International Rice Congress 2006

Proceedings of the Second International Rice Congress, 9-13 October 2006, New Delhi, India
Edited by J.K. Ladha, P. Aggarwal, and B. Hardy

Weed flora landscapes and innovative management in direct-seeded culture
Azmi, M. and Baki, B. B.

Direct-seeded (DS) culture has become increasingly important in rice cultivation. The scarcity of rural labour coupled with escalating production costs constitute the main reason for the shift in DS rice culture and its rapid and eventual adoption from transplanting. In Malaysia, wet seeding is normally preferred. The economic incentives for adoption of wet seeding were provided for by its labor saving feature as exemplified by 1-2 man day/ha vis-a-vis ca. 20 man day/ha in the transplanting rice culture. A cardinal and perennial constraint in wet-seeded rice is weed infestation, requiring good field drainage and judicious water control for satisfactory crop establishment and weed control. Farmers practising wet seeding normally use higher seeding rates, spent more on herbicide-based weed control. Some of the factors influencing weed prevalence in rice fields include the rice culture system, soil moisture regime, crop rotation, cropping pattern, land preparation and tillage regimes, light, soil temperature, fertilizer application, rice cultivar and seeding rate, as well as weed control technology. Farm surveys assessing the magnitude and extent of weed infestations in rice-growing areas are an important step in formulating an appropriate control package. Prior to 2000, the dominance of Scirpus grossus and Marsilea crenata, were registered in major rice granaries in Malaysia although Echinochloa spp. (principally represented by E. crus-galli var. crus-galli, E. crus-galli var. formosensis, E. oryzicola,and E. colonum), Leptochloa chinensis, Fimbristylis miliacea and Sphenoclea zeylanica were highly prevalent in all seasons since 1995. The rice weed flora in the new millenium were dominated by measurable and parallel increase in infestation and population density especially the four most widespread and abundant weed recalcitrant and millennial species, viz. weedy rice (WR) or Oryza sativa complex, L. chinensis, E. crus-galli complex and Ischaemum rugosum, were consistently observed. Similar trends were also observed in Vietnam, Thailand, Sri Lanka, Korea, and the Philippines. We believe that this phenomenon resulted from continuous practice of DS culture leading with continuous season-mediated accumulation of seed bank of the named weed species. It is reasonable to argue that this might be due to no selective herbicide being available to control WR, perhaps the farmer’s inability and reluctance to manually control this weed at the early stage of crop growth was possibly due to crop mimicry. On the contrary, grassy weeds like E. crus-galli complex and L. chinensis can be controlled by selective herbicides such as cyhalopfop-butyl, quinlorac, molinate, propanil, fenoxaprop-ethyl and bispyribac-sodium if applied correctly. The continuous prevalence of WR calls for effective measures against the scourge aligned with other grassy weeds as the primary target of control.

Crop losses due to weed competition vary with the duration of weed infestation. Integrated approach based on critical period (CP) for weed management in DS involving indirect- and direct control measures should be adopted. Sympatric weed species emerging with rice crop plants have an adverse effect on crop yields. Crop losses due to weed competition vary with the duration of weed infestation of the crops. Rice crop is likely to experience yield reduction unless it is kept weeds free during the CP of its growth duration, the phenomenon otherwise referred to as the CP of weed competition. Based on the predicted Logistic and Gompertz response curves the CP for WR control based on 5% yield loss was estimated from 16 to 53 days after sowing (DAS) in DS culture, or from 12 to 60 DAS under mixed weeds situation. To ensure weeds are suppressed during CP, pre-emergence herbicides are normally applied before or after crop sowing and these herbicides must have residual activity to control weeds at CP of weed competition. If early post-emergences are used, it should be applied at the onset of CP. If weeds still persist, late post-emergence herbicide treatments can be instituted at mid CP of weed competition. Manual weeding where necessary should be carried out during CP. Due to crop mimicry of WR, manual weeding is cumbersome in WR-infested fields. Alternatively, rouging of WR panicles must be done after CP to reduce seed banks of the ensuing crops.

Choice of appropriate crop establishment technique is an important step towards good agricultural practice in rice culture. Water seeding (pre-germinated rice seeds broadcast onto standing water) appears to provide a valuable alternative to the usual wet seeding culture, and this leads to improved weed control besides providing good crop establishment. Standing water used for puddling is not drained, but conserved in the field. The presence of standing water during rice establishment significantly reduced grassy weeds particularly WR and some sedges. A major limitation of this method is seed drift, but this can be avoided with proper land preparation with the following pre-requisites, viz. the land must be flat and level; and leveling must be done with furrows during final tillage for better water distribution; minimize straw residue; use extra seed rate (30% of the normal seeding rate); use pre-germinated seeds; fields must have clear standing water maintained at 5-10 cm depth; seed treatment (with growth regulator if necessary) to ensure better establishment, and the bunds are strong and not permeable. The choice of crop establishment method should be based on WR population in the previous season. If WR infestation in the previous season is less than 5 panicles/m2 conventional wet seeding technique can be practiced. This method of rice culture can be adopted if land is thoroughly prepared to reduce WR seed bank. In situations where WR populations exceeded 6 panicles/m2, water seeding technique is highly recommended. This calls for the use of certified rice crop seeds devoid of WR. Through water seeding, water can be saved, reducing unnecessary wastage compared to normal wet seeding. In the latter practice, standing excess water need to be drained before the pre-germinated seeds can be sown. A field scale exploratory study to evaluate the impact of continuous water seeding technique in an area heavily infested by WR (at 117 panicles/m2 with usual wet seeding), registered 90% reductions in WR populations (35 panicles/m2 in the first season of water seeding and 8 panicles/m2 in the ensuing season) resulting in nearly 100% increment in rice yields.

Molecular analysis of metabolic regulation for stress tolerance in rice
H. Takahashi and H. Uchimiya

Metabolic modification in rice plants has been one of the most important breeding targets for many years. Modification of metabolic composition is crucial for nutritional improvements for amino acids, lipids, starch, and other ingredients, which are important components for human consumption. The metabolic engineering of plants through modifying the biosynthesis pathway would provide stress-resistant as well as nutritious rice. We present a good example of metabolic engineering of rice plants through modifying flavonoid and the NAD pathway leading to stress-resistant plants. Such plants also acquired resistance to rice blast disease and other abiotic stresses. These results suggested that the regulation of a small proportion of metabolites in transgenic rice contributed to multiple stress tolerance.

Researchable Issues In Rice Grain Quality
S.G. Sharma, Avijit Das & Sanjukta Das

Grain quality in rice is determined largely by the genetic make up of the plant but environmental conditions, cultural practices and good post harvest handling can improve it further. Though quality means different things to different people and consumer preferences vary across countries or regions some quality parameters like high head rice content and translucent grains are preferred all over the world. As it is the consumer acceptability that determines the market price, it is essential for rice scientists to correctly identify the quality characteristics that are valued by the consumer so as to develop varieties that would attract premium price and also meet the nutritional requirements.

Bringing hope, improving lives
Robert S. Zeigler

The world has changed enormously since IRRI developed its last strategic plan a decade ago. Recent scientific discoveries—particularly in genetics and genomics—now open up new opportunities to achieve impact that would have been difficult if not impossible as recently as the turn of the century. A reduction in poverty and sustainability of the rice production environment, through the use of modern technology and the latest communication tools, are at the heart of IRRI’s exciting and innovative plan.

Rice remains the most important staple food on the planet since it feeds roughly half the population on a daily basis. Approximately 750 million of the world’s poorest people depend on it to survive. So, an agenda for continued research on this vital crop is still very relevant.

This paper spells out how IRRI’s plan (1) brings the best rice technologies to all regions of the world that need it, including East and southern Africa where demand is increasing; (2) focuses on health and nutrition; and (3) is committed to the long-term conservation and use of rice genetic resources.
Five strategic goals and seven programs embodied in the plan are described as are three Frontier Projects being designed to continue beyond the life of the plan in research areas that have the potential to make an enormous impact on the lives of poor rice farmers and consumers.

The new plan endeavors to take IRRI over a modest 9 years so that it can join colleagues and partners from around the world to reach the Millennium Development Goals by 2015. Nevertheless, much of the work outlined here will obviously extend well beyond that date.

Hybrid rice seed production – a success story in Andhra Pradesh, India
R.Vijaya Kumar and Paresh Verma

China not only developed the worlds first commercial rice hybrid, but also optimized technology which made hybrid rice seed production economically viable. The Hybrid Rice technology has helped China to increase its rice production from 129 million tons in 1976 to more than 185 million tons in 2004. In India, Indian Council of Agricultural Research launched a goal oriented and time bound project on Hybrid Rice in 1989 which was coordinated by Directorate of Rice Research, Hyderabad, and resulted in the release of its first rice hybrid in 1994. So far 25 Rice Hybrids have been released in India. The biggest limitation to large scale adoption and commercialization of Rice Hybrids was lack of a practical seed production technology which could give economical seed yields. Initially, the seed yields obtained in Hybrid rice seed production plots in India were very low ranging from 0.5 to 0.75 t/ha. The Research work on Hybrid Rice seed production was intensified by both Public and Private sectors. As a result, the favorable agro-climatic areas of North Telangana zone, Southern Telangana zone and Scarce Rainfall zone were identified for seed production in the state of Andhra Pradesh, India. Various seed production techniques like, Differential seeding time, Method of transplanting, Row ratio, Flowering synchronization, GA3 application, Supplementary pollination were optimized to suit the local situations. Dry (post rainy) season was found to be the best compared to the Wet(rainy) season. Several hands on training programmes on Hybrid rice seed production technology were organized by Directorate of Rice Research, State Agricultural Universities, Private seed companies and Krishi Vignan Kendras for the benefit of the farmers and seed production officers. Hybrid rice seed Production manuals were made available both in English and local language. Progressive farmers in the state of Andhra Pradesh quickly adopted these techniques and developed skills needed to successfully produce seed of hybrid rice. Their experience over the years lead to an even greater success. Consequently, there has been a significant improvement in the hybrid seed yields which currently range from 1.5 to 3.5 t/ha with an average of 2.0 t/ha. Seed production technology is no longer a constraint for increasing hybrid adoption rates in India. More than 80% of the total Hybrid rice seed in the country is produced in Andhra Pradesh. During the Dry season 2005-2006 more than 20,000 tons of Hybrid rice seeds were produced from the state of Andhra Pradesh. The hybrid rice seed production which has now become economically viable, has also tremendously benefited the farmers of Andhra Pradesh.

Practical Experience of the Public Sector in Plant Biotechnology Product Development and Regulation
Gerard Barry

Numerous research and development programs on a wide range of transgenic crops are being pursued by the public sector, and most notably in lesser developed countries. Often these projects were initiated following a national or regional prioritization process that took into account the importance of an unmet need for food or fiber production, recognized the state of relevant research, and cost effectiveness of pursuing a transgenic approach. To date, only a small number of the transgenic crop products have been developed to the stage of commercial release by the public. These include one of the Bt Cotton products available in China, the Virus Resistant Papaya developed for Hawaii, and six other products developed within China (and that now also include a Virus Resistant Papaya product).

Separately, in essentially all countries, regulatory authorities have relied on their own national scientists to evaluate and to make recommendations on regulatory approval requests for the importation for food and feed use and for cultivation of transgenic crops. Most of these submissions have been made by the private sector and in most cases these have also been for products already approved in an advanced country. This experience has produced a competent cadre of scientists with practical biosafety regulatory experience who aid their own countries in the development of nationally important indigenous products. This experience is also important in that many of the same genes that have used to develop these private sector products are also being used to develop similar products in a number of countries, often in different crops or germplasm but which have high priority for the countries.

Also in initiating publicly funded projects, countries would have already made an assessment of the benefits of the plant biotechnology products and an assessment that the risks were not expected to result in a squandering of scarce research budgets. The practical experience and scientific competence of so many national scientists will help countries to decide for themselves the relevant data that are required to make the appropriate final risk assessments of the products on a case-by-case basis. In addition, we are beginning to see the likelihood of public sector products, or advanced projects, being transferred between countries - these examples provide valid opportunities for countries to accept each other's data or to otherwise lead of a harmonization of data requirements.

Synergies of resource-conserving technologies in rice-based systems
D. Gustavson and T. Friedrich

Resource-conserving technologies (RCTs) have become popular in many cropping systems as a response to increasingly limited agricultural production resources and in view of the projected demand for agricultural products. Worldwide experiences have shown synergies between RCTs when they are applied in combination as, for example, in conservation agriculture.
Conservation agriculture (CA) is a concept for resource-saving agricultural crop production characterized by three principles that are linked to each other: zero tillage, soil cover, and crop rotations. As such, CA is being applied worldwide in different agro-climatic zones and farming situations, providing socioeconomic benefits for farmers and environmental services. Traditional paddy rice cultivation practices involve intensive soil tillage during puddling operations not compatible with the concept of CA. Adapting rice growing to CA principles is possible and is being progressively implemented. Besides offering the known benefits of CA, adoption in rice would bring further benefits for saving water as an increasingly scarce resource and providing scope to address greenhouse gas emissions from rice paddies without sacrificing production potential.

Opportunities for increasing efficiency of N, P, and K management for rice
Roland J. Buresh, Christian Witt, Mirasol F. Pampolino, and Marianne Samson

The production of rice at high yield levels with high efficiency of input use helps ensure sufficient rice at affordable prices for consumers and adequate profit for farmers. Fertilizers are one of the main inputs in rice production. The quantity and management of fertilizers to optimally match the needs of rice crops for essential nutrients can vary greatly from field to field. Trends toward increasing intensity and diversity of cropping practices will likely lead to increased field-to-field variation in crop needs for supplemental nutrients, thereby increasing the benefits from field-specific management approaches for increasing nutrient-use efficiency and crop yields. Optimally supplying rice with essential nutrients as and when needed to achieve high yields and high efficiency of input use involves three steps. The first step is to establish an attainable yield target, which is location- and season-specific depending upon climate, rice cultivar, and crop management. This yield target or goal reflects the total amount of nutrients that must be taken up by the crop. The second step is to ensure effective use of existing indigenous nutrients such as from soil, organic amendments, crop residue, manure, and irrigation water. The third step is to apply fertilizer to dynamically fill the deficit between crop needs and indigenous supply and to maintain soil fertility. The requirement for fertilizer N can be approximated from the response in grain yield to fertilizer N and a targeted efficiency of fertilizer N use. The required fertilizer N is apportioned in several doses during the growing season to ensure that N supply matches crop need. Young rice before active tillering requires only a moderate amount of fertilizer N. The efficiency of fertilizer N in farmers’ fields can often be improved by reducing the portion of fertilizer N applied early and ensuring that fertilizer N doses are sufficient at critical stages of active tillering and panicle initiation. The leaf color chart is a tool for adjusting fertilizer N use to field-specific needs of rice from tillering onward. The indigenous supply of P or K, estimated by either the nutrient omission plot technique or soil testing, and an estimate of the yield gain with the use of fertilizer P or K can be used to determine the requirement for fertilizer P or K. Opportunities exist to use farmers’ historical use of fertilizer P and K, farmers’ straw management practice, yield targets of farmers, and simple field observations to estimate field-specific fertilizer P and K needs. Simple guidelines should be developed to use such information together with existing knowledge on soils to empower farmers in a participatory fashion with trained extension workers and researchers to develop improved practices for their specific rice fields.

Residue management for improving soil fertility and sustainable crop productivity in China
Kairong Wang, Huanzhe Lv, Kaifeng Wang, and Roland J. Buresh

About 7.95 x 108 tons of crop residues are produced annually in China. The straw of cereals accounts for 61% of these residues. Before the mid-1970s, the straw of cereals was mainly used for feeding buffaloes and goats, for producing barnyard manure, and as fuel for cooking. In the 1980s, with the start of rural economy reform in China, straw was widely used by farmers for improving soil fertility either directly through incorporation and mulching or indirectly through the production of barnyard manure that was then applied to soil. In the 1990s, with changes in the rural economy, the use of straw and organic manure in building up soil fertility and crop production decreased, and the use of chemical fertilizers increased. Large amounts of crop straw, accounting for 45–60% of the total annual straw resources, were burned in fields, resulting in serious deterioration of air quality, which adversely affected human health and traffic safety. For this reason, the Agriculture Ministry of China issued an urgent notice in 1997 forbidding straw burning in fields and encouraging comprehensive use of crop residues. Since then, the use, rather than burning, of crop straw has increased. Meanwhile, new techniques in treating straw with high economic value have been developing, such as producing packing and building materials and fuel gas by industrial gasification. Three aspects in crop residue management should receive more attention: (1) control of methane emissions associated with the return of rice straw to submerged soils; (2) development and evaluation of new techniques in soil preparation, crop cultivation, and fertilizer management for returning straw to fields; and (3) identification of new techniques of residue management with high economic value.

Toward a rice-based agricultural transformation: a science-led partnership in Africa
Kanayo F. Nwanze, Savitri Mohapatra, Aliou Diagne, Shellemiah Keya, and Patrick Kormawa

This paper briefly describes the role of rice research in sub-Saharan Africa (SSA) with particular reference to WARDA’s science-led partnership strategies, examines whether investments in rice research have paid any dividends, and underlines the prerequisites needed to achieve a rice revolution in SSA. Rice is the most rapidly growing food source in SSA and more than US$1.5 billion in foreign exchange is spent every year on rice imports. Many actors have played a role in the history of rice research in SSA. In the 1960s and ‘70s, national and international programs focused on introducing improved varieties from outside SSA. However, because of the greater diversity of farming systems in SSA, the introduced varieties were not useful beyond some limited domains. In the 1990s, WARDA explored innovative pathways to target the more difficult rice production ecologies of uplands and rainfed lowlands. It developed the New Rice for Africa (NERICA) that combines the ability of the African parent to withstand local stresses with the productivity of the Asian parent. Now, about 150,000 ha are under upland NERICA production in Africa. Using a slightly different breeding approach, a new generation of NERICA varieties adapted to lowland rice ecologies was developed in 2005 by WARDA in close partnership with its national partners. Notable successes for the irrigated ecology have been the Sahel varieties. To enhance the productivity, profitability, and sustainability of irrigated rice farming, an integrated crop management (ICM) approach has been developed. WARDA has explored a range of research partnership models that cover strategic to adaptive research and development. For upstream research, a mechanism was developed to bring together the pool of expertise from advanced research institutes to national programs. The partnership model that has been most acclaimed by its national partners is the ROCARIZ rice network. WARDA has developed several farmer participatory models, which have been the key to NERICA success. In association with its national partners, it is developing strategies for competitive rice sector development in SSA. Its research grants to national partners and capacity-building efforts have contributed significantly to broad institution-building goals in SSA. According to important impact assessment studies, rice research has made and is continuing to make a big difference in Africa. Three impact studies are described here. The first one carried out in West Africa revealed that genetic enhancement and transfer increased the net revenues by $93 ha–1 between 1980 and 2000 and the returns to investment in rice research have exceeded 20% annually. The second study conducted on the impact of rice research in Senegal and Mauritania showed that the internal rate of return was about 74%. The third one on the socioeconomic impact of NERICA on farming households in Benin showed a 3% increase in child school enrollment and retention rate and a 2% reduction in frequency of child sickness. New WARDA projections on NERICA adoption indicate that SSA countries can save 5% of current rice imports. However, SSA will fully benefit from improved technologies only when governments institute policies that guarantee prices, create access to credits, inputs, and markets, safety nets, and subsidies to support vulnerable groups, particularly farmers. These conditions create level playing fields and give farmers incentives to adopt new technologies that raise incomes and lift households out of poverty. SSA has become increasingly dependent on a relatively ‘’thin” world rice market for one of its staple foods. It should urgently review its rice importation policy to avoid a crisis in the near future. Outside SSA, rice continues to be one of the most protected commodities. Although science-led partnership will be a key element to achieve a rice-based agricultural transformation in SSA, the onus is on Africans themselves to take the lead in this. For there is no country, and no people, whose economic and political development was not an endogenous and intrinsic process, engraved in its own culture and adapted to its own soil and climate.

Approaches to sustainable pest management in the rice ecosystem
Jia-an Cheng, Zeng-rong Zhu, Yong-gen Lou, and Ming-xing Jiang

The developmental history of rice production indicated that sustainable rice production had to be accompanied by sustainable pest management. The historical development of rice pests showed that all the biological components in a rice production system interact. As the main producer in the rice ecosystem, rice plays a fundamental role in determining arthropod community structure in the system. As one of the main strategies in an IPM program, the biological characteristics of rice varieties have been modified through conventional or transgenic methods to regulate interactions between rice plants and pests, but positive impacts on some pest and natural enemy species might come along with negative impacts on other species. The wide use of hybrid rice made whitebacked planthopper one of the most important pests in China, as well as in Vietnam. In the meantime, the impacts of interactions between biotic components in the rice ecosystem could be mediated by various environmental factors. Cropping systems can have major influences on numerical and genetic structures of pest populations in the rice ecosystem. Since migratory insect pests have been the major pests in many Asian countries, the influences of cropping systems on pest problems could occur at a regional level. The development of virulence to rice varieties and resistance to insecticides for brown planthopper revealed that the genetic structures of pest populations interacted between populations in various regions. Therefore, the concept of meta population should be taken into consideration in rice pest management. The developments of modern technology provide opportunities to establish a sustainable pest management system by modifying interactions among biotic components. In this paper, impacts of rice varieties and cropping systems on pest management are reviewed and approaches to developing a sustainable pest management program using new technology are discussed.

Resource-conserving technologies in the rice-wheat system: issues and challenges
Olaf Erenstein

The rice-wheat system is both the rice bowl and bread basket of South Asia, covering an estimated 14 million ha of cultivated land primarily in the Indo-Gangetic Plains. The recent stagnation of productivity growth in this system has led to increased calls for resource-conserving technologies and conservation agriculture. To date, the most significant progress has been made by addressing the challenge of reducing tillage. With the rapid spread of tractor-drawn zero-tillage drills, tillage intensity has declined dramatically for wheat. Survey results, however, show that the use of zero-tillage in wheat had limited spillover for the productivity and management of the subsequent rice crop. Despite promising on-farm experimental results, a reduction in tillage intensity for rice still has limited acceptance among farmers, not least because of weed management issues. The prevailing rice germplasm developed for puddled conditions is another issue. Increasing water scarcity in the region and global trends in energy prices add to the attractions of reducing tillage. Moving the rice-wheat system toward conservation agriculture also implies tackling the challenges of crop residue retention and diversification. A final challenge is to keep our interventions “pro-poor.” This calls for a better understanding of livelihood implications and stakeholder dialogue/participation.

Opportunities for improved micronutrient and secondary nutrient management for rice
J.M. Duxbury, J.G. Lauren, Md. Bodruzzaman, and Attaur Rahman

Although the need to supply secondary nutrients and micronutrients to rice has long been recognized, intensification of rice-based cropping systems has increased the demand for these nutrients. The need for S addition is widely documented. Soil acidity and/or lack of Ca and Mg inputs are important constraints on highly weathered soils and possibly also on acid alluvial soils in South and Southeast Asia. Recent work, for example, has shown yield responses to applications of dolomitic lime in Bangladesh. The main, and most successful, method for supplying secondary nutrients is application to soil. A broader range of options exists for micronutrients where smaller amounts are needed. Soil application is the most common method, but not necessarily the most effective or the most economical. Other strategies include application to the nursery only, foliar spray, and seed soaking. More recently, the use of in vivo micronutrient-enriched seed has also been found effective, but simple methods for seed enrichment have not yet been developed. Zinc is by far the most commonly reported micronutrient deficiency, especially for paddy rice. The redox chemistry associated with paddy rice reduces the availability of Zn and probably Cu, but increases that of Fe and Mn. The most probable mechanisms for reduction in Zn and Cu availability include precipitation of mixed sulfides with Fe at very low redox potentials and competition with Fe and Mn for plant uptake at redox potentials above that for sulfate reduction but below those for Fe and Mn reduction. In upland rice systems, soil pH is an important variable regulating micronutrient availability. The importance of B has been documented in several cases but its importance is inadequately characterized at present. Modern information tools such as GIS provide opportunities to target nutrient management to sites where the potential for deficiency is high. Such sites may be identified by direct nutrient mapping or by use of correlated variables such as soil pH, texture, and mineralogy. Plant breeding programs also need to focus more directly on nutrient efficiency traits, especially for micronutrients. Finally, there is a need to improve the grain content of nutrients such as Fe and Zn in order to address widespread human deficiencies of these nutrients.

Use of rice cropping and residue management to mitigate water quality problems and subsidence of California Delta peat soils
William R. Horwath, Joseph Gallucci, Phillip Bachand, Steve Deverel, Joseph Fleck, and Daniel Mourad

Rice cultivation on peat soils in California’s Delta is desirable to restore wetland habitat, mitigate oxidative subsidence, and potentially reduce total dissolved organic carbon (DOC) and N (DON) loads leaving Delta islands. DOC is a water quality constituent of critical concern because of its relationship to disinfectant by-product formation potential, particularly trihalomethane formation (THMF), during treatment of chlorine to produce drinking water. Rice cultivation and residue management are especially an attractive approach to reverse oxidative subsidence of peat soils, a source of DOC. In addition, managing rice residue in the field has a significant positive effect on soil fertility. Soil, hydrologic, and water quality data were collected from two newly converted rice paddies over two growing seasons in the California Delta. Treatments consisted of traditional low-water drain management and an alternative high-water drain management. The intent of this study was to investigate the effects of drainage ditch water height draining rice paddies as a means of improving water quality by reducing exports of DOC, DON, and inorganic nitrogen. Surface and subsurface water data were collected to determine the effectiveness of the treatments. Concentrations of DOC, THMF potential, and DON were affected by paddy water residence time and controlled by surface processes. Peaks in DOC and DON in surface water were correlated with rewetting events from seasonal precipitation. Ammonium concentrations in water leaving paddies were correlated with fertilizer use. Different drain heights led to significant differences in water quality constituent fluxes during all seasons primarily affecting subsurface flows and loading. High-water drainage ditches reduced subsurface hydraulic gradients and decreased loading, and when coupled with decreased flows helped minimize subsurface exports. Nitrate loading and exports were controlled by subsurface fluxes. Significantly greater nitrate loading and exports occurred in the low-water drain. DOC and DON were also controlled by subsurface flows, but are likely from a separate source than that found in surface water. Total loads were significantly higher for nitrate in the low drain during the winter, emphasizing the importance of subsurface drain management in controlling nitrate release. In general, this research supports the notion that decreasing surface and subsurface gradients by implementing high-water drain management will decrease the loading of DOC, DON, and NO3. Additionally, reduced flows generally decrease exports of water quality constituents, suggesting that water management should be of the utmost importance at all stages of rice production and during fallow periods. Maintaining water on paddies combined with in-field residue management shows promise in reversing oxidation subsidence of Delta peat soils. In addition, incorporating rice residues significantly reduces fertilizer nitrogen needs up to 40% after 2 to 3 years. Finally, rice cultivation and in-field residue management also achieve other positive environmental benefits, most importantly the creation of water bird habitat. Water bird foraging significantly reduces weed competition, thus reducing the need for herbicides.

Salinity, submergence, and nutrient deficiency in rice: bases of tolerance and progress through breeding
Abdelbagi M. Ismail, Matthias Wissuwa, Glenn B. Gregorio, Michael J. Thomson, R.K. Singh, Sigrid Heuer, and David J. Mackill

Abiotic stresses such as submergence, salinity, drought, and nutritional disorders are major constraints to rice production across rainfed rice ecosystems, and they predominantly impact poor farmers in these areas. Our efforts intend to identify sources of tolerance of these abiotic stresses, understand the causal mechanisms, and identify the genetic determinants, particularly for tolerance of salinity, submergence, and phosphorus (P) deficiency. Tolerance of these stresses is complex, involving several diverse physiological and adaptive mechanisms. Tolerant donors also seem to vary with respect to the presence/absence and extent of expression of any particular trait associated with tolerance, suggesting that an approach involving targeting individual traits associated with tolerance could probably be more effective, particularly if QTLs/genes for each trait were targeted. Major QTLs for salinity (Saltol), submergence (Sub1), and P-deficiency tolerance (Pup1) were identified using populations developed from contrasting parental lines. These QTLs were further fine-mapped and the respective loci were sequenced/annotated and are being analyzed to identify and validate candidate genes underlying tolerance at each locus. For submergence, a cluster of genes coding for putative ethylene responsive transcription factors (ERFs) was found to be responsible for the tolerant phenotype conferred by the Sub1 locus and work is in progress for the Saltol and Pup1 loci. Parallel efforts aim at identifying PCR-based markers that are QTL-/gene-specific to be used in marker-assisted backcrossing (MAB) to incorporate these loci into popular but sensitive varieties. Substantial progress was made with the Sub1 locus, which was introgressed into several widely grown cultivars using MAB. The new varieties maintained high yield and other agronomic and quality attributes of recurrent parents and are tolerant of submergence. Use of these varieties is expected to provide protection against damaging floods and increase food security for farmers in flood-prone areas. Similar approaches are being pursued to incorporate Saltol and Pup1 into popular varieties. The ultimate goal is to integrate combinations of these QTLs/genes into suitable varieties and elite lines, based on prevailing stresses in target environments, to develop resilient cultivars for high and stable productivity.

Changing rice production in China and its potential impact on the international market
Funing Zhong and Shunfei Liu

China is a major rice trader in the international market, accounting for 7.6% of the world’s total imports between 1960 and the early 21st century. However, the share of Chinese exports in the international market fluctuated from 27.7% (1973) to less than 0.1% (1994).

This paper demonstrates that China’s rice exports are determined by excess supply, with some time lag. As China’s rice sown areas continue to decline due to rapid income growth associated with fast industrialization and urbanization, rice production is gradually moving to less favorable regions. Therefore, an increase in rice output will rely even more on yield gains. As such, China’s long-run ability to export rice may decrease if the yield gains cannot offset the loss in sown area and the negative effect of some relocation (to other areas). In addition to a potential reduction in average quantity in the long run, the annual fluctuation of rice exports is likely to increase as production moves to new and less favorable regions. Finally, the composition of the rice supply, japonica vs. indica varieties, may also influence China’s rice exports in terms of both destination and quantity.

Greenhouse gas emissions from rice fields: mechanisms, experiments, and mitigation options
Reiner Wassmann and Achim Dobermann

Rice fields are sources of the greenhouse gases methane (CH4) and nitrous oxide (N2O) and can also be source or sink of carbon dioxide. CH4 and N2O budgets of rice fields are both affected by the structure and dynamics of anearobic/aerobic conditions in the soil, but specific impacts are often diverging for both gases. CH4 emissions increase under continuous flooding while N2O is primarily emitted in pulses after fertilization and strong rainfalls (including fallow periods). Both gases predominantly escape to the atmosphere through the aerenchyma of the rice plant. The documented morphology of the aerenchyma allows the reconstruction of vertical gas transfer, including the speed-limiting passage from root to culm. Nutrient supply affects the development of aerenchyma as well as root exudation and thus the budgets of CH4 (and N2O). The results of a field experiment at IRRI and a greenhouse experiment at IFU in Germany are assessed using global warming potentials (GWP) of 21 for CH4 and 310 for N2O (GWP compares the ability of a gas to trap heat in the atmosphere relative to CO2). Systems with high GWP are restricted to rice fields with long flooding periods and considerable amounts of organic inputs. The GWP of these systems is driven by CH4 emissions whereas N2O emissions are of minor importance. In systems with low GWP, however, CH4 and N2O have almost equal shares in GWP as long as fallow periods are taken into account. Inclusion of N2O emissions further limits effective mitigation options in rice fields, for example, midseason drainage only reduces GWP in systems with high baseline emissions of CH4. Net fluxes of soil-borne CO2 in rice fields are associated with changes in agricultural management, for example, reduced tillage, modified irrigation patterns etc. However, most rice production systems also entail emissions from fossil fuel consumption due to farm operations and indirect emissions due to fertilizer production. Thus, mitigation assessments have to aim for a full greenhouse gas “accounting” in combination with economic cost-benefit analysis.

Empowering rural women through microfinance: lessons from Sri Lanka
Sirimevan S. Colombage and Alia Ahmad

The objective of this study is to assess the impact of microfinance on women’s empowerment in Sri Lanka, which has a relatively better position among developing countries in human development achievements. In contrast, around one-third of the population is estimated to be poor. As many as 90% of the poor live in rural areas. Microfinance has emerged as a major tool to alleviate poverty and empower women in the last two decades. Women’s empowerment can be defined as a process by which powerless women gain power to control their livelihoods. The study is based on a sample survey in five districts covering 1,080 clients of selected microfinance institutions (MFIs) and 157 nonclients. Both quantitative and qualitative techniques were used to gather information. About 60% of the sampled MFI clients are women. A marginal improvement in female decision making after joining an MFI is reflected in the women’s empowerment index (WEI) computed for agriculture, domestic affairs, and business activities. This is mainly an outcome of multifaceted services offered by MFIs to poor women through self-help groups (SHGs). The SHGs have enabled them to obtain greater social status at individual, family, and community levels, as revealed by the qualitative information of the survey. Given these positive effects, the study recognizes several shortcomings of microfinance as a tool for women’s empowerment. Microfinance has not helped a majority of MFI clients to graduate out of poverty, according to the study, largely due to the lack of economies of scale of small enterprises run by MFI clients with their tiny loans. Limited product diversification is another factor inhibiting growth. MFI clients are inclined to continue their traditional family businesses rather than launch innovative activities. Unless MFIs prioritize gender-specific issues in their agendas, microfinance will not necessarily empower women. The extreme poor have minimal access to microfinance. Adoption of best practices by MFIs, backed by an appropriate legal and regulatory framework, is needed to integrate them with the mainstream financial sector and to sustain their commercial viability. Microfinance is not a substitute for macroeconomic policies geared to promote pro-poor economic growth. It acts rather as a safety net for the poor.

Crop residue management options in rice-based cropping systems in Asia
Bijay-Singh, S.E. Johnson, Y.H. Shan, Yadvinder-Singh, and R.J. Buresh

Intensification and diversification are the two characteristics of rice-based cropping systems in Asia as they have evolved. Farmers practicing these systems produce large quantities of both food grains and crop residues. More than 900 million tons of crop residues were produced in rice-based cropping systems in Asia during 2004. Managing crop residues is becoming a challenge because different options may not be productive and profitable under a given set of crop management, resource-use, and environmental considerations. On-farm management of crop residues differs with crop rotation, turnaround time between crops, and harvesting and planting practices. Incorporating residues of rice or upland crops into soil irrespective of the amount of residues and time of incorporation did not increase the yield of rice or upland crops. Unless residues were incorporated during normal cultivation and preparation of the field before planting of the crop, extra cost was always involved in incorporating residues and, with little or no yield increase, it was not a profitable proposition. It also resulted in increased emissions of methane, a greenhouse gas. On the other hand, mulching wheat with rice residues resulted in conservation of soil moisture, suppression of weeds, and increased yields with little or no adverse effect on the environment. With significant developments in machinery for cost-effective planting of zero-till wheat leaving rice stubble and loose straw as mulch in the field, this option can be profitable in the rice-wheat system in South Asia. Mulching with crop residues in flooded rice was expensive and less productive and in conventional-till-sown upland crops it was more labor-intensive, as was transportation of residues to another field for mulching. Adequate information is not available for not so widely used management options such as in situ composting and off-farm composting.

Comparative analysis of rice and wheat genomes as a tool for gene discovery
Nagendra K. Singh, Vivek Dalal, Kamlesh Batra, Archana Singh, Mahavir Yadav, Rekha Dixit, Irfan A. Ghazi, Awadhesh Pandit, Harvinder Singh, Pradeep K. Singh, Kishor Gaikwad, Trilochan Mohapatra, and Tilak Raj Sharma

Complete genome sequences of model species such as rice and Arabidopsis are being compared with those of other plant species largely based on the available expressed sequence tag (EST) information. Apart from the evolutionary significance, such studies are important for gene discovery and genetic improvement of crop plants. Early comparison of rice genome sequences with those of bread wheat showed complex patterns of synteny (gene content) and colinearity (gene order). The large–size wheat genome appears to have evolved through extensive duplication and divergence of genes and noncoding repetitive sequences. These duplications and rearrangements pose a real problem in the analysis of synteny and colinearity, which is required for the transfer of information from model species to other economically important crop species. We found presence of the same ancient polyploidy in wheat that was first identified by the computational analysis of rice genome sequences. We also found that single–copy rice genes have a much higher conservation of synteny and colinearity with wheat than multicopy genes. A large proportion of the single–copy rice genes is still distributed randomly to all the nonsyntenic wheat groups and this could be explained only by a background dispersal of genes in the genome through transposition. The breakdown of rice-wheat synteny was much greater near wheat centromeres, suggesting wheat-specific transposition activity. The single–copy rice genes reveal a conserved primordial gene order that gives clues to the origin of rice and wheat from a common ancestor through polyploidy and aneuploidy followed by chromosome fusions. On the basis of conserved colinearity of 1,244 mapped single–copy rice genes, we predicted the location of 6,178 unmapped single–copy rice gene homologs in the wheat genome and experimentally validated the location of a random set of 213 of these. More than 50% of the single–copy genes do not have any known protein functional domains, and hence represent an important but yet underexplored category of genes.

Indexing physical productivity of soils
Pradeep K. Sharma

A decline in factor productivity has necessitated research on soil quality. Soil quality is a multifaceted concept, of which soil productivity is an essential component. Characterization of soil physical productivity has remained a challenge because of wide temporal and spatial variability in soil physical properties, their interdependence, and their complex interaction with crop growth and yield. Establishment of quantitative relationships among soil physical properties and crop yields has been attempted by several workers, but has failed to generate universal conclusions. The use of single-value indices that incorporate all or most of the soil physical properties affecting plant growth appears to be a potential means of characterizing soil physical productivity. The nonlimiting water range (NLWR) appears to be a useful index. It is based on three primary soil physical properties that affect plant growth: soil water, soil air, and soil penetration resistance, and has been significantly correlated with crop yields. The NLWR was successfully used in studying the impact of the long-term use of chemical fertilizer and organic materials on soil physical productivity under different cropping systems.

Rice seed systems: local, national, and global
Michael Turner

Seed supply to farmers throughout the world depends on the parallel contributions of formal/organized sources that provide certified seed (or equivalent) and informal mechanisms that provide seed at the farm/community level. The main exceptions are when the crop consists entirely of hybrid varieties, which is often the case in maize, or when seed production is a quite different activity, which applies in some horticultural crops. The relative importance of formal and informal supply channels varies widely between crops and depends on many technical, geographic, and socioeconomic factors. The purpose of this paper is to analyze these factors in the specific context of the seed supply system for rice. In traditional rice-growing areas, seed production is not a problem. Physiologically, the crop is well adapted to the humid tropics, which present a challenging environment for seed storage. Furthermore, by reason of its continuous cultivation in many farming systems, the seed storage time for rice is often quite short. The self-pollinating habit of rice also reduces risks of genetic contamination. Therefore, the divergence between seed production and the normal grain crop is relatively small, probably no more than some roguing in the field and extra care with seed storage at the household level. There are many examples of farmers maintaining considerable genetic diversity for their local environments, so seed production is clearly within their capability. We can therefore conclude that the main reason for developing a formal seed supply system relates to production that is commercially oriented or presents some special challenges for seed quality. Put another way, the default mechanism in rice is the local seed system. What we need to discuss is the reasons for, and extent of, penetration by more formal systems. These may include the objectives or needs of giving farmers more choice by providing a regular supply of new varieties from breeding programs; this is the most widespread and essential role of the formal seed system, and it applies in virtually all production environments, to produce hybrid seed, which by definition requires more intensive management. This applies in some countries, depending on the uptake of hybrid varieties, to ensure certain quality attributes in the seed that cannot be so easily controlled at the farm level and to preserve the identity and purity of a particular variety in order to ensure a premium in the market through “traceability” and to comply with official controls, if genetically modified varieties become more widely used. Some of these points apply mostly in “industrialized” rice production, particularly for the export market, where quality attributes are especially important, but that is a very small part of global rice production. Because of the strong social context of rice, especially in Asian countries, economics plays a key role in defining the seed system. The crop is not sufficiently profitable at the farm level to justify very high seed costs. Consequently, both formal and informal systems will continue to co-exist in a complementary way. Indeed, the barter of seed for grain is a common practice in some countries. It is not realistic to plan or impose a level of certified seed supply that is not technically justified or financially viable, unless that forms part of a wider national policy, and that may require subsidies to the production system, a practice that is now unfashionable! This raises issues for governments about the allocation of resources to support the seed system and for companies about the opportunities for commercial returns on their investments in rice breeding and seed marketing.

Public policy and international collaboration for sustaining and expanding the rice revolution
Joachim von Braun

Rice continues to shape the lives of millions of people. Public policy is therefore attracted to all production, distribution, and consumption aspects of rice, as well as its environmental implications. Public policy is changing, however, in view of developmental and societal change, especially in Asia. The importance of rice in the diet of Asia is expected to decline over time with urbanization and the increase in incomes beyond the level at which people begin to diversify their diets. This pattern is not observed in other parts of the world; in Africa and Latin America, rice is becoming increasingly important. Rice is a strategic commodity because it is a most important element in the diet of the poor and a main source of income and employment for farmers in Asia. Traditionally, governments have sought to maintain stable prices for consumers in urban areas and to provide input subsidies to farmers. A shift of policies toward less intervention in the rice market is noted. Governments are increasingly pulling out of managing rice and private enterprises play the main roles. Appropriate policies need to facilitate the private actors’ roles in the rice-related food chain. Rice is increasingly a “health food” with many characteristics and diverse tastes, and can be developed further in such directions. New science on rice focusing on the diet quality aspects of rice may actually transform rice into an even more important agent of change, especially for the poor. At the same time, high-income consumers are expected to increase their demand for specialty rice. The expanded supply of rice must be tackled by increasing yields. To achieve this, increasing investments in research and development are needed in international cooperation, especially to reduce water and energy use in rice production. These objectives will need to remain high on the agenda of rice research for decades to come. Public policy in support of making the best of rice needs adaptation to the new circumstances at national and global levels.

Financial and economic profitability of rice farming across production environments in Indonesia
Tahlim Sudaryanto, Dewa K.S. Swastika, Bambang Sayaka, and Sjaiful Bahri

In Indonesia, rice is the main staple food for more than 95% of the population. Rice farming provides job opportunities and income for about 21 million farm households. Rice is also a strategic and political commodity. Rice sufficiency at an affordable price has been pursued as a desirable policy objective to prevent hunger as well as economic and political chaos. It is not surprising that the government of Indonesia has intervened heavily in both rice production and marketing, with other food sources getting less attention. This article aims to provide an overview of the status of the rice economy and its profitability in Indonesia. The data showed that, from 1970 to 1995, rice production grew significantly at 3.85% per year. This significant growth was mainly attributed to massive intensification programs in line with inputs and credit subsidies, the provision of irrigation facilities, and price support policies. Meanwhile, in 1997, production declined, mainly because of El Niño. During 1997-2004, production increased by 1.30% per year, indicating a recovery for rice production in Indonesia, although with low growth. However, for more than three decades, domestic production has not been able to meet the exploding demand for rice, due to increases in per capita consumption and population growth. Therefore, Indonesia had an increasing deficit and became the largest rice-importing country in the world. Rice farming is financially profitable, indicated by return to management of 31–32% of the total cost in irrigated area, about 6% in tidal swamp, and 12% in upland. For the last two production environments, profits are too low and, hence, financially less attractive. However, farmers in these two areas grow rice as a subsistence crop for home consumption. In addition, the share of upland and swamp rice is only 5–6% of total rice production. Economically, rice farming on irrigated land has a high comparative advantage. To improve farmers’ competitiveness, price support should be gradually reduced and replaced by a policy that improves efficiency. Without any intervention, irrigated rice farming in East Java and South Sulawesi will begin to lose competitiveness against imported rice when the international price falls to US$182 per ton and $101 per ton f.o.b. Bangkok, and $242 and $250 per ton f.o.b. Bangkok, respectively, for upland and tidal swamp rice in South Kalimantan. In addition, all rice farming is still profitable if the rupiah appreciates to Rp 9,000 per US$. In the future, improvement in cropping intensity followed by the use of improved technology (new high-yielding varieties and cultural practices) will be the new sources of rice production growth and efficiency.

Harnessing IT: pervasive networking at its best in agricultural research and development
Bharath Krishnan

Information technology is ubiquitous in today’s knowledge-driven era. Modern economies, especially in parts of the developing world, have developed talent and expertise in providing computer-based services to developed countries, thus enhancing their own gross domestic product. Agriculture is very much a part of this revolution. Innovations in telecommunications have brought scientists and researchers in different parts of the world together on one common platform: the Internet. Along with email, the mobile revolution and wireless Internet accessibility in rural areas are facilitating speedier communication and providing opportunities for networking, enabling instant dissemination of knowledge and creating platforms for sharing ideas and results. Looking ahead, farming communities can benefit from the amalgamation of this medium with traditional broadcasting media (radio and television).

Leveraging the potential and the promises of modern information and communication technologies (ICT) in agricultural research and development is always going to be a challenge. This greatly depends on a variety of factors—comparable to a “marketing mix”—that constitute a larger part of the whole package to first foster, and then to sustain and later manipulate, the advantages and pitfalls of information technology implementation. One example of a “mix” could represent the availability of infrastructure, the will to implement an ICT road map, and the necessary financial backing.

The good news is that many countries already have variations of their own ICT road maps, while others are in the process of having one up and running. The single common goal of any road map is to enhance networking, that is, to develop knowledge-sharing systems that provide myriad opportunities to scholars and other stakeholders in agriculture to contribute and to learn from each other’s experiences. Certainly, this would necessitate evolving site-specific practices that would help enhance research knowledge, improve farm productivity, and alleviate rural poverty.

Adaptations in mechanized harvesting systems for rice in Asia
Eulito U. Bautista and Alfred Andrew Schmidley

The rice harvesting system in Asia is mostly traditional and still dominated by manual reaping and custom machine threshing despite decades of attempts to introduce mechanical harvesters. Presently, however, the need for mechanical systems within the region is peaking as harvesting costs and unreliability of labor reach high levels while recent technical advances toward mechanized systems are increasingly felt. Although the IRRI axial-flow thresher continues to be important to Asian rice fields and has been intensively adapted differently throughout Asia, various other harvester designs are being improved and introduced to meet the requirements of Asian farmers and the extreme field conditions under which harvesting machines operate during the wet season. In Vietnam, locally adapted reapers, which are wider and faster than the introduced IRRI reapers, are complementing big, mobile threshers. A wider IRRI stripper is also useful in some rice fields in the Philippines and Indonesia. Smaller, simpler, and cheaper combine designs based on the reaper’s cutter bar with an axial-flow thresher are being introduced in southern China, the Philippines, Vietnam, and India even as Western combines are being introduced in some Asian countries. As researchers and manufacturers continue to address technical and socioeconomic constraints to the adoption of appropriate mechanized harvesters, these developments lead to reduced harvesting cost and lower grain losses while also improving the economic conditions of Asian rice farmers.

Competing claims for natural resources and the need for system transitions in rice cultivation
M.J. Kropff, P.S. Bindraban, and M.A. Slingerland

The world entered the 21st century facing many challenges, often in an agricultural context. Prominent is the concern for feeding an ever-growing population with safe and healthy food. A sustainable living environment and socioeconomic development are major issues as well. All these concerns are strongly related to the management of natural resources such as land, water, energy, and minerals and the distribution of the products. Many resources are limited (e.g., land and fresh water) and several resources are not renewable, such as oil. The Millennium Development Goals attempt to resolve these concerns, aiming to increase benefits from Earth’s resources for people living in developing countries. Now, the political arena shows the dependency of the world on an oil-based economy, in which demand for oil increases rapidly due to economic growth and political instability, driving market prices up. Not surprisingly, demand for bio-based products, and especially bio-based fuel as a renewable resource, is booming. The strongly increasing demand for food and nonfood agricultural produce challenges our agricultural production capacity worldwide.
As many natural resources have multiple uses and multiple users, increasing demand can create constraints and be a trigger for conflicts at different scales, from local to international. To minimize these constraints, it is essential that current uses, increased demand, and resulting constraints at different scales be analyzed simultaneously to identify socially and economically viable options for local innovation in which the different objectives of a variety of stakeholders are met. Such options can be identified only through the involvement of these stakeholders, including scientists. When they work closely together, this may result in increasing space for solutions and co-innovation. Scientists can contribute in several ways in the policy-making process from problem identification to implementation. They can raise awareness of competing claims at different scale levels and identify options based on which stakeholders can make decisions about the way they want to deal with multiple uses of natural resources. In other words, the stakeholders who are responsible have to set goals. Of course, scientists have to continue their contributions to new technology development at different scales based on clearly defined questions. This technology should focus on a major increase in resource-use efficiency and expand the scope for solutions. In this way, we move from a technology push to a technology pull strategy and we need close interaction between social and natural scientists.

This paper discusses the challenge we face, which is to address the increase in different and often conflicting claims by transforming our systems, with specific attention to rice production systems. While transition in production systems calls for adjustments in socio-political conditions, the drastic transformations required cannot be achieved without technological breakthroughs using our best technical knowledge and means.

Challenges for market intelligence in an increasingly differentiated global rice economy
Eric Wailes

Flows of technologies are driving the demand for capturing information and sharing information vertically within global rice supply chains. The dynamics of the global rice economy, increasingly influenced by product differentiation and food safety concerns, are expanding and changing the demand for information and market intelligence. Genetic engineering and technologies such as the emergence of organic production necessitate enhanced vertical information flow, specifically the increasing need for identity preservation within the entire food supply chain system. Identity preservation (IP) and the coexistence of genetically modified (GM)–non-GM and organic-nonorganic imply differentiation, a situation distinct from co-mingled mass-marketed rice that is handled and stored in bulk for efficiency reasons. Because of distinct taste, cooking, and appearance, the trade of rice has long recognized the value of identify preservation, and certainly much more so relative to all other grains and oilseeds. Nevertheless, market intelligence, information, and data on rice trade have been treated largely as a homogeneous product by national and multinational public agencies. This has created significant challenges to economic analysts in developing models of the global rice economy and furthermore has limited the value of the research results generated by such models. This paper provides examples of the problems, challenges, and prospects for improving market information and intelligence in an increasingly product-differentiated global rice economy.

Sustaining conservation agriculture: lessons learned from the EU project KASSA
Rabah Lahmar

The questioning of the sustainability of conventional plough-based agriculture led to the emergence of alternative concepts and practices such as conservation agriculture (CA), which is currently spreading in many places. CA-based systems are said to rely on the simultaneous use of three main components: (1) reduced tillage or no-tillage and direct seeding for less disturbance of the soil and proper crop establishment; (2) soil cover to mitigate erosion, reduce weeds, and improve soil fertility and functions; and (3) crop rotation to control pests and diseases. These systems are thought to respond to production-protection requirements; interest in their applicability and results is growing.
Knowledge Assessment and Sharing on Sustainable Agriculture (KASSA) is an EU-funded project that intended to extract lessons from past research on CA. It did it through a step-by-step and iterative process that took place within four regional platforms: Asia, Europe, Latin America, and the Mediterranean.
In the four platforms of KASSA, implementation of the concept of CA gave rise to many farming practices. The no-till–based systems are the most common: in some places, they are about to replace completely the conventional plough-based systems. However, soil cover and sound crop rotation are still hardly practiced because of biophysical conditions; low biomass production; competition from livestock; lack of adapted varieties, of implements, and of knowledge; and general market conditions. The absence of these components makes the systems rely mainly on using chemicals to control weeds, pests, and diseases.

The reduction in production costs CA systems provide often acts as a powerful argument for their introduction and adoption. But this argument alone is risky because (1) the development and fine-tuning of these systems is knowledge-consuming and (2) their suitability and efficiency are highly sensitive to local biophysical, social, cultural, technological, institutional, market, and policy environments. Furthermore, there are relatively few scientific data on CA systems; particularly, their long-term agronomic, environmental, and socioeconomic impacts are still not well understood. Substantial systemic and multidisciplinary research effort is needed to understand the functioning of CA systems and their socioeconomic and ecological sustainability conditions.

Women’s role in poverty reduction in Asia
Jonna P. Estudillo and Keijiro Otsuka

There is a general observation that women’s role in agriculture, in general, and rice farming, in particular, has been declining as household income structure has shifted away from rice production to nonfarm sources. This paper explores how the Green Revolution, the increasing profitability of high-value crops, and development of the nonfarm sector have induced changes in household labor allocation in rice-growing households. A major finding is that the reallocation of women’s labor away from farm activities to nonfarm activities has resulted in a higher household income, a reduction in poverty, and a rise in investments in human capital of the next generation. Yet, in all likelihood, it was the Green Revolution that stimulated the development of nonfarm sectors and the investment in children’s schooling in the earlier periods.

Managing and sharing crop information for functional genomics and molecular breeding
Richard Bruskiewich, Martin Senger, and Graham McLaren

A new generation of crop information systems and their integration via web service networks is emerging from the informatics activities of the Generation Challenge Program (GCP; www.generationcp.org), which is a global consortium involving international agricultural research centers of the Consultative Group on International Agricultural Research (CGIAR; www.cgiar.org), several advanced research institutes, and a number of national agricultural research and extension systems (NARES). The GCP’s research agenda is directed toward genomics-driven crop improvement for CGIAR crops, using a strategy of comparative biology across crop species, high-throughput molecular characterization of genetic resources for allele mining, and deployment of efficient gene transfer technologies into plant breeding programs.

The information platform involves the adoption and/or development of common, public scientific domain models and ontology to cross-link all data types and analysis processes within the program, and the deployment and extension of data templates, web services, and registry technologies to capture, share, and integrate information across diverse and globally dispersed data sources. Public software tools are being adopted or developed to create an integrated platform of software and databases available as web services.

The activities of GCP partners and the International Rice Functional Genomics Consortium (IRFGC; www.iris.irri.org/IRFGC) require a high level of networked information. For this reason, a computer networking design and implementation project is developing a distributed network for rice functional genomics information, as a model for other crop networks. The BioMOBY Web Services protocol is being used and the project also leverages extensive scientific domain modeling and ontology development efforts within the GCP. The objective is to develop a standard package of easily deployed MOBY technology for use by various rice functional genomics research groups.

The software for the project is being documented on the GCP Web sites http://moby.generationcp.org (for general information about BioMOBY application to the GCP consortium network) and http://pantheon.generationcp.org (for data modeling and software engineering components). The open-source software for these projects is hosted on the CropForge collaboration site (http://cropforge.org), with technical discussions hosted on a GCP Wiki site (http://cropwiki.irri.org).

Potential and prospects of medicinal rice with special reference to Navara
P.V. Balachandran, S. Leena Kumary, Rose Mary Francies, and Jiji Joseph

In addition to being the staple food of half the human race, rice is believed to have many medicinal properties. In the ancient Indian records such as the Susrutha samhitha and Charakasamhitha of about 1000 BC, there is a mention of rice having many medicinal values. In Chhattisgarh, many traditional varieties are reported to have medicinal properties. Collection surveys made during the 1970s by Dr. Richaria and in the late ’90s by Das and Oudhia have led to the identification of more than 50 medicinal rice varieties. It is reported that variety Aalcha is used for the treatment of pimples while Baissor is used for chronic headache and epilepsy and Gathuhan, Karhani, and Kalimooch, respectively, are used for the treatment of rheumatism, paralysis, and skin diseases. In the Jeypore tract of Orissa, rice varieties Meher, Saraiphul, and Danwar are reported to be used by local tribal people against various ailments. In Uttara Kannada District of Karnataka, the presence of two medicinal rice varieties, Atikaya and Kari bhatta, has been reported. While Atikaya is used as a health tonic, Kari bhatta is used as a cure against skin infections. In Kerala, the important medicinal varieties grown are Navara, Chennellu, and Rakthasali. Among the medicinal rice varieties of India, Navara developed and conserved by the farmers of Kerala is unique in many respects. It is believed that Navara, which matures in 60 days, has medicinal property in redressing thridosa, the root cause of all body ailments. This rice has the rare capability to enrich body elements; exclude toxic metabolites; strengthen, regenerate, and energize the body; regulate blood pressure; and prevent skin diseases and premature aging. The ancient Ayurvedic texts distinguish yellow-glumed and black-glumed varieties of Navara. Agronomic evaluation of Navara cultivated in Kerala revealed immense variation. Twelve ecotypes of Navara collected from different parts of Kerala when evaluated for yield and yield characters exhibited wide variability. Hence, it is important to identify and characterize the “real” Navara employing molecular techniques and to find out which biochemical compounds confer unique medicinal property to Navara. It should be emphasized that the system of Ayurvedic medicine practiced in Kerala over thousands of years has established the multiple medicinal properties of this variety. Also, its importance as a health food offers an opportunity to establish a niche global market. There is an urgent need for careful conservation, characterization, and validation by modern methods.

Water—an emerging critical factor in Chinese rice production and trade
Funing Zhong and Shunfei Liu

China’s rice exports have been large and volatile in the world market, with the quantity of exports basically determined by excess supply in the domestic market. Restructuring following fast economic growth has reduced the importance of rice production in terms of sown area and gradually shifted rice production from south to north. As a result, rice production in China is likely to be more dependent on yield growth, more constrained by water shortage in the north, and volatile in yield and output.

Efficient management of nutrients in rice-based cropping systems in Asia
Yadvinder-Singh, Bijay-Singh, and J.K. Ladha

Rice-rice and rice-wheat (RW) are the two largest agricultural production systems in Asia. Asian soils are generally low in organic matter and have consistently been depleted of nutrients due to continuous cropping. Fertilizer has been and will continue to be the major input for achieving future food production targets, which will also involve improved nutrient management. The principal constraints to increasing nutrient-use efficiency include an inadequate understanding of soil nutrient supply, crop nutrient requirements, and a lack of technologies that match nutrient supply to crop demand. Fertilizer N-use efficiency (NUE) in rice-based ecosystems is low (30–40%) and offers a great challenge to researchers. In many parts of India and China, farmers are indiscriminately using N, causing low NUE and nitrate pollution of water bodies. Three major factors govern NUE: N uptake by the crop, N supply from soil and fertilizer, and N losses from soil-plant systems. Need-based fertilizer N management approaches using a chlorophyll meter and leaf color chart have shown great promise for producing optimum crop yields by avoiding excessive use of N fertilizers. As P fertilizers leave significant residual effects, application of P to wheat and growing of rice on residual P in a majority of soils are advocated in the RW system. At high productivity levels, however, this strategy leads to a negative P balance. Similarly, in the rice-rice system, winter rice responded more to applied P than summer rice. Critical soil test values of P for getting a response to rice and wheat vary markedly and should be established. There are opportunities for research on the management of soil and fertilizer P to increase P-use efficiency. Very little or no potassium fertilizer is being applied to rice-based cropping in India and thus most of it comes from potassium reserves of the soil and irrigation water. Since soils in China are at a more advanced stage of weathering than in the Indo-Gangetic Plains (IGP), responses of both rice and wheat to applied K are substantial in China. The response to applied K is highly variable and depends on soil K supply parameters, yield levels, and time of K application. In rice-based systems, summer rice responds more to applied K than winter rice or wheat. The continued omission of fertilizer S is causing yield losses at many locations in rice-based cropping systems. About 20% of the soils are deficient in S in the IGP. The extent of the S problem depends more on input of S through irrigation water and atmospheric deposition, precise information on which is not yet available. Rice showed more response to S than wheat. Plant uptake of P, K, and S using the omission plot technique can provide a quantitative approach for determining site- and season-specific soil nutrient supply. Instead of blanket fertilizer recommendations, site-specific nutrient management would help improve yield and profitability. A nutrient balance approach must be considered while revising existing fertilizer recommendations. Organic manures and crop residues have good potential for meeting the nutrient needs of rice and wheat. To stabilize yields at a maximum level without deteriorating soil health, an integrated use of organic manures, green manures, and chemical fertilizers is suggested.

Computational analysis and exploration of rice genome sequence data
T.R. Sharma, V. Dalal, S. Singh, S.P. Kumar, M.S. Madhav, and N.K. Singh

We are working on various aspects of comparative and functional analyses of disease resistance and defense response genes and gene loci using whole-genome sequence data of Oryza sativa subsp. japonica and O. sativa subsp. indica and various computational tools. We performed in silico analysis of the genome sequence of O. sativa subsp. japonica to find the total number of candidate disease resistance and defense response genes. The precise physical location and orientation of all the genes were determined on all 12 chromosomes. Chromosomes 1, 2, and 11 are rich in candidate disease resistance and defense response genes, containing more than 25% of the genes present in the whole genome. A 40-kb region on the long arm of chromosome 11 rich in defense response genes was identified to perform micro-syntenic analysis between japonica (Nipponbare) and indica (93-11) rice lines. Comparative analysis of the sequences of japonica and indica lines in constructing a physical map of the rice blast resistance locus on chromosome 11 led us to characterize and clone a dominant rice blast resistance gene, Pi-kh, from rice line Tetep. A 100-kb region was selected from a japonica type on chromosome 11 flanking the Pi-kh locus and compared with the indica-type sequence. Analysis of simple sequence repeats in this region showed that the japonica type has 46 monomer, dimer, tetramer, and pentamer repeats, whereas the indica type has 36 repeats. Our analysis showed that, with a high stringency level, the maximum percentage (69.8%) of Sorghum unigenes was homologous to all the rice genes, followed by barley (56%), maize (49.0%), and wheat (33.7%).

Host-plant resistance to insects as a core of rice IPM
J.S. Bentur

Studies on plant resistance to insect pests of rice in the past have culminated in effective breeding for resistant rice varieties with quality and high yield potential. However, limitations such as a lack of resistance against some pests in the primary gene pool, continuous changes in relative pest status with the emergence of new pests, the prevalence of pest complexes, and rapid evolution of virulent insect biotypes require continued research efforts to face new challenges. Recent advances in tissue culture, molecular biology, and biotechnology have provided new tools to effectively attempt to overcome these limitations. Better understanding of plant insect interaction has opened up a new vista with potential implications for pest management. Many novel insect resistance genes have been identified and introgressed from wild relatives of cultivated rice into elite cultivars. DNA marker technology has helped to tag and map several major resistance genes conferring resistance against hopper pests and gall midge and quantitative trait loci (QTLs) associated with planthoppers. PCR-based closely linked markers for these and new genes are being used in developing gene pyramids for durable and multiple pest resistance in an elite background. The genetic engineering approach has resulted in the incorporation of several classes of novel insect resistance genes from a bacterium, protease inhibitor genes from cowpea and potato, and a lectin gene from noncrop plants into rice. These transgenic rice lines are at various stages of evaluation. While Iran is the first country to release Bt rice for commercial cultivation, China is in the advanced stage of field-testing inbred lines and hybrids with insecticide resistance genes. Though no insect resistance gene has been cloned so far, expression-profiling studies on plant genes in relation to insects feeding on susceptible and resistant rice varieties are implicating a subset of genes for susceptibility and resistance. Similar studies on insect pests are aiming toward tagging, mapping, and understanding the functions of avirulence genes. Epigenetic causes of variation in virulence in pest populations due to endoparasites are also being studied. One of the main limitations of a sustained use of resistant varieties is the rapid evolution of insect pest populations capable of overcoming resistance. Through recent intensive ecological studies and simulation modeling, alternative strategies to meet this challenge are proposed and are being tested. Thus, we need to carefully plan and deploy plant resistance genes if we are to harness new opportunities for stabilizing and enhancing crop productivity.

Rice breeding for the 21st century
Gurdev S. Khush

The adoption of Green Revolution varieties led to major increases in rice production. Between 1966 and 2005, the population of densely populated low-income countries grew by 95% but rice production increased by 140% from 257 million tons in 1966 to 618 million tons in 2005. In spite of these advances in rice production, 800 million people still go to bed hungry every day and most of them are poor rice consumers. Micronutrient deficiencies affect millions of rice consumers. Per capita rice consumption is increasing due to rising living standards, particularly in Africa. The population of rice consumers continues to grow. It is estimated that we will have to produce 38% more rice in 2030. This increased demand will have to be met from less land, with less water, less labor, and fewer chemicals. This additional rice must be produced from good land without opening up more fragile lands for rice cultivation.

To meet this challenge, we need rice varieties with higher yield potential, greater yield stability, and dense micronutrients. Although the yield potential of rice is 10 tons per hectare, farmers on average still harvest 5 tons. To close this yield gap, we must develop varieties with more durable resistance to diseases and insects and tolerance of abiotic stresses. Various strategies for increasing rice yield potential include (1) conventional hybridization and selection procedures, (2) ideotype breeding, (3) hybrid breeding, (4) wide hybridization, and (5) genetic engineering. Various conventional and biotechnological approaches are being employed to develop durable resistance to diseases and insects and tolerance of abiotic stresses. Rice varieties with higher levels of iron and zinc have been identified and are being used as donors to develop improved varieties with dense micronutrients. Natural variation for beta carotene (a precursor of vitamin A) does not exist in rice. Therefore, a team of Swiss and German scientists has introduced the biosynthetic pathway through genetic engineering, leading to the production of beta carotene in rice endosperm. The capability of beta carotene production is now being transferred into widely grown national varieties.

Total factor productivity and returns to rice research in India
Praduman Kumar

Green Revolution technologies have contributed to the more than doubling of rice production over the last 35 years in India, driven mainly by a productivity increase approaching 85%. This strong increase in rice production that came from small farmers underlines the impressive role of smallholders in the Green Revolution process. Both the unit cost of production and real rice prices have fallen. A surplus of rice exists for trade. Agricultural research has contributed significantly and substantially to these trends, and returns to agricultural research have remained both stable and high since the 1970s. This paper assesses the total factor productivity (TFP) of rice grown in various states/regions of India and examines the sources of productivity growth and marginal rates of return to public investment in rice research. The TFP index has risen about 1% per year and has contributed about one-third of production growth. A decelerating tendency in TFP growth is observed. To maintain a surplus of rice, the study emphasizes the need to strengthen efforts to increase production by maintaining or increasing TFP through public investment in irrigation, infrastructure development, research, and efficient input use. It is also important to conserve natural resources and promote the ecological integrity of the agricultural system.

Discovering transcriptional regulation networks in stressed plants using combined kinetic modeling and promoter motif analysis
Xiao Yang, Ping Li, Yihua Zhou, and Jingdong Liu

Identification and detailed analysis of gene regulatory systems provide insights into how biological processes operate at the molecular level. We developed a novel in silico method for identifying transcriptional regulatory networks based on kinetic modeling of mRNA concentrations of the transcriptional regulator and its targets. Using time-series gene expression microarray data, the kinetic models predict a connection between a transcription factor and its targets. Such a relationship is refined by the promoter analysis that takes into account the enrichment of specific promoter motifs in co-regulated gene clusters. When applied on a gene expression profiling data set produced from Arabidopsis stress response experiments, our method successfully identified regulatory relationships that have been established in the literature, and predicted novel regulator-target pairs for future studies.

Selection of intraspecific (O. sativa × O. sativa) and interspecific (O. glaberrima × O. sativa) lines for their tolerance of blast, RYMV, stem borers, and AfRGM in West Africa
M. Sié, Y. Séré, D. Dakouo, B. Kaboré, O. Youm, S.A. Ogunbayo, and A. Togola

Rice is grown in rainfed upland, rainfed lowland, and irrigated systems. The rainfed lowland system covers over 70% of the cultivated land and 48% of Burkina Faso’s rice production. However, farmers have been progressively abandoning inland valleys because of the poor distribution of rains in time and space and high insect pest and disease pressure. Our study was designed to identify genotypes adapted to inland valleys with stable resistance to or tolerance of those major constraints that are responsible for rice yield losses in Africa, with particular reference to Burkina Faso. It was based on the agro-morphological characterization of 76 intraspecific (O. sativa × O. sativa) lines and 493 interspecific (O. sativa x O. glaberrima) lines obtained from 18 crosses during 1999. Progenies were tested in the Banfora rainfed lowland during the 2000, 2001, and 2002 rainy seasons. At the end of the first season, 91 lines were selected (14 intraspecific and 77 interspecific) and grown in the same conditions in 2001. Fifteen lines were then selected (6 intraspecific and 9 interspecific). These lines were tested in rainfed lowland conditions at Banfora and in the irrigated rice scheme of Karfiguela in the 2002 rainy season. Tested lines showed low susceptibility to disease and insect attacks, with scores below 5 for blast and RYMV for the 2000 rainy season. Individual crosses that seemed to be most susceptible to blast the first year were WAS 127 and WAS 131 (O. glaberrima × O. sativa) and WAS 115 (O. sativa japonica × O. sativa indica). At the end of the 2001 rainy season, 15 lines (6 intraspecific and 9 interspecific) were selected based on genotypes with good resistance to diseases (blast, RYMV) and insect attacks (stem borers and African rice gall midge) and good agronomic characteristics such as short duration, resistance to lodging, good yield potential, and good grain quality.

A transgenic approach for developing insect-resistant rice plant types
Jagannath Bhattacharya, Rajeswari Mukherjee, Ananya Banga, Abhijit Dandapat, Chandi Charan Mandal, Munshi Azad Hossain, Nandini Banerjee, Arnab Kumar Ghosh, Asif Hasan Chaudhuri, Ashish Mandol, Mrinal Kumar Maiti, Asitava Basu, Dipankar Ghosh, Sampa Das, Debabrata Basu, Sushma Mishra, Pritilata Nayak, and Soumitra Kumar Sen

Rice is one of the most important crops in the world. Rice yield lost to direct insect damage is estimated to cost at least several billion dollars. It is also known that several devastating diseases in rice are caused by viruses and transmitted by insects. Conventional control of insect pests in rice cultivation often depends upon the use of chemically synthesized insecticides, which already cause public concern on food safety and environmental pollution. Recent progress in rice transformation technologies has made it possible to produce genetically modified (GM) new rice cultivars with improved resistance to insect pests by genetic engineering. The major insect pests that attack rice plants in the field include the green and brown rice planthopper, gall midge, yellow stem borer, striped stem borer, leaffolder, gundhi bug, and rice hispa. Proteins with insecticidal activity that are known include crystal ?-endotoxins of Bacillus thuringiensis (Bt), protease inhibitors, ?-amylase inhibitors, and lectins. They have been used for engineering plants with intrinsic insect pest resistance. Research has advanced to maximize the potential of Bt and to an extent lectin-producing rice plants. It has been documented in China that Bt rice has the potential to increase yields, to decrease pesticide applications, and hence to improve groundwater quality. The performance of insect-resistant GM rice in trials in China has already been impressive. Thus, substantial benefits already experienced by Bt cotton and Bt maize should motivate the development of improved Bt rice lines and accelerate approval of Bt rice for farmers in rice-growing countries in the developing world. Developing countries such as China, India, and Brazil indeed have real capacity to generate new varieties with the help of GM technologies on the basis of farmers’ needs as well as profit potential. In fact, Bt rice has been under development at several institutions for several years and some is indeed ready for commercial release. Advancements such as expression of the transgene, pyramiding resistance genes to broaden protection and delay resistance of the insects against these genes and modification of the resistance gene to improve its toxic potential and broaden the range of insect sensitivity have been actively considered. Although we have advanced markedly in the generation of insect-resistant GM rice lines to enter into the expansion phase of crop biotechnology, certain areas still need improvement.

Increasing water savings while raising rice yields with the System of Rice Intensification (SRI)
Norman Uphoff

Competition among uses for surface water and groundwater is beginning to affect the agricultural sectors of many countries in this new century. Rice farming as the largest agricultural consumer of water is coming under increasing pressure to economize on water use. Finding ways to reduce the demand of rice producers for water is thus a major concern for farmers, researchers, planners, and policymakers. The System of Rice Intensification (SRI) developed in Madagascar over 20 years ago offers an opportunity for reducing rice sector demand for water. Its methods include either (a) minimum application of water or (b) alternate wetting and drying, with the effect of cutting water requirement for irrigated rice production by 25–50% or more. Concurrently, creating more aerobic soil conditions contributes to higher paddy yields by 50–100%. Using the full set of SRI practices raises the profitability of rice production by reducing production costs at the same time that outputs are increased. This gives rice farmers an incentive for water-saving cultivation. SRI’s positive-sum dynamics have seemed too good to be true, but these effects have been demonstrated already in 24 countries across Asia, Africa, and Latin America, including the three largest rice-producing countries: China, India, and Indonesia. This paper reviews the water savings possible with SRI that can accompany increases in yield and profitability. An initial trade-off/constraint has been the need for greater labor investment while the new methods are being learned. But several independent evaluations have shown that SRI can become labor-saving at the same time that it saves water, seeds, and production costs. An additional opportunity for increasing rice production is the development of rainfed versions of SRI in India, Madagascar, Myanmar, and the Philippines. Adaptations of SRI concepts and practices to unirrigated rice production can give yields in the 4–8 t ha–1 range. In any case, SRI should be regarded as still a work in progress, being adapted and further developed as more users and researchers become involved with using and elaborating on its insights and principles for attaining higher productivity of land, labor, capital, and, particularly, water.

Hybrid rice in the tropics: Where do we go from here?
Sant S. Virmani

Following the success of hybrid rice in China and considering the urgent need to increase rice production and productivity, the International Rice Research Institute (IRRI) was encouraged in 1979 to lead the development and dissemination of hybrid rice technology in the tropics. Currently, about 2 million hectares are planted with hybrid rice varieties, primarily under irrigated conditions in India, Vietnam, the Philippines, Bangladesh, Myanmar, and Indonesia, resulting in a yield advantage of 1–1.5 t ha–1 over inbred high-yielding varieties. This has encouraged the participation of the seed industry in public, private, NGO, and farmers’ cooperatives sectors. Experimental evidence has been generated that indicates a proportionately higher yield advantage of rice hybrids over inbred rice under certain unfavorable rice ecosystems having moderate drought, salinity, submergence, etc. The cytoplasmic male sterility system has been primarily used to develop rice hybrids. The future of hybrid rice in the tropics is even brighter. This paper highlights future opportunities for the development of better technology and its faster dissemination.

Lessons from the Rice Knowledge Bank
David Shires

It is often said that “access to information is the major component in improving the livelihoods of farmers in Asia.” The use of the International Rice Research Institute (IRRI) Rice Knowledge Bank (RKB) across the region is built upon the premise that the livelihoods of rice farmers will be significantly improved only by access to, and application of, validated research-based farming practices. The RKB was introduced in 2002 to collect and make available to extension officers and farmers the validated research-based knowledge that is able to improve farming practices and, hence, contribute to improvements in livelihoods. As the use of the RKB has grown significantly, testifying to a thirst for knowledge, several issues have emerged that suggest that the expression “access to knowledge” must be carefully and more comprehensively defined if the knowledge and its ICT delivery systems are to realize their potential to improve livelihoods. These issues are the scope, form, and organization of the knowledge, and the process of application of that knowledge by farmers. This paper explores the lessons learned, by both IRRI and its country partners, about the nature of the knowledge required by farmers, the organization of that knowledge, and the human networks that are necessary to produce a successful farmer information system. This paper suggests ways in which these lessons must be used in further development of the RKB.

Hermetically sealed storage systems for farmers and millers
M. Gummert, J.F. Rickman, E. Aquino, Myo Aung Kyaw, Diep Chan Ben, and Ridwan Rachmat

Farmers and rice millers in tropical regions are facing much loss of quality in their traditional open storage systems. Poor drying techniques, high relative humidity, high ambient temperatures, and storage pests reduce grain and seed quality quickly, resulting in financial loss when selling commercial grain and in low crop establishment rates.

Hermetically sealed storage involves enclosing the grains inside a hermetically sealed container. Respiration of the grains and the insects inside the storage system quickly reduces intergranular oxygen levels from 21% to less than 5%. Under these conditions, most insects die and the insect population is reduced to around 1 insect per kg of grain without the need to use pesticide. A hermetic storage container also protects the grains from absorbing moisture from the ambient air.

The International Rice Research Institute has conducted studies in many Asian countries using commercially available hermetically sealed storage systems with 5-t capacity. These studies have shown that hermetic storage maintains the quality of seeds, commercial grain, and brown rice much longer than traditional open storage. Benefits include an extended viability of up to 12 months for seeds, higher head rice recovery, longer storage time for commercial grain and brown rice, and protection from pests and moisture. The results of these studies have encouraged the development of a 50-kg super storage bag, which fits into the commonly used traditional bag and has all the characteristics of a hermetic storage system. This paper summarizes the results of various hermetic storage research trials that were conducted in Cambodia, Myanmar, Lao PDR, Indonesia, and the Philippines in collaboration with farmers and rice millers.

The complete rice genome sequence: a gold mine for innovation in rice research
Takuji Sasaki

The map-based complete rice genome sequence is now freely available to researchers worldwide, providing a fundamental tool that should further accelerate efforts to improve the staple crop that feeds more than half of the world’s population. The finished quality sequence covers almost 95% of the 389 Mb genome, including virtually all of the euchromatin and two complete centromeres. A total of 37,544 nontransposable-element-related protein-coding genes were identified. The complete genetic information of rice will serve as a gold mine for genomic research in rice and other cereal species. It will facilitate the identification of many important genes by both forward and reverse genetics strategies, and clarify the relationships between sequence variation and phenotypes. The genome sequence derived from Oryza sativa subsp. japonica can be used as a reference sequence for comparative analysis among Oryza species that will help in understanding the major factors involved in speciation and searching for useful genetic resources. During the last couple of years, high-quality rice genome sequence data have led to several milestones in rice genomics such as the discovery of genes that contributed to domestication or modern rice breeding. Furthermore, the completed sequence also begins to prove its value as a standard for cereal genome comparison and identification of rice orthologous genes in other grass species, thereby providing a platform for establishing the genomics of the major cereal crops.

Rice production and hybrid rice research in China
Cheng Shihua, Cao Liyong, and Zhai Huqu

Rice is the main staple food in China. More than 60% of the population in the country lives on it. The performance of the rice sector in production and yield has been very impressive in most of the last five decades. The wide adoption of semidwarf varieties facilitated an increase in rice yield from 2 t ha–1 in the 1960s to 3.5 t ha–1 in the 1970s. In 1973, the development of the first cytoplasmic male sterile (CMS) line in China made it possible to exploit the heterosis of hybrid rice in commercial use. Hybrid rice outyields the leading conventional varieties by 10–20%, enabling China to increase its rice yield to more than 6.0 t ha–1 and increase production by nearly 450 million tons on 370 million ha from 1976 to 2005.

China’s experience with hybrid rice research could be attributed to the use of various CMS resources, the high outcrossing rate of CMS lines and stable environmentally induced genetic male sterile (EGMS) lines, improvement of resistance to diseases and in grain quality, and a combination of ideo-plant type with heterosis in the hybrid rice breeding program. Innovative breeding techniques, for example, for the root system, molecular marker-aided selection, and wide hybridization should be considered in the further development of hybrid rice in China.

Promoting agricultural growth among lagging regions in India: implications for women’s participation and empowerment
Amita Shah

There has been an increasing recognition of the critical role that the agricultural sector in India plays in reducing poverty besides boosting overall economic growth. The recognition has come at a time when the agricultural sector faces yet another crisis, which poses important challenges such as low and fluctuating growth rates over time and space, the continued depletion of natural resources, and persistent technological stagnation that complicates overcoming problems in both drought-prone and flood-prone areas, which occupy a large proportion of India’s agrarian communities. It is imperative that women’s participation and empowerment become part of the processes that evolve for addressing these challenges. This calls for clear recognition that Indian farmers are women. This obviously goes beyond the rhetoric; the reality is that women are increasingly replacing men on the farm as more and more men are leaving farming, by compulsion or by preference. This recognition should therefore essentially bring women’s concerns onto the center stage of agricultural growth, especially in the lagging regions.

Fortunately, women already have greater space in some activities with special significance for the next phase of agricultural growth in dryland and high-potential rainfed areas with subhumid conditions in the northeastern parts of the country. For instance, women are in the forefront of various allied activities such as livestock, fishery, and cultivation of vegetables/horticulture in dryland regions such as Gujarat and Maharashtra. This kind of diversification is likely to be an important feature of future growth in these regions. Similarly, women have already occupied major roles in managing farming and other related activities in large parts of the subhumid regions and hilly areas having a high incidence of male migration. These regions, unlike dryland areas, are characterized by fairly substantial untapped potential in crop yields.

The strategy for attaining higher growth in both dryland and rainfed agriculture in subhumid areas may call for adopting a three-pronged approach consisting of (1) increased diversification within the context of a farming systems approach; (2) sustainable management of natural resources, especially water, thorough appropriate institutions; and (3) setting up of adequate information and market linkages. It is imperative that the road map for the strategy lay foundations for women’s empowerment. This would imply that operationalization of the new strategy would enhance women’s role in making informed decisions, increase returns to their labor, and eventually ensure improved well-being among women farmers, rather than merely increasing their work burden. Bridging or at least narrowing the gender gap in terms of access to factors of production such as land, credit, and knowledge should be considered as a necessary precondition for turning women farmers into champions of agricultural growth with higher productivity, environmental sustainability, and gender equity.

Given this backdrop, this paper depicts present scenarios, identifies challenges, and proposes a road map for achieving higher agricultural growth in dryland and rainfed regions in the manner narrated above.

Breeding rice of tolerance to highly variable abiotic stresses: submergence and drought
G.N. Atlin, R. Venuprasad, J. Bernier, A. Kumar, S. Verulkar, R.K. Sahu, H.R. Lafitte, R. Serraj, J. Cairns, P.K. Sinha, N.P. Mandal, H.E. Shashidhar, R. Chandrababu, S. Robin, J.L. Dwivedi, and S. Rathi

Drought regularly causes yield losses in bunded upper fields and unbunded uplands under rainfed conditions. Drought causes both direct yield loss and losses due to the disruption of important management steps, most notably transplanting. Progress in developing cultivars combining improved drought tolerance with high yield potential can be made if breeding programs incorporate direct selection for grain yield under drought stress as a selection criterion, in addition to selection for yield potential. Yield under drought stress is a trait that is at least as heritable as yield under favorable conditions. Currently, no secondary physiological traits are confirmed in their utility as selection criteria for drought tolerance in rice. Drought stress can be imposed by planting screening trials in drought-prone upper fields and withholding irrigation in an intermittent manner so that stress brackets the period of flowering. With these screening methods, several drought-tolerant upland- and lowland-adapted genotypes have been identified at IRRI, including hybrids, which generally outperform pure lines of similar background under both moderate drought stress and delayed transplanting. Aerobic adapted varieties that produce high yields under dry direct sowing are a promising option for areas where the risk of drought disrupting establishment is high. There is evidence that yield differences among genotypes under severe stress may be explained, at least in part, by the action of a relatively few QTLs with large effects. Some of these loci appear to have effects that are large enough to permit fine-mapping, and may be useful in marker-assisted selection.

Physiological and morphological traits associated with high yield potential in rice
Takeshi Horie, Koki Homma, and Hiroe Yoshida

To break through the current plateaus of rice yield potential, it is necessary to understand yield determination processes and identify traits associated with high yield potential. Many previous studies indicate that rice yield is most closely related to spikelet number per unit area (Sn) and then to grain-filling percentage (Fp), both of which are determined through physiological processes of genotype by environment interaction (G × E). The Sn is determined as the difference between spikelet number differentiated and that degenerated. Analysis of data from G x E experiments on nine widely different genotypes grown at eight different locations in Asia, covering cool temperate to tropical climates, revealed that the generated Sn is proportional to plant nitrogen (N) accumulated at 2 weeks before heading and that the degenerated Sn is inversely proportional to crop growth rate (CGR) during the 2-week period preceding heading. There were large genotypic differences in both the generated Sn per unit plant N at 2 weeks before heading and CGR during the 2-week period. Genotypes having higher N-use efficiency in spikelet production tended to have more secondary rachis branches per primary rachis branch with a moderate panicle nu