), the on-farm investigations of maize response to N were simulated using a prototype ‘P-aware’ maize model in APSIM. The differences in nitrogen response efficiency measured across several on-farm sites were strongly related to soil P status and seasonal conditions. Although it was assumed in the model that all sites had similar soil water characteristics, the general responses in maize grain yield to additions of N were well represented by the “P-aware” maize model. This new capability in APSIM is being used to refine nutrient management strategies for smallholder farmers in Southern Africa.

Mohammad Nuruzzaman1, Hans Lambers1, Mike D.A. Bolland2 and Erik J. Veneklaas1

Two pot experiments were conducted to determine whether legume crops influence the growth and phosphorus (P) uptake of subsequent wheat plants, and to determine whether the roots of the preceding legume crops are responsible for any improved P uptake and growth by the subsequent wheat. In the first experiment, field pea, faba bean, white lupin and wheat were grown in three different P-deficient soils to which no or 20 mg P/kg soil was added. This experiment clearly demonstrated a residual benefit of the legumes on the growth of the subsequent wheat crop due to enhanced P uptake. Faba bean was the best of the species tested in promoting subsequent wheat growth, and therefore it appears to be a suitable P-mobilising legume crop for use in rotations with wheat. The results of the second experiment, using one soil type, showed that the increased growth and P uptake of the subsequent wheat did not require the presence of the roots of the previous crops, suggesting that rhizosphere effects on soil P status were more important for P availability than mineralization of root residues.

Sovuthy Pheav1, Richard W. Bell2, Peter F White3 and Guy JD Kirk4

The fate of residual P fertiliser and P in crop residues in sandy rainfed lowland soils is poorly understood. Field experiments were undertaken to determine the effects of rice straw incorporation, and of residual fertiliser P on biomass of volunteer pastures and to quantify the fate of P recycled from them on subsequent rice growth. Returning rice straw with P fertilisation had additive effects on growth and yields of rice during the main wet season. Straw addition alone increased grain and straw yields on the nil-P and applied-P soils by about 10 and 5 %, respectively. Subsequently, in the early following wet season, the biomass of volunteer pastures responded significantly to the residual P and the straw incorporation. All soil P fractions significantly increased at 2 weeks after rice straw incorporation. The minor resin-P fraction fluctuated more over time compared to major soil P fractions (NaOH-Pi and NaOH-Po). Phosphate added with straw increased microbial biomass C but had only small effects on microbial biomass P. Microbial biomass P declined dramatically in the active growth stage of rice, suggesting strong competition for available P from crop uptake, whereas, microbial C increased progressively for up to 40 weeks after straw incorporation. In conclusion, the application of crop residues alone marginally increased rice productivity, soil P fractions and microbial biomass C and P, whilst greater increases were obtained with the combined application of P fertiliser with crop residues. There remains to be investigated the long-term impact of residual P fertiliser and organic inputs on crop yields, soil P forms and P turnover processes.

Nhamo Nhamo1, Pauline P. Nhamo2 and Dominica B. Shumba3

Cowpea can increase the on-farm nitrogen (N) budgets through the biological N fixation. However, legumes require adequate phosphorus (P) for efficient N fixation to occur and to reduce the cost of purchased nitrogen fertilizers. Field experiments were conducted on P application effects in maize-cowpea sequences. In the first season, 20 kg/ha of P2O5 increased both maize and cowpea yields significantly (P<0.05) on P-deficient sandy soils. There was a decline in the kg grain/kg P applied with fertilizer P rates beyond 20 kg/ha P2O5 in the first and the second (residual) year on both maize and cowpea. The relative effect of each kg of P was higher on maize than on cowpea in the residual year. Yields in the second season were higher from plots where higher P levels were previously applied, with the residual treatments being statistically significant (P<0.05). Total grain yields for the rotation were highest when the P fertilizer was applied to cowpea, followed by maize grown on the residual P and the incorporated cowpea residues.

S.O.S. Akinyemi1, A.O. Olaleye2, Tijani-Eniola Hassan3 and J.O. Akinyemi2

An on-farm experiment was conducted on an Oxic Paleustalf in south western Nigeria in the 1993 and 1995 cropping seasons with the aim of determining optimum K fertilizer for plantain and melon crops when intercropped, and also to determine the most economic fertilizer rate to be applied. The experimental design was a randomised complete block with four replications. Potassium fertilizer was applied at rates of 120, 240, 360 and 480 kg K ha-1 and a control. Economic analysis was carried out to assess the profitability of this intercrop at different K rates using a partial budgeting method. Results showed that this soil is deficient in K and intercropped plantain-melon responded to the application of the fertilizer. The following parameters responded significantly (p<0.05) to K fertilizer application: number of hands and fingers bunch-1, mean length of plantain bunch as well as mean bunch and total bunch weight.Maximum yield was obtained at 360 kg K ha-1 in both cropping seasons. Optimum K fertilizer for melon was 240 kg K ha-1. Results of the partial budgeting method for the intercrop at different K fertilizer applied were N10, 000.00 (or $384.60) in 1993 and N 6, 700.00 ($ 257.69) in 1995 cropping seasons. In conclusion, the optimum K fertilizer that will give the best marginal rate of return was estimated to be 360 kg K ha-1.

D. Harris1

Poor crop establishment is a major problem in many areas of the world, particularly for subsistence farmers in rainfed- and poorly-irrigated environments. ‘On farm’ seed priming – soaking seeds, usually overnight, before sowing – is a simple technology that farmers can use to improve crop establishment and increase yield. It has been tested, developed and refined in a range of crops, countries and agro-environments using a combination of in vitro, on-station and farmer-participatory research and regularly increases yield. In addition, priming has been associated with increased disease resistance in some crops and can also be used as a vehicle to alleviate some micronutrient deficiencies.

Yusuf Genc1, Glenn McDonald2 and Robin D. Graham2

Zinc deficiency limits yield of cereals on vast areas in the world, and developing genotypes with the ability to grow and yield on zinc deficient soils is considered a long-term sustainable approach. A good understanding of this ability will facilitate breeding for this agronomically important trait. In a growth room study, using a soil culture, we compared some of the physiological differences in two wheat genotypes previously shown to differ in zinc efficiency. Our results indicate that higher zinc efficiency may be achieved through greater distribution to younger parts and lower internal requirement. Selection for such attributes can be considered in breeding programs aiming to develop zinc efficient genotypes for cropping zinc deficient soils.

Sawika Konsaeng and Benjavan Rerkasem

The mobility in phloem of boron (B) has been reported to vary among plant species. Boron is phloem immobile in many species and completely mobile in others. Recent reports regarding phloem B mobility or immobility only considered temperate plants, and there is no information on tropical species. Information of phloem B mobility is useful for improving the diagnosis of B deficiency and management of B status in crop production. This study aimed to survey tropical species for their B mobility. Leaf samples of 17 species, including coffee (Coffea arabica L.), custard apple (Annona squamosa L.), guava (Psidium guajava L.), jackfruit (Artocarpus heterophyllus Lamk.), lime (Citrus aurantifolia Swingle.), cashew (Anacardium occidentale L.), mango (Mangifera indica L.), papaya (Carica papaya L.), passion fruit (Passiflora edulis Sims.), teak (Tectona grandis L.), cassava (Manihot esculenta Crantz.), Cork wood tree (Sesbania grandiflora (L.) Pers.), Indian walnut (Samanea samen (Jacq.) Marrill.), Tamarind (Tamarindus indica L.), Lychee (Lychi chinensis Sonn.), Longan (Euphoria longana Lam.) and Star fruit (Averrhoa carambola L.), were collected in the position of the youngest fully expanded leaf (YFEL), the middle leaf age of branch (ML) and the oldest leaf (OL). Based on a premise that nutrient concentration gradient between young and old leaf will be steeper in those species in which B is immobile, B concentrations in the different leaf positions was examined in comparison with calcium (Ca is phloem immobile) and potassium (K is phloem mobile). Concentrations of K in all leaf types were not significantly different or decreased with leaf age, while Ca concentrations were always higher in the older leaves. Seven species; coffee, guava, jackfruit, papaya teak, tamarind and longan, showed concentration gradients of B that were similar to K. The results suggested that B may be retranslocated from older to younger leaves of these species, hence indicating that B may be phloem mobile in these species. However, this hypothesis needs conformation through studies examining retranslocation of B using B10 isotope or identification of B-complexing molecules in the phloem, e.g. sugar alcohols.

Supannika Punchana, Sansanee Jamjod and Benjavan Rerkasem

Significant wheat yield reductions have been attributed to boron (B) deficiency and toxicity all over the world. However, it is as yet unclear how the two responses are related in wheat genotypes. The relationship between responses to B toxicity and deficiency in wheat genotypes was examined in two experiments. In the first experiment, three genotypes with known B deficiency responses, Fang 60 (Efficient; E) Bonza and Turkey 1473 (Inefficient; I), were grown for 23 days in sand culture with five levels of B added to nutrient solution (10, 50, 100, 150, 200 mg B L-1). Effects of B toxicity were measured in root and shoot length, tiller number, and toxicity symptoms (leaf necrosis and chlorosis). The toxic effect of B on root length and leaf chlorosis and necrosis clearly indicated that Bonza was the most tolerant and Fang 60 least tolerant to B toxicity. In the second experiment the 18th Semi-arid Wheat Screening Nursery from CIMMYT (18th SAWSN, 180 entries) was evaluated for tolerance to B deficiency with grain set in a sand culture without added B and for tolerance to B toxicity with root length at 100 mg B L-1. Three types of response to B deficiency and toxicity by individual genotypes were identified, (i) B efficient, but sensitive to toxicity; (ii) B inefficient, but tolerant to toxicity; (iii) B inefficient and sensitive to toxicity. The fourth type, B efficient, as well as tolerant to toxicity, the ideal, was not found in this international germplasm collection.

José S.S. Foloni and Ciro A. Rosolem

A well managed K fertilization program can avoid nutrient losses, and soil K depletion thus minimizing costs. Cover crops can be important in recycling K, contributing to the sustainability of the crop system. An experiment was conducted in Botucatu, SP, Brazil, for two years, using different K rates and managements in a soybean-millet-black oat rotation system in no-till. Soil, plant and straw samples were taken during the experiment period and analyzed for K contents. Soil exchangeable and non-exchangeable K were analysed. In order to maintain K levels in the system relatively stable, it was necessary the apply at least 38 kg ha-1 of K2O per year (Fig 3-a). If K contents in the straw were not taken into account, in two years K deficit in the system would amount to over 180 kg ha-1 (Fig 3-C and 3-D), which highlights the importance of the cover crops and the mulch in recycling the nutrient in the system. Cover crops can act in the system in two ways: preventing K leaching below 60 cm, and bringing up some K from deeper soil layers, in both cases releasing K from the straw during early growth of soybean to match the K demand and avoiding nutrient loss. Therefore the K accumulated in the winter cover crops was paramount as a nutrient source for the following soybean crop and for the sustainability of the system.

M. Bodruzzaman1, J.M. Duxbury2, J.G. Lauren2, Craig Meisner3, M.H.H. Khan1 and M.A. Sadat1

Many soils in the tropics are deficient in micronutrients especially Zn, B and Mo. Micronutrient deficiency can cause serious yield limitations to crops. Eighteen on-farm trials were conducted to investigate the performance of micronutrient enriched wheat seed and B application in 9 sites in northern Bangladesh. The experiments were established as 4 treatments in a randomized complete block design. The treatments were: T1) micronutrient enriched seed, T2) micronutrient enriched seed plus B to soil, T3) normal (non-enriched) seed and T4) normal seed plus B to soil. There were used 2 wheat varieties of known distinct responses to micronutrient enrichment. The results indicated that both enriched seed and normal seed with B produced higher yield compared to normal seed alone. The mean increase yield of 9 sites was 21 and 31% in enriched seed plus B treatment with the wheat varieties Kanchan and Shatabdi over normal seed, respectively. Inclusion of B with normal seed produced 11% for Kanchan and 23% for Shatabdi higher yield compared to normal seed. Kanchan was found more tolerant to micronutrient deficiency compared to Shatabdi. Crop response indicated that 2 site soils were not deficient in micronutrients, while all other sites showed clear micronutrient deficiencies.

Ryuji Yoshida1, Yasuhisa Fukuta1, Kunji Shimotsubo1, Kazuya Iwai2, Shigeyuki Watanabe3 and Toru Tanaka3

Growth promotive effects of 5-aminolevulinic acid (5-ALA) on the yield of Komatsuna were studied under alkaline soil conditions in the presence of micronutrients. The low yield of Komatsuna on alkaline soil was reduced by the foliar application of 5-ALA or pentakeep-V (PKV) alone or of the 5-ALA- chelating iron mixture. In conclusions, these chemicals were very useful for the production of vegetables under alkaline soil conditions.

D.F. Khan1, D.F. Herridge2, Mark Peoples3, G.D. Schwenke2, S.H. Shah1, S.M. Shah1, T. Khan4 and D. Chen5

Significant amounts of N2 fixed by legumes are incorporated into the soil as fallen leaves and stems, but nitrogen (N) will also be contributed by roots, nodules and root exudates. Generally, large proportion of the N accumulated during the growth of crop legumes is removed with the harvested seed, it is commonly concluded that the net return of fixed N to the soil is likely to be small. When the amounts of N2 fixed by legumes have been compared with the N removed in seed, most calculations have relied totally on above-ground measures of fixed N. However, recent applications of the 15N-shoot labelling techniques to field grown crops suggest that the below-ground pool of legume N (nodules, roots and their exudates) may represent between 24% (fababean) and 76% (chickpea) of the total plant N. In the past, the values of legume rotations have been greatly underestimated as the root contribution of N has previously been ignored.

Saideh Maleki Farahani1,Reza Tavakkol Afshari2, Hosein H. Sharifabadi3 and Mohammad Reza Chaichi4

Continuous grain cropping in many areas of the world has reduced soil N levels to a degree such that agricultural production is now largely dependent upon nitrogen fertilizer. Identification of highly effective legume and Rhizobium strain combinations, increased production of protein- rich livestock forage and also improved the soil structure. Four species of annual medics (Medicago truncatula, M. littoralis, M. polymorpha, M. rigidula) were grown in all combinations with four various strains of Rhizobium meliloti (Locally, Hoomand, R95 and S13). There was also an uninoculated check for each species. Control treatment (uninoculated) included mineral nitrogen (2.5 mMol nitrate). All combinations of medics and Rhizobium were grown without nitrate. The control treatment was wetted with nutrient solution contained 2.5 mMol nitrate. Growth chamber experiment was conducted for 90 days to evaluate shoot dry matter and total shoot N. Medic lines varied in their ability to form an effective symbiosis with the rhizobia. M. truncatula has higher symbiotic association with the strains Locally, Hoomand and R95. M. littoralis also in four inoculated treatment has %N near to control treatment. M. rigidula had the highest symbiosis with R95 and then with S13. M.polymorpha had low symbiosis with all the strains. M. trumcatula and M. littoralis exhibited similar response to all strains. M. rigidula required specific strains of Rhizobium meliloti in order to fix nitrogen. . M. polymorpha has no effective symbiosis with any one of the strains, this implies that this plant requires specific strains.

Jude J.O. Odhiambo

Legumes have great potential for improving soil fertility. A field study was conducted at two different planting seasons at the University of Venda, School of Agriculture experimental farm on a deep, well-drained clay, Hutton form soil type. The objective of the study was to assess the biomass production and N content of some dual-purpose legumes and determine their potential role in smallholder farming systems in the province. Five legume species: Mucuna pruriens, Lablab purpureus (Cv Rongai), Clitoria ternatea (butterfly pea, Var. Milgara) and Vigna unguiculata (two varieties) were planted as treatments in a randomized complete block design. At 120 days after planting, plant samples were collected and biomass production, N concentration and N content determined. Lablab consistently produced more than 2.2 t ha-1 of biomass in both the growing seasons. Legume N concentration and accumulation ranged between 12 to 40 g kg-1 and 4 to 106 kg ha-1, respectively, over the two growing seasons. Influence of growing season on growth performance of legume species was evident in this study. Lablab biomass production was consistent in both the growing seasons, indicating that it has the potential to be incorporated into cereal monoculture systems in the region when planted in summer or can be used as a green manure when planted in the winter and incorporated before the summer planting season.

Anthony O. Anyia, Daniel J. Archambault and Jan J. Slaski

Production of wheat typically requires intensive use of chemical fertilizers. Reliance on fertilizers may be decreased by exploitation of plant growth promoting organisms. This work examines the responsiveness of Canadian cultivars of Hard Red Spring wheat to inoculation with Azorhizobium caulinodans, a diazotroph isolated from the legume Sesbania rostrata. This bacterium has been shown to colonize wheat roots through crack entry of the lateral roots. Inoculation of wheat cultivar CDC Teal grown in field soil caused increases in grain yield and total biomass of 34 and 49%, respectively. Inoculated plants produced more tillers and had larger leaf area than un-inoculated plants. In contrast, wheat cultivar AC Taber did not benefit from inoculation. A screening bio-assay was developed to test whether the effects of inoculation are common within Canadian wheat cultivars. Low levels of nitrogenase activity were detected in preliminary studies. It is yet to be verified whether the nitrogen being fixed is sufficient to be of significant benefit. We have hypothesized that the observed effects may be caused by other growth promoting mechanisms. For example, we have observed changes in root morphology that may increase nutrient and water use efficiencies and drought tolerance.

Manas R. Banerjee and Laila Yesmin

To hasten the process of sulfur (S) oxidation in soil, a S-oxidizing bacterial inoculant BioBoost was used as canola seed treatment to meet the plant S requirement and to increase canola production in Western Canada. BioBoost is a contaminant free peat based inoculant, having a shelf life over five months with the adequate level of viable bacterial cells. The active ingredient of the inoculant BioBoost is a selected strain of Delftia acidovorans isolated from Canadian soil, which is also a canola plant growth promoting rhizobacteria (PGPR). Our multi year multi sites field studies with BioBoost showed that the bacterial inoculant significantly enhanced canola performance and yield. Being PGPR, BioBoost inoculant promoted canola production irrespective of the soil S status of the fields. Seed analysis showed that BioBoost inoculant helped in canola S-uptake but did not change the seed quality traits like oil, protein, oleic acid, linolenic acid and glucosinolate content of canola seed. Thus, this research has developed a bacterial inoculant that improves canola production without having any effect on the seed quality aspect of canola. In fact, this research has developed a new microbial inoculant BioBoost which is the first S-inoculant for canola to the best of our knowledge.

Yen Thao Tran

Results from published experimental findings on inoculation of soybean in the south of Vietnam are reviewed. Soybean responded considerably to inoculation by producing more grain yields. On average, yields were improved by 38% (59% in Mekong River Delta and 16% in Eastern region of the south). Inoculation resulted in seed yield increase of 100-500 kg/ha and 500-1000 kg/ha in 67% and 30% of the trials, respectively. In most soils, savings in fertiliser N were 40-60 kg N/ha. The economic analysis of 4 experiments showed that farmers gained more benefits (19%) from inoculation compared to urea application. This benefits came from lower cost of fertilizer input (no urea was used) and grain yield increase. In virtually all situations, there would have been an economic benefit of inoculation, both for the legume itself and for subsequent crops. Unfortunately, farmers do not usually inoculate soybean in the south of Vietnam. Instead they apply large quantities of fertiliser N, at rates of 25 – 50 kg N/ha in some areas to as much as 80 – 150 kg N/ha in others. This is a large unnecessary expense. The money spent on fertiliser N could arguably be better spent on other inputs such as weeding, insect control and use of other fertilisers. What is needed is a coordinated program to develop a capacity to produce and supply sufficient quantities of high – quality inoculants to farmers and to educate extension workers and farmers about the benefits of inoculation.

Laila Yesmin1, Ivan Oresnik2 and Manas R. Banerjee1

Within the leguminosae family, soybean (Glycine max L.) and peas (Pisum sativum) are the two most predominant legume crops in Canada and the United States. The use of Rhizobium inoculant for better crop production is a common practice in the region. The use of an inoculant allows the legume plants to form root nodules within which atmospheric nitrogen is fixed and supplied to the plant. In the present study we are investigating a synergistic response that occurs when a sulfur-oxidizing plant growth promoting rhizobacteria (PGPR) Delftia acidovorans RAY209 is added to some Rhizobium inoculants. Preliminary experiments using a Bradyrhizobium japonicum/D. acidovorans consortium (SJ1) and Rhizobium leguminosarum/D. acidovorans consortia (SL1 and SL2) have yielded promising results on soybean and peas, respectively. These results suggest that if these legumes are inoculated with consortia SJ1, SL1 or SL2, the plants show enhanced seed emergence, increased biomass, and increased nodule numbers. By utilizing an inherent antibiotic resistant phenotype of RAY209 we have been able to determine that RAY209 strain can colonize peas roots and also capable of causing nodule-like outgrowths on these roots in some cases. It is hoped that by gaining an understanding of this association a consortia based inoculant can be developed.

E. B. Gergon1, M. B. Brown2, and S. A. Miller3

Mychorrhizal inoculants containing vesicular arbuscular mycorrhizal (VAM) fungi were evaluated in M. graminicola-infested soil, and their effects on growth and yield of onion were determined under greenhouse conditions. The study showed that the mixture of Glomus mosseae, G. fasciculatum and Mykovam applied at sowing was the best inoculant for onion. Mycorrhizal inoculation improved the growth of Yellow Granex and Red Creole onions in the presence or absence of M. graminicola in NPK-deficient soil. With complete NPK fertilization, inoculation enhanced the bulb development of Yellow Granex and Red Creole. In nematode-free soil, bulb weight of Yellow Granex increased by 54% and Red Creole by 23% while bulb diameter increased by 24% and 13%, respectively, compared with the untreated control. In M. graminicola-infested soil, yield of Red Creole was seriously affected but Yellow Granex showed tolerance to root-knot infection with increase in bulb weight by 262% and bulb diameter by 96.4% over the control. Field studies showed no differences in onion yield between inoculated and non-inoculated plants because of the presence of indigenous mycorrhizae in the field. Similarly, there was no difference in yield of inoculated plants that were given 120-240-120 kg NPK ha-1 and 60-120-60-kg NPK ha-1. This indicates that half of the recommended fertilizer rate was sufficient for mycorrhizal onion plants thereby reducing the fertilizer inputs in the field.

S.S. Duhoon1, A. Jyotishi1, M.R. Deshmukh1 and N.B. Singh2

India ranks first in area (29%), production (26%) and export (40%) of sesame (Sesamum indicum L.) in the world. Sesame seeds are rich source of food, nutrition, edible oil, health care and bio-medicine. Sesame oil has excellent nutritional, medicinal, cosmetic and cooking qualities for which it is known as 'the queen of oils'. Due to the presence of potent antioxidants, sesame seeds are called as 'the seeds of immortality'. With the growing health consciousness, the international demand and export of sesame are continuously increasing. Consequently, sesame has recently emerged as a valuable export crop, presently earning over Rs. 1000/- crores of valuable foreign exchange from the export of 2.5 lakh tonnes of sesame seed. So much so, India’s share in world’s trade of hulled sesame has gone up to 60 % during 2002-03. However, pesticide residue had been the major problem in the promotion of sesame export. To enhance the production and export of sesame, the technology needs reorientation and refinement with emphasis on the quality of the produce to match with export standards and demands of international markets. The organically produced sesame will suit to the tailor-made requirements of the foreign buyers and will get premium in the international market.

The studies on the optimization of sesame production through the use of bio/natural inputs conducted at four centers of All India Coordinated Research Project, during 2002-03 and 2003-04 revealed that among 12 treatments with recommended dose of nutrients through different combinations of bio/natural inputs, the highest seed yields were recorded with the application of [FYM 3.75 t/ha + Neem cake @ 900 kg/ha + wood ash 75 kg/ha + bone meal 75 kg/ha + ELS 20 kg/ha + PSB 5 kg/ha + Azotobactor 5 kg/ha + Trichoderma viride (0.4%) seed treatment + Neem oil (2.0%) spray thrice at 15, 30 and 45 DAS/ Azadrichtin (0.03% at 30 DAS)]. The mean yield pooled over locations and years (782 kg/ha) recorded in T2 was on par with the highest yield (786 kg/ha) recorded in T1 with the application of recommended dose of chemical fertilizers @ 60 N+40 P+20 K+20 S kg /ha and pesticides. The maximum 1000-seed weight (2.63 g) and oil content (52.0 %) and oil yield (406 kg/ha) were also recorded in treatment T2., besides other direct and indirect beneficial effects on agro-ecology, oil, soil and human health. The results confirmed the feasibility of substituting chemical fertilizer and pesticides by organic resources without sacrificing the yield levels in sesame crop. The use of organic sources will reduce dependence on chemical fertilizers and pesticides besides being ecologically sound and eco-friendly in nature. Marginally higher net monetary return and benefit-cost (B:C) ratio observed with the application of chemical inputs were due to the same rate of produce without consideration of premium for organic treatments.

Bettina Lythgoe1, Daniel Rodriguez1, De Li Liu2, John Brennan2, Brendan Scott2, Gordon Murray2 and Peter Hayman3

We used the Agricultural Production Systems Simulator (APSIM) to quantify the economic value of the five SOI phases seasonal forecasting system. We used APSIM to estimate the profits and risks of cropping wheat under a “fixed” N management strategy i.e. ignoring seasonal forecasts, and a “flexible” N management strategy i.e. deriving the rate of N as a function of the June-July phase of the five SOI phases seasonal forecasting system. We showed that higher profits can be achieved without increasing the level of risk of economic loss by adopting a seasonal forecasting system to determine the rates of N to be applied in split N applications between pre-drill and tillering. This was particularly valid for the less marginal environments, and better initial conditions i.e. initial soil moisture. Improved profit–to-risk ratios could be achieved by applying a more flexible N management and adopting a seasonal forecasting system particularly at locations having more than 380mm of annual rainfall and on soils having potential plant available water higher than 115mm.

Mehari Tesfazgi Mebrhatu1, M. Tsubo2 and Sue Walker1

A deterministic model was developed to investigate how global rainfall predictors relate to the two main rainy months in the highlands of Eritrea. The main aim of looking at these relationships was to develop a simple statistical model for forecasting rainfall amount. Farmers could make better management decisions if they had a better assessment of the forthcoming season. In a preliminary step, in order to identify the most influential rainfall predictor, a correlation matrix and stepwise regression of 10 predictors with different lags were analysed. The influence of the southern Indian Ocean Sea Surface Temperature was identified as the most influential predictor for the highlands of Eritrea. A model was developed and validated giving a promising result.

B. Sultan1, Christian Baron2, Michael Dingkuhn2 and Serge Janicot1

Agriculture in the Sudano-Sahelian zone is heavily dependent on the seasonal characteristics of rainfall, i.e. onset, length and termination of the wet season, seasonal rainfall totals and intra-seasonal rainfall distribution. This study seeks to characterize components of regional climatic variability and their impact on simulated, attainable, plot-level yields of millet.

First, we will characterize at a regional scale two main events in the seasonal pattern of the monsoon over West Africa by using a daily rainfall dataset over the 1968-1990 period, that is, (1) the "onset" of the summer monsoon characterized by an abrupt northward shift of the ITCZ from 5°N to 10°N around the 24th June, and (2) large and coherent, intra-seasonal rainfall fluctuations at two different spectral windows, between 10 and 25 days and between 25 and 60 days.

Second, we will investigate the impact of these regional phenomena on local crop yields using SARRAH, a crop model simulating water-limited yield, by means of sensitivity analyses. The response of attainable yield (limited by climate and water resources but not mineral nutrition) to sowing date was studied for 19 years of the 1968-1990 period for a 90-day millet crop at Niamey. Yield variability is analysed with respect to the apparent validity of regional (climatic) and local (rainfall events) decision criteria for sowing date, while taking into consideration interannual variability of rainfall and intra-seasonal dry spells. Results indicate that information on regional climate dynamics might help improve crop production locally.

Mehari Tesfazgi Mebrhatu1, M. Tsubo2 and Sue Walker1

Fitting the least squares line to the long–term annual rainfall (88 years) for Asmara gave a decreasing annual trend of 0.25mm. But the statistical analysis of the deviation from zero is not significant (p = 0.28). This means that the rainfall distribution fluctuates with time, but the annual amount did not significantly decrease over time during the last century. The Markov chain model (with threshold level of 0.8mm per day) was used to predict the length of dry spells during the rainy season (June to September). This information can be used to select the best planting date by avoiding the period of high risk of long dry periods near the beginning of the rainy season. Thus it can assist farmers in land preparation and planting strategies for different cultivars and crops.

Prakash Dixit1, 2, Daniel Rodriguez2 and D. Chen3

Extreme temperatures around anthesis of wheat have the potential to reduce grain yield. However, at paddock level their impact can be expected to be highly spatially variable due to topographic features. In this study we develop simple algorithms to spatially model the existing variability in extreme temperatures at paddock level in order to identify areas of high risk of extreme temperatures around the time of the anthesis of wheat. Twenty-five tinytag data loggers were installed at 0.8m height to represent crop head height across a 164.3 ha paddock at Birchip in the southern mallee of Victoria, to spatially record the daily course of temperatures around the average date of anthesis in the region. Multiple linear regression analysis techniques were used to build models relating extreme temperatures to topographic features of the paddock i.e. elevation, aspect, slope and maximum and minimum temperatures at the farm. During calibration the developed model explained up to 94% and 95% of the observed variability in maximum and minimum temperatures, respectively. Elevation was negatively correlated with the observed maximum and minimum temperatures whereas aspect was correlated positively with the maximum temperatures and negatively with the minimum temperatures. Slope was correlated negatively with the maximum temperatures and positively with the minimum temperatures. During validation the developed equations explained up to 85% and 95% of the observed variability in maximum and minimum temperatures, respectively. We concluded that the temperature variation within the paddock can be explained by the variation in its topographic features.

Ramasamy Selvaraju1, Holger Meinke2 and James Hansen3

Irrigated crop production systems in Southern India are exposed to high year-to-year rainfall variability. Most of the rainfall is received during the summer (June-September; 33%) and winter (October–December, 47%) monsoon seasons, respectively. Over the last five decades, cropping patterns on small farms in this region have undergone substantial change – from less-intensive millets to semi-intensive cereals (rice, maize) and commercial crops (cotton and sugarcane) with high water requirements. Farmers exploit scarce groundwater resources to manage production uncertainties to improve household food and financial security. As a result, water tables have fallen by up to 25-30 meters in one decade. This alarming over-exploitation of groundwater has reduced the resilience of the production systems and increased the vulnerability of the farming population. The water table depth in the study region varies with seasonal rainfall. Analysis showed that the ground water table is responsive to interannual rainfall variations that are also influenced moderately by El Niño-Southern Oscillation related phenomenon. Our calculations show that irrigation requirements for a 120-day summer monsoon maize crop increase as the season progresses, particularly during an El Nino. An associated reduction of groundwater recharge during the season might limit the area under irrigated maize. The ability to anticipate groundwater recharge based on ENSO phases, has implications for crop selection and irrigation decisions in the dry (February-May) season and subsequent summer monsoon (June – September) following the winter monsoon. In El Niño years, increased water deficit during the summer monsoon increases the benefits of supplemental irrigation. Stakeholder meetings communicated the potential application of climate information for risk management to farmers and community workers. Our preliminary work describes a framework to use climate information for risk management in irrigated cropping systems in a highly vulnerable area. Additional research work is needed to find out the interaction between rainfall and ground water recharge conditioned by El Niño-Southern Oscillation.

A.J. Challinor1,2, T.R. Wheeler2, J.M. Slingo1, Peter Craufurd2, D.I.F. Grimes3 and T. Chee-Kiat3

The productivity of crops in tropical regions is highly vulnerable to inter-annual and sub-seasonal climate variability. The strong climatic seasonal cycle in seasonally arid regions make these areas ideal for the study of the predictability of the impacts of weather on crop yield. Where predictability exists, it can be capitalised upon using pragmatic crop models that simulate key processes, together with accurate meteorological data and model output. This paper describes issues and progress in this area, principally using a case study of groundnut in India.

Sue Walker1, H.O. Ogindo1 and M. Tsubo2

In regions like Africa that face food insecurity, small-scale farmers practise traditional cropping techniques such as intercropping. Many studies have reported that intercropping has higher productivity and higher resource use than sole cropping. In this study, risk for maize–bean intercropping was evaluated by quantifying long-term yield of maize and beans in both intercropping and sole cropping in a southern African semi-arid region (Bulawayo, Zimbabwe and Bloemfontein, South Africa). The crop simulation model was run with different cultural practices (sowing date and plant density) for 49 summer cropping seasons (1951–2000). Since soil water content at planting in each of the growing seasons was unknown, the simulation was run with a range of different root zone water contents at planting. Simulated long-term yields for maize–bean intercropping were analysed in terms of intensity of land use, production of constituents and capital return, and clearly demonstrated its advantages.

Carlos G.H. Díaz-Ambrona1, Ruben Gigena Pazos2 and Carlos O. Mendoza Tovar2

Rainfall variability will increase under climate change in the Subtropical dryland of Honduras (Central America).We investigated the impact of traditional management practices on the maize productivity of subsistence farming systems in a dry subtropical environment. In Honduras, food production has not increased as rapidly as population growth in the last 40 years. The CropSyst model was tested locally and used with long-term weather data to analyze the variability of yield associated with alternative farming practices. Experiments were also carried out at the Escuela Agrícola Panamericana Zamorano. Model estimates were compared with yield, phenology and soil organic matter collected from different experiments conducted from 1998 to 2002 under a wide range of weather, rotations, cultivars, management practices and soils. The simulations of yield were close to measured yield for maize (observed range from 0.6 to 6.5 t ha-1; RMSE = 1.2 t ha-1). The model provided reasonable estimates of crop yields and phenological development. Climate series from Zamorano showed significant relationships between the six month anomaly of the Southern Oscillation Index and the rainfall during the wet season. The impact of climate change on subsistence maize production was explored with CropSyst. To evaluate different future scenarios. Under current management practices, future climate change scenarios increased yield variability and reduced yield by 0 to 22 %. Sowing opportunities and the crop maturity date are particularly sensitive to climate change. Further studies are needed to investigate strategies to reduce those impacts and to explore mitigation tactics.

M. Inés Mínguez, M. Ruiz-Ramos, Carlos G.H. Díaz-Ambrona, M. Quemada and F. Sau1

The EU project PRUDENCE was established to evaluate deficiencies in climate projections and focuses on reducing uncertainties in impact predictions. The work applies the outputs of several high resolution Atmosphere General Circulation Models and Regional Climate Models to crop models to evaluate uncertainties in the impacts of climate projections and to identify major adaptation strategies for the Iberian Peninsula. Differences among climate models that exist under current and future scenarios are transferred to impact models. Uncertainties may be enhanced or attenuated by the impact models.

Meredith Fairbanks and Alexandra Edward

The Department of Agriculture (Western Australia) is developing a prototype climate analogue selection system (Global ENSO Sequence System (GESS)) which indicates potential growing season rainfall for the current season. This paper looks at how the information from GESS together with the decision support tool, Season Protein Likelihoods and Tradeoffs (SPLAT), can be used to make farming decisions to increase the potential gross margin return. The potential gross margin for Merredin in the 2002 and 2003 season, using GESS climate outlook, is compared to the expected gross margins made when expecting the average growing season rainfall, and the actual growing season rainfall. This paper found that by making decisions based on the seasonal outlook using GESS, Merredin farmers in 2002 and 2003, would receive a larger profit than if they had made farming decisions based on receiving and reacting to the average growing season rainfall.

De Li Liu1, Peter Hayman2 and Brendan Scott1

The variable time of the autumn break and the duration of sowing opportunities in the autumn period are important features of farming in south eastern Australian. A simple daily soil water balance model was developed to calculate plant available water during late summer and into the autumn sowing period. After testing the model with historical trial data we used the long term climate data to investigate the impact of El Niño, Southern Oscillation (ENSO) on 36 sites in south eastern Australia. Generally, the autumn break in El Niño years was delayed by 2 weeks, while seasonal breaks in La Niña years were 2 weeks earlier. The durations of sowing opportunities in April, May, June and July averaged, respectively to 4, 10, 18 and 22 days in El Niño years and 7, 16, 20 and 27 days in La Niña, while the changes in durations from all other years in the respective month were by -29%, -25%, -14%, and -15% in El Niño years and 48%, 33%, 10% and 10% in La Niña years.

Kerry L. Bell, Sarah Lennox and Peter DeVoil

There is strong evidence that human influences have affected climate change due to continued emissions of carbon dioxide and other greenhouse gases from fossil fuels and other sources. Understanding these changes and projecting future changes is important in order to maintain or increase economic returns and decrease environmental impacts from agricultural production. This requires statistical tools that confidently identify trends in noisy time series. We explore the use of the REML (Restricted Maximum Likelihood) procedure as a statistical tool that accounts for an autoregressive term, cyclic trends and deterministic trends in the form of line and spline terms. The yearly minimum temperature at Emerald in Central Queensland is used as an example.

Sarah Lennox1, Peter K. Dunn2, Brendan Power3 and Peter DeVoil4

The finding of an accurate and reliable rainfall model has been the point of much discussion in previous research and has promising input applications in areas such as crop growth, hydrological systems and simulation studies. In the past it has been necessary to model rainfall as two separate processes: rainfall occurrence (whether the period is dry/wet) and rainfall amounts (rainfall amount observed during a wet period). As the rainfall process involves both discrete (rainfall = 0 mm) and continuous parts (rainfall >0 mm), two separate models have previously been fitted and the information from the two models combined in order to provide a summary of the rainfall model. The Tweedie distribution however is able to combine both aspects to provide one complete rainfall process. This results in a more accurate, reliable and practical model that can then be incorporated into other areas such as crop growth systems.

Andries Potgieter1, Holger Meinke1 and Alastair Doherty1,2

We investigated the impact of four climate change scenarios derived from the CSIRO Mk3 Global Circulation Model on wheat and sorghum production for the shires of Emerald and Banana in central Queensland using shire-scale simulation models. Simulated wheat and sorghum yields for these scenarios were compared with current climate for the years 2030 and 2070. The four scenarios involved temperature increases of 0.3 and 1.9o C combined with rainfall changes of -13% and +7%. The study indicated that a large decline in yield was likely under the most extreme scenario of higher temperature combined with lower rainfall; the decline was greater in wheat than in sorghum, and greater in the Banana shire. One challenge for the grain industry (including government and scientific agencies) is to anticipate these impacts and develop an R&D strategy that will allow the continuation of a profitable and sustainable cropping industry.

Brendan Power1, Holger Meinke1, Peter DeVoil1, Sarah Lennox1 and Peter Hayman2

Cropping systems are sensitive to climate variability and climate change. This study identifies long-term trends (non-stationarity) in minimum winter temperatures and rainfall at Gunnedah (NSW, Australia) and assesses their impacts on monoculture wheat systems in the same region using the Agricultural Production System Simulator (APSIM). To identify these trends in climatic and agricultural time series it was necessary to account for variation due to auto-correlation and ENSO before a climate change signal emerged. Significant increases were found in minimum winter temperatures and accumulated seasonal rainfall. Resultant wheat yield increases were then found, once ENSO variability was identified, however such increases would likely be offset in “real-world” systems by increases in lost natural resources, such as soil and water.

Aline de H.N. Maia1, Meinke Holger2 and Sarah Lennox2

The establishment and communication of climatological forecast ‘skill’ are complex issues requiring simple approaches. The major issues are: (a) inappropriate use of significance testing to quantify signal intensity, (b) skewed probability distributions of time series of bio-physical data (such as rainfall, crop or pasture production) rendering parametric skill measures based on Normal distribution inadequate, (c) for a spatial assessment of forecast skill, the use of skill measures derived from parametric tests require location-by-location checking of assumptions about underlying distributions, making the process cumbersome and expensive, (d) the level of significance required for forecast skill to be useful depends on the user and the application rather than on an arbitrary, pre-determined significance level and (e) signal intensity varies temporally and spatially. Hence, we propose the use of p-values derived from non-parametric tests such as the Log-Rank test as direct indicators of signal intensity. This method does not require any knowledge of the underlying data structure, nor does it require any arbitrarily chosen level of significance. Further, given adequate spatial coverage, p-values can be mapped using interpolation methods, providing a powerful and intuitive means of communicating the spatial variability of signal intensity. We illustrate this method by assessing the ability of a three-way ENSO classification in forecasting winter rainfall across Australia.

Alexis Donald1, Holger Meinke1, Brendan Power1, Matthew Wheeler2 and Joachim Ribbe3.

The Madden-Julian Oscillation (MJO) is a tropical atmospheric phenomenon first recognised in the early 1970s. The MJO, also commonly known as the 40-day wave, develops over the Indian Ocean and then travels east across the tropics at 5-10 m/s. With a timescale ranging from 30 to 60 days, the MJO has a frequency of 6-12 events per year. In its active stage, the MJO is associated with increased convective activity. Trailing the active centre is region of suppressed convective activity and mean surface level westerly winds. Statistical analysis shows that the MJO can influence rainfall in Australia and elsewhere in the world, beyond the tropics. As MJO forecasting tends to bridge the gap between synoptic and seasonal forecasting, the potential for on-farm risk management is significant.

Rizaldi Boer, Perdinan Rakiso and A. Faqih

The use of simulation modelling approaches to evaluate how systems respond to historical climates and how systems will respond to change in management practices has been widely applied. This approach normally requires long records of historical daily climatic data. However, in most developing countries, historical records of daily climate data are not well maintained, but the historical monthly data is frequently available. This study evaluated the use of generated daily climatic data from the monthly means in simulation studies to overcome the problem of data scarcity. Two simulation models, APSIM and VIC-BASIN, were run using the generated and observed daily climatic data. It was found that the outputs from the models resulted from the generated and observed daily climatic data were not significantly different. This result promotes the use historical monthly climatic data to assess historical response of biological systems to variable climate.

Muhammad Aslam1, Muhammad Asim2, Holger Meinke3 and Nafees Sadiq Kisana2

In Pakistan general, non-specific climate and climate forecasting information for producers is available from a range of sources. While general information is somewhat useful and of interest, it usually stops short of providing the level of detail needed in order to affect better agricultural management decisions. In case of wheat high temperature anomalies have been observed during January – April, resulting in rapid maturation of crop, and more rainfall in summer (especially late months) providing early wheat planting opportunities. Analysis of historical climate data indicated that there is opportunity for the improvements in wheat planting window and selection of a wheat varieties / cultivars to be adjusted accordingly. ENSO (El Nino Southern Oscillation) phases of the Southern Oscillation (SO) can be used in seasonal forecasting, may enhance decision-making. The ENSO based data analysis has shown that in case of the northern rain-fed regions of Pakistan, rainfall in July is of critical importance. July rains have shown to have an important relationship in respect to moisture availability for wheat during its sowing season.

James Hansen1

Constraints to use and shortage of credible demonstration raise questions about the potential for poor smallholder farmers to benefit from seasonal climate forecasts. I briefly discuss questions related to the degree of fine-scale predictability, farmers’ ability to adjust decisions in response to forecasts, farmers’ ability to bear risk, understanding of probabilistic forecasts, and distribution of benefits of forecast use. While not sufficient to fully answer the question posed in the title, the answers support guarded optimism.

Rizaldi Boer1, Ismail Wahab2, Perdinan1 and Holger Meinke3

Variability of rainfall at Bandung district is significantly correlated with global climate forcing, SOI (Southern Oscillation Index) and IOD (Indian Ocean Dipole), particularly dry season rainfall. The relationship is consistently positive with SOI and consistently negative with IOD. Further analysis suggested that the linear effect of IOD was not significant in all stations, but the interaction effect of the SOI and IOD was significant in some of the stations. The relationship between the anomaly rainfall and the SOI and IOD interaction were positive. This means that if the SOI is negative (indicating El-Nino) and IOD is also negative, the interaction effect will be positive. In other word the IOD negative will counteract the reducing effect of El-Nino on rainfall at Bandung districts. SOI and IOD can also be used to estimate likely yield of soybean, maize and potato. For example, yield of the crop planted in the period of September-December (PT in Julian Day) could also predicted from June-August SOI, and IOD, population density (P in plants per m2), and nitrogen application (N in t/ha). About 84% of potato yield variability could be explain by the equation. The form of the relationship is as follows: Ln(YOPT) = 2.14 + 13.7 N - 2.20(P*N) -0.000822 (PT*IODJA) +0.000890 (PT*SOIJA*IODJA) - 0.279 (IODJA*SOIJA) + 0.0000002(PT2*SOIJA)

T.L. Jeng1, C.S. Wang1, J.M. Sung2

In the present study, the in situ grain enzyme activities expression by nitro-blue tetrazolium staining was compared between a low amylase rice mutant (SA419) and its wild type (Tainung 67). All enzymes including sucrose synthase, invertase, hexokinase, UDPglucose pyrophosphorylase, ADPglucose pyrophosphorylase, starch synthase could be visualized in the growing endosperm. The activities of enzymes for SA419 showed blue staining in all the endosperm cell at 7 days after anthesis (DAA), then de-colored from middle part at 11 DAA. The de-colored region increased progressively coinciding with grain development. Marked changes were observed in the growing grains of Tainung 67 at 18 DAA. The de-coloration patterns of NBT enzyme activity in situ staining for the starch synthesizing enzymes correlated with the shift in enzyme activities measured during grain development. It appears that the in situ enzyme activity staining could provide more information to support the biochemical analysis for physiological investigation.

Thusitha A. Gunawardena and Shu Fukai

Increased rates of nitrogen fertilizer application lead to increased spikelet sterility. A field experiment was conducted to investigate the effects on engorged pollen production and spikelet sterility, of nitrogen and assimilate availability during microspore development, in two rice cultivars (Doongara and Amaroo) grown under two different water depths. Despite the temperature not being low enough during microspore development to cause spikelet sterility, the number of engorged pollen grains was lower in cv. Doongara than in cv. Amaroo. Nitrogen application decreased the number of engorged pollen grains per anther through increased spikelet density. Nitrogen application increased spikelet sterility as a result of increased panicle density showing pronounced indirect effect of N on spikelet sterility. Engorged pollen number was also closely related (r = -0.636*) to the nitrogen content of the leaf blade, indicating a direct negative effect of plant N status on engorged pollen production. The results suggest that the intrinsic pollen producing ability is the key element in the difference in cold tolerance between the two cultivars, particularly under high N rates. Opening the canopy for increased solar radiation interception by the treated plants increased the level of engorged pollen, indicating the importance of immediate assimilate availability for engorged pollen production. Shading reduced crop growth rate, but did not effect engorged pollen production. There was no effect of variation in assimilates production on spikelet sterility.

Hiroyuki Shiratsuchi1, Youichi Ohdaira2 and Jun-ichi Takanashi

The relationship among dry weight and nitrogen content of each tiller and spikelet number of the tiller was investigated in order to elucidate the factors determining spikelet number in each tiller of rice. Various treatments were used to change the spikelet number per panicle: three cultivars with different growth duration, 'Mineasahi' (short), 'Hinohikari' (medium) and 'Akebono' (long) were transplanted at two transplanting dates in 1999 and in 2000, 'Hinohikari' was grown with GA3 application, nitrogen top-dressing, and thinning of the hills at panicle initiation. The slopes of the regression lines of spikelet number on dry weight at heading of each tiller were larger in the short-duration cultivar 'Mineasahi' than in the others. The slopes were not affected by the treatments within each cultivar. The treatments changed the intercepts of the regression lines somewhat within each cultivar. In 'Hinohikari' in 2000, spikelet number of each tiller was also regressed on nitrogen content of the tiller at heading across the treatments. Partial correlation analysis among dry weight, nitrogen content and spikelet number of each tiller at heading suggests that dry weight rather than nitrogen content determines spikelet number of each tiller. Differentiated spikelet number did not affect surviving spikelet number of each main stem. In conclusion, the spikelet number of each tiller was determined by dry weight of the tiller at heading, regardless of differentiated spikelet number. The treatments affected the regression line a little within each cultivar.

Tohru Kobata and Kumi Iida

Grain ripening in the new plant type rice (NPT) is sometimes poor; our objective was to clarify why. NPT and two rice cultivars with high grain ripening were grown in a paddy field. Panicles cut five days after heading were transported to the laboratory and incubated in a liquid cultural solution under artificial environmental conditions for about one week. The spikelet weight increased as sucrose concentration in the solution increased to a maximum of 40 ~ 60 g/L, which was the optimal concentration of sucrose for all three cultivars. However, the spikelet dry weight of the NPT under the incubated condition was significantly higher than that under the field condition, while the other cultivars showed similar weights or only slight increases. The ratio of panicle dry weight increase/absorbed sucrose was 0.7 and similar among the three cultivars. Thus, spikelet dry weight in the NPT would increase if there was an abundant supply of assimilates. When the plant density of field-grown NPT was halved after heading to increase assimilate supply to the grain, the grain filling improved. It was concluded that the low grain ripening in NPT results from a shortage of assimilate supply to grain. Likewise, neither the inadequacy of assimilate transport system to the grains or a low efficiency of assimilate partition in the grain can be assumed to limit the grain ripening in NPT.

Tsuneo Kato1, Ayano Taniguchi1, Dai Shinmura2 and Akira Horibata1

Rice cultivars with numerous spikelets in a panicle (extra-heavy panicles) have been developed aiming at higher yield derived from higher capacity of photoassimilates storage. However, these cultivars did not realized the original object in many cases due to the increase in their number of spikelets on secondary branches (SB), which showed relatively poor grain filling. On the other hand, some cultivars showed some better grain filling even in the spikelet on SB. This study examined the variation in the activities of sucrose synthase and ADPglucose pyrophosphorylase (AGPase) both of which are important for the sucrose-to-starch conversion in developing endosperm and may consequently concern the variation in grain filling, among rice cultivars with extra-heavy panicles. The results indicated lower activities of both enzymes in then poor grain filling cultivar Akenohoshi, particularly in the spikelet on SB in the early stage of development. In contrast, the enzyme activities were higher in the better grain filling cultivar, Nanjing 11. Nucleotide sequence polymorphisms were also searched for 5’ regulatory region of AGPase large subunit gene among the same cultivars. There were several nucleotide differences among cultivars. These results suggest that the structural differences in those genes encoding sucrose-metabolism enzymes should cause the change of gene expression and enzyme activity. These changes would, at least partly, be relevant to the variation in grain sink strength, and consequently in grain filling among rice cultivars with extra-heavy panicles.

Hajime Watanabe and Masahiko Saigusa

Seedling establishment is one of the most important agronomic traits in direct seeding rice cultivation. We investigated the effects of two plant growth regulators (PGRs), gibberellic acid (GA3) and ethephon (ET), on seedling growth under flooded soil conditions. Seedling growth was increased by a single treatment of GA3 or ET over that of the control. However, effects of combined applications of GA3 and ET were more pronounced than that of GA3 or ET alone at both growing temperatures (15 and 20°C). The growth of different organs of rice seedlings, such as coleoptiles, first leaves and second leaves were also increased by PGR treatment. No significant differences were found in nitrogen concentration and the ratio of shoot dry weight to shoot length of the seedlings among the treatments. Taken together, a high seedling establishment rate in direct seeding cultivation in the cold regions of Japan will be possible by using proper combinations of PGRs.

Chisato Masumoto1, Takashige Ishii2, Tomoko Hatanaka2, Hyoe Tsugawa2 and Naotsugu Uchida3

The study was carried out to collect some information for using wild rice species to raise grain yield. We examined photosynthetic rates and properties of dry matter production in 4 lines of BC2F4 generated by backcrossing O. rufipogon (W630) with O. sativa cv. Nipponbare. These 4 lines were progenies of BC2F1 plants whose maximum photosynthetic rates measured by an O2 electrode were higher than Nipponbare. The photosynthetic rates under saturated light and ambient air conditions in BC2F4 lines were average 7% higher than Nipponbare. The maximum value was increased 32%. These results suggested that the maximum photosynthetic rate was reflected to some extent by the photosynthetic rates of the progenies under natural conditions. Results of growth analysis indicated that relative growth rate (RGR) was limited by net assimilation rate (NAR). RGR and NAR in one of the four BC2F4 lines were higher than those of Nipponbare. The grain yields per plant of BC2F4 lines were average 16% higher and its maximum was 54% higher than that of Nipponbare. Sink sizes of BC2F4 lines were not significantly different from Nipponbare. The increase in grain yield is thought to be due to high percentage of filled spikelets.

Taiichiro Ookawa, Yukiko Naruoka, Ayumi Sayama and Tadashi Hirasawa

The high yield rice cultivar, Akenohoshi achieves a higher rate of photosynthesis during ripening than cv. Nipponbare by maintaining a higher level of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco). To determine the causal factors resulting in the differences in the levels of Rubisco in leaves of these two rice cultivars and the role of cytokinins in maintenance of high levels of Rubisco in leaves, the levels of rbcL and rbcS mRNAs and the nitrogen content of leaves during ripening were investigated, as well as the absorption and partitioning of nitrogen. The results in this study indicate the two probable effects of the cytokinin, 6-benzylaminopurine (BA) on the leaf levels of Rubisco. The first is the direct effect of BA on the induction of Rubico synthesis, and the second is the indirect effect of BA on inducing the effective partitioning of nitrogen to leaves. Cytokinins may account for the differences in the reduction of the leaf levels of Rubisco during senescence between the rice cultivars.

Toshinari Ishioh and Katsu Imai

A japonica lowland rice, cv. Koshihikari, was exposed to the combinations of O3 (0, 0.1ppm) and CO2 (400, 800 ppm) atmosphere for up to 2 weeks at the vegetative and reproductive growth stages and their interactive effects on net photosynthetic rate, dry-matter production, yield and yield components were examined. The O3 (0.1 ppm) inhibited all eco-physiological characters. However, the detrimental effect of O3 was ameliorated by elevated CO2 (800 ppm).The reason was considered to be the decline of stomatal conductance induced by elevated CO2, which suppressed the invasion of O3 inside the leaf cavity as a physical barrier. The O3 effect on yield was attributed to increases in infertile caryopses at lower positions of the rachis-branch of panicle.

Izumi Oh-e, Kuniyuki Saitoh and Toshirou Kuroda

Many studies on the crop response to climate change have been examined for the isolated plants or the plants grown in a small-scale population. We constructed the Temperature Gradient Chamber (TGC) in the paddy field of Okayama University to clarify the effect of rising temperature on growth, yield and dry-matter production of rice during the whole growth season. The four experimental plots were arranged by the distance from the intake side, TG1 (control), TG2, TG3, and TG4. The temperature gradient occurred from TG1 to TG4, the daily maximum temperature in TG4 increased 4.0-4.4℃ than that in TG1. The number of panicles decreased with rising temperature. The dry weight at maturity was highest in TG3 in 2002 and TG2 in 2003, respectively, and lowest in TG4. The photosynthetic rate of flag leaf decreased rapidly in TG4 (highest temperature plot) than that in TG1, meaning that the higher temperature enhanced the leaf senescence. The brown rice yield was highest in TG2 (2002) and TG3 (2003) due to the higher percentage of ripened grain, and lowest in TG4 because of the decrease in a grain size and increase in sterile grains. The share percentage of heat-damaged white grains increased linearly with higher the temperature. Clearly, grain yield starts to decline when daily mean temperature exceeds 29 ℃, and grain quality decline linearly with higher the temperature.

Timothy C. Farrell1,2, K. M. Fox2, Robert L. Williams2 and Shu Fukai1,2

Low temperature, particularly during the reproductive stage of the development of rice, limits productivity in the Riverina region of New South Wales (NSW). This study primarily examined genotypic differences in cold damage that are associated with low temperature during reproductive development. Results from experiments in temperature-controlled rooms and the cold water facility were combined with four years of field experiments, which used natural exposure to low temperature to examine the response of over 50 cultivars from diverse origins. Plants were exposed to day/night air temperatures of 27°/13°C in temperature-controlled rooms and to a constant temperature of 19°C in the cold water facility. Low temperature treatments were imposed from panicle initiation (PI) to 50% heading. In field experiments several techniques were used to increase the likelihood of inducing cold damage such as sequential sowing dates (five to eight sowing dates each year), shallow water depths (5cm) and high nitrogen rates (e.g. 300kgN ha-1). Several cultivars were identified that were more cold tolerant than Australia’s commercial cultivars.

Hai Yan He, Michiko Koike, Tsutomu Ishimaru, Ryu Ohsugi and Tohru Yamagishi

Four rice cultivars, Nipponbare, IR72, Takanari, and IR65598-112-2 (abr. IR655), were used to study carbohydrate metabolism in the third leaf sheath counted from top. Results show that sucrose and starch contents increase from the tip to the base segment in the third leaf sheath. However, the gradient of starch content differs greatly among cultivars. It shows a steeper pattern in the order: IR655<Nipponbare< Takanari<IR72. Comparing with other cultivars, the whole third leaf sheath of IR655 owns significantly lower starch concentration and two-fold higher sucrose concentration which changes similarly to starch, suggesting that sucrose also acts as a storage substrate in IR655. Among the four measured enzymes, the activity of starch synthase correlates very well with the starch concentration. A possible accumulation pattern across the transverse sections is also proposed through morphological observation using light microscope.

Yumiko San-oh1, Taiichiro Ookawa and Tadashi Hirasawa

A planting pattern in which each hill contains one rice plant (planting pattern I) results in a higher yield of dry matter, especially during the reproductive stage, than a planting pattern in which each hill contains three plants (planting pattern III). Plants in planting pattern I maintain a higher rate of leaf photosynthesis during senescence in the ripening stage, which may contribute in part to the higher yield of dry matter in these plants. We found close linear relationships between the ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) content and the rate of photosynthesis, as well as between leaf contents of nitrogen and Rubisco during the ripening stage. These relationships were independent of planting pattern and the position of a leaf on the stem. Thus, plants in planting pattern I maintained a higher rate of photosynthesis and also contained a higher level of Rubisco than plants in planting pattern III. Plants in planting pattern I could keep the higher content of leaf nitrogen due to their higher capacity of nitrogen accumulation than plants in planting pattern III. This may contribute to the higher content of leaf Rubisco which, in turn, is associated with a higher rate of photosynthesis.

Tanguy Lafarge1,2, Brenda Tubana1 and Estela Pasuquin1

Tiller senescence occurs in most tillering crops since maximum tiller number produced during the vegetative phase is higher than the number of tillers that will be productive at maturity. The assimilate stored in senescent tillers are, however, mostly wasted as few translocation of assimilate between tillers of the same plant occurs. The opportunity to improve grain yield through an increase in tiller fertility rate was addressed in a high tillering crop like rice by comparing two genotypes, an improved inbred line and a hybrid rice with different tillering strategy but similar crop duration. Seedlings were grown in seedling trays and wet-bed nurseries and transplanted 7, 14 and 21 days after sowing at 25 or 50 pl m-2. Early plant development of both varieties during wet and dry seasons did not differ until mid-tillering, as plant tiller number and leaf and stem dry weight per plant were similar. From mid-tillering onwards, shoot dry weight per plant was again similar for both genotypes, but the tillering emergence rate of IR72 was maintained whereas the hybrid stopped its tiller emergence earlier. This reduced the number of tillers in hybrid rice that were likely to senesce as productive tiller number per plant at maturity was similar for both varieties. Grain yield was then significantly higher for hybrid rice as hybrid increased assimilate allocation towards productive tillers. The higher efficiency in assimilate partitioning reported for hybrid suggests that crop management that could improve control in tiller emergence will increase grain yield in rice significantly.

Nednapa Insalud1, Richard W. Bell2 and Benjavan Rerkasem1

In many countries, including Thailand, rice is largely grown in rainfed condition, where the soil is waterlogged for only some of the time during the growing season. However, there is limited understanding of how rice cultivars adapt to aerobic soil. The objective of this work was to compare the performance of a rainfed cultivar (KDML105), an upland cultivar (Kae Noi) and a high yielding cultivar bred for irrigated lowlands (Chainat 1) in well drained and waterlogged soil. The rice was grown for 3 weeks and their performace assessed in root and shoot length, root and shoot dry weight, aerenchyma appearance and nutrient content. Shoot concentrations of nitrogen and phosphorus indicated limited supply in all three cultivars and in both well drained and waterlogged soil. Aerenchyma development was affected by soil water differently in the different cultivars. Kae Noi and KDML105 developed more aerenchyma in their root in waterlogged than in well drained soil, while Chinat 1 had more aerenchyma in aerated soil. The effect of this difference on plant growth and nutrient uptake was not measurabale at 3 weeks. In general the rice grew better in waterlogged than in well drained soil. The main exception was Kae Noi which exhibited increased root elongation in well drained soils. Otherwise there were limited differences among the three rice cultivars in their response to aerated soil at the seedling stage.

Mohammad Bannayan and Kazuhiko Kobayashi

Changes in dry weight and grain yield of rice (Oryza Sativa L.) plants were analyzed to determine whether partitioning of biomass is affected by atmospheric CO2 concentration ([CO2]) and N supply. Plants were grown in local farmers fields at three levels of N and at ambient and elevated (ambient plus 200 ppm) [CO2]. Oryza2000 model was also applied to compare with the observed patterns of biomass partitioning. Observed values showed that both CO2 and N enrichment stimulated net dry matter production. [CO2] did not affect partitioning of dry matter at FACE compared to ambient except lower leaf to total biomass ratio mainly at panicle initiation and around flowering stages across N levels and years. Oryza2000 model does not consider any effect of either [CO2] or N on dry matter partitioning hence it overestimated leaf biomass, and LAI under elevated [CO2]. We suggest that the formulation of LAI based on nitrogen rather than carbon allocation is more promising in simulating leaf area growth under elevated [CO2].

Denis Fabre, Pierre Siband and Michael Dingkuhn

Abiotic stresses such as salinity affect rice yield components and grain quality. A new, automated methodology is presented to analyze grain weight, length and width distributions for grain samples. Frequency distribution analyses on the basis of histograms generally gave bimodal patterns for grain weight (filled and unfilled grains) and monomodal patterns for grain dimensions. These histograms permit the distinction of unfilled, partially filled and fully filled grains. Peak shape and location on the histogram provide further information potentially useful for the diagnostics of physiological stresses affecting grain hull development, spikelet fertility and filling, and may be of value in breeding and grain quality research. The methodology was applied to rice grain samples taken from farmers’ fields having different levels of soil salinity in the Camargue delta region in France. High salinity levels were associated with an increased fraction of unfilled spikelets and reduced grain dimensions and weight, which point at salinity affects taking place largely before flowering during hull development. The methodology is being completed with a biometric tool for histogram analysis, and will be extended to other stresses and germplasm.

Zhao Ming2,3, Renee Lafitte1, Erik Sacks1, Glenn Dimayuga1 and Xiuqin Zhao3

There was a wide range in leaf photosynthetic rates (Pn) of 16 different species of Oryza measured in a tropical environment where O. sativa and O. rufipogon were identified as potential sources of enhanced photosynthetic rate. Two F1 hybrids between O.sativa × O. rufipogon were significantly greater than the O.sativa parents and other F1 hybrids. Among the F2 progeny, segregants with even greater rates of photosynthesis were identified, while the F3 derived from superior F2 plants maintained the high-photosynthesis trait, with a highly significant parent-offspring regression coefficient of 0.86. The progenies with high Pn when grown in the tropics were also planted in a temperate area, and good stability of high photosynthetic capacity was found. Genetic resources in the genus Oryza could serve as a source of alleles to increase photosynthetic rate in the cultivated species.

Toshihiro Hasegawa1, Masumi Okada2, Meguru Inoue2 and Hiroyuki Shimono2

This study demonstrates that a contrasting response of lamina length to elevated CO2 exists among rice (Oryza sativa L.) genotypes. Four cultivars of different earliness were grown under ambient (A) and elevated CO2 (200 µmol/mol above ambient, E) for a whole developmental cycle, and lamina lengths were compared according to their leaf position. The ratio of lamina length under E to A (E:A ratio) ranged from 0.93 to 1.05. Elevated CO2 had a significant positive effect on lamina length of an early variety (Bouzu 5), with a higher E:A ratio in the main stem and primary tillers than in the secondary tillers. A negative effect of E was found in medium (Akitakomachi) and late (Sasanishiki) cultivars. The reduction in lamina length by E for these varieties was largely due to the decreased length in relatively upper positioned leaves. Developmental responses to elevated CO2 may have a link to the contrasting effects of elevated CO2 on lamina length among genotypes. The negative effect of E on lamina length in some varieties may partly explain the limited response of plant or canopy leaf area to elevated CO2 observed in the past experiments. Whether the positive response found in an early variety could confer a greater biomass and yield responsiveness to elevated CO2 remains to be tested.

Marcel de Raïssac1, Alain Audebert2, Sandrine Roques2 and Jerôme Bolomier1

Whole cycle and successive phases durations of crop are key traits for adaptation to local conditions. They are known as highly genetically controlled and rice breeders used to refer lines and genotypes to short, medium or late materials. However, even expressed in thermal time, these crop and phases durations are also influenced by environment conditions. To test effect of competition levels between plants on rice phenology, a density experiment was carried out in fields in Camargue region, France, with two genotypes on two consecutive years.
Results show that leaf appearance rate is affected by densities during the two observed phases of leaf appearance : the rapid one up to beginning of stem elongation and slower one after. They also show that, with increasing plant densities, rice cultivars reduce the number of leaves on the main stem, initiate panicle sooner, and delay flowering date. Analysis shows that relative growth rates during successive phases are highly correlated to observed variations.

Hidemitsu Sakai1, Han-Yong Kim2, Toshihiro Hasegawa1 and Kazuhiko Kobayashi3

Rice (Oryza sativa L.) yield enhancement by elevated CO2 concentration ([CO2]) has often been reported to a varying degree ranging. To identify possible reasons for the variation in yield enhancement by elevated CO2, we analysed the results from the experiments conducted in six naturally sunlit, controlled environment chambers for five years (from 1998 to 2002). Rice plants (cv. Nipponbare) were grown season-long under ambient (354-383/397-448 µmol mol-1; day/night) and elevated (670-721/702-780 µmol mol-1) [CO2] each in three chambers. Air temperature inside the chambers was controlled at the outside level. Relative humidity was kept 77-80 %. Total nitrogen application was 8 g m-2 in 1998 and 1999, and 12 g m-2 in 2000-2002. In 2001, two subplots in which the timing of top-dressing was different were made in all chambers.

Final total dry weight was significantly increased by 8.0-18.7% by elevated [CO2] in all five years. Enhancement of final total dry weight by elevated [CO2] at each N level was similar across years. Days to heading were significantly shortened by 2.6-8.0 days. Grain yield was significantly increased by elevated [CO2] by a varying degree ranging from 4.1 to 22.4 %, but the relationship between grain yield and final total dry weight enhancements was not clear. On the other hand, a strong negative relationship was found between grain yield enhancement and the days to heading hastened by elevated [CO2]. These suggest that degree of acceleration of plant development can have a significant impact on the rice yield responsiveness to elevated [CO2].

Freshteh Mahdavi1, Mohammad Ali Esmaili1, Hemmatollah Pirdashti1,2 and Allahyar Fallah3

In order to study on the morphological and physiological indices of rice genotypes, a field experiment was carried out in the Rice Research Institute of Iran, Deputy of Mazandaran (Amol) in 2003. Design arranged in completely randomized block with three replications was used, in which 10 genotypes [including Tarom, Ramazanali Tarom (traditional genotypes), Fajr, Shafagh, Neda, Onda, Jahesh, Fuji Minori, Dasht and Khzar (improved genotypes)] were the treatments. In this experiment, the traits such as plant height, tillering capacity and physiological indices such as CGR, RGR, and LAI were evaluated every ten days once. Because of the differences in developmental pattern and maturity among the genotypes used in this study, we have used growing degree-days (GDD). Morphological indices (leaf angle and flag leaf area) were evaluated in the flowering stage. Results showed that physiological indices of improved genotypes were greater than traditional genotypes. LAI of all genotypes was greater in the flowering than other stages. CGR and RGR had a positive and negative significant correlation respectively. Morphological indices of modern genotypes were greater than old genotypes. Old genotypes had higher plant height and less tillering capacity than modern genotypes. Plant height and tillering capacity had negative and positive correlation with yield, respectively. Generally, traditional genotypes reached physiological maturity earlier than improved genotypes. In the other hands, flag leaf area had no correlation with grain yield and flag leaf angle had positive correlation with grain yield.

Andrew Fletcher1, Derrick J. Moot1 and Peter Stone2

The objective of this study was to examine the effects of fertiliser P on sweet corn biomass, biomass partitioning and ear quality (ear dimensions) in a cool temperate climate. ‘Challenger’ sweet corn was sown at 71,000 plants/ha in 2001/02 and 2002/03 at a low P site (Olsen P= 6 μg/ml) at Lincoln, Canterbury, New Zealand. In 2001/02 crops received 0, 50, 100, 150, or 200 kg P/ha. In 2002/03 these same plots were used but an additional 0, 10, 20, and 40 kg P/ha were added respectively. Thus total P fertiliser rates over two years were 0, 50,110,170, and 240 kg P/ha.

Crop biomass ranged from 9.7 t ha-1 with no P fertiliser in 2001/02 to 16.7 t ha-1 with 170 kg P/ha in 2002/03. Despite this range biomass partitioning was conservative across treatments being 46% vegetative, 33% ears and 21% kernels. P fertiliser affected the quality of ears, with the unfilled tip length decreasing by 2.2 mm for every 1 t ha-1 increase in total crop DM. Thus saleable yield and quality of sweet corn was maximised by fertiliser treatments that maximised total crop yield.

Zoltan Berzsenyi and Dang Quoc Lap

In two-factorial split plot experiments, carried out at Martonvásár, Hungary in 1997-1999, the growth analysis method was used to examine the effect of six plant densities (20, 40, 60, 80, 100 and 120 thousand plants/ha) on the dynamics of growth and growth indices of three maize hybrids with different vegetation periods (FAO 290–FAO 530). The Richards function was used for the functional method of growth analysis. The plant density had a significant effect on the dry matter accumulation, the absolute growth rate (AGR) and the absolute acceleration rate (AAR) of the maize plant and grain yield. The multiple linear regression analysis showed that the asymptotic maximum of the maize plant and the AARmax were the most important in determining grain yield.

Bertrand Hirel1, Isabelle Quilleré1, Bernard Pommel2, Matthieu Floriot2, Bruno Andrieu2, Jean-Louis Drouet2, Michael Chelle2, Antoine Martin1, Marie-Hélène Valadier1, Xana Belastegui-Macadam1, Alain Fortineau2, Michel Chartier2, Christian Fournier2, André Gallais3, Jean-Louis Prioul4, Caroline Lelarge4 and Thérèse Tercé-Laforgue1.

In this poster, we present recent developments towards a better understanding of the controls of nitrogen use efficiency in the model crop maize. In this species, a better knowledge of the regulatory mechanisms controlling the transition between nitrogen assimilation and nitrogen recycling is vital for improving nitrogen use efficiency and for reducing excessive input of fertilisers without affecting yield. Using plants grown in the field at low and high nitrogen fertilization regimes, classical physiological studies combined with gene expression profiling were developed to build up a model depicting the evolution of source/sink relationships in maize in relation to the evolution of leaf senescence. Using representative physiological markers, the genetic variability of the evolution of the source/sink relationships was also studied. In parallel, 15N labelling experiments were performed using different maize genotypes, thus allowing the demonstration that there are genotype-dependent differences in the capacity to absorb mineral nitrogen before and after silking, as well as in the efficiency of leaf proteins remobilisation. An attempt was also made to characterize the relationships between nitrogen content and light perception during leaf senescence in three-dimensional architectural models. These models may provide a way to identify representative physiological markers that can be further used during a selection process. They could be also be used and for QTLs detection in quantitative genetics.

Barbara George-Jaeggli1,4, Ian Broad2, Graeme Hammer2,3 and David Jordan1

Sorghum yield is known to correlate with height in breeding populations and some recent studies have found enhanced radiation use efficiency (RUE) in a tall (single dwarf) sorghum hybrid, which may explain the correlation. The experiments reported in this paper were undertaken to investigate whether plant height per se was related to radiation use efficiency in sorghum. Two field experiments were conducted with mutant lines differing only in one height gene – conventional triple dwarfs and their mutated (taller) double dwarfs. In experiment 1, a significant increase in biomass due to higher RUE was observed for the tall mutant in one genetic background but not in the other. In experiment 2, however, the same genotype showed significantly increased biomass with the tall mutant form, but this was caused by enhanced light interception rather than difference in RUE. Hence, at this stage it was not possible to draw a clear conclusion about the possible relationship between RUE and height in sorghum. The question remains unresolved and is the subject of on-going study.

Pushpa Seth, G.C. Nanawati and V. Sharma

The yield for tropical maize is lower than the temperate maize and it has been suggested that poor transport and partitioning of total dry mater to grain are the major constraints. Grain filling is a function of position of the ear leaf, photosynthesis rate, plant growth regulator level and rate of assimilate transport. Structural complexity of leaf and kernel tissue can limit the development of grain. Infusion of chemicals through stem can be used as a tool to ascertain their role during seed formation. The chemicals used for this study were kinetin(kin), thiourea(thio), n-propyl gallate (n-PG), L-histidine (L-hist) and n-ethyl maleimide (NEM) injected through internode below the ear at 3 days after pollination (DAP) and 10 DAP. Stem infusion of kinetin, thiourea, n-propyl gallate, L-histidine significantly increased kernel weight, number of kernels and yield of apical, middle ear and basal ear position kernels in all four varieties of maize viz Prabhat, Navjot, Malan and Surya while NEM significantly decreased them. The result suggests accumulation of sucrose in field grown ear cob and kernel pedicel due to symplastic/apoplastic or both restrictions as evident by NEM application. Kinetin and biomodulators like thiourea, n-propyl gallate, L-histidine partially overcome such restrictions of assimilate transport leading to an increase in growth and development of seeds in kernels. Levels of total lipoxygenase, alpha- amylase and protease differed among the ear positions. The chlorophyll content of leaves was also affected by the infusion of these chemicals.

Brenda L. Gambín1, Lucas Borrás2 and María E. Otegui1

The curvilinear relation between plant growth rate around silking (PGR) and kernel number in maize implies that, from a given threshold, the intrinsic efficiency of the plant to set kernels declines as PGR increases. This suggests that improved growing conditions around silking increase the assimilate availability per kernel during the first grain-filling phase. So, we hypothesize that increased PGR not only results in higher kernel numbers but also in higher potential kernel weight (KW) at the end of the lag phase. Since maize kernels seem to grow under conditions of sufficient assimilate availability during the effective grain-filling period, this potential KW is usually attained. Thus, we conducted an experiment with twelve genotypes differing in final KW to evaluate if PGR around silking could help explain differences in final KW within and between hybrids. We estimated potential KW from kernel water content values at the end of the lag phase. Each genotype showed a different response pattern in potential KW to changes in PGRs. However, we validated our hypothesis stating that within each genotype, higher PGRs were related to higher potential KWs because of an increase in plant growth rate per kernel during the kernel set period.

Kimberley B. Ritter1, Scott Chapman1, David Jordan2, Ian Godwin3 and Lynne McIntyre1

This paper outlines a current investigation of sugar accumulation in sweet sorghum to assist in understanding and simplifying this complex trait in sugarcane. A recombinant inbred line (RIL) sorghum population, between a sweet and a grain sorghum, has been developed and phenotyped for various morphological and agronomic traits related to grain yield, biomass and stem sugar content. A genetic linkage map will be constructed for the sweet sorghum population with the objective of identifying genomic regions associated with sucrose accumulation in sweet sorghum. This will lead to further work, including comparative mapping in sugarcane, to identify the extent to which sweet sorghum can be used as a model for investigating sugar accumulation in sugarcane.

H. Rahimian Mashhadi1 and E. Zand2

Distribution of leaf area, radiation and nitrogen within the canopy of some Iranian wheat cultivars which were developed for the cold to cold-temperate region of the country within the last 50 years were studied in two separate trials during 1998 and 1999 growing seasons in Mashhad, NE Iran. In both trials 6 wheat cultivars were investigated in a complete randomized block design with 3 replicates. In the first experiment all cultivars were sown at the same date and with the same planting density and N fertilization. However, in the second experiment cultivars were sown using their recommended sowing date, plant density and N rate. Other management practices were identical in both years. Recently introduced wheat cultivars had a higher- light extinction coefficient (K) and positioned a higher proportion of their leaf area in the upper canopy layers. Such a canopy structure led to better interception of radiation at top canopy layer. A decreasing trend of specific leaf nitrogen (SLN), specific leaf area (SLA) and leaf nitrogen content (LNC) was observed moving from the top to the bottom canopy layer. A negative correlation existed between SLW and LNC.

Tabitha Armour1, Peter D. Jamieson1, Anton Nicholls2 and Robert Zyskowski1

Recently, a grower in North Otago, New Zealand, applied to be listed in the Guinness Book of Records for producing a 15.048 t/ha wheat yield. This exceeds the world record achieved in Scotland in 1981 by over 1 t/ha. However, such high yields are not possible every year. In this paper we use experimental field data to examine the environmental and management circumstances that colluded to enable the production of a 15 t/ha wheat crop. We conclude that the recipe for a world record includes a combination of cultivar and sowing date that will lead to grain growing through the solar radiation peak, a cool but sunny summer, and attention to agronomic detail so that no growth constraints apply.

Shigeto Fujimura1, Pei-Li Shi2, Kazuto Iwama1, Xian-Zhou Zhang2, Junichi Yamaguchi1, Yun-Fen Liu2, O. Shuhou1 and Zhi-Ming Zhong2

Lhasa on Tibet plateau, China is located about 3700 m altitude and has lower CO2 and O2 partial pressure, lower night air temperature and high radiation compared with low altitude area on the same latitude. Because of this specific growth condition, it is anticipated that the responses to increased [CO2] might be different from those in low altitude area. To clarify the effect of increased [CO2] on crop production in this area may give useful information for estimating future crop production not only in this region but also in the world.

Penny Riffkin and Pedro Evans

Changes in dry matter, water-soluble carbohydrates and crude protein concentration in the plant parts of 4 wheat cultivars were measured throughout the 2003-growing season in the high rainfall zone of south-western Victoria, Australia. Consistent with previous years, cultivar Silverstar produced more, but smaller grains per ear and per m2 than to the other three cultivars. Total amounts of water soluble carbohydrates ranged from 276 g/m2 for Brennan to 365 g/m2 for Silverstar. Patterns of accumulation and distribution of water soluble carbohydrates appeared to be related to wheat type (spring or winter) and, in this experiment, there was no obvious relationship with grain yield. Significant differences also occurred in the magnitude and rate of accumulation of crude protein in the stems and leaves of Silverstar relative to the other cultivars. Data will be further analysed to examine relationships between crude protein, water soluble carbohydrates and soil N and moisture.

Matthew Reynolds1, Anthony G. Condon2, Gregory J. Rebetzke2 and Richard A. Richards2

Yield improvement in spring wheat has largely resulted from increased harvest index (HI), and since HI has remained static since the mid 1980s, increasing radiation use efficiency (RUE) is likely the most viable route to increasing yield. As RUE is influenced indirectly by sink strength, it follows that biomass may be increased by increasing grain number. Experiments with high yielding spring wheat lines containing the 7DL.7Ag translocation showed increased grains m-2 (15%), yield (12%), and biomass (10%) compared with checks. The translocation was also associated with a larger investment in spike mass at anthesis (15%), more grains/spike (11%), and increased photosynthetic rate especially during grain-filling (10%). No effect of the translocation were detected on light interception or canopy architecture, suggesting that increased biomass in 7DL.7Ag lines was largely due to the positive feedback on photosynthesis associated with a larger kernel number. The hypothesis that photosynthesis may respond directly to increased sink was tested experimentally by imposing a light treatment during boot stage. The treatment was associated with a small increase (5%) in the proportion of biomass invested in spike mass at anthesis and 3 extra grains/spike at maturity. Yield and biomass were increased by 20% and 18% respectively compared with checks, while flag-leaf photosynthetic rate during grain-filling was increased by 10%. Results suggest that RUE can be increased indirectly by increasing sink strength and that determination of kernel number is currently a yield limiting process in spring wheat warranting investigation into its physiological and genetic basis.

M. Saifuzzaman1, Q.A. Fattah2, A.F.M. Maniruzzaman3, M.S. Islam4 and Craig Meisner5

The probable cause(s) of spikelet sterility of wheat and solution(s) thereof was investigated in a sub tropical environment. Experiment was conducted in a controlled environment, both in field and in greenhouse, simulating weather and soil conditions (high humidity and low light intensity due to dense fog and low soil boron) of the wheat sterility-prone areas of the country.

Kazukiyo Tetsuka

To attain an understanding of the spikelets formation, differentiation and development of wheat, I approached to elucidation of the physiological and genetical step involved in the supernumerary spikelets differentiation process of wheat. From the viewpoints of physiology and genetics on spikelets formation, I cultured some parents and crossbred of wheat by gibberellic acid, nucleic acids, its metabolite, anti-metabolite and phosphoric compounds extracted from young seedlings of wheat that have the supernumerary spikelets(Extracts).

The results of these experiments provide some information on the role of chemical metabolism related to genetic background and daylength conditions in the induction of the supernumerary spikelets differentiation, and indicate that the endogenous phosphoric compounds (phosphatide or derivative nucleic acids-like substances), exogenous Extracts, GA and nucleic acids may be directly involved as essential step in process of induction of the supernumerary spikelets differentiation. But the action of Extracts on the supernumerary spikelets differentiation and on the heading is independent.

Shaukat Ayaz, Derrick J. Moot, George D. Hill, Bruce A. McKenzie and David McNeil

In 1999/2000, the relationship of individual plants was studied in four grain legumes: chickpea (Cicer arietinum), lentil (Lens culinaris), narrow-leafed lupin (Lupinus angustifolius) and field pea (Pisum sativum). The influence of neighbouring plants was assessed in populations of 10, 100 and 400 plants/m2, and sowing depths of 2, 5 and 10 cm. A central plant, surrounded by four other measured plants, was treated with nitrogen (N) to create additional environmental diversity. There was a strong linear relationship (R2 > 0.90) between seed weight/plant (SWT) and plant weight (PWT). Both mean SWT and PWT fell as plant population increased from 10 to 400 plants/m2. The effect on individual plant harvest index (PHI) was also examined. The relationship between PHI and PWT tended to be asymptotic. In all four species, N treated plants performed better than the surrounding plants. In all cases, plants to the north had the least reduction in yield, plants to the east and west had intermediate values, and plants to the south had the lowest yields, particularly at the higher plant populations.

The objective of this study is to elucidate the effects of CO2 enrichment during different growth periods on flowering, pod set and seed yield in soybean (Glycine max (L.) Merr.). Soybean cultivar ‘Fukuyutaka’ was grown in a growth chamber of the Institute of Bioresources Research Center of Kyushu Electric Power Co., Inc. at Saga, Japan (33°17´-N, 130°18´-E) under natural light. The CO2 concentrations were maintained at 350μmol CO2 mol-1 for ambient CO2 and at 700μmol CO2 mol-1 for CO2 enrichment. CO2 concentration was enriched during the whole growth period (WP), vegetative growth period (VP) or reproductive period (RP). Seed yield was increased by 25% by CO2 enrichment during RP or WP due to the increase of pod number, but was not by CO2 enrichment during VP. Although CO2 enrichment had no effect on the number of flowers, CO2 enrichment during RP increased the pod number on all raceme orders and that during WP increased the pod number in the secondary and tertiary racemes. It is suggested that an increase of seed yield by CO2 enrichment is mostly brought by the improvement of pod set, mainly on the high-order racemes that opened later during flowering period, and that the response of seed yield is mainly attributed to CO2 enrichment during RP.

Shao-Hui Zheng, Akinori Maeda, Yoko Kashiwagi, Akihiro Nakamoto and Masataka Fukuyama

Soybean flowers continue to open for a long period but the pods mature simultaneously. The developmental differences of pods and seeds between early- and late-opened flowers are not well known. We investigated the timing of growth beginning of pods and seeds set on different raceme orders with different flowering time in soybean. Soybean plants were grown in a greenhouse in 2001 and in the field in 2003 in Kyushu University, Fukuoka of Japan. Soybean pods grew very slowly after flower opened whereas the pods of other three legumes (common bean, azuki bean and mung bean) started to elongate immediately after flower opened. In soybean, the pods that opened earlier started to elongate later, leading to uniform development of the pods that opened at different dates. The similar phenomenon was observed in seed growth but it seemed to be more pronounced in pod elongation than seed growth.

Media summary

John H. Miranda1 and Richard R. Williams2

Blue and yellow light increased the level of sucrose in plants developed in vitro when compared to white light. CO2 enrichment and airflow into the culture container increased sucrose content compared to closed system. Light qualities or CO2 levels did not alter fructose or glucose concentration. Light quality effect on sugar concentration was shadowed by high concentrations of CO2.

Shigenori Morita1, Jun Abe2, Shuho Furubayashi2, Alexander Lux3 and Ryosuke Tajima2

A problem in soybean culture in Japan is excessive soil moisture and waterlogging, because soybean is often grown in field converted from lowland paddy field. Growth of taproot and its lateral roots is suppressed by waterlogging, while formation of adventitious roots is promoted. Thus, soybean plants often form shallow root system under waterlogging conditions. Molding may be an effective management to avoid waterlogging stress. Adventitious roots develop well in the gathered soil of molding, which results in quick recovery of root activity after waterlogging evaluated by bleeding rate.

Philips Varghese1, S.P. Taware1, G.B. Halvankar1 and V.M. Raut1

A study was done on duration of reproductive stages (R1 to R8) of soybean in relation to seed yield using 56 soybean varieties. Wide range of variability was observed for these traits. Significant negative correlation was revealed between seed yield and days taken to physiological maturity stage (R7). Possible use of these characters in breeding for yield improvement in soybean is suggested.

N.A. Karaivazoglou1, D.K. Papakosta2, E.M. Sfaciotakis3 and S.D. Koutroubas4

Ethylene is a plant growth regulator that promotes senescence of plant tissue. Studies regarding the role of ethylene production on Oriental tobacco (Nicotiana tabacum L.) leaf ripeness and senescence are limited. The purpose of this study was to investigate the rate of ethylene production by intact, attached leaves of tobacco plants, Oriental type, during ripening and senescence. Plants were grown in the field during the 2001-growing season. Twelve samplings and measurements were carried out every other day throughout the whole period of leaf development, mature and senescence starting 70 days after transplanting (DAT) up to 92 DAT. Ethylene production of leaves declined up to 76 DAT. Senescence of lower leaves began around 78 DAT when leaves began to lose their chlorophyll and a progressive increase of ethylene production appeared. In addition, during this period leaf dry weight began to decrease. Ethylene production is reached in a peak, a climacteric-like surge, within 6 days after the beginning of increase and after the beginning of rapid chlorophyll breakdown and dry matter loss. This peak involved a 5-6 fold increase in the rate of ethylene production. The subsequent rise of ethylene production appears to be associated with the rapid phase of chlorophyll breakdown, and may indicate the final stage of senescence process.

S.D. Koutroubas, George Vassiliou, Sideris Fotiadis and Christos Alexoudis

Lodging, one of the major factors limiting yield production and degrading seed quality in nonoilseed sunflower (Hellianthus annuus L.) is usually caused by increased plant height combined with a relatively restricted root system. A field study was carried out to investigate the effect of foliar application of paclobutrazol at 0.0125, 0.025 and 0.05+0.05 kg/ha, mepiquat chloride at 0.025, 0.0375+0.0375 and 0.05+0.05 kg/ha and chlormequat chloride at 1.5, 3 and 4.5+4.5 kg/ha on sunflower plant growth and development. Plant growth regulators (PGRs) were foliar-sprayed 33 days after sowing, when plants were on average 55 cm tall. The second split application of PGRs was made two weeks after the first one. Mepiquat chloride treatments of 0.025 and 0.0375+0.0375 kg/ha as well as paclobutrazol at 0.0125 kg/ha reduced plant height at maturity. Reduction was significant (11.7%, 9.5% and 11.4% compared to untreated plants, respectively), though of limited practical importance, due to inadequate shortening effect. Reductions in plant height by PGRs application were due to the shortening of internode length. No differences were observed in stem width. An increase in total number of achenes per capitulum was obtained by chlormequat chloride at all rates, mepiquat chloride at 0.0375+0.0375 kg/ha and paclobutrazol at 0.0125 kg/ha. However, this increase was not accompanied by an increase in achene yield. Paclobutrazol at 0.025 and 0.05+0.05 kg/ha reduced achene yield by 29% and 26% compared to untreated plants, respectively.

Steve Wright1, Bob Hutmacher2, Anil Shrestha3, Gerardo Banuelos1, Mark Keeley2, Raul Delgado2 and Shelly Elam1

Studies were conducted in 2002 and 2003 to compare different plant densities in double row and single row seventy-five -centimeters bed cotton near Visalia, California. For 2002, the double row had final plant densities of 9, 14, and 20 thousand plants per hectare. The single row had 19, 30, and 33 thousand plants per hectare. Higher densities were attempted but there was approximately 40 percent stand loss using the Great Plains planter in 2002. In 2003, the double row had 18, 24, and 29 thousand plants per hectare using a “Monosem” planter. The single row had 12, 17, 24, and 32 thousand plants per hectare. Light readings showed that double row cotton intercepted more light early in the season and about 5-6 days ahead in terms of light interception. In 2002 there were not significant lint yield differences between double row cotton on 9, 14, or 20 thousand plants per hectare or single row seventy-five centimeters at 19 thousand plants per hectare. Single row densities of 29 or 33 thousand plants per hectare significantly reduced yields. In 2003, there were no significant differences between double row 30-centimeters cotton with densities from 18 to 29 thousand plants per hectare and single row 75-centimeters cotton with densities of 30 to 32 thousand plants per hectare. There were no significant differences between mepiquat chloride application treatments in either year.

Cundong Li1, Zhixia Xie, Wenxin Wang, Yuechen Zhang and Hongchun Sun

Some physiological characteristics of both source and sink of different boll-weight genotypes of cotton were studied. It showed that genotype have different characteristics for both sink and source. Compared to small-boll genotypes, large-boll genotypes had more soluble sugar in the boll-shell and have higher starch content before 35th day of boll development. Further, leaves of the large-boll genotypes on main stem were also found to have more soluble sugar at most of the different developmental stages, which might indicate the better photosynthesis capacity of such genotypes.

Cundong Li1, Hongchun Sun, Wenxin Wang, Yuechen Zhang and Zhixia Xie

The harmonious relationship between source and sink can be a key factor to the high yield and quality of cotton. Changing the ratio of source/sink by cutting off the buds or leaves on reproductive branches could affect the relationship of source and sink with different levels. The results of this experiment showed that changing source/sink ratios significantly affected the content of chlorophyll, dissoluble protein and starch of leaves on the lower reproductive branches. Cutting off buds could enhance the content of dissoluble protein (during July 20 – August 9), and starch (during July 9 – August 1) of the leaves. While cutting off leaves led to rapid decrease of chlorophyll and reduced the content of dissoluble protein of the leaves at the same time.

Daijiro Kaneko1, Masao Ohnishi2, Takashi Ishiyama3 and Ryutaro Tateishi3

This paper aims to develop a remote sensing method of monitoring grain production in the early stages of crop growth in China and India. It is important to oversee the quantity of grain in production at an early stage in order to raise the alarm well in advance if a poor harvest is looming, especially in view of the rapid population increase in Asia and the long-term squeeze on water resources. Grain production monitoring would allow orderly crisis management to maintain food security in Japan, which is far from producing enough grain for its own population. We propose a photosynthesis-based crop production index (CPI) that takes into account all of: solar radiation, effective air temperature, vegetation biomass, the effect of temperature on photosynthesis by leaves of grain plants, low-temperature sterility, and high- temperature injury. The proposed photosynthesis-based crop production index has accurately predicted the rice yield expressed by the Japanese Crop Situation Index in three years, including the worst yield in the last 15 years, at a test site in Japan.

Claudio O. Stöckle and Armen R. Kemanian

Simple models of potential biomass accumulation based on radiation- or transpiration-use efficiency were compared in four locations with distinctive climates. These simple models, which have been integrated into many crop growth models that are widely used today, were found to require local calibration, with parameters obtained in one region not readily transferable to another with different climatic conditions. A proposed transpiration-use efficiency model seems to provide adequate estimations across environments when calibrated only in one location. Research will be needed to experimentally evaluate this concept and better formulate the response of transpiration-use efficiency, transpiration rates, and canopy conductance to changes in air humidity, atmospheric CO2 concentration, and plant water availability.

Daniel K.Y. Tan1,2, Colin J.Birch1, Alan H. Wearing1 and Ken G. Rickert1

Broccoli is a vegetable crop of increasing importance in Australia, particularly in south-east Queensland and farmers need to maintain a regular supply of good quality broccoli to meet the expanding market. A predictive model of ontogeny, incorporating climatic data including frost risk, would enable farmers to predict harvest maturity date and select appropriate cultivar – sowing date combinations. To develop procedures for predicting ontogeny, yield and quality, field studies using three cultivars, ‘Fiesta’, ‘Greenbelt’ and ‘Marathon’, were sown on eight dates from 11 March to 22 May 1997, and grown under natural and extended (16 h) photoperiods at the University of Queensland, Gatton Campus. Cultivar, rather than the environment, mainly determined head quality attributes of head shape and branching angle. Yield and quality were not influenced by photoperiod. A better understanding of genotype and environmental interactions will help farmers optimise yield and quality, by matching cultivars with time of sowing. The estimated base and optimum temperature for broccoli development were 0°C and 20 °C, respectively, and were consistent across cultivars, but thermal time requirements for phenological intervals were cultivar specific. Differences in thermal time requirement from floral initiation to harvest maturity between cultivars were small and of little importance, but differences in thermal time requirement from emergence to floral initiation were large. Sensitivity to photoperiod and solar radiation was low in the three cultivars used. This research has produced models to assist broccoli farmers in crop scheduling and cultivar selection in south-east Queensland.

Peter D. Jamieson1, Pierre Martre2, Vitalie Samoil2, John R. Porter3, Robert Zyskowski1, Mikhail Semenov4 and Eugène Triboï2

Protein accumulation in wheat is subject to both genetic and environmental influences. Recent work strongly suggests that both forms of influence are regulated by the sources of N within the plant, rather than demands by the grain. We have extended Sirius, an existing model of wheat that includes N uptake and redistribution within the plant, to predict the accumulation of broad fractions of protein types within the grain. Genetic control of grain protein content is through the manipulation of the capacity a major vegetative N-pool. Environment and management determine whether or not the pool can be filled, and hence how much plant N is available for translocation. Partitioning rules for N among structural and major storage proteins determine grain protein composition. The model was tested using data from experiments in France and New Zealand, both from the field and semi-controlled environments.

Rob Kelly1, John Cooper1, Greg Thomas2, Wayne Strong1, David Butler1 and Armando Apan3

A handheld 8-channel multispectral radiometer was used to capture canopy spectral signatures on wheat grown in a long-term tillage and fertilizer experiment during 2002 and 2003 in southern Queensland. The experiment was designed, among other things, to measure long-term responses to nitrogen (N) application at 0, 30 and 90 kg/ha.year. We used the radiometer to collect canopy spectral responses at several dates during the growing season which corresponded to tillering, pre-anthesis, anthesis and post-anthesis. In 2002, grain protein was best explained by capturing the reflectance at 710 and 810 nm of the crop canopy at 118 days after sowing (r2=0.59). In 2003, the same wavelengths were closely related to observed grain protein, but at 98 days after sowing (r2=0.56). The close relationship between grain protein and tissue N concentration at anthesis may be why spectral-based prediction of grain protein can take place. Further testing of this model in subsequent years under varying conditions will allow a more robust model to be developed for region-wide grain quality prediction.

Gregory S. McMaster

Understanding and predicting crop phenology and canopy development is important for many reasons including improving the efficacy of management practices and accuracy of simulation models and decision support systems. This paper reports the status of a model for predicting crop phenology (Phenology MMS) that can be used independently to simulate crop development or incorporated into existing crop growth models. This new model is intended to synthesize and quantify the entire developmental sequence of the shoot apex of many crops, making this information readily available to users with limited knowledge of phenology or the crop being simulated. Developmental sequences for winter wheat and corn are presented as examples of model structure, use, and performance.

R. L. Vanderlip1, R. W. Heiniger2, S. A. Staggenborg1, W. D. Rosenthal3 and M. R. Tuinstra1

The sorghum growth model, SORKAM, is used to illustrate the impacts a crop growth model can have in crop model development, risk assessment, crop physiology, crop phenology, and crop breeding. In some cases, e.g. risk assessment, a single function from the model was adequate to determine the probability of freeze before crop maturity. In other cases, e.g. the determination of rate and duration of grain fill, finding adequate methods of simulation provided a source-sink approach to rate of fill and a constant growing degree day summation for duration of grain fill for current hybrids. This led to identification of lines with genetically longer grain fill duration which have been shown to increase yields and seed size. Thus crop models can provide new ideas and products in a number of ways.

Soo-Hyung Kim and Vangimalla Reddy

Temperature is a key environmental variable that regulates growth and development of plants. The rate of change in growth and development in response to temperature is usually nonlinear with initial quasi-exponential to linear response reaching an optimum after which the rate declines steeply. This response is well mimicked by the beta distribution model whose parameters are biologically meaningful unlike polynomials. A simple simulation model of maize development was developed in which the simplified beta function was incorporated to represent temperature responses of various developmental events. The model was calibrated with data from the literature. Predictions by the simulation model compared reasonably well with independent experimental results. Implementation of nonlinear temperature response using the beta function in crop simulation model appeared to be promising, and should improve the capability of the model to simulate temperature responses mechanistically.

Ashok Alva1, Javier Marcos2, Claudio Stockle3, Vangimalla Reddy4 and Dennis Timlin4

Application of CROPSYST-SIMPOTATO model was evaluated for potato production systems in the Pacific Northwest of the United States. Model predictions showed that unaccounted N at the end of the crop growth varied from 102 to 170 kg/ha in the year 2001, and were much greater in the year 2002. Further studies are needed to account for this N. Results also demonstrated the use of model predictions to assess N transport and losses under different water and N management practices. Therefore, the model simulation can be used to predict the fate and transport of N under different N and water management options. This information is useful to optimize the rate and timing of N and water applications to support the maximum production, while minimizing the negative effects of N losses.

Javier Marcos1, Ashok Alva2, Claudio Stockle3, Dennis Timlin4 and Vangimalla Reddy4

Crop simulation models, coupled with field data, can predict the fate and transport of N while providing basis for improved crop management practices. The potato crop simulation model Simpotato was integrated into the multi-year, multi-crop simulation model CropSystVB to improve overall model capabilities for the assessment of N dynamics in potato-based cropping systems. In the integrated model, CropSystVB simulates the soil-water-plant-atmosphere system for a crop rotation, as well as the water and nitrogen budgets. When the crop in the rotation is potato, Simpotato simulates potato growth and development and plant C and N balances. Descriptions of growth and phenology submodels of the Simpotato component are presented here since this model has not been well documented and was modified from its original version for this inclusion. In addition, a simulated scenario is included to illustrate model capacities for the prediction of the fate and transport of N under different N management and water levels for a typical crop rotation in the region.

Andrew Robson1, 2, Stuart Phinn2, Graeme Wright1 and Glen Fox3.

The indeterminate flowering pattern, field variability and subterranean podding habit of peanut crops all combine to make maturity assessment very difficult. Less than optimum harvest timing can lead to lower quality produce, resulting from a range of factors including harvest losses, reduced grain filling and associated lowering of kernel grades, and high aflatoxin infection in years conducive to the contamination. These quality-associated factors can substantially reduce grower returns. The research reported in this paper examined near infrared spectroscopy (NIR) and low cost infrared aerial imagery as methods for determining variations in crop maturity in field grown peanuts. Reliable and accurate methods for sampling, processing and statistical analysis of canopy biomass, kernels and shells were developed. Partial least squares regression and discriminant function analysis of pre-treated spectral data identified a number of maturity-correlated wavelengths, while infrared (IR) aerial imagery identified a relationship between canopy reflectance and pod maturity.

D.R. Wilson1, Robert Zyskowski1, S. Maley1 and A.J. Pearson2

Diverse types of forage brassica crops are sown throughout the year in a wide range of climates and soils to supplement pastures in grazing animal production systems. A potential yield model is being developed for these crops as the basis of a forecasting system to optimise crop management. It is similar in principle to existing models for other crops. Canopy development is simulated by calculating the leaf area of an average plant each day, and then accumulating over all plants in the population. Leaf area calculations account for the production and loss of successive leaves. Daily biomass production is the product of the amount of radiation intercepted by the canopy and a constant radiation use efficiency. New biomass is distributed to leaf, stem and root fractions using empirical partitioning coefficients. The model accurately predicts canopy development, biomass production, and biomass distribution for two different brassica types (Pasja and kale, which produce mainly leaf and stem biomass respectively). Further model development is needed to cope with variable plant size which leads to self-thinning in brassica types such as kale which have relatively low populations, large average plant size and slow development rate. More research is needed to check the wider applicability of the model, to define the distinguishing features of other brassica types, and then to adapt the model for them.

Antje Herrmann1, Alois Kornher1, Frank Höppner2, Jörg Michael Greef2, Jürgen Rath3 and Friedhelm Taube1

The determination of harvest time in silage maize is a prerequisite for minimizing losses during silage storage and the feedout phase, and for exploiting the yield and forage quality potential of hybrids. With respect to harvest time prediction, models can provide useful tools. The objectives of the present study therefore were to test the suitability of three models for predicting contents of dry matter (DM) and starch: two growing degree (GDD) approaches and the dynamic FOMAQ model, which was originally developed for grass growth and forage quality, and is driven by temperature, solar radiation, and soil water. Model calibration, which was based on a multi-year, multi-site experiment, showed a generally satisfactory agreement between observed and calculated values. The consideration of radiation and soil water availability in the FOMAQ model could improve model fit considerably compared to the GDD models.

Robert Zyskowski, D.R. Wilson and S. Maley

Forage brassica crops are grown to supplement pastures in grazing animal production systems. A model is being developed that will predict yields of diverse types of forage brassica, sown throughout the year in a wide range of climates and soils. In many of these crops, plants germinate and emerge over an extended period. This results in variable plant size, which either persists or leads to self-thinning in the population. It is a particular problem for modelling brassica types such as kale which have relatively low populations, large average plant size and slow development (leaf appearance) rate. This paper describes a cohort-based model, which separately simulates plants in distinct size class hierarchies within the populations. It has been developed as part of the overall model that simulates canopy development, radiation interception and utilisation, and biomass production and partitioning. Biomass is partitioned to each cohort on the basis of its leaf area, which is a measure of its capacity to generate biomass, and each cohort grows and develops separately. Model predictions of aggregated biomass production for kale agreed closely with values measured in crop populations with mixed plant sizes.

Xike Zhang1,2, Holger Meinke1,2, Peter DeVoil1,2, Gon van Laar3, Bas A.M. Bouman4 and Yahya Abawi1

A lowland rice module operating in the APSIM framework was developed based on ORYZA-2000. This required rewriting the code to simulate rice physiological processes as intended in ORYZA while using the existing APSIM suite of modules for water and nitrogen. The model can now be used to simulate rotational systems. This paper describes the key features of APSIM-ORYZA, including its input requirements, interactions with other components of APSIM (e.g. evapotranspiration, soil water balance, soil nitrogen dynamics, etc) and output. We also test the model’s performance against some original ORYZA test data. The future development needs are highlighted.

A.M. Manschadi1, J. Hargreaves3, Jan Grenz2, Peter DeVoil1 and Holger Meinke1,

Parasitic weeds of the genus Orobanche (broomrapes) cause substantial yield losses to a wide variety of crops in Mediterranean-type environments. Being unable to assimilate carbon, Orobanche species act as an additional sink for assimilates. Thus crop yield loss is primarily the consequence of a shift in assimilate partitioning from host plant organs to parasites.

This study describes a mechanistic modelling capability for simulating the biomass competition between legume crops and parasitic weeds within the Agricultural Production Systems Simulator (APSIM). A generic cohort-based approach has been adopted to simulate daily age classes (cohorts) of legume pods and parasites. Each cohort is characterised by the number of pods/parasites, their physiological age (degree-days) and potential assimilate demand. Total available assimilate is partitioned among cohorts according to their potential demand and a sink priority scheme. A supply to demand ratio for each pod cohort is used to determine pod abortion.

The model was parameterised for faba bean (Vicia faba L.) infested with the parasitic weed Orobanche crenata Forsk. (crenate broomrape) and evaluated against independent datasets. Model evaluation revealed the capability of APSIM’s fruit cohort component to simulate the observed dynamics of pod setting and yield formation for faba bean crops exposed to various levels of abiotic and biotic (O. crenata) stresses. With this modelling capability, APSIM can assist as a systems analysis tool in developing integrated parasitic weed management strategies that minimise crop yield losses.

Neil A White1, Sukumar Chakraborty2,3 and Gordon Murray4

Stripe rust can cause significant losses to the wheat industry in southern Australia. There have been very few attempts to develop process-based models linking life cycles of a pathogen and its host and much of the research in crop modelling to date has focussed on providing yield estimates in the absence of diseases. Modelling provides a logical framework to incorporate quantitative relationships between the host, pathogen and the environment to help formulate disease management strategies and assist in tactical decision-making for disease control. We have developed a process-based linked wheat-Puccinia striiformis model and compared the predicted yield with that from field studies.

Shao-kun Li1,3, Zhong-Ying Bai2, Zhi-li Qi2, Xiao-hong Liu2, Shi-ju Gao1 and Shuang-ning Zhao1

A recognition system based on a self-learning back propagation (BP) neural network was designed to extract wheat crop features such as total green area and areas of individual leaves from digital images. It is discussed here along with some techniques to create favorable conditions for image recognition. These comprise: (1) the method of collecting images with a digital camera and associated equipment under natural conditions in fields, (2) an algorithm of pixel labeling to segment images and extract crop features, and (3) a high pass filter based on Laplace transformation to strengthen image information. The results of the study show that the Artificial Neural Network (ANN) system is capable of image recognition of wheat population features.

Greg McLean1,3 and Alastair Doherty2

The successful development and maintenance of crop growth and development models requires information from detailed physiological experiments conducted under varying environments and conditions. These datasets are usually collected by many different researchers, each using their own style of data storage, ranging from databases and spreadsheets, through to text files and field books. The Research Experiment Management System (REMS) was written to assist model developers by providing a common storage system for datasets. This system had to be easy to add to, provide graphical data display and with flexible output files designed as crop model inputs. Information in REMS is stored in three sections: general information (e.g. region, site, soil), experiment information (e.g. design, planting, irrigation), and data (e.g. crop, soil, meteorological). Program Plug-ins are used to gather experimental information that does not easily fit into these sections or that requires pre-processing. User written output templates are combined with REMS information to format output files that are suitable for crop models or data analysis. REMS has been successfully used with APSIM and the report package APSIMReport to provide graphs of observed and predicted trait data as an aid to model development and validation.

P. Tixier1, E. Malezieux2, M. Dorel1 and J. Wery3

Monospecific banana (Musa spp., AAA group, cv. Cavendish Grande Naine) based cropping systems may present important threats to the environment. In these agro-systems, pesticides cause significant risks of pollution for surface and ground water, enhanced in the tropical insular conditions of French West Indies. In order to assess these risks and to help the design of more sustainable cropping systems a specific model called SIMBA was built. SIMBA simulates banana cropping systems through several cropping cycles. SIMBA includes sub-models that simulate soil structure, water balance, root nematode populations, yield, economic outputs, etc. Agri-environmental indicators linked to the model allow environmental assessment. The model is used in Guadeloupe and allows practical recommendations to farmers, virtual test of agro-technological innovations or field management strategies.

Carina Moeller1, A.M. Manschadi2, Holger Meinke2, Mustafa Pala3 and Joachim Sauerborn1

Accurate predictions of multi-seasonal soil N, C and water dynamics are essential for assessing rotational effects and system sustainability. The cropping systems model APSIM was evaluated for its ability to simulate wheat and chickpea systems at a site in northwest Syria. Simulated soil water dynamics suggested that the two-stage soil evaporation model used in APSIM’s cascading water balance module does not sufficiently explain actual discharge of the soil profile following crop maturity at the study site. A more appropriate representation of soil water dynamics was achieved by resetting the soil water content in the upper profile layers (0-30 cm) to ‘air dry’ between cycles of the rotation. APSIM captured the trends in soil organic matter dynamics, although it overpredicted the likely increase in soil microbial biomass carbon under wheat-chickpea. By increasing the amount of N in chickpea roots through a different set of parameters for chickpea root N concentration limits, simulated wheat yields improved. With this parameterisation, APSIM was capable of simulating the observed dynamics of N and C and crop yields in wheat/chickpea rotations conducted at the study site.

Hamish E. Brown, Derrick J. Moot1 and Bruce A. McKenzie

Water use (WU) of lucerne crops was measured over a two-year period at Lincoln University (43°38'S, 172°28’E, 11 m a.m.s.l.) and used to validate empirical methods of estimating soil evaporation (ES) and crop transpiration demand (ET demand). The most realistic estimation of ES was given by a modified form of the Ritchie ES calculation. Modifications included calculating second stage ES as a function of accumulated Penman potential evapotranspiration (PE) and a crop cover (I/Io) factor that reduced ES to account for crop roots drying the soil. Unmodified Ritchie ES overestimated ES by >45 mm over a 300 d continuous drying cycle. The product of transpiration efficiency and vapour pressure deficit (ET_eff*VPD) was variable throughout the season, indicating estimates of ET demand based on a constant ET_eff*VPD may be erroneous. However, the seasonal variation of ET_eff*VPD could be explained by a linear increase (R2 = 0.81) from 7 to 22 kg DM ha-1 mm-1 kPa-1 as temperature increased from 7 to 14°C. The ET_eff*VPD decreased below this relationship in autumn when increased partitioning of DM to roots reduced shoot DM production.

Hamish E. Brown and Derrick J. Moot1

Irrigated crops of ‘Grasslands Kaituna’ lucerne were grown over five years in a temperate climate at Lincoln University, Canterbury, New Zealand (43°38 'S, 172°28 ’E). From these the environmental responses of main-stem node appearance were determined. A broken stick temperature threshold with a base temperature (Tb) of 1°C at air temperatures (Ta) <15°C and a Tb 5°C for Ta ≥15 was required to accurately accumulate thermal time (Tt). Using this, main-stem node appearance (phyllochron) was constant in relation to Tt within a regrowth cycle (30–42 days). The phyllochron was 37 ± 7°Cd except in declining photoperiods from 15.7–11.4 h when it decreased from 60–37°Cd. These results demonstrate one of several peculiarities of lucerne physiology in a temperate climate that need to be considered to provide a quantitative framework for lucerne crop simulation.

Jianwei Zhang1, Qi Feng2, Caoqing Jin2, Lida Zhang1, Dejun Yuan1, Bin Han2, Qifa Zhang1 and Shiping Wang1

Expressed sequence tags (ESTs) and full-length cDNAs of rice in public databases represent less than 40,000 genes. This number is far smaller than the upper limit of the predicted genes of the rice genome. In addition, the majority of the expressed rice sequences (62%) in the databases are from japonica subspecies. Divergence in the coding regions by single-nucleotide polymorphism, insertions and deletions between japonica and indica cultivars has been observed. Thus, a large-scale collection of ESTs from indica cultivars is a prerequisite for genetic studies, gene identification and isolation, and the comparative study of the two subspecies of cultivated rice. In this study we collected 22,409 unique ESTs, including 2,643 new ones, from the indica rice cultivar Minghui 63, an elite restorer line for a number of rice hybrids that have occupied more than 20% of the total rice production area in China for the last two decades. A total of 18,844 (84.1%) of the ESTs were mapped in the rice molecular linkage map by BLASTN searches against rice genomic sequences with known chromosome locations. Another 730 ESTs had sequence homology with rice genomic sequences of unknown chromosomal location. More than half (10,116) of the mapped ESTs are from single-copy genes. The rest of the mapped ESTs (8,728) detected two or more loci in the rice genome. Thus, an EST map containing 66,623 loci was constructed. These data provide information for comparative studies of gene expression, gene structure and genome evolution of the two subspecies of cultivated rice.

Baozhu Guo1, Meng Luo1,2, Phat Dang3, G. He4 and Corley C. Holbrook5

An EST (expressed sequence tag) project of peanut, a part of U.S. Peanut Genome Initiative supported by U.S. Industry and Peanut Growers, has been successfully initiated at Crop Protection and Management Research Unit, USDA-ARS, Tifton, GA, to develop genomic resource for peanut research. Given its economic and nutritional importance of peanut, peanut is virtually unexplored at the genomic level because of the peanut genome size (2800 Mb or about the size of the human genome) and the complication. There is wide recognition of the need for peanut EST resource. Our EST project has showed the power of developing genomic resource for peanut research community. Expressed sequence tag (EST) libraries for cultivated peanut (Arachis hypogaea L.) were developed from two cDNA libraries constructed using mRNA prepared from leaves of peanut line C34-24 (resistant to leaf spots and tomato spotted wilt virus) and immature pods of peanut line A13 (tolerant to drought stress and preharvest aflatoxin contamination). Randomly selected cDNA clones were partially sequenced to generate a total of 1825 ESTs, 769 from the C34-24 cDNA library and 1056 from the A13 cDNA library, in which 536 and 769 unique ESTs were identified, respectively. We have released the first batch of 1350 ESTs (Genbank accession number CD037499 to CD038843) to GenBank, and recently 100 (GGC)n simple sequence repeats in peanut (accession number AY526357 to AY526456) have been released to GenBank from sequencing 5000 clones of two SSR enriched genomic libraries. Four hundred unigenes have been selected from these ESTs and arrayed on glass slides for gene expression analysis. The application of genomic tools and information in breeding programs would greatly facilitate the genetic enhancement of cultivated peanut.

Jiajie Wu, Xiuying Kong, Yue Liu, Jianhui Xiao, Cuiyun Jin, Chunqing Zhang and Jizeng Jia

About 200kb BAC from hexaploid wheat Aibai/10*CS BAC library was sequenced. Random-sheared subclones of BAC 1J9 containing Rht-D1c were sequenced at both ends to give a total of 2877 reads, 1.5x107 base pairs. The final assembled sequence covered BAC 1J9 with 7.5 x coverage. Sequence analysis showed that repetitive sequences accounted for about 73% of the DNA sequenced. The LTR retrotransposons made up to 83% of the repetitive sequences. Five genes were identified and distributed in 100kb at one side of the BAC sequence. Three of the five genes were clustered in a 16kb gene-enriched island, while the other two were not in the cluster and separated by repetitive DNAs. Comparison with the orthologous rice BAC AC087797 revealed that three genes shared the same gene order and orientation, but small rearrangements were also detected in the compared orthologous region.

S Senthilvel1, V Mahalakshmi1,2, P. Sathish Kumar1, A.R. Reddy3, G Markandeya3, M.K. Reddy4, R Misra4 and C.T. Hash1

Additional simple sequence repeat (SSR) markers for pearl millet (Pennisetum glaucum) will facilitate application of marker-assisted breeding in this orphan crop. We attempted to develop additional SSR markers using freely available sequence information from 2494 expressed sequence tags (ESTs) from root and shoot tissues of pearl millet seedlings exposed to cold, drought and salt stresses. EST sequences were analyzed for the presence of SSRs using the ‘Tandem Repeat Finder’ program and 410 SSR sequences were detected. Using the ‘Primer3’ program, primer pairs could be designed for 282 of these 410 SSR motifs. Visual scanning to select those most likely to be polymorphic (based on repeat numbers) in di-, tri-, and tetra-nucleotide repeat classes was followed by synthesis of 38 unique primer pairs. These were tested for amplification and polymorphism using DNA from ICMB 841 and 863B, the parents of an ICRISAT pearl millet mapping population. Clear amplification products were obtained for 25 primer pairs. Of these, 13 detected polymorphism between the two elite seed parent maintainer lines. Three primer pairs did not work and PCR conditions for the remaining 10 primer pairs need to be optimized to improve amplification specificity. The 13 polymorphic SSR markers are being added to the pearl millet framework map, and being used in assessments of genetic diversity among elite inbred lines. We will test a small number of additional primer pairs from the initial set of 282 candidates, and will repeat this procedure as and when additional pearl millet EST sequences are made publicly available.

Ju-Kyung Yu1, Mauricio La Rota1, Hugh Edwards1, Hailu Tefera2 and Mark E. Sorrells1

Tef [Eragrostis tef (Zucc) Trotter] is the major cereal crop in Ethiopia constituting about 2/3rds of that nation’s diet. Tef is an allotetraploid (2n = 4x = 40) with a genome size of 730 Mbp and belongs to the family Poaceae. A total of 3,230 ESTs (Expresses Sequence Tags) were generated from tef cDNA libraries as a first step towards a sequence database for this organism. Sequences were generated from four cDNA libraries; seedling leaf, seedling root and inflorescence of Eragrostis tef, and seedling leaf of Eragrostis pilosa, a wild relative of Eragrostis tef. Clustering of the sequences among libraries resulted in 535 clusters (comprising 42% of the ESTs) and 1873 singletons. Of the assembled 2,408 sequences, 25% did not match any existing sequences in public databases. Annotation of the assembled sequences associated 57% of the putative identified tef genes with six major biological roles. Investigation of the translated assembled sequences for conserved protein domains revealed 175 Pfam domains. A total of 170 ESTs (5.3%) containing simple sequence repeats were identified. A collection of 1,425 ESTs from two libraries, seedling leaves of Eragrostis tef and Eragrostis pilosa, was assembled to identify single nucleotide polymorphisms (SNPs) and 37 contigs were found to contain one or more possible SNPs. The EST data generated in this study will be a valuable resource i) to identify native transcribed tef sequences, ii) to develop PCR-based markers and iii) to compare transcribed sequences with those from related cereal crops such as wheat, rice and barley.

G. Krishna and Naveen Puppala

Cultivated peanut or groundnut (Arachis hypogaea L.) is an important source for oil and protein. The extensive polymorphism of microsatellite markers makes them an ideal choice for studies in population genetics, diversity analysis, and linkage mapping and marker development. The widespread application of microsatellite markers is limited by the requirement for species-specific primers. Development of novel microsatellites remains a costly and lengthy process despite continuous improvements in its efficiency. Transfer of primers across genera (cross-taxa application) offers an alternative to de novo development in plants, with transfer rates ranging from 35-90% and potential polymorphism rates between 58 and 78%. There are few studies that have used cross-transferred microsatellite loci to address questions related to plant populations. In the present study we explore a large number of microsatellites available in common bean to examine their transferability and validity. The results reveal that cross-taxa microsatellite primers amplified PCR products in peanut, and that some of the amplified bands contained microsatellite repeats in them.

Bo Shen1, Lynne McIntyre1, Evans Lagudah2 and Chunji Liu1

We have constructed a hexaploid wheat bacterial artificial chromosome (BAC) library using the genotype ‘Chinese Spring’. The library consists of 395136 clones sorted in 1029 384-well plates. About 92% of these clones contain inserts with an estimated average size of 157 kb. Clones containing chloroplast DNA were estimated to be 0.5%. Thus these BAC clones provide an estimated 3.4x genome equivalents. Of these, 221,184 clones have been robotically arrayed onto 24 high-density nylon filters. Screening of the filters with 21 single-copy RFLP probes identified 106 positive BAC clones. The average number of BAC clones identified from the 221,184 grided clones by these probes agreed with that of the expected from the estimated genome coverage of the clones tested. Given the vast range of precise genetic stocks, the numerous DNA libraries and the sequence data derived from this genotype, the CS BAC library could be highly valuable in wheat research.

John Manners1,4, Lynne McIntyre1,4, Rosanne Casu1,4, Giovanni Cordeiro2,4, Mark Jackson1,4, Karen Aitken1,4, Phillip Jackson3,4, Graham Bonnett1,4, Slade Lee2,4 and Robert Henry2,4

Sugarcane has the most complex genome of any crop plant. Commercial sugarcane cultivars are the result of a limited series of crosses and backcrosses derived from two Saccharum species and are poly-aneuploid hybrids with chromosome numbers in excess of 100. Almost all traits are quantitatively inherited and genetic mapping is mainly restricted to dominant single dose DNA markers. In 2003, enormous amounts of DNA sequence information became available via the release of 255,000 expressed sequence tags for sugarcane. It is now possible to identify candidate gene sequences that may underpin important traits in sugarcane and to characterise single nucleotide polymorphisms (SNPs) in these genes. Combinations of SNPs in a gene sequence act as signatures for individual gene haplotypes that may be considered as allele equivalents in the sugarcane genome. Techniques for reliably measuring the dosage of SNPs in the sugarcane genome have emerged and can be used to provide information that enables the gene haplotype (allele) content in a sugarcane genotype to be deduced. This paper describes how these genomics-based tools provide new strategies for genetic analysis and plant improvement in sugarcane.

Zhaohui Wang and Michael G.K. Jones

Plant parasitic nematodes are major pathogens of a wide range of crops. Giant cells induced by root-knot nematodes are highly specialised cells which function as transfer cells and provide nutrients to support the growth and reproduction of the nematode. Using a differential display approach, 81 differentially displayed bands were detected between the cytoplasm of giant cells induced in tomato roots by Meloidogyne javanica and control tissues. Of these, 73 were up-regulated and 8 were down-regulated. Sixteen were further analysed by real-time quantitative RT-PCR. The most highly up-regulated transcript increased 56 fold in giant cells, and the greatest down-regulation was 11 fold. A time course of expression of selected transcripts using RT-PCR from giant cell enriched tissue showed similar changes. Sequenced transcripts showed significant similarity to mitogen-activated protein kinase, S-adenosylmethionine decarboxylase, cysteine synthase, cytochrome c reductase subunit, and ribosomal proteins. The observed gene expression patterns reflect the high metabolic rate in mature giant cells rather than processes of giant cell induction. This work has been extended to analysis using Affymetrix GeneChip microarrays. A comparison of transcripts between giant cell enriched and control tissues revealed a total of 2,448 genes with more than 2-fold changes in expression (about 10% of the 24,000 genes on the chips). Of these genes, 744 were up-regulated in nematode feeding cells and 1,704 were down-regulated. These genes have been classified into functional groups, and the results show substantial changes in gene expression in giant cells that is consistent with the function of giant cells in supporting the development of the nematode parasites.

Saratha Kumudini1

Genetic improvement in yield of a number of crop species including soybean has been associated with delayed leaf senescence (“stay-green”). Elucidation of the genetics regulating the onset and rate of leaf senescence will be of great agricultural importance for genetic improvement in yield. An interesting group of genes has been characterized in soybean that may prove beneficial in studying soybean leaf senescence. A series of loci with two alleles at each locus characterized by researchers working on photoperiod and light quality studies were given the prefix E. Studies on E-gene NILs have reported that plants with the dominant E alleles have higher dry matter accumulation in response to post-anthesis long-day photoperiod. It was hypothesized that this phenomenon was due to a delay in leaf senescence. In 2003, a randomized complete block, split plot experiment was conducted. The main plot was two different planting dates and the split-plot was nine E-gene NILs from two different genetic backgrounds (‘Harosoy’ and ‘Clark’). Chlorophyll concentration (SPAD) and photosynthesis measurements were taken of NIL under field growing conditions. The E-gene dominant alleles did delay leaf senescence in terms of photosynthesis and chlorophyll concentration. The dominant E1 allele especially seemed to have a marked effect on maintaining a high photosynthetic rate. The dominant E1 allele has a role in delaying the onset of leaf senescence in soybean further in to the growing season, but accelerates the onset of leaf senescence after reaching first flower, and this pattern is apparent in both Clark and Harosoy backgrounds. The impact of the E1 locus on regulation of leaf senescence appears to be distinct from its impact on plant phenology.

Li-Ke Liu1, Xiao-Li Guo2 , Dong-Cheng Liu1, Hua-Bo Wang1 and Ai-Min Zhang1

In yeast and human, the ATP-dependent Lon protease plays an important role in removal of the abnormal proteins and maintaining mtDNA integrity. In this paper, using RT-PCR and RACE techniques, we isolated a gene in wheat that encodes a product belonging to the Lon protease family. This gene, designated as TaLon1, is predicted to encode an 886 amino acid protein. TaLon1 shows a constitutive expression pattern in wheat, which indicates that the TaLon1 plays a housekeeping role in wheat. Like its counterpart in yeast, it may degrade abnormal proteins in mitochondria and maintain the mtDNA integrity. Unlike the lon gene in yeast and E. coli, the TaLon1 does not respond to heat-shock at 42 °C. Under salt stress, the TaLon1 expressions decline after treatment at both 150 m mol/L and 250 m mol/L NaCl for 24h. Given its important roles in yeast and E. coli, the salt stress damages to plant may be partly interpreted by the decrease of the TaLon1 expression. It has been demonstrated that the Lon protease has some effects on cytoplasmic male sterility (CMS) in common bean. But in wheat, there is no difference in TaLon1 expression between K-CMS line and normal lines.

Rak Chun Seong1, Jae Yoon Kim2, Jae Woong Haam3 and Yong Weon Seo2

Immature barley embryos in culture show a high ability of plant regeneration, but the period during which immature embryos can be used is limited. To overcome this difficulty, mature embryos of barley (Hordeum vulgare L.) have been used to establish regenerable tissue cultures with potential use for transformation. In order to provide information on molecular events during plant regeneration, a cDNA library was constructed using tissues of the 6 day-old initiated shoots. A differential hybridization method was used to isolate genes expressed differentially during plant regeneration. Of the forty cDNA clones that were highly expressed during shoot initiation, gibberellin responsive gene (HvGR) was isolated and characterized. Northern analysis was conducted on total RNAs extracted from 3 week-old calli, 1, 3, and 6 day-old initiated shoots, and from shoots of plantlets. The HvGR gene expressed specifically during shoot development. Tissue localization of HvGR gene transcripts during different stages of shoot induction and callus tissue by in situ hybridization showed similar results. A high level of HvGR expression was observed in day 6 initiated shoots, where the signal was localized primarily in the developing shoot primordial. Effects of plant growth hormones, ABA, cytokinin (BAP), and gibberellic acid, and wounding on the expression of HvGR were analysed.

Paul R. Wiley, Paola Tosi, Huw D. Jones and Peter R. Shewry

Grain hardness is a major determinant of the milling and processing quality of wheat. Current theories suggest that hardness is determined by the degree of adhesion between various components of the starchy endosperm cells of the mature wheat grain, notably between starch granules and matrix (gluten) proteins but also between proteins and cell walls. Furthermore, it has been proposed that one group of proteins, called puroindolines (PINs), play a specific role by acting as “non-stick” proteins on the starch granule surface, resulting in grain softness.

Erik van Oosterom1, Graeme Hammer1,2 and Scott Chapman3

Quantitative models could predict the functioning of gene networks if those networks were sufficiently understood and appropriately quantified. Such capability would facilitate the application of crop growth simulation models in crop improvement programs, and hence improve the connectivity of research between crop and cell biology. Crop response to photoperiod is a useful physiological case study, as its genetic control is relatively well understood. Based on existing literature, we present here a simplified network for this process in Arabidopsis thaliana, a long-day crop. Although the current version of the model is strictly qualitative, it illustrates how a simple gene network can generate critical and ceiling photoperiods as an emergent property of the framework dynamics. We argue that simulating causes of physiological processes, rather than their consequences, will provide simulation models with the functionality required to extend the domain of genotype x environment (GxE) combinations.

Hirofumi Saneoka1, Daiso Toyonaga1, R.E.A. Moghaieb1,2 and Kounosuke Fujita1

Phytic acid (myo-inositol 1,2,3,4,5,6-hexakisphospate) is the main storage form of phosphorus in many plant seeds. Myo-inositol-1-phosphate (Ins(3)Pi) synthase (MIPS EC catalyzes the first step in phytic acid biosynthestic pathway. An oat (Avena sativa) MIPS cDNA was isolated by RACE-PCR using consensus primers designed from highly conserved regions in other plant MIPS sequence. The oat MIPS clone sequence analysis shows an 1936 bp encoding a polypeptide of 510 amino acids with highly homologous to other plants. Northern blot analysis indicated that MIPS gene is high expressed during early stage of seed maturity, while it was decreased at late maturity stage. Phytic acid concentration also gradually increased with seed maturity.

Annabelle U. Novero, Paul W.J. Taylor and Rebecca Ford

β-cyanoalanine synthase (β -CAS) is an enzyme that catalyzes the conversion of cysteine and cyanide to produce β-cyanoalanine and sulphide. β-cyanoalanine is a neurotoxin found in vetch seeds rendering them unfit for animal or human consumption. This compound can be readily metabolized into asparagine but this route seems to be blocked in vetch, leading to neurotoxin buildup. Vetch is an important fodder crop in Australia because of its ability to grow under poor conditions such as low rainfall and alkaline soils. Cysteine synthase (CS), which catalyses the formation of cysteine from O-acetyl-L-serine (OAS) and sulphide has been observed to exhibit CAS activity in some plants. Likewise, CAS has been shown to exhibit CS activity. Using genomic DNA, regions encoding CAS and CS in vetch were amplified. Primers were designed based on highly-conserved regions of available CAS and CS gene sequences from each member of the β-substituted alanine synthase family. One CAS gene had been isolated and analyzed previously the Biomarker Lab. In this current study, six CS genes were cloned and three were sequenced and analyzed. Molecular and biochemical characterization of CAS and CS genes is underway in order to: 1) determine genetic relatedness of vetch-specific genes to other known gene family members, and; 2) establish functional expression of the genes. Homologous sequence regions will be targeted for use in post-translational gene silencing.

Shao-Kai Lin1, Meng-Chi Chang1, Yeou-Guang Tsai2 and Huu-Sheng Lur1

Rice caryopsis proteins were profiled by two-dimensional polyacrylamide gel electrophoresis (2D-PAGE), and differentially expressed proteins were analyzed by Liquid chromatography/tandem mass spectrometry (LC\MS\MS). In results more than 400 polypeptide spots were monitored during development, and more than 70 of them were analyzed by LC\MS\MS. Fifty four proteins with function annotations were identified. Among them 21 were carbohydrate metabolism related proteins, 14 were protein synthesis and sorting related proteins, 9 were stress response related proteins. Wx proteins and glutelins were the most significant spots showing increase during development. Allergen-like proteins, PPDK (Pyruvate, orthophosphate dikinase) and NADH-SDH (NAD-dependent sorbitol dehydrogenase) were also expressed along the development, implying their physiological roles in caryopsis. Expression of large isoforms of Wx proteins were correlated with the amylose content of rice caryopsis. One protein, with high GC content in its DNA sequence, showed correlation with chalky trait of kernels. High temperature (35/30 ℃) decreased expressions of Waxy proteins, allergen-like proteins and elongation factor 1 β; but increased expression of small heat shock proteins (sHSP), glyceraldehydes-3-phosphate dehydrogenase and prolamin. Abundance of sHSP seemed to be positively related to the chalky appearance of kernels. Wx proteins and glutelins were phosphorylated, and glutelins were glycosylated during development, suggesting the existence of post-modification on the molecules.

Junxiang Mu, Hongju Zhou, Shenjie Zhao, Caiguo Xu, Sibin Yu and Qifa Zhang

A series of near-isogenic introgression lines were developed from an advanced backcross population derived from a cross between the sequenced japonica cv. Nipponbare, and an elite indica hybrid parent (Zhenshan 97B). Each line contains only a single defined introgression segment from Nipponbare in the indica genetic background. Furthermore, a novel population consisting of 88 lines carrying different but mutual overlapping chromosomal segments provides approximately a complete coverage of the japonica rice genome. These contiguous introgression lines (CILs) present an extremely useful base for fine mapping and functional analysis of genomic regions (genes) underlying traits of agronomical importance.

Andrew K. Borrell1, David Jordan1, John Mullet3, Patricia Klein3, Robert Klein3, Henry Nguyen4, Darrell Rosenow5, Graeme Hammer2, Andrew Douglas1 and Bob Henzell1

Drought is the major environmental factor constraining crop production globally. Identifying and understanding the function of genes and gene networks that contribute to improved plant drought resistance under water-limited conditions is a fundamental component of sorghum breeding programs in Australia and the United States. In particular, genes located in four genomic regions (Stg1, Stg2, Stg3 and Stg4) controlling the functional basis of the B35 source of ‘stay-green’ are being sought. Plants with the stay-green drought-resistance trait maintain green stems and upper leaves when water is limiting during grain filling. This paper discusses the multi-disciplinary approach to gene discovery implemented by Australian and U.S. scientists in pursuit of the key stay-green genes. In this project, map-based gene cloning is the primary approach to gene discovery. Multiple cycles of phenotyping and genotyping have enabled scientists to close-in on the genes of interest via fine-mapping, and will ultimately lead to the discovery of gene function. Candidate genes will be identified within each of the four genomic regions using an integrated genetic and physical map of sorghum, together with detailed physiological dissection of genotypes with different stay-green alleles. Proof of gene function will follow. Gene function in a range of environments will be assessed in silico using crop simulation modelling. Overall, this integrated approach to gene discovery will enable plant breeders to more efficiently custom-make sorghum varieties for specific water-limited environments.

Takami Hayashi1, Tomoya Yamaguchi1, Katsuhiro Nakayama1, Setsuko Komatsu2 and Setsuo Koike1

We used proteome analysis to investigate the cooling damage on anthers of rice plants grown under high nitrogen conditions. Proteins were extracted from mature anther samples and separated by two-dimensional gel electrophoresis. The anther proteome maps of different treatments were compared and 20 protein spots, which were changed by the treatments, were found. These protein spots were identified based on the rice proteome database and/or digested with trypsin for peptide mass fingerprinting (PMF) analysis. Digested samples were analyzed by matrix-assisted laser desorption/ionization-time flight mass spectrometry (MALDI-TOF MS) to produce PMF data. Database searches using these PMF data revealed the identities of 16 proteins. These proteins included polypeptides involved in carbon metabolism, nitrogen metabolism and stress responses.

Xinxin Zhang1, Tetsuo Takano2 and Shenkui Liu1

Sodium carbonate (NaHCO3、Na2CO3) causing stress for plants is called “carbonate stress” in this study. Some genes that related to carbonate stress were screened from rice (Oryza sativa. L) root cDNA library, rice mitochondrial ATP synthase 6kDa subunit gene (shortened form: RMtATP6 gene) is one of these genes. The encoded amino acid sequence has homology to mitochondrial ATP synthase 6kDa subunit (F0 part of F1F0-ATP synthase) purified from potato (Solanum tuberosum) mitochondria by Jansch et al. (1996), but the function of this small protein is not clear and the gene has not been identified. In this report, the gene was cloned (Genebank accession no: AB055076), and its expression in plant and yeast under carbonate stress and subcellular targeting were characterized. Results suggested that the RMtATP6 gene encoding protein is rice mitochondrial ATP synthase 6kDa subunit. Southern analysis suggested that the RMtATP6 gene is a single-copy gene in the rice genome. Through analyzing the RMtATP6 gene expression in plant, and its expression in yeast under carbonate stress, we can infer that RMtATP6 gene is probably related to carbonate stress. Moreover, experimental data indicated the moderate expression of RMtATP6 gene in yeast can improve the ability against carbonate stress. RMtATP6 protein is targeted to mitochondria in yeast cells as shown by RMtATP6-GFP fusion protein.

Enrico Perotti1,2, Daniel Grimanelli1,3, Peter John2, David Hoisington1 and Olivier Leblanc1,3

Apomixis, or asexual reproduction through seeds, is a natural phenomenon that holds the potential of increasing dramatically the world food production. Apomixis produces progeny that are clones of the mother, a feature allowing the fixation of any favourable genetic combination. Apomixis is a complex phenomenon that displays a wide variety of developmental modifications of sexuality. Despite this complexity, genetic studies show that apomixis is inherited as one or two dominant mendelian traits located on a recombination-less chromosomal segment. Apomixis is typically facultative as only a proportion of the progeny are apomictic while others are sexually derived. The incidence of apomixis depends on the global genetic background and does not seem to be linked to the apomixis locus. For more than four decades, scientists have strived in vain to transfer the trait to commercially important plants through conventional backcrossing schemes. The failure to recover apomictic crops seems to be a direct consequence of the genetic complexity of apomixis. Although apomixis is complicated, it has arisen naturally in many forms, most if not all of which depend on the plasticity of plant reproductive development. Increased understanding of reproductive machinery in plants should enable the engineering of apomixis in sexual crops.

Heather Way, Scott Chapman, Gangping Xue, Rosanne Casu, Lynne McIntyre and Ray Shorter

Gene expression patterns in wheat plants subjected to a gradual water deficit stress initiated from two important developmental stages, terminal spikelet (TS) and boot (BT) are being studied. Two suppressive subtractive hybridisation libraries were prepared between well-watered and water-stressed wheat leaves and used to construct a small microarray containing approximately 300 expressed sequence tags (ESTs). The microarray was screened with RNA isolated from well-watered wheat leaves and wheat leaves from plants subjected to water deficit stress initiated at either TS or BT. Overall, 20% of the genes were significantly up-regulated and 10% were significantly down-regulated under water deficit stress with more changes in gene expression observed in leaves from plants subjected to stress initiated from the BT stage. Clustering analysis revealed five distinct patterns of differential expression, with two clusters showing different patterns of up-regulation, one cluster containing genes significantly down-regulated and two clusters containing genes displaying non-significant differential expression patterns. Northern analysis has confirmed the differential expression of these genes with progressive reduction in leaf relative water content. These genes will be mapped to see if they co-locate with QTLs associated with adaptation to water stress.

Graham Bonnett1,2, Rosanne Casu1,2, Anne Rae1,2, Chris Grof1,2, Donna Glassop1,2, Lynne McIntyre1,2 and John Manners1,2

Sugarcane is an important crop in tropical and sub-tropical regions. A major objective of sugarcane improvement programs worldwide is to increase the stem sucrose content. However, unlike yield, the sugar content of commercial cultivars has not been increased in the last 40 years, at least in Australia. This paper describes recent attempts and current strategies to identify genes associated with sucrose accumulation. Differential gene expression studies using microarrays to compare immature internodes with internodes rapidly accumulating sucrose have identified candidate genes associated with sucrose accumulation. Of the genes encoding proteins involved in sugar metabolism and storage a group of sugar transporters have been shown to be the most highly up regulated in the maturing stem. These genes and their gene products have been further studied by northern analysis, in situ hybridisation and immunolocalisation allowing hypotheses to be generated about their potential roles in the sucrose accumulation process. Other differential gene expression studies using microarrays to compare internodes of high and low sucrose content genotypes from a segregating population have also been undertaken and identified candidate genes. The role of the developing area of metabolomics in candidate gene identification by discriminating metabolites and their relative abundance is also discussed.

Gretel M. Hunzicker 1, Elmar W. Weiler, and I. Kubigsteltig

For the biotechnological use of higher plants, it is necessary to ensure the formation of the desired recombinant product in the right organ at the right time, and in the right cellular location, in large quantities and without exerting toxic effects in the cell. For many purposes, it may be desirable to exert exogenous control over the production of recombinant proteins using chemically controllable promoters. In our group, the promoters of 12-oxophytodienoic acid reductases (OPR1 and OPR2) have been isolated in order to investigate jasmonic acid biosynthesis. Although OPR1 is not the isoform that is important for in vivo jasmonate production, the OPR1-gene has a very sensitive promoter which can be activated by mechanical and chemical inducers (Biesgen and Weiler, 1999; Sanders et al 2000; Schaller et al 2000; Stintzi et al 2000; He and Gan, 2001). One of those chemical inducers is the non-ionic detergent Tween 20. A number of deletions of the OPR1-promoter have been designed and tested for their properties and range of applications, using reporter gene analysis (ß-glucuronidase) to assay for promoter strengths and characteristics by Northern Blot and GUS fluorometric assays. In order to know which genes are induced by the application of Tween 20, microarray analysis has been done. Promoter functionality will be tested in a range of agricultural plants. The aim of the project is to advance our understanding of application-oriented promoter-design in the biotechnological use of higher plants.

Zhaohui Chu1, Binying Fu2, Zhikang Li2, Qifa Zhang1 and Shiping Wang1

Bacterial blight, caused by Xanthomonas oryzae pv. oryzae (Xoo), is one of the most serious diseases of rice. About 30 bacterial blight resistance (R) genes (21 dominant R genes and 9 recessive ones) in rice have been identified. These R genes are known to act in a gene-for-gene manner and are the main sources for genetic improvement of rice for resistance to Xoo. Three cloned dominant R genes for resistance to Xoo belong to either LRR receptor kinase-like proteins or the NBS-LRR type, but little is known about the recessive R genes. To clone and characterize the recessive R genes at the molecular level, we fine-mapped a recessive gene, xa13, for bacterial blight resistance to a DNA fragment of 14.8 kb using map-based cloning strategy. Sequence analysis of this fragment indicated that this region contained only one complete open reading frame. These results will greatly facilitate the isolation and characterization of xa13.

Jayampathi Basnayake, Ouk Makara, Thum Votany, Sideth Kang, Pith Khon Hel, Shu Fukai1, Men Sarom and Ken Fischer1.

The magnitude and nature of genotype-by-environment interactions (G×E) for grain yield (GY) and days to flower (DTF) in Cambodia were examined using a random population of 34 genotypes taken from the Cambodian rice improvement program. These genotypes were evaluated in multi-environment trials (MET) conducted across three years (2000 to 2002) and eight locations in the rainfed lowlands. The G×E interaction was partitioned into components attributed to genotype-by-location (G×L), genotype-by-year (G×Y) and genotype-by-location-by-year (G×L×Y) interactions. The G×L×Y interaction was the largest component of variance for GY. The G×L interaction was also significant and comparable in size to the genotypic component (G). The G×Y interaction was small and non significant. A major factor contributing to the large G×L×Y interactions for GY was the genotypic variation for DTF in combination with environmental variation for the timing and intensity of drought. Some of the interactions for GY associated with timing of plant development and exposure to drought were repeatable across the environments enabling the identification of three-target populations of environments (TPE) for consideration in the breeding program. Four genotypes were selected for wide adaptation in the rainfed lowlands in Cambodia.

Carlos M. Löffler, Jun Wei, Tim Fast, Robert E. Merrill and Mark Cooper

The effectiveness of a product evaluation system largely depends on the genetic correlation between multi-environment trials (MET) and the target population of environments (TPE). Previous characterizations of maize environments based on climate and soil did not quantify their impact on the genetic correlations among environments. Consequently, plant breeders have favoured characterizations based on the similarity of product discrimination in trials. However, these efforts frequently fail to provide adequate assessments of the TPE, due to the cost of collecting long-term performance data. To describe the TPE, we performed crop simulations for each US corn-belt township for the 1952-2002 period, using standard CERES-Maize model inputs. To characterize METs, input data were collected at or near the trial sites. Grain yield and biotic stress data for model validation were collected from 18 hybrids grown in replicated trials in 200 environments in 2000-2002. Based on prevailing conditions during key growth stages, and observed patterns of genotype-by-environment interactions (GEI), six major environment classes (EC) were identified. The relative frequency of each EC varied greatly from year to year. Stratification of grain yield by EC accounted for around 39% of the hybrid-by-environment variance component. Our environmental characterization system provided a useful description of both the TPE and MET. Knowledge of the spatial (locations) and temporal (years) distributions of ECs that influence GEI can be used to improve product performance predictability in the US corn-belt TPE.

Ioannis Papadopoulos1, Ioannis S. Tokatlidis2, Konstantinos Tertivanidis1 and Efstathios Tamoutsidis1

Two local dry bean populations were used in the study. A total of 432 widely spaced plants (80 x 80 cm) of each population were grown in the greenhouse. Another 500 widely spaced plants (100 x 100 cm) of each population were evaluated in the open field. In the greenhouse grain yield and pod number distributions of population A did not depart from normality. For both traits of population A in the open field, and for both traits of population B either in the greenhouse or in the open field, skewness and kurtosis were significant. Leftward transposition of mean due to positive skewness was accompanied by increased CV values. Although both populations had higher yield and pod number per plant in the open field than in the greenhouse, attributable to less competition, standard deviations increased in higher rates in the open field resulting in higher CV values. Compared to the greenhouse, in the open field CV values of yield and pod number were by 59 and 54% higher for population A, and by 42 and 20% higher for population B. Results revealed a stronger environmental impact on phenotypic expression in the open field, and therefore the greenhouse seemed to ensure conditions under which more objective and reliable selection could be applied.

Ky L. Mathews1, Scott Chapman2, Richard Trethowan3, Wolfgang Pfeiffer3, Maarten van-Ginkel3 and Ian DeLacy1

Results are presented from a nursery (International Adaptation Trial - IAT) to investigate environmental stresses in spring-wheat production areas. These illustrate concepts of using probe and reference genotype sets to characterize environments. A probe pair compares presence/absence of the Rht1 dwarfing gene in a Nesser background with results presented on maps. A reference genotype set of twenty-one broadly adapted CIMMYT-derived lines, grouped seventy-eight trials into three main groups, Australian rain-fed, high-yielding irrigated international trials and lower yielding irrigated or rain-fed international trials.

Martine Leflon1, Anne Laperche2, Wen-Ying Rong2, Jacques Le Gouis2, Christophe Lecomte3, Beghin Denis2 and Maryse Brancourt-Hulmel2

Environmental characterization has been shown to aid interpretation of genotype environment interaction. In this study, we present a novel method to characterize environments and its use to explain specificity of QTLs to environments. The study examines variation in kernel number in a wheat double haploid population. The environmental characterization method is based on the use of a simple yield components relationship between maximal thousand kernel weight and kernel number per square meter for each of four probe genotypes. Deviations from thresholds defined in the relationship are used to identify environmental indicators related to yield limitation in the test environments. The environmental indicators are used to partition the QTL x environment interaction and to explain the specificity of some QTLs to some environments using a four-step strategy.

Hua-qin He1, Li-hua Shen, Yu-chun Guo, Jing-Yuan Wang and Wen-xiong Lin

Random amplified polymorphic DNA (RAPD) markers were used to estimating genetic diversity among 57 allelopathic rice accessions (Oryza sativa L.). There were 59 polymorphic bands in the 85 RAPD loci within the tested accessions, and the percentage of polymorphic bands (PPB) was 69.4%. The result from the clustering analysis by Unweighted Pair Group Mathod Arithmetic Average (UMGMA) indicated that those accessions from the same geographical location were clustered into one group. It was also found that some rice accessions with higher allelopathic potential were clustered together, such as IAC25、IAC47and IAC120 implying that the genes conferring allelopathy in those rice accessions might be isolocus. However, some rice accessions with different allelopathic potential clustered into the same group performed lower level of generic polymorphism which was attributed to oriented selection for other traits in breeding program. This offers us a genetic pool for the selection of rice cultivars with high allelopathic ability.

Jun Hyeon Cho, D.Y. Kwak, K.H. Yi, Y.J. Weon, J.M. Ko, H.M. Park, S.J. Yang and Min-Hee Nam

Bulked segregation analysis(BSA) was used to identify random amplified polymorphic DNA(RAPD) markers linked to the rice stripe virus resistance gene, Stvb-i, in rice. Using two pools of phenotyped lines from a 169 DH population, we identified four RAPD markers positively linked to Stvb-i gene. The RAPD markers were mapped to chromosome 11 on the SSLPs map and one RAPD marker, OPO11, showed complete linkage to Stvb-i. When the selected specific marker was used on all of japonica, indica and tongil type varieties developed in Korea, the positive amplication of about 2500bp fragment generated from OPO11 was observed in only japonica varieties in which Stvb-i gene was used as a source of RSV resistance gene while the other susceptible japonica and all indica as well as tongil varieties showed negative reaction. Therefore, this can be used in the marker-assisted selection of stripe resistant individuals carrying the Stvb-i gene.

P. Strelchenko1, Kenneth Street2, O. Mitrofanova1, M. Mackay3 and F. Balfourier4

To investigate the genetic diversity of 78 landraces that originated from 22 countries and the relationships between them the polymorphism of 20 wheat microsatellite loci was estimated. Data obtained was later compared with the results of a more recent study of the same set of landraces using AFLP and RAPD methods. Each of the three approaches was useful for characterizing genetic diversity and defining relationships between landraces with different geographical origins. However SSRs were more effective genetic markers for detecting genotypes containing combinations of rare alleles. Multivariate statistics techniques were applied to identify groups of genetically similar landraces on the basis of the band data generated by both SSR and combined set of data. This analysis divided the landraces into European and Asian wheats. Within the Asian set the groups largely consisted of landraces originated from the same region. Distinctions between European and Asian wheats, and also between groups within Asian wheats, were mainly determined by differences in the frequency of a considerable number of SSR alleles or AFLP and RAPD bands. The incongruity between the taxonomic division of hexaploid wheats and relationships of the landraces revealed by DNA markers is discussed.

Jan Valkoun, Ahmed Amri, Jan Konopka, Kenneth Street and Eddy De Pau

Crop wild relatives and landraces in the Central and West Asia and North Africa (CWANA) region of origin and diversity of wheat, barley, lentil, chickpea, faba bean and forage legumes are a rich reservoir of genes for drought-stress tolerance adaptation to dryland environments. However, they are under rapid genetic erosion and have to be conserved both ex situ in genebanks and in situ in original habitat to meet the present and future needs. Out of the total of 131,000 accessions held in ICARDA’s genebank collections, two-thirds originate from the CWANA region. In more than 160 collection missions to 32 countries the Center collected 26,000 new genebank accessions. For 57,000 geo-referenced accessions 65 climatic variables were generated using GIS. Accessions sampled from drylands, i.e. hyper-arid, arid and semi-arid zones prevail with 2%, 12% and 41%, respectively. In a complementary effort, the GEF/UNDP Dryland Agrobiodiversity Project is testing in Jordan, Lebanon, the Palestinian Authority and Syria the in situ or on-farm biodiversity conservation through promotion of its profitable utilization by farm families and communities. Both approaches are essential for maintaining the rich genetic diversity of CWANA and providing breeders, molecular biologists and other scientists with sources of drought-tolerance genes.

Igor G. Loskutov

This research presents the field results of studying of wild oat species with different ploidy level. The evaluation was targeted at agronomic traits and resistance to the most widespread diseases: crown and stem rusts and barley yellow dwarf virus (BYDV). Besides, representative collection of all species has been analyzed for groat protein content – amino acid and groat oil content – fatty acid composition. The study representative set of accessions of genus Avena L. species helped to determine intraspecific diversity in all researched characters. All identified sources may be involved in the conventional and other breeding process for disease resistance, agronomic traits and grain quality in oats.

David Jordan1,3, David Butler1, Bob Henzell1, Janneke Drenth2 and Lynne McIntyre2

The genetic diversity of Australian sorghum breeding populations has declined partially as a result of selection for sorghum midge (Stenodiplosis sorghicolar (Coquillett)) resistance and stay-green (a drought resistance trait). Wild relatives of sorghum represent a potentially valuable source of novel alleles to diversify Australian sorghum breeding populations, enhance yield advance and reduce genetic vulnerability. Diversification using wild sorghum via conventional pedigree breeding is likely to be inefficient due to the disruption of favourable linkage blocks. Instead, we have used a limited backcrossing strategy to produce a population of 255 BC1F4 lines derived from a cross between a wild sorghum (Sorghum arundinaceum) and an elite parent (31945-2-2). These lines were top-crossed to an elite female and the resulting F1 hybrids tested for grain yield at four trials. Significant numbers of progeny with grain yields similar to or greater than the recurrent parent were recovered. The lines were then screened with molecular markers and the regions associated with enhanced grain yield from the S. arundinaceum parent identified.

Marilyn Warburton, Pinzghi Zhang, Susanne Dreisegacker, Jacob Lage, Maarten Van Ginkel and Richard Trethowan

The expansion of the bread wheat gene pool can be achieved via the creation of synthetic hexaploid wheats (SHWs) and the backcrossing of these synthetics to elite breeding lines. Resistance to many biotic and abiotic stresses has been incorporated into new bread wheat cultivars using synthetic donors. Sufficient microsatellite markers (SSRs) were used to create a dense coverage of all the chromosomes to assess the genetic diversity present in synthetic hexaploid wheats, their backcross derived families, and their parents (where possible). SSRs were also used to test for the selective advantage of SHWs alleles in backcross families after several generations of selection. The SHWs investigated in this study had a high gene diversity and PIC for all SSRs, but highest for D genome markers. The SHWs clustered with their durum parents, but were clearly separated from bread wheat cultivars in a dendrogram. Gene diversity of the synthetic backcross derived lines (SBLs) for the A and B genomes was higher than that of their SHW and bread wheat parents. Gene diversity partitioned within each SBL family was extremely high. Principal coordinates analysis of the SBLs and their parents showed that lines from each SBL family clustered together and closer to their bread wheat parent than their SHW parent. De novo generation of genetic variation was seen in many of the SHWs, which was stably inherited in the SBL families. Non-Mendelian inheritance of alleles favoring the SHW parent was seen in some of the markers in one or more SBL families, suggesting that these genomic regions are being actively selected for.

Hong-liang Zhang, Zichao Li, Dongling Zhang, Junli Sun, Meixing Wang, Yongwen Qi and Xiang-kun Wang

The selection strategies of SSR markers in sampling a core collection and estimating genetic diversity were studied, using a population with 358 rice landraces from China, and 72 SSR loci. Combining different locus numbers and four types of locus with different polymorphisms got forty-four sets of locus compositions. Two hundred and thirty core collections were sampled randomly and by clustering using different locus compositions, in different proportions to the whole population. Analysis was made on: (i) the correlation coefficient between the genetic distance/similarity matrix in the whole population estimated by different locus combinations, (ii) the correlation coefficient between the genetic distance matrix in the whole population and that in each core collection, and (iii) the genetic diversity at 72 SSR loci in each core collection. The conclusion was that different aspects in selection strategies of SSR markers should be focused on for different research purposes and objectives. The effects on estimating the genetic differences and sampling a core collection in fact related to the locus number rather than simply to the allele number. To precisely estimate the genetic diversity and sample a representative core collection, no less than 18 and no more than 36 SSR loci randomly selected could be recommended.

Hui Chen1, Yuanhong Fan2, Qing Cai3 and Ya-ping Zhang4

In this study, 195 accessions of Saccharum Spontaneum L. from different geographical populations in China were studied using random amplified polymorphic DNA (RAPD) analysis to estimate their genetic diversity. Phylogenetic analysis was done to assess relationships among haplotypes. A total of 266 bands were scored of which 145 were reproducibly polymorphic. The extent of genetic variability was between 62.95% and 37.05% within populations. The topology of the phylogenetic tree of S. spontaneum corresponds to the population geographical distribution. The genetic variation and diversity among different populations was consistent with existing knowledge on the geographical distribution of S. spontaneum in China. We tentatively propose that Yunnan province was the center of origin for S. spontaneum in China, based on previous collections and archeological information when combined with these results.

Kuniyuki Saitoh1, Kuniko Nishimura1 and Toshirou Kuroda1

Characteristics of flowering and pod set were compared between wild and cultivated types of soybean grown in pots (1/5000 a) in a vinyl house. The wild type had 10-fold more nodes than the cultivated type. The wild type developed 10-fold more flowers than the cultivated type, but set relatively few pods. During the process of domestication from wild to cultivated type, i) the pole climbing characteristic disappeared and development of branches and racemes with compound leaves was repressed, resulting in a decreased number of nodes, ii) flower production decreased and the rate of pod set increased markedly, iii) the number of pods decreased, but seed size became bigger, and iv) photosynthetic capacity might be improved and the leaves became larger, with increased rate of dry-matter production.

Jack C. McCarty1, Johnie N. Jenkins1 and Jixiang Wu2

Cotton, Gossypium hirsutum L., is an important cultivated crop that is grown throughout the world. Improvements in agronomic trait performance and quality are needed to ensure its economic viability. To improve economic traits genetic resources must be identified and utilized. Primitive accessions of cotton offer a wealth of genetic variability; however, since most of these accessions are photoperiodic (short-day responsive) they are not readily useable in breeding programs. Day-neutral lines have been developed and are being studied for use in cotton improvements programs. The study reported herein involved crossing 114 day-neutral derived lines as male parents with two commercial cultivars, Stoneville 474 and Sure-Grow 747. Parents and F2-bulks were grown in field plots during 2001 and 2002 and agronomic and fiber traits were determined. The yield for most of the F2-bulks was not greater than that of the high yield cultivars. All male lines had lint percentages that were significantly lower than the cultivars. The F2-bulks had better fiber traits micronaire and fiber strength than the cultivars. These day-neutral derived accessions are a new source of genetic diversity that can be used in cotton breeding programs. They offer the potential to improve important fiber traits and expand genetic diversity among cultivars; however, their low lint percentages must be considered when they are used as sources to develop improved cultivars.

Chan-Sik Jung, Ki-Won Oh, Hyeun-Kyeung Kim, Myung-Hee Lee, Chung-Berm Park, Jea-Duck Sung, Yong-Ho Kwack and Duck-Yong Suh

Recently diploid (2n=20) wild type Perilla species was reported from Japan. We collected several wild type Perilla in Jeju island, Korea. Two collections, Jeju-3 and Jeju-17, could be classified as P. citriodora and P. hirtella, respectively. Their bract color and type of serration at leaf base are agreed with the classification. Collections and their corresponding species shared specific RAPD markers which distinguished them from other species.

C. Thami Alami1, J. Al Faiz1, C. Papineau2, F. Huyghe2, Brhada3 and A. Filali Maltouf3

In Morocco, many species of Lupins grow spontaneously. Collection of local varieties and some native genetic species and their evaluation allowed us to initiate, in collaboration with INRA-France (Lusignan), a breeding Program of sweet Lupins (L. albus) by crossing the best sweet lines from INRA-France selection and some selected Moroccan populations.

Indigenous rhizobial strains associated with native lupin species in Morocco were collected and some phenotypic characteristics and the genetic diversity were studied.The REP-PCR of 159 rhizobial isolates from the nodules of six Lupinus species, indicated a high genetic diversity. The strains showed fast growth rates and typical characteristics of the Rhizobium genus. Moreover, their good abiotic stress tolerance seems to be close of Bradyrhizobium. Most of them showed an interesting biological nitrogen fixation potential. Further characterisation will be useful to study the taxonomic position of these bacteria within the Rhizobiaceae family. Selection of lupinu-rhizobia symbiosis adapted to calcareous alkaline soils will result on the extension of lupins in large areas as an alternative forage legume.

Yash Chauhan, Graeme Wright, NageswaraRao C. Rachaputi and Kevin McCosker

Homoclime analysis is a method used to identify locations with similar climatic conditions. In this study we used this approach to identify opportunities for the better targeting of introduction of chickpea (Cicer arietinum L.) germplasm from India into Queensland, Australia. The analysis involved clustering of climate profiles from 39 Australian locations from latitudes over 14 to –36°S and 29 locations in India spread over 12 to 32°N during the chickpea growing season. All locations from both countries could be clustered into four groups on the basis of maximum and minimum temperatures, and day length. Locations within a cluster were defined as being a homoclime with each other. Locations from central Queensland and central India were clustered into one group, locations from northern Australia and peninsular India into a second cluster and locations from southern Queensland and northern India into a third cluster. A fourth cluster consisting of most of the southern Australian locations did not cluster with any of the Indian locations. The analysis revealed that all Queensland locations studied had homoclimes in India, which suggests there may be good scope to introduce promising Indian chickpea cultivars from each of the respective homoclimes.

Jens Berger1, Neil C. Turner1,2 and Renee P. Buck 2

In contrast to its annual, cool-season wild relatives, the chickpea (Cicer arietinum) developed as a post-rainy season, spring-sown crop early in its evolution. We suggest that these different life cycles imposed different selection pressures on the wild and cultivated Cicer species, and that as a result different phenological strategies are likely to be expressed. To test this hypothesis, diverse wild and cultivated Cicer species from a wide range of habitats were subjected to different cold treatments, and evaluated in the field. In terms of days to flowering, C. arietinum, C. yamashitae, and most C. judaicum accessions were unresponsive to vernalization, whereas the opposite was the case for C. echinospermum and C. pinnatifidum. C. bijugum and C. reticulatum were intermediate, with around 50% of accessions vernalization responsive. Since both C. echinospermum and C. reticulatum are commonly used in chickpea improvement programs this has important ramifications for breeders. The time interval between flowering and podding was significantly smaller in wild Cicer species (mean: 5-7 days) than in the cultigen (mean: 14 days), and this may be a reflection of reduced susceptibility to cold temperatures in the wild species, a trait urgently required in chickpea.

Anupreet Kour and S.P. Singh

The objective of this study was to assess the genetic divergence available in different genotypes of Brassica juncea based on analyses of seed storage proteins, for the identification of genetically diverse and agronomically superior accessions of rapeseed, which may generate putative transgressive segregates on hybridization. Diversity within species of Brassica juncea can be analyzed at molecular level with the help of seed storage protein by using SDS-PAGE. On the basis of banding pattern on the gel zymogram (Diagrammatical representation of different protein bands) was sketched. By which, Euclidean distances were measured and a dendogram was formed on the basis of Rf values of different bands on the gel. With the help of this dendogram genotypes were clustered into different groups, by applying UPGMA (Unweighed paired group mean analysis).

Qiu Lijuan, Guan Rongxia, Li Yinghui, Wang Lixia, Guan Yuan, Yan Zhe, Ma Yansong, Piao Rihua, Li Linhai, Ning Xuecheng, Zhu Li, Li Wei, Lin Fanyun, Luan Weijiang, Liu Zhang Xiong and Chang Ruzhen

China owns the most soybean germplasm in the world, and it becomes urgent task to evaluate and utilize the collection efficiently. Based on the phenotypic data of Chinese soybean germplasm, a total of 20 sampling methods were compared and the best one was subjected to establish primary core collection, which was proved to have representative for the whole collection. A core set of SSR loci were identified with 80 autumn soybean accessions and confirmed with 190 random soybean accessions from the whole country. By analyzing the primary core collection with a core set of SSR loci, 1055 cultivated soybean accessions, taking of the 5% of the whole collection, was selected as the core collection, which represent over 85% genetic diversity of the whole collection. Meanwhile, the good quality sub-collections were set up in order to meet the needs of soybean breeding, and they were compared with the reserved collections for the frequencies of accessions with lacking 28K or high 11S/7S ratio. The results showed that the prior collections had higher ratio for the targeted traits and a novel cultivated soybean lacking β subunit was found. It indicates that the core collection will play a very important role in mining gene, functional genomic study and soybean cultivar improvement.

Mingpei You1, Jeffery Boersma2, Bevan Buirchell1,2, Mark Sweetingham and Huaan Yang1,2

Anthracnose caused by the fungal pathogen Colletotrichum lupini is the most serious disease in lupin worldwide. An anthracnose resistant cultivar Tanjil was crossed with a susceptible cultivar Unicrop in narrow-leafed lupin (Lupinus angustifolius). Glasshouse disease tests on F2 and F8 progenies indicated that anthracnose resistance in Tanjil was controlled by a single dominant gene designated as Lanr1. The parents and the representative progenies were used in searching for candidate molecular markers using MFLP and NBS-FLP methods. Two pairs of co-dominant polymorphisms were detected, and were converted into sequence-specific PCR markers desirable for routine marker implementation. Linkage analysis suggested the two markers were flanking the anthracnose resistance gene Lanr1. One marker (AntjM1) is 3.5 centiMorgans (cM), and the other marker (AntjNBS) is 2.1 cM to the gene Lanr1. The markers have been implemented in the Australian national lupin breeding program. In 2003, over 7000 lupin breeding materials were screened with these markers for marker-assisted selection.

Maria Luz C. George1, David Hoisington2 and Kevin Pixley2

The Asian Maize Biotechnology Network (AMBIONET), a collaborative research, training, and information network, aims to help national programs in China, India, Indonesia, Philippines, Thailand and Vietnam apply modern science and technologies for maize improvement. Network activities are geared towards building capacity through workshops and exchange visits, supporting collaborative research through the provision of funds and scientific/technical support, and promoting the sharing of research results, technologies and materials.

Collaborative research under AMBIONET is focused on the use molecular markers to more efficiently address maize production problems of national and regional importance. Characterization of a collection of inbred lines, including tropical and subtropical lines from the Asian national programs, showed that breeding activity in the region has not caused a decline in the overall amount of diversity. About half of the alleles observed in the Asian lines had frequencies of 0.10 or less, and only 2 % had frequencies > 0.80, indicating the presence of many alleles, and thus a high level of diversity. Quantitative trait loci with significant effects on resistance to the five downy mildew diseases in the region, including a strong and stable QTL on chromosome 6, were identified. The next steps that build on the existing momentum generated by the network are also discussed.

Shihuang Zhang and Xinhai Li

Characterization of the quantitative trait loci (QTL) involved in flowering time will be helpful for selection in maize breeding. In this study, three flowering traits of 234 F2:3 families, derived from the cross X178×B73, were evaluated under well-watered and water-stressed regimes in Linfen city of Shanxi province, China. The Simple Sequence Repeat (SSR) marker map was used to identify QTL conferring flowering traits. Correlation analysis showed that anthesis silking interval (ASI) was significantly correlated with female flowering trait (FFT). With composite interval mapping, 9, 7 and 6 QTLs were identified for male flowering trait (MFT), FFT and ASI under water-stressed regime, respectively, and individual QTL could account for 2.88%- 31.65% of phenotypic variation. Some QTLs for MFT were found to overlap with those for FFT and ASI. The QTL adjacent to nc134 on chromosome 9 was consistently mapped for MFT, FTT and ASI under two water regimes, and the QTL near phi053 on chromosome 3 was mapped both for MFT and FFT.

Masao Watanabe1, Go Suzuki2, Yoshinobu Takada1, Tomohiro Kakizaki1, Hiroshi Shiba3, Seiji Takayama3 and Akira Isogai3

Self-incompatibility (SI) discriminating self vs. non-self pollen is regulated by S-locus genes in Brassica species. In most of the S haplotype, a highly polymorphic S-locus glycoprotein (SLG) gene is tightly linked to genes for the SI determinants, S-receptor kinase (SRK) and S-locus protein 11 (SP11), although the precise function of SLG in SI reaction has not been clarified. In the present study, we performed DNA gel blot analysis for S32, S33, and S36 haplotypes of B. campestris showing normal SI phenotypes, and concluded that there might be no SLG in their genome. RNA gel blot analysis of the SLG-less S haplotypes indicated the possible existence of eSRK transcripts in the stigma. Furthermore, we constructed a catalogue of cDNA clones, which were hybridized to SLG45 cDNA, in S36 haplotypes. These three S haplotypes are useful resources to discern the molecular mechanism of the SI reaction without SLG.

Gail Timmerman-Vaughan1, A Mills1, TJ Frew1, R.C. Butler1, J.A. McCallum1, Sarah Murray1, C.P. Whitfield1, A.C. Russell2 and D.R. Wilson1

Improvement of yield in pea is a major objective. Yield is a complex trait that is strongly influenced by both genotype and environment. The yield of pea crops can be described in terms of its components which include plant number per unit area, seed weight and seed number. These yield components show interdependence or “plasticity” which makes it very unlikely that selection for increased yield based on a single component will succeed. Using molecular linkage maps of the pea genome and QTL mapping we have characterised the genetics of yield per se, yield determinants (seed weight, seed number and harvest index) as well as developmental traits. The traits were measured in three replicated field trials managed to ensure maximum expression of yield potential. Genetic loci affecting yield-related traits occur in 19 pea genomic regions. In addition, QTLs for different yield-related traits coincided in clusters, providing the basis for understanding at the genetic level the “plasticity” that is observed among yield components.

S.N. Ahn, C.S. Oh, S.J. Lee, D.B. Yoon

This study was conducted to identify the genetic basis of the domestication-related traits in weedy rice. An RIL population consisting of 80 lines was developed from a cross between the japonica weedy rice, Hapcheonaengmi 3 and the Tongil-type cultivar Milyang 23. The population was genotyped with 133 DNA markers, and also evaluated for 20 traits related to domestication and agricultural performance. A total of 52 QTLs and two loci associated with qualitative variation for pericarp and base coloration were identified using single point and interval analysis. The number of QTLs per trait ranged from one to six. These 52 QTLs were located in 24 intervals distributed on 11 chromosomes. The results indicated that most domestication-related traits clustered in chromosomal blocks, and the positions of many of these clusters were consistent with those reported in previous studies. For 10 (40%) of the QTLs identified for agricultural performance in this study, the Hapcheonaengmi 3-derived allele contributed a desirable agronomic effect despite the overall undesirable characteristics of the weedy phenotype. Favorable wild alleles were detected for days to heading, panicle exertion and primary branch number. When compared with previous studies involving interspecific crosses, it can be concluded that weedy rice is useful as a source of valuable alleles for rice improvement.

Kyujung Van1, Eun-Young Hwang2, Moon Young Kim1, Suk-Ha Lee1 and Perry B. Cregan2

Single nucleotide polymorphisms (SNPs) including insertion/deletions (indels) serve as useful and informative genetic markers. High throughput and inexpensive SNP typing systems are another reason why there is much current interest in the development of SNP markers. Fifteen soybean genotypes from Korea and USA were used for surveying sequence variation. After fragments were amplified with primers derived from 110 soybean ESTs from GenBank using genomic DNA as a template, direct fluorescent dideoxynucleotide sequencing data of PCR products were analysed by SeqScape software to ensure accurate SNP discovery. Among 35 ESTs with at least one SNP in the 15 soybean genotypes, SNPs occurred at a frequency of 1 per 2,038 bp in 16,302 bp of coding sequence and 1 per 191 bp in 16,960 bp non-coding regions (5’ UTR, 3’ UTR and introns). This corresponds to a nucleotide diversity (θ) of 0.00017 and 0.00186, respectively. Of the 97 SNPs discovered, 80.4% were present in the six North American soybean mapping parents Archer, PI 209332, Peking, Minsoy, Noir 1 and Evans. Only 66 (68%) of the SNPs were present among the nine Korean cultivated genotypes. The addition of Pureunkong to the North American mapping parents increased the number of SNPs detected to 84 (86.6%) while the addition of Hwaeomputkong, which originated from Japan, increased the number to 92 or 94.8% of the total SNPs present among the 15 genotypes. Thus, Hwaeomputkong and six North American mapping parents provide a diverse set of soybean genotypes that can be successfully used for SNP discovery in coding DNA and closely associated introns and untranslated regions.

Young-Sup Ahn1, Yeon-Sang Song1, Byeong-Choon Jeong1 and Kyung-Soo Min2

Korean sweetpotato varieties were examined for their flowering response, and self- and cross-incompatibility, and RAPD analysis was tried to assess genetic variation in cross-incompatible groups. Six cross-incompatible groups were revealed from complete diallel crosses with thirty three Korean Ipomoea batatas varieties. The standard variety for classification of cross-incompatible S1, S2, S3, S4, S5 and S6 group was determined on the basis of flowering, self- and cross-incompatibility. From the results of reciprocal crosses with standard varieties, 8 varieties including Jinhongmi were classified as cross-incompatible S1 group, 12 varieties including Mokpo #39 as S2 group, and etc. Saengmi was determined as a variety of complex cross-incompatible S2S1m group, Hwangmi as one of unidirectional cross-incompatible S2m group, Mokpo #32 and Mokpo #34 as those of unidirectional cross-incompatible S3f group. Further studies with more primers were needed for classification of cross-incompatible groups by RAPD analysis.

Ki-Won Oh1, Chan-Sik Jung1, Hyeun-Kyeung Kim1, Myung-Hee Lee1, Chung-Berm Park1, Byung-Joo Kim2 and Duck-Yong Suh1

Enrichment methods were optimised in order to isolate large numbers of simple sequence repeat (SSR) markers for Allium senescens, with the aim of developing a comprehensive set of loci for apomixis and developing useful markers for genetic studies of Allium species. Four libraries were constructed showing greater than 20 % enrichment for a variety of SSR-motif types. Sequence characterisation of 796 clones identified 263 SSR-Containing closes. Truncation of flanking sequences limited potential primer design to 100 clones. The enrichment efficiency of six cutter restriction enzyme Sau3AI was higher than that of four cutter restriction enzyme MseI (48% vs. 22%). Developed primers were characterized and the size of amplified fragment was same as expected.

Subhash Chandra, Hutokshi K. Buhariwalla, J. Kashiwagi, S. Harikrishna, K. Rupa Sridevi, L. Krishnamurthy, Rachid Serraj and J.H. Crouch

The approach widely adopted to identify genetic markers (QTLs) linked to quantitative traits is based on using a genetic map uniformly populated with 100-300 markers. In less studied crops, this may not be feasible due to paucity of adequate number of polymorphic markers. With only a few (say m) polymorphic markers available, we propose a multiple marker analysis approach to reliably identify important markers for use in marker-aided selection (MAS). Assuming availability of a large mapping population, the approach is based on Bayesian information criterion applied on all possible 2m regressions. We demonstrate the approach using data on 257 RILs genotyped for 14 microsatellite markers to identify markers linked to three drought-avoidance traits in chickpea.

Shravani Basu1, Jeremy Roberts1, Richard Mithen2, Sayed Azam-Ali1 and Rémy Pasquet3

Bambara groundnut (Vigna subterranea (L.) Verdc.) is an African legume valued for its drought tolerance and resistance to pests and diseases. It consists of two botanical forms: var. spontanea, comprising the wild forms, restricted to Cameroon; and var. subterranea comprising the cultivated forms found in many parts of the tropics particularly sub-Saharan Africa. To date, there are no established varieties of bambara groundnut, and marginal and subsistence farmers throughout Africa grow locally adapted landraces. A cross was made between wild (VSSP11; V. subterranea var. spontanea) and cultivated (DipC; V. subterranea var. subterranea) accessions (2n = 22), from Cameroon and western Botswana, respectively, and the F1 hybrid self-pollinated. The resultant F2 progeny have been used to study a range of traits of agronomic interest including internode length, Water Use Efficiency (WUE) using Carbon Isotope Discrimination (Δ13C), seed weight and testa colour. Polymorphic AFLP (Amplified Fragment Length Polymorphism) markers, using different primer combinations, have been identified between the two parental lines and their segregation studied in the F2 mapping population, the latter comprising more than 100 plants. In addition to mapping monogenic traits like the presence (DipC) or absence (VSSP11) of an eye pattern around the hilum, QTL (Quantitative Trait Loci) analysis of traits such as internode length, Δ13C, testa colour and seed weight will help to identify the regions of the bambara groundnut genome associated with these important traits.

Jong-Sik Lee1, W.G. Ha1, J.K. Chang1, K.L. Ryu1, Jun Hyeon Cho1, You-Chun Song1, Oh-Kyung Kwon1, S.J. Yang1, H.Y. Kim2 and H. S. Suh3

The objective of this study was to identify QTLs associated with the chemical traits and palatability of cooked rice in japonica rice recombination. The population used in this study consisted of 179 F7~8 recombinant inbred lines (RILs) derived from a japonica rice cross between Ilpumbyeo with an excellent eating quality and YR15965Acp33 with a poor eating quality through method a single-seed descendent. The high palatability of Ilpumbyeo was mainly originated a high palatability Japanese variety, Koshihikari. YR15965Acp33 was derived from a combination between temperate japonica variety, Hwayeongbyeo, and sub-tropical japonica, Shennung 89-366. The 179 RILs and their parents were cultivated at three locations, namely: Sangju (mid-mountainous area), Yeongdeog (coastal area) and Milyang (plain area) in 2000 and 2002. To obtain the putative QTLs associated with amylose content, protein content, and Mg/K equivalent ratio, Toyo taste meter value (TTV) were analysed. In the chemical traits, four QTLs For amylose content were detected in two environments and located in the same on chromosomes 2 and 12, respectively. All of the QTLs for protein and Mg/K were not detected in any more two environments. Eighteen QTLs for TTV were detected on six out of twelve chromosomes. The QTLs on chromosomes 1, 6, 7, and 12 were detected in more than two environments and located in the same or similar loci. The QTLs associated with on chromosome 12 were detected in all environments tested. Two RILs showing significant transgressive segregation for TTV should be useful as a good breeding material for eating quality.

Jun Hyeon Cho, D.Y. Kwak, K.H. Yi, Y.J. Weon, J.M. Ko, H.M. Park, S.J. Yang and Min-Hee Nam

Bulked segregation analysis(BSA) was used to identify random amplified polymorphic DNA(RAPD) markers linked to the rice stripe virus resistance gene, Stvb-i, in rice. Using two pools of phenotyped lines from a 169 DH population, we identified four RAPD markers positively linked to Stvb-i gene. The RAPD markers were mapped to chromosome 11 on the SSLPs map and one RAPD marker, OPO11, showed complete linkage to Stvb-i. When the selected specific marker was used on all of japonica, indica and tongil type varieties developed in Korea, the positive amplication of about 2500bp fragment generated from OPO11 was observed in only japonica varieties in which Stvb-i gene was used as a source of RSV resistance gene while the other susceptible japonica and all indica as well as tongil varieties showed negative reaction. Therefore, this can be used in the marker-assisted selection of stripe resistant individuals carrying the Stvb-i gene.

Daryl Mares1, Benedette Cavallaro2, Eric Storlie2 and Mark Sutherland2

Molecular markers were linked to a QTL (Quantitative Trail Locus) controlling grain dormancy on chromosome 4A of wheat. Seven Simple Sequence Repeat (SSR) and one candidate gene markers were linked within an interval of 110 cM. The most likely position of the QTL was estimated to reside within a 20 cM span between two SSR markers, GWM397 and WMC468. These markers explained 13 and 11 percent of the variation, respectively, for germination index (GI) scores, an indicator of dormancy and predictor of preharvest sprouting. The results suggest flanking markers for a QTL on chromosome 4A will facilitate the selection of less susceptible preharvest sprouting genotypes.

Theerayut Toojinda1, Somvong Tragoonrung2, Apichart Vanavichit3, Jonaliza L. Siangliw1, Nathinee Pa-In1, Jutarat Jantaboon1, Meechai Siangliw1 and Shu Fukai4

In the past 20 years, the rice-breeding program in Thailand had little success in developing new cultivars to replace Kao Dawk Mali 105 (KDML105) and Kao Khor 6 (RD6). Main reason is a poor adoption of new cultivars by farmers due to poor adaptation of new cultivars to the rainfed environments, susceptibility to diseases and insect pests and unacceptable grain qualities. The conventional breeding program also takes at least 15 years for releasing new cultivars. New breeding strategy can be established to shorten period for cultivar improvement by using marker-assisted selection (MAS), rapid generations advance (RGA), early generation testing in multi-locations for grain yield and qualities. Four generation of MAS backcross breeding were conducted to transfer gene and QTL for bacterial blight resistance (BLB), submergence tolerance (SUB), brown planthopper resistance (BPH) and blast resistance (BL) into KDML105. Selected backcross lines, introgressed with target gene/QTL, were tolerant to SUB and resistant to BLB, BPH and BL. The agronomic performance and grain quality of these lines were as good as or better than KDML105.

Peter Wenzl1, 3, Vanessa Caig3, Jason Carling3, Cyril Cayla1, Margaret Evers1, Damian Jaccoud2, Sujin Patarapuwadol2, Grzegorz Uszynski1, Ling Xia3, Shiying Yang2, Eric Huttner1, 2, 3and Andrzej Kilian1, 2, 3

Genetic diversity is the raw material available to plant breeders. By productively recombining genetic diversity, plant breeders have been successfully producing year after year improved cultivars of the major domesticated species used in the world’s diverse agricultural systems. Molecular genetic markers offer a powerful tool to accelerate and refine this process. Existing genetic marker (genotyping) technologies, mostly developed for applications in human health, have been applied successfully to agricultural species too, but their cost remains prohibitive for most agricultural applications. This is particularly true for species for which no molecular data and very limited resources are available. Because of the limitations of existing marker technologies, we have developed Diversity Arrays Technology (DArT), a novel method to discover and score genetic polymorphic markers. DArT is a sequence-independent, high-throughput method, able to discover hundreds of markers in a single experiment. DArT markers are typed in parallel, using high throughput platforms, with a low cost per datapoint. DArT fingerprints will be useful for accelerating plant breeding, and for the characterisation and management of genetic diversity in domesticated species as well as in their wild relatives. We have developed DArT successfully for rice, barley, wheat and cassava and have produced a dedicated data management and analysis package, a key part of the technology, entirely built from Open Source components. We have a high interest in developing partnerships to establish DArT for many species, and we are developing a network model for the delivery of technology to users.

S Senthilvel1, P Govindaraj1, S. Arumugachamy1, R Latha1, P Malarvizhi2, A Gopalan1 and M. Maheswaran3

Rice cultivars with improved nitrogen use efficiency are becoming a prerequisite for lowering production costs. Such cultivars protect the environment and improve rice yield with a guarantee for sustainability in agriculture, while maintaining soil and ground water quality. This warrants a better understanding of the genetic and physiological control of nitrogen uptake and assimilation in rice for which application of molecular markers is considered as viable option. In this study, an attempt was made to identify genomic regions associated with nitrogen uptake and grain yield under sub-optimal level of applied nitrogen using 190 F2 individuals of the cross Basmati370 × ASD16. Parental survey with 264 SSR primer pairs and 9 ISSR primers showed 52 per cent polymorphism between the parents. The segregation patterns of 60 SSR markers were scored on F2 population and a framework map was constructed with 12 linkage groups corresponding to 12 rice chromosomes. The F3 families derived from 190 F2 lines were evaluated in the field without addition of nitrogenous fertilizer. Nitrogen content in grain and straw, grain yield and dry matter production were estimated and the nitrogen uptake and translocation efficiency were derived for parents and segregating progenies. ASD16 was more efficient in N uptake and use compared to Basmati370. Wider variation with transgressive segregation for different traits was observed among the F2:3 families. By adopting single marker analysis, the SSR markers associated with each phenotypic trait were identified, which may be used to proceed further to track down the network of genes associated with NUE in rice.

E. Ravindra Babu, V.P. Mani and H. S. Gupta

Maize endosperm consisting of approximately 9-12 per cent protein is, however, deficient in two essential amino acids viz., lysine and tryptophan, which leads to poor net protein utilization and low biological value of traditional maize varieties. The low nutritive value of maize is genetically corrected in the biofortified form known as Quality Protein Maize (QPM), which contains twice the amount of lysine and tryptophan with high protein biological value. The opaque-2 gene along with necessary modifiers is primarily responsible for the enhanced protein quality. Four normal inbreds viz., CM212, CM141, CM145 and V25, which are parents of three single cross hybrids were targeted for conversion into high quality protein versions using three SSR markers located within opaque2. Two SSR markers viz., phi057 and umc1066 were co-dominant while phi112 was dominant in nature. Upon screening of appropriate back cross populations (BC) with phi057 and umc1066, around 50 per cent plants in each BC population were found to be heterozygous for the opaque-2 (Qq) gene. The selected BC2 progenies were advanced to selfing generation and similar molecular marker analysis was performed to identify the desirable homozygous recessive individuals (qq) in the selfed populations. The converted maize lines had twice the amount of lysine and tryptophan than the native lines and hence could be used as potential food and feed alternatives in resource-poor and marginal areas in general and hill ecosystems in particular. Based on the results obtained in our experiment, we propose that foreground selection in an early (BC1) generation combined with background selection at a later generation (BC2) along with the phenotypic selections for quantitative/continuously distributed traits would result in rapid genetic gain in a cost effective manner.

Ping Mu, Zi-chao Li1, Chun-ping Li, Hong-liang Zhang and Xiang-kun Wang

A DH (doubled haploid) population, derived from a cross between Japonica upland rice IRAT109 and Japonica paddy rice Yuefu, was used in this study. Three culm traits, basal culm thickness(BCT), culm length (CL) and culm strength (CS), of DH lines and their parents under upland and lowland cultural conditions at milk stage were evaluated. Data from upland and lowland cultural conditions were analyzed based on a constructed molecular linkage map(including 94 RFLP markers and 71 SSR markers and covering 1535.1cM )and the software QTLmapper version 1.0. QTLs and QTL×environment interactions for BCT, CL and CS were obtained. A total of six additive QTLs and eight pairs of epistatic QTLs associated with these traits were found. There was only one additive QTL performed significant interactions with environment. Two pairs of epistatic QTLs associated with CS were detected with a high general contribution of 24.01% and 36.45% respectively.

Adele L. Schmidt1*, Chunji Liu1, David Martin2, Allison Kelly2 and Lynne McIntyre1

This paper reports results of a three-year study aimed at the identification of molecular markers for key quality traits specific to the Australian Northern Region. Using Australian germplasm, we have identified molecular markers for milling yield, water absorption, flour colour and specialised dough development properties required for expansion into markets where sponge and dough style baking dominates. Novel marker-trait associations were identified for milling yield, dough strength and dough development time. A novel sponge and dough QTL has been located on chromosome 4B and work is currently underway to refine the genetic map and further characterise this locus.

Mahmoud Toorchi1,*, H.E. Shashidhar2, Naveen Sharma2 and Shailaja Hittalmani2

A dynamic root system is fine-tuned to soil moisture status and is known to regulate the amount of water available to the plant depending on its distribution in the soil. Recent advances in genome research, particularly in the field of molecular marker technology, have generated opportunity to dissect the variation in quantitative traits in a more meaningful way. We adapted selective genotyping strategy and STMs markers for mapping QTLs for maximum root length in rainfed lowland rice. Total of 69 extreme plants were selected from P124 x IR64 mapping population for selective genotyping because of good combination of genetic factors conferring drought tolerance and yielding ability. Forty-two pairs of STMS primer pairs that were earlier found to be polymorphic between the IR64 and Azucena were selected and used in the present study. A total of 4 QTLs were found for maximum root length under well watered and low moisture stress and mean conditions.

Bob Eisemann1, Phillip Banks1, David Butler1, Mandy Christopher1, Ian DeLacy2, David Jordan3, Emma Mace3, Paul McGowan1, Lynne McIntyre4, David Poulsen3, David Rodgers1 and John Sheppard1

The pedigree-based genome mapping project will investigate and develop systems for implementing marker assisted selection to improve the efficiency of selection and increase the rate of genetic gain in breeding programs. This is a pilot project to test protocols for implementation of pedigree-based whole genome marker analysis in northern region winter cereal breeding programs. It aims to provide useful information about the use of simple sequence repeat (SSR) and other types of molecular markers for routine genomic analysis, the integration of genotypic, phenotypic and pedigree information for targeted wheat and barley lines, the genomic impacts of strong selection pressure in case study pedigrees, and directions for future pedigree-based marker development and analysis.

Theerayut Toojinda1, Somvong Tragoonrung2, Apichart Vanavichit3, Jonaliza L. Siangliw1, Nathinee Pa-In1, Jutarat Jantaboon1, Meechai Siangliw1, Shu Fukai4

In the past 20 years, the rice-breeding program in Thailand had little success in developing new cultivars to replace Kao Dawk Mali 105 (KDML105) and Kao Khor 6 (RD6). Main reason is a poor adoption of new cultivars by farmers due to poor adaptation of new cultivars to the rainfed environments, susceptibility to diseases and insect pests and unacceptable grain qualities. The conventional breeding program also takes at least 15 years for releasing new cultivars. New breeding strategy can be established to shorten period for cultivar improvement by using marker-assisted selection (MAS), rapid generations advance (RGA), early generation testing in multi-locations for grain yield and qualities. Four generation of MAS backcross breeding were conducted to transfer gene and QTL for bacterial blight resistance (BLB), submergence tolerance (SUB), brown planthopper resistance (BPH) and blast resistance (BL) into KDML105. Selected backcross lines, introgressed with target gene/QTL, were tolerant to SUB and resistant to BLB, BPH and BL. The agronomic performance and grain quality of these lines were as good as or better than KDML105.

Karen Aitken1, Phillip Jackson2, George Piperidis3, and Lynne McIntyre1

Sugarcane is a highly complex, heterozygous interspecific polyploid and cultivars commonly have over 100 chromosomes. Using more than 1000 AFLP and SSR markers scattered across the genome we have analysed the inheritance of quantitative traits (QTL) for yield components on 230 progeny from a cross between sugarcane cultivar (Q165 A) and a S. officinarum clone (IJ76-514). The population was evaluated in a replicated field trial for three yield components, stalk weight, stalk diameter and stalk number. Thirty-two putative QTL were identified for the three traits. Each QTL explained from 3 to 9% of the variation and eleven of these QTL were identified for more than one trait. Further work is underway to determine their repeatability in populations derived from progeny of this cross and their value for marker-assisted selection.

P.V. Balakrishna1, H. S. Bariana1, R. P. Singh2, A.Verbyla3& R. F. Park1

Stripe rust, caused by P. striiformis f. sp. tritici is an important disease of wheat that causes wide spread losses in many countries. This study was aimed to identify molecular markers linked to adult plant resistance to stripe rust in wheat (Triticum aestivum L), which could ease the incorporation of such resistance into newer wheat germplasm. A single-backcross derived F6 population from the cross Avocet S x 11IBWSN50 was used. Simple single marker regression analysis identified 2 genomic regions, 7DS and 4BL, involved in reduction of stripe rust severity. These findings putatively establish Yr18/Lr34 association on 7DS in 11IBWSN50. This also indicated that stripe rust resistance controlled by a genomic region on chromosome 4BL may be associated with leaf rust resistance similar to that of Pavon 76.

Bahman Fazelienasab1, Mansour Omidi2 and Mehdi Amiritokaldani3

Response of five cultivars of Iranian bread wheat to mature embryo culture and different concentrations of ABA was examined. Mature embryos from five cultivars (Tabasi, Bolani, Shiraz, Shoaleh and Azar) were placed in MS medium supplemented with 10 mg/l 2-4-D and 30 g/l sucrose and under different levels of ABA (0, 2, 4, 6 and 8 mg /l). Callus growth was measured by volume using a hoker scale. There were significant differences among cultivars in callus growth rates. Tabasi and Bolani showed the best and the least callus growth, respectively. In addition, ABA levels had significant effects in callus induction. The best and the least callus volume were observed in control and 8 mg/l ABA treatment, respectively. In fact, the more hormone used, the less callus gained. The interaction between ABA levels and cultivars was not significant, indicating this hormone in all levels affected callus induction of all cultivars in the same manner. In control treatment calluses had the brightest colour and with increase in ABA concentration calluses became darker; in 8 mg/l ABA calluses became dark-brown. In this manner, with increase in ABA concentration in mediums calluses compacted and the most friable calluses were observed in control medium. When regeneration rates were compared, there were significant differences among cultivars and ABA levels. The best and the least regeneration percentage were observed in control and 8 mg/l ABA level, respectively. Tabasi showed the maximum regeneration rate. In contrast with callus induction, the interaction between cultivars and ABA levels was significant and suggested that different ABA levels had different effects on cultivars.

H.M. AbdElGhany1, A.A. Nawar2, M.E. Ibrahim2, Sh.A. El-Shamarka2, M.M. Selim1 and A.I. Fahmi2

Breeding wheat varieties tolerant to drought stress is an important aim of the breeding programs in Egypt. The aim of this study was to examine the growth and regeneration of calli, derived from embryos of range of bread wheat varieties, under different mannitol concentrations (osmotic potentials = 0, 0.6, 0.9, and 1.2 MPa) and to compare any differences in growth with their growth and yield in field experiment. There were highly significant interactions between variety and mannitol concentration for callus survival and regeneration ability. Sakha 8 and Giza 157 gave the highest mean values for all callus traits and Sakha 8 and Sids 1 had the highest callus survival % and regeneration ability at high concentration of mannitol. Sakha 8 and Sids 1 also had the highest mean values for grain yield/plant in the field experiment when water was withheld after flowering. The varieties which had high and/or stable mean values for most traits under the two irrigation systems were Sahka 8, Giza 157 and Sids 1, suggesting the possibility of selection for drought tolerance under laboratory condition.

Mukta Sirohi, Navneeta Kaushik and V.K. Khanna

Six wheat genotypes were crossed with a composite maize variety “Kanchan” and frequencies of haploid embryo formation were compared. All the wheat genotypes produced seeds and embryos following post- pollination treatments with 2,4 –D and GA3. Seed set percentage among six wheat genotypes varied from 77.5 to 93.36 % while the frequency of embryo formation ranged from 2.2 to 9.53 % across all genotypes. Analysis of variance clearly revealed the effect of wheat genotypes on the percentage of embryo formation. Reasons for the genotypic effect of wheat need to be investigated to increase the efficiency of the wheat x maize haploid production system. Using normal microscopy and aniline blue as a dye for staining, pollen tube behaviour was studied. Correlation studies were done between various pre- fertilization and post- fertilization factors. Number of embryos obtained showed a highly significant positive correlation with average pollen tube length and a highly significant negative correlation with abnormal pollen tubes.

Pablito M. Magdalita1, Olivia P. Damasco1, Joseph C. Beredo1 and Stephen W. Adkins2

The acclimatization and ex vitro establishment of tissue cultured coconut plantlets regenerated either from zygotic or somatic embryos could result to serious losses. Although high germination rates can be achieved in vitro, the survival of zygotic embryo derived plantlets in soil is very low (0-30%). Hence, treatments that could promote development of good quality seedlings having well-developed shoot and root is needed to increase seedling survival ex vitro. The effect of physical, chemical and light quality treatments on germination and growth of coconut embryos and tissue-cultured seedlings respectively, was investigated. The germination of coconut embryos was promoted when placed in a liquid Euwens (Y3) medium and incubated using a roller drum. Gibberellic acid (GA3) significantly affected growth of seedlings as it promoted shoot elongation, shoot and root expansion, and fresh and dry weight increase. However, GA3 did not significantly affect germination. In addition, the blue, red and yellow light significantly affected growth of seedlings as it promoted leaf and shoot elongation, fresh and dry weight increase, and root and leaf production. These conditions could be used to improve the growth and survival ex vitro of tissue cultured coconuts.

Yoko Akasaka-Kennedy1,2, Hidefumi Yoshida2, Masao Watanabe2 and Yoshihito Takahata2

We examined the frequency of bud formation in twenty genotypes of rapeseed (Brassica napus L.) from leaves. Two of the twenty genotypes reviewed are commercial cropping types, one a spring and the other a winter type. Excised leaves were cultured on B5 basal medium containing various PGRs. About three weeks after the initiation of culture, adventitious buds were formed at the cut surface of explants. The frequency of bud formation was strongly influenced by genotype, ranging from 0% to 91%. However, no relationship was found between spring and winter types.

Navneeta Kaushik, Mukta Sirohi and V.K. Khanna

Wheat polyhaploids were regenerated from embryos resulting from crosses with maize variety “Navin”. The frequency of the recovery of embryos was low when an aqueous solution of 2,4-D was injected to the uppermost internodes of crossed spikes or when 2,4-D was applied via spray and dipping methods. Higher embryo recovery was obtained using spikelet culture method due to the availability of favorable cultural conditions. The best age of the hybrid embryos to be rescued for in vitro condition was 17-19 days after pollination, which produced healthy looking seedlings. The embryos also varied in shape, size and developmental stage.

Victoria C. Lapitan1, Ernesto B. Cayaban2, Leslie T. Roferos1, Genaro O. San Valentin3 and Leocadio S. Sebastian4

Biotechnology can certainly provide solutions to most problems associated with breeding for rice improvement. Anther culture technique offers great opportunities for accelerating breeding progress and generating as well as directing variation to increase genetic diversity useful for rice improvement.

Through anther culture, we have generated 10 doubled haploid lines (DHLs) from F1-506, a cross between C4044-2B-2-2 and IR13540-56-3-2-1. Further evaluations of these lines both under screenhouse and field conditions resulted to selection of three (3) outstanding DHLs. Aside from giving stable performance, these lines were selected for their high phenotypic acceptability, high yield, and uniformity. Likewise, results of grain quality evaluation revealed that the selected DHLs were better than the parents. On the succeeding replicated yield trials (RYT), from R4 to R6 generations, these elite DHLs consistently outyielded the check varieties, IR72 and PSBRc 18. The results connote that anther culture technique shortened the breeding cycle as we have generated and developed elite breeding lines within 3 years while conventionally, it takes 6 to 7 years for selected inbreds to reach RYT.

From the other set of experiment, variants were generated from the popular IR64 variety utilizing the technique. Three (3) outstanding DHLs were produced with resistance to different soil-related stresses such as P, K, Zn, S, and Cu deficiencies. Evaluation of these variants showed improvements on their root system in terms of root length and weight as compared to the seed-derived IR64 variety.

Tomoko Hatanaka1, Shinya Yoshihara, Seiko Imoto, Naotsugu Uchida and Hyoe Tsugawa

Tanbaguro, a local variety of Japanese soybean [Glycine max (L.) Merrill] with a black seed coat, is very popular in Japan. In spite of its high price, its uses and demands are increasing. The objectives of this study were to establish a micropropagation system for black seed coat soybeans to obtain many uniform plants. A standard procedure of embryogenic culture was applied to two strains of Tanbaguro, “Hyokeikuro-3” and “Shin-tanbaguro”. Two regular cultivars, “Jack” and “Tamahomare” were used as controls. Our results showed that “Hyokeikuro-3” had a higher embryogenic capacity than Jack, a model cultivar for tissue culture study.

H Alizadeh, M.R. Naghavi, M. Omidi and B. Saatian

A new, simple and efficient method was developed for multiple shoot regeneration of wheat. The effects of different explants and various combinations of plant growth regulators on direct shoot regeneration of wheat were investigated. This method yielded a number of shoots within a short period of time. Shoot proliferation and elongation was achieved on shoot regeneration medium without any subculture. Direct shoot regeneration is important since fewer somaclonal variations are likely to arise in indirect regeneration method. Among different explants and different combination of 2,4-D, IAA, NAA and BAP tested, embryo explants cultured in MS medium supplemented with 1mg/l BAP, 0.2mg/l 2,4-D and 0.2mg/l IAA and excised embryo explants cultured in MS medium supplemented with 0.2 mg/l 2,4-D and 2 mg/l BAP resulted in the most efficient direct shoot regeneration and produced a maximum of 7 shoots per explants. Also important for shoot regeneration was the effect of the 4-week period of exposure to darkness followed by light exposure. Plantlets were successfully transferred to rooting medium.

H.Z. Wang, X.F. Wang, G.H. Liu, Y.B. Zheng and Q. Yang

In this study, totally 42 accessions of Brassica napus, most of them were maintainers and restorers of pol-CMS, were used to investigate the influence of genotypes on embryogenesis of microspore culture. The influence of genotypes, agar concentration in solid B5 medium and culturing temperature on direct plantlet formation from embryoids was also studied. The results showed that there were significant genotypic differences for embryogenesis among these genotypes. But the restoring or maintaining genes of pol-CMS did not affect embryogenesis of microspore culture. The efficiency of direct plantlet formation from embryoids was related to genotype, agar concentration in medium and culturing temperature. The results indicated that embryoids transferred to solid B5 medium with 1.5% agar and cultured initially in 4℃ for 10d could develop easily into normal haploid plantlets.

Deepak Prem1, Kadambari Gupta1 and Abha Agnihotri2

Indian mustard, Brassica juncea, is an important oilseed crop for the South East Asian region. An efficient doubled haploid generation system still remains a major constrain for crop improvement. Microspores isolated from flower buds containing majority of late uninucleate microspores from two B. juncea genotypes of Indian origin, namely ‘Pusa Bold’ and ‘Varuna’, were cultured in NLN-13 medium containing 10 µM silver nitrate. Activated charcoal associated with agarose gel significantly increased microspore embryo induction with an average of 349.5 embryos produced per petri dish containing 2.5 ml of culture suspension at a density of 40,000 cells per ml. The 21-30 days old dicotyledon embryos were germinated on B5 medium containing 2% sucrose (w/v) and 0.1 mg/L Gibberellic acid. A cold treatment of 4°C for 10 days in dark, followed by incubation at 25°C, resulted in an average of 82.9% embryo germination. The proportion of spontaneous diploids ranged from 0 to 12%. Root dip colchicine treatment was performed and effective chromosome doubling of achieved at 0.34% colchicine for 2 hour duration with an average of more than 60% plants producing doubled sectors. The plants were hardened and grown to maturity with a survival rate of more than 80% under controlled environment growth conditions. The frequency of microspore embryo/ doubled haploid production from the present investigation is about ten times higher than earlier reports and offers a great potential for its use in genetic enhancement of Indian mustard.

Janine Croser1, Monika Lulsdorf2, Bifang Cheng2, Kara Allen2, Julia Wilson1, Tim Dament2, Kadambot Siddique1, Tom Warkentin2 and Albert Vandenberg2

The ability to produce doubled haploid plants is an effective tool for accelerating homozygosity in many broad-acre crop species. The leguminous species are generally recalcitrant to this technique and there are only isolated reports of successful embryogenesis or plant regeneration. Collaboration between Australian and Canadian researchers has led to the development of protocols for the development to early stage microspore-derived embryos in chickpea and field pea. Stress pretreatments are used to induce the switch from gametic to sporophytic development. Immature chickpea flower buds are pretreated for 16 h at 32.5ºC, and field pea buds at 4ºC for 48 h. The microspores are cultured on AT3-1 or ML6 media to induce cellular division and embryogenesis. DAPI staining is used to enable analysis of cellular divisions which proceed via a symmetrical division of the vegetative nucleus and then continued division to a synctium prior to cellularisation. Experiments are underway to induce embryo maturation and plant regeneration.

Koichi Futakuchi1, Monty P. Jones2 and Olu Osiname3

After the success of developing interspecific Oryza sativa x O. glaberrima progenies for upland, WARDA has extended the target of the interspecific breeding to lowland. The interspecific crosses between the two species were initiated in 1996. After two backcrosses to the O. sativa parents, pedigree selection in lowland conditions started in 1998, of which major targeted characteristics were vegetative growth of O. glaberrima and reproductive growth of O. sativa associated with weed competitiveness and yielding ability, respectively. Expected interspecific progenies have been identified during the selection. Some interspecific progenies showed better growth (height and dry weight) and more allocation of dry matter to the leaves than the O. sativa check variety at the seedling stage, as did the O. glaberrima check. All interspecific progenies tested had the same or higher levels of yield than the O. sativa check varieties in both irrigated and rainfed lowlands. Yield of two interspecific progenies was more than double compared to that of the best O. sativa check in irrigated lowland.

R.S. Sain, P. Joshi and S.N. Sharma

Results of crossability revealed that crosses involving C. colocynthis as female parent had lower percent of fruit setting (4.76%) than the reciprocals (8.33%). Pollen fertility of F1 hybrids involving C. colocynthis as female parent was lower (30.1%) than the reciprocal (80.2%). The F1 plants of the hybrid resembled female parent for many morphological attributes including leaf shape, size and colour and flower size. The hybrid exhibited intermediary values between the parents for leaf area, days to opening of female flower, 1000 seed weight and oil content. While for fruit circumference, number of fruits per plant, fresh fruit weight, seed weight per fruit and number of seeds per fruit, hybrid was inferior to either of the parents. Hybrid involving C. colocynthis as female parent showed higher rate of seed abortion than reciprocal. In the F1 hybrid of cross GP 177 x TD 7 the majority of chromosome configurations was 1IV + 9II (17.8%), whereas the F1 hybrid of reciprocal cross was characterized by chromosome association 11 bivalents in majority (28.0%) followed by 1IV + 9II (23.1%) of pollen mother cells. Results of present study have clearly revealed that involving interspecific tumba derivative as seed parent, superior recombinants with higher frequency could be isolated. Present trend also indicated that interspecific derivatives with broader genetic base, large seeds, thin testa and with low seed-pulp ratio have enough scope for increasing the productivity under arid conditions.

Johnie N. Jenkins1, Jack C. McCarty1, Jixiang Wu2, Sukumar Saha1 and David Stelly3

Gossypium barbadense line 3-79 has exceptionally good fiber length, fineness, and strength. Chromosome substitution (CS-B) lines with individual 3-79 chromosomes or chromosome arms backcrossed into TM-1, G. hirsutum, were studied for combining ability following a top cross to five elite cultivars. General Combining Ability (GCA) effects predominated. Among the CS-B lines, CS-B25 had the highest GCA for fiber length and strength. Among the cultivars PCS 355 and FM 966 were the best in GCA for fiber length and FM 966 for fiber strength. Line 3-79 was the highest in GCA for fiber length and strength; however it also had very high negative GCA for yield and lint percent. These data suggest that these CS-B lines are useful for introgressing fiber quality genes from 3-79 into G. hirsutum; however, these CS-B lines do not solve all the problems with interspecific hybridization at the whole genome level commonly seen when crossing the two species.

Andres Godwin C. Sajise1, Simeona V. Siar1 and Juanito B. Sangalang2

Cross compatibility of four papaya inbred lines to an F1 intergeneric hybrid, Carica papaya x Vasconcella quercifolia line 410 was studied. Parental lines used were characterized morphologically. Resistance to papaya ringspot virus (PRSV-P) and pollen viability of line 410 was evaluated under local conditions. The genotypic compatibility among four crosses between the F1 intergeneric hybrid and papaya inbreds (4108, 4172, 5648, and 5893) was evident. Crosses to inbreds 5648 and 5893 produced fruits filled with many non-viable seeds while 4108 and 4172 produced few seeds but had embryos that grew in vitro. Remarkable differences were observed in morphological characters among papaya inbreds as well as between papaya and F1 intergeneric hybrid line 410. Cluster analysis divided parent materials into three. Papaya inbreds derived from local selections (4108 and 4172) and inbreds that were introduced from other countries (5648 and 5893) were on separate clusters. Line 410 has a separate cluster of its own.

Symptomatology and serological test by indirect ELISA (Enzyme Linked Immunosorbent Assay) confirmed that intergeneric hybrid line 410 plants have resistance against PRSV-P. A pollen viability assay using tetrazolium showed some viable pollen under local conditions.

C.G. Xu, H.Y. Liu and Qifa Zhang

Hybrid sterility frequently occurs in crosses between indica and japonica subspecies of Asian cultivated rice. In this study, we investigated the cytological processes involved in formation and development of male and female gametes as well as their interactions in fertilization, using an indica/japonica hybrid in comparison with an indica/indica hybrid. It was found that more than 50% of the microspores generated in the indica/japonica hybrid could not develop into functional pollen. The abortion rate of microspores in the indica/japonica hybrid was much higher than that in the indica/indica hybrid. Abortive embryosacs made up roughly 70% of the embryosacs examined in the indica/japonica hybrid, which was also much higher than that detected in the indica/indica hybrid. Moreover, the amount of pollen adherence on stigmas of the indica variety by hand-pollination of pollen from the japonica variety was much smaller than the indica/indica pollination, and the number of pollen grains adhered on the stigmas by natural self-pollination was much larger in the indica/indica hybrid than in the indica/japonica hybrid. The indica/japonica hybrid also encountered difficulties in pollen tube growth after pollination, and the fertilization rate of indica/japonica hybrid was much lower than indica/indica hybrid. These results clearly illustrated the complexity of the mechanisms underlying the inter-subspecific hybrid sterility in rice involving both pre- and post-zygotic reproductive isolation mechanisms.

Sanjeet Kumar, Vineeta Singh, Major Singh, Sanjeev Kumar, G. Kalloo and Mathura Rai

Validity of two RAPD markers (OPP131397 and OPW19800) associated with fertility restorer (Rf ) gene was tested in a panel of 47 newly identified restorer and maintainer inbred plants of pepper (Capsicum annuum L.). Among the 37 restorer lines identified during this study, OPP131397 and OPW19800 fragments were although repeatable and consistent, they were present only in 17 and 10 restorer lines, respectively. Thus the presence of these two markers often did not coincide with the presence of Rf gene, which suggest that the distribution and origin of both the markers are narrow. Hence search for more widely distributed Rf gene associated markers would be required to exercise marker assisted selection (MAS) for restorer and maintainer plants of pepper. The case specific applications of both the repeatable and consistent RAPD markers in cms heterosis breeding of pepper have been described.

Kinya Toriyama and Tomohiko Kazama

An ms-bo type cytoplasmic male sterile (CMS) line and its fertility restorer line are widely used for F1 hybrid seed production of japonica rice cultivars. We have carried out map-based cloning of the Rf1 gene and found that a 4.7-kb genomic fragment of a restorer line restored the fertility when introduced into a CMS line. The genomic fragment contained a single ORF encoding 791 amino acids protein, and the corresponding cDNA was isolated. The Rf1 gene encodes a protein with a mitochondrial targeting presequence of 26 amino acids and 18 repeats of the 35-amino-acid pentatricopeptide repeat (PPR) motif. A nonrestoring genotype (rf1) was identified to have deletions within the coding region. Introduction of the Rf1 gene is shown to promote the processing of an aberrant B-atp6 RNA in transgenic CMS lines with the Rf1 gene.

Ioannis S. Tokatlidis1 and Leonidas Giakalis2

Inbreeding depression is usually used to measure the load of deleterious genes. In this work inbreeding depression was related with reduced yield potential per plant and increased coefficient of variation (CV) of individual plant yield, as they had been estimated in F1 and F2 of eight maize (Zea mays L.) hybrids under very low density (0.74 plants/m2). Hybrids developed through selfing and on the basis of line performance per se, were found to have improved yield potential per plant in both F1 and F2, lower CV values in F2, and lower inbreeding depression. Results were indicative of effective exploitation of the additive genetic effects, in the aim to reduce the load of deleterious genes and to produce less heterozygous hybrids characterized by improved yield potential per plant, an essential trait for high and more stable productivity.

S. Gangaprasad, R.V. Sreedhar, P.M. Salimath and R.L. Ravikumar

Studies on induction of male sterility in crop plants using gametocides is of considerable economic importance since it facilitates production of F1 hybrid, which facilitates exploitation of hybrid vigour and produce highly productive recombinants. N-71 variety of niger (Guizotia abyssinica Cass.) was selected for induction of male sterility using various chemicals. GA3 proved to be the most potent gametocide for inducing male sterility in niger to the extent of 82.0% compared to 2, 4-D and surf excel. Both 2, 4-D and surf excel were found to have adverse effects on normal growth and development of plants.

S. Manonmani1, S Senthilvel2, A.K. Fazlullah Khan3 and M. Maheswaran4

Success of rice breeding depends on the ability to exploit the vast amount of genes and gene combinations in the rice gene pools that produce higher heterosis. Magnitude of heterosis depends on the choice of appropriate parental lines. Fourteen indica rice plants were assessed for diversity among them through isozyme and RAPD markers. The four isozyme systems viz., esterase, peroxidase, super oxide dismutase and polyphenal oxidase grouped the genotypes into eight clusters based on polymorphic marker loci. Diversity analysis using Randam Amphified Polymorphic DNA (RAPD) markers grouped the genotypes into a maximum of nine clusters. The genotypes viz., CR 1009, TNAU 841434 and AS 95035 were identified as more divergent by both the methods though these three genotypes share a common ancestral parent, Peta. Forty crosses were made using (four lines and 10 testers) the above fourteen parents and F1s were evaluated in two seasons along with their parents for expression of heterosis in plant height, number of productive tillers, days to 50% flowering, panicle length, number of filled grains per panicle, 100 grain weight and grain yield. Genetic distance based on isozyme analysis were correlated with mean performance and heterosis showed that there was no significant correlation between genetic distance and heterosis for any of the biometric characters in both the seasons. But positive correlation was observed between RAPD marker distance and statistical parameters viz., F1 per se performance, relative heterosis, heterobeltiosis and standard heterosis for number of productive tillers per plant and panicle length. The maximum heterotic value was observed in CR 1009 / HA 891037 in which both the parents were from different clusters. Thus RAPD's provide an effective tool for exploiting heterosis in rice.

Guoyou Ye, Mark Dieters, Alexander Pudmenzky, Kevin Micallef and Kaye Basford

Two positive assortative mating (PAM) schemes and the random single pair mating (RS) were compared by computer simulation for genetic gains over five breeding cycles and at each breeding cycle in the context of inbred line development. For the first scheme crosses were selected using the average genotypic value of the two parents (GV). For the second scheme, all parental lines were ranked in descending order based on their genotypic values, and then partial disconnected diallel mating was used to generate the required number of crosses (GP). Simulations carried out using 16 combinations of four inheritance modes (purely additive, dominant, and two-gene and three-gene epistasis), and four numbers of crosses (30, 60, 80, and 120) suggested that; 1) both GV and GP increased genetic gain substantially with GV being better than GP, 2) the benefit of PAM was greater under additive and dominant models, 3) the differences among the mating methods were largest in the first breeding cycle and decreased with subsequent breeding cycle, and 4) the resource allocation between making more crosses and testing more lines per cross under fixed testing capability (24,000 lines) was secondary to the mating method used. Though gain increased with the number of crosses for RS, 60-80 crosses were more appropriate for GV and GP. When number of crosses was fixed at 30, little extra gain could be achieved by testing more than 200 lines per cross. GV not only resulted in more gain but also reduced the number of lines per cross required to maximise gains.

Yuqing He, Xin Li, Jingfeng Zhang, Gonghao Jiang, Shiping Liu, Sheng Chen, Juming Tu, Caiguo Xu and Qifa Zhang

Shanyou 63, a cross between Zhenshan 97 and Minghui 63, is an elite hybrid rice cultivar widely grown in China. This study reports on the results of a series of marker-assisted breeding experiments designed to improve the disease and insect resistance of this hybrid. The main results are as follows: (1) two wide-spectrum bacterial blight resistance genes, Xa21 and Xa7, were incorporated into the restorer line Minghui 63 by molecular marker-aided selection (MAS). (2) Minghui 63 was transformed with a Bt δ-endotoxin gene to improve the stem borer resistance. (3) Xa21 and Bt genes were combined into a line with the of Minghui 63 background. (4) Two genes, Pi1 and Pi2, showing broad-spectrum resistance to fungi blast, were introgressed into Zhenshan 97 to improve the blast resistance by MAS. (5) Two genes, for to brown planthopper resistance, Qbph1 and Qbph2, were introgressed into Zhenshan 97. The above versions of improved lines can be combined in various ways to make new hybrids to meet the needs of rice production.

R Latha 1, S Senthilvel2 and K Thiyagarajan3

The utilization of thermo-sensitive genic male sterility (TGMS) system has great potential for revolutionizing hybrid rice production in tropical countries through simple, less expensive and efficient seed production technology with out any limitation on fertility restoration. However, for successful utilization of this novel male sterility system in hybrid breeding, knowledge on the fertility behaviour of TGMS line is highly essential. A set of six promising TGMS lines available at Tamil Nadu Agricultural University, Coimbatore, India viz., TS6, TS16, TS18, TS29, TS46 and TS47 were characterized for their fertility behaviour under field conditions. The pollen and spikelet fertility recorded on the plants raised at fortnightly interval revealed that all lines had stable sterile phase with 100 per cent pollen sterility for more than 50 consecutive days during high temperature condition (30/20°C maximum/minimum temperature) and they reverted to fertile during low temperature condition (less than 30/20°C) with more than 60 per cent pollen and spikelet fertility. The critical panicle developmental stages sensitive to temperature were ascertained for each line. The daily mean temperature of 24 to 26°C was found to be the critical temperature for fertility alteration. In addition to temperature, relative humidity and photoperiod were also appeared to influence fertility alteration in some lines. The environmental conditions influencing fertility alteration varied among the lines, which might probably be due to different sources of male sterile genes and different genetic backgrounds. However, all the lines satisfied the requirement of stable fertility behaviour to the level of commercial exploitation in two-line hybrid breeding and found as potential TGMS donors to develop new TGMS lines.

Wen-Tao Teng1 and Jian-Sheng Li2

In this investigation, maize heterotic groups and patterns were analyzed based on the planting areas from 1992 to 2001 using 84 parent lines of 71 widely extended hybrids and classification results by SSR markers. The results indicated that a change occurred in the major heterotic groups of maize took place during the past decade in China. The major heterotic groups were Lancaster, Reid, Tang SPT, Zi330 and E28 in the early 1990s, while they became Reid, Tem-tropic I, Zi330, Tang SPT and Lancaster in the early 21st century. Tem-tropic I was a new heterotic group, which contained tropical maize germplasm. The changes for heterotic patterns also occurred. Some new heterotic patterns associated with Tem-tropic I appeared, such as Reid × Tem-tropic I, Zi330 × Tem-tropic I, Tang SPT × Tem-tropic I, etc. Another change was the order of heterotic patterns. In the early and middle 1990’s, the top five heterotic patterns were Reid × Tang SPT, Zi330 × Lancaster, Lancaster × Tang SPT, Lancaster × E28 and Reid × Zi330, while they became Reid × Tem-tropic I, Reid × Zi330, Reid × Tang SPT, Zi330×Tem-tropic I and Lancaster × Tang SPT in early 21 century. Reid × Tem-tropic I and Zi330 × Tem-tropic I were laid on the first and forth Chinese heterotic patterns respectively in 2001.

S.S. Duhoon

Sesame (Sesamum indicum L.) is an ancient indigenous oil crop of India with the highest area, production and export in the world. Sesame seeds are excellent food, they are nutritious, edible oil, providing good health care as biomedicine, all in one. Nevertheless, the productivity of this very high value crop is low in India as compared to other countries. Exploitation of hybrid vigor is a means for increasing productivity as in many other crops. The Indian Council of Agricultural Research launched a network project to exploit hybrid vigour for raising productivity of sesame at eight Centres of All India Coordinated Research Project. Two thousand six hundred twenty five germplasm lines were studied and 3834 crosses involving 1550 diverse parents, identified as donors for important economic traits, were made at different centres to study heterosis and combining ability using diallel, half diallel and line x tester designs. Simultaneously studies were also undertaken to identify an effective hybrid seed production technique and develop CMS/GMS sources.

One thousand six hundred thirty six hybrids were evaluated in replicated and un-replicated trials at different locations. Observed standard heterosis ranged from 9.5 to 327% for seed yield. Capsules/ plant, plant height and branches/plant exhibited high to medium and seed weight and days to maturity low heterosis. Large-scale multiplication of 26 promising hybrids involving parents with high general and specific combining ability was done to evaluate their performance in multi-location coordinated trials. Seven experimental hybrids, AHY.Til-5, AHY.Til-12, RTH-1, AHYT-13, RHT-3, TKG-HY-5 and TKG-HY-4, identified with superior in seed yield 31.0 to 54.3% and in oil yield 13.0 to 48.0%over TKG-22, the national check variety.

The most effective economic and viable for hybrid seed production system involved emasculation and pollination simultaneously in the same morning between 7 to 11am. The cost of manually produced hybrid seed ranged from Rs.350/kg at Tikamgarh to Rs.1000/kg at Jagtial depending mostly upon labour cost. Wider spacing of 45 x 10 cm was significantly superior to realize high yields of hybrids over 30 x 10 cm spacing. Stable CMS lines with 99.0% pollen sterility were developed through interspecific hybridization between S. malabaricum x S. indicum and back crossing with indicum types.

Kadambari Gupta2, Deepak Prem2, Madan Singh Negi1 and Abha Agnihotri1

Inter Simple Sequence Repeats (ISSRs) have emerged as an efficient and effective tool for clonal fidelity and genome mapping. In the present study eight ISSR UBC primers were used to characterize a total of 21F1’s involving B. juncea as female and B. campestris and B. carinata as male donors. The size of amplified bands ranged from 400 to 1000 bp resulting into a polymorphism of 92%. Bands specific to female and male parents were present in all hybrids ascertaining the hybrid nature of F1 progeny. The dendrogram constructed using Jaccard’s similarity coefficient grouped parent genotypes and hybrids into four major distinct clusters. All hybrids were first grouped into two clusters based on the presence of male donors, B. campestris and B. carinata, and then further sub- grouped depending upon the presence of female parent in specific crosses. Hybrids generated from cross B. juncea x B. campestris resembled the female and male parents, at a genetic similarity value of 0.71 and 0.45, respectively, while those of cross B. juncea x B. carinata resembled the female and male parent at a genetic similarity value of 0.67 and 0.37, respectively. The genetic similarity values indicated more influence of female parent in the hybrids in both types of crosses. The male parent specific ISSR markers can be converted to co- dominant SCAR or STS markers for hybrid screening. The present study elucidates the utility of ISSR markers as an efficient tool to screen hybrids obtained from similar crosses.

Sabine Gruber and Wilhelm Claupein

Individual plants from four oilseed rape cultivars grown within an assortment of different cultivars in a field were prevented from open-pollination. The comparison of seeds from self-pollination and open-pollination of the same cultivar resulted in somewhat significantly different levels of secondary dormancy induced in the laboratory. Self-pollination enhanced the level of secondary dormancy in highly dormant cultivars and reduced it in low dormant cultivars. In a second experiment, previously dormant and non-dormant seeds were grown to maturity in the greenhouse. All plants produced dormant and non-dormant seeds. The seed progeny of plants deriving from previously dormant seeds had a higher level of dormancy than the progeny of non-dormant seeds and the control, although differences were not significant (P=0.06). All individual plants differed from each other in the dormancy level of their progeny. If the mean dormancy level of a cultivar is consequently composed of various dormancy levels of all individuals in the population, breeding for low dormancy could be performed by simple mass selection from within the cultivar. The risk of affecting secondary dormancy by outcrossing should be considered if gene flow in time by volunteers emerging from the soil seed bank is undesired.

A. Taleei1 and D.E. Falk2

The RIPE (Recurrent Introgressive Population Enrichment) method has been developed to enable barley breeders to apply basic principles of recurrent selection to a normally self-pollinated crop Yield trials were conducted with F3:4 lines with 10 lines per family at each of the top level of the RIPE system. Stepwise random deletion was used to generate ten new sets of four to nine lines per family at each level; these sub-sets were compared to the original ten lines for yield means, and variances. The results indicate that five randomly selected lines were as effective as the ten original lines in identifying good families and superior lines within families. Comparisons of yield means, maximums, minimums, and variances of the Elite, High and Intermediate levels showed that there is considerable variability in all levels, including the Elite level, therefore it is possible to continue to make progress in selecting for yield within this population, Families at the Intermediate level had the highest relative yields, the greatest proportion of families above the checks in yield, and the highest average variances within families, and so may be the optimum balance of adapted and exotic germplasm for yield expression, The Intermediate level had the best resistance to powdery mildew and rust.

Myung Kyu Oh1 , Bo Kyeong Kim2, Mun Sik Shin2, Jin Choung2, Ki Young Kim2, Jong Cheol Ko2, Jae Kweon Ko2, Jae Kil Lee2 and Im Soo Choi1

This study aims to determine the effect of nitrogen level and year on variation for panicle traits in rice. It also aims to examine the desirable panicle structure for rice to ripen better and yield more. Four different panicle types of rice varieties were transplanted under two different nitrogen levels in 2002 and 2003. There were more primary rachis branches (PRBs) per panicle and grains set on Sindongjinbyeo and Iksan#467, but secondary rachis branches (SRBs) per PRB was fewer than in Dongjin#1 and Saegyehwa. Variety × year interaction was significant for PRBs and SRBs per panicle. The yearly variation of the number of PRBs per panicle and grains setting on PRB per panicle was not large. The pathway coefficient of panicle characters was not only greatly different with year. The number of PRB per panicle, the number of grains setting on PRB per panicle, and the number of grains setting on SRB simultaneously increased both ripened grain ratio and rice yield. SRB per PRB and grains setting on SRB per PRB decreased ripened grain ratio, although it didn’t decrease rice yield.

Takeshi Ebitani1, Masahiro Yano2, Takeshi Takarada1, Motoyasu Omoteno1, Yoshinobu Takeuchi3, Shigenori Nonoue4 and Yoshitaka Yamamoto1

We report a novel breeding approach using DNA-marker-assisted selection introduced based on the development of introgression lines (ILs) developed with a chromosome segment of Kasalath, an indica rice variety, in the genetic background of Koshihikari, an elite japonica variety. ILs are a powerful tool for detecting quantitative trait loci (QTLs) whose genetic contribution is difficult to evaluate. Once a QTL of agricultural interest is detected on a particular chromosome, near-isogenic lines for QTLs (QTL-NILs) can be developed in 1 or 2 additional generations from advanced back-crossed populations. We demonstrate the usefulness of these ILs in the genetic analysis and breeding of spikelet numbers per panicle and culm length.

Glen Fox1, Maria Sulman1, Vanessa Johnson2, Kevin Young2 and Andy Inkerman1

Grain colour defects, including staining and black point, have been a problem for Australian barley growers for a number of years. This has resulted in thousands of tonnes of malting barley being downgraded each year. Over the last decade, research has been conducted into many aspects of these disorders, including objective assessment, biochemical evaluation, crop management, storage effects and resistance breeding. A number of key findings in the area of barley staining, including sources of improved resistance and crop management, will be presented.

Alexander Pswarayi1 and Bindiganavile Vivek2

The area sown to early-maturing maize varieties (maize that reaches physiological maturity in about 120 days at 1500 m above sea level, latitude 17.48º S, longitude 31º E (Harare, Zimbabwe), in the main season) across seven southern African countries is at least 4.2 million ha. Although long-season types yield more under favourable conditions, the demand for early-maturing maize is high. Heterotic relationships amongst CIMMYT’s early-maturity germplasm are not well known and early-maturing testers have not been identified. The single crosses CML312/CML442 (heterotic group A) and CML395/CML444 (heterotic group B) currently being used as testers are intermediate and late in maturity, respectively. This slows the identification of early maturing three-way cross hybrids directly from the phase of early generation testing of inbred lines. In an effort to identify earlier maturing replacements for the above testers, 66 testcrosses (generated from a twelve-parent diallel using one OPV and 11 inbred lines) were evaluated at two optimal, one low nitrogen and one droughted environment in Zimbabwe in 2003. The single cross (L7/L8) was identified as a potential new tester for group A because (a) inbred lines L7 and L8 belonged to the heterotic group A; (b) both L7 and L8 had good GCA effects for grain yield; (c) the hybrid, L7/L8 had good yields: 9.8 t/ha (optimal), 3.4 t/ha (low nitrogen) and 2.1 t/ha (drought), an important consideration for selecting single-cross testers.

A.H. Rezaei1 and V. Roohi2

A complete set of diallel crosses among 10 corn inbred lines were used to determine the genetic control of yield and some of its components, at Research Farm, College of Agriculture, Shahrekord University, Iran, in 2002. A triple lattice design was used. Significant differences (P<0.01) were detected among genotypes for all the 10 traits studied. Genotypic variances were partitioned into additive and non-additive genetic components based on the method of Hayman. Both of these components were significant (P<0.05) for all traits. The highest and lowest degrees of dominance were observed for ear height and number of kernel rows, respectively. Broad-sense heritability estimates ranged from 0.91 for cob percentage to 0.68 for number of kernel rows. Narrow-sense heritability estimates ranged from 0.73 for days to tassel emergence to 0.06 for grain yield. The parental lines with the most dominance or recessive allelic frequencies were determined based on their distribution along the regression line of array covariances on array variances.

H. Singh, S.N. Sharma and R.S. Sain

The F1 and F2 progenies of a ten-parent diallel cross (excluding reciprocals) were analyzed for combining ability for some quantitative traits in hexaploid wheat (Triticum aestivum L. em. Thell). The General (GCA) and specific combining ability (SCA) components of variance were significant for all traits. However, SCA component of variance was predominant indicating the predominance of non-additive gene effects for the traits studied except days to heading in both F1 and F2 generations. Among the parents, PBW 373 and UP 2425 were the best general combiners for grain yield and average to high combiners for other important traits. Parents HD 2329, WH 542, Raj 3077 and UP 2338 were the best general combiners for harvest index, grain yield per spike, early heading and dwarfness, respectively. Similar trends for GCA effects were observed in both F1 and F2 generations. The best specific crosses for grain yield were Raj 3765 × HD 2285, HD 2285 × PBW 343, Raj 3765 × UP 2338 and PBW 343 × Raj 3077. Many of the specific crosses for grain yield involved high × average, average × average and average × poor general combiners. To ensure further increase in grain yield combinations of desirable yield components is advocated. Inclusion of F1 hybrids showing high SCA and having parents with good GCA, into multiple crosses, biparental mating, and diallel selective mating could prove a worthwhile approach for further amelioration of grain yield in hexaploid wheat.

Yu Shuxun1, Song Meizhen2, Gong Wankui3, Wang Wu4 and Fan Shuli5

Five short season cultivars (SSC) with no premature senescence were selected to cross with 5 SSC cultivars with premature senescence. Parents, and F1 and F2 progeny from reciprocal crosses were field tested in replicated trials in 2001 and 2002.The results indicate that the activity of CAT,POD,SOD, and the content of MDA, chlorophyll all belong to typical quantitative traits. CAT activity, SOD specific activity and ABA content exist significant maternal effect, and then follows the dominant effect. Specific activity of CAT, POD, activity of SOD, content of soluble proteins, IAA and MDA also exist, to a certain extent, cytoplasm effect, but the main inheritance factors controlling them are the nucleolus dominant effect. POD activity and ABA content are mainly controlled by nucleolus additive effect, but there also exist a significant cytoplasm inherent effect.

JaHwan Ku1, Jung-Kyung Moon, Hong-Tae Yun, Keum-Yong Park, YeongHo Lee, Moon Tae Song, HanSun Hur and SeongHo Choi

Soy products contain isoflavones (genistein, daidzein, and glycitein) that display biological effects when ingested by humans and animals. Therefore, the content and quality of isoflavones in soybean is a key to their biological effect. The objective of the present study was to understand inheritance of isoflavone content in soybean seeds. The study used F2 and F3 lines developed from the cross of ‘Shinpaldalkong2’ and ‘Hwangeumkong’, two cultivars that contrast for isoflavone content. Seed isoflavone content of each lines was determined by high performance liquid chromatography (HPLC). The distribution of isoflavone content was continuous and unimodal. Narrow-sense heritability estimates with high content selection were 67% for total isoflavone, 80% for daidzein, 57% for genistein, and 79% for glycitein. Heritability estimates for low content selection were 30% for total isoflavone, 37% for daidzein, 27% for genistein, and 42% for glycitein.

Golam Faruq1, O. Mohamad2, K. Hadjim3 and Craig Meisner4

An investigation was made to understand the inheritance of cooked kernel elongation in crosses using the rice cultivar Mahsuri Mutant. In the all three Mahsuri Mutant crosses, the frequency distribution of kernel elongation ratio of segregating populations formed a bimodal curve. However, in crosses of Mahsuri Mutant and Mahsuri (and its reciprocal cross) the bimodal curve was skewed towards lower kernel elongation. This suggests that this character may be governed by 1 or 2 loci. However, in crosses of Mahsuri Mutant and 9192 a very smaller peak compared to the other was noted, which denotes the predominance of one major gene along with few modifier genes.

M. Fazel Najafabadi, M.R. Ghanadha, A.A. Zali and B. Yazdi Samadi

For estimating gene action in germination and seedling stage, one drought-resistant and one susceptible genotype were selected from a prior experiment. F1, F2 and backcross progeny were produced and these generations as well as their parents were sown at two osmotic potentials, 0 and -0.4 Mpa, provided using PEG-6000 at 22ºC. A factorial experiment based on completely randomized design with different replications for each generation was used. First factor was different generations and the second was osmotic potential. Measurements were made of rootlet number and length, and coleoptile length after one week. The additive component of genotypic variation in segregating generations was larger than the dominance component in most cases. This indicated that selection for better performing individuals in early generations will lead to improvement of germination characteristics. Generation mean analysis did not fit an additive-dominance model for any trait with additive × additive and dominance × dominance epistatic effects predominating in most osmotic potentials for most traits.

Wang Bolun, Wang Shu, Huang Yuancai

Analysis of plant height and panicle type was conducted in two populations, Norin 315/Shennong 8801 and Norin 310/Shennong 8801, using the Maximum Likelihood Method for qualitative-quantitative traits. Results indicated that plant height of Shennong 8801 was mainly controlled by a single, dominant gene and the gene could be modified by a group of polygenes. The panicle type Shennong 8801was mainly determined by an additive gene and the gene could be modified by a group of polygenes too. The polygenes in Norin 315 might be different from that in Norin 310. There was a positive correlation between the plant height and the panicle curve degree.

Andrew T. James1 and Ian A Rose2

In Australia, soybean cropping extends from 16oS in the tropics to about 37oS in the temperate zone. Varietal improvement is underpinned by research aimed at understanding adaptation to diverse photothermal regimes, tolerance to drought and pre-har