6. COUNTRY REPORTS

Australia

Dr. John Lacy informed the participants that Australia grows rice in an area of 150,000 ha to produce 1.3 million tonnes of Japonica rice, 85% of which is exported. Prior to 1985 yield levels were low, which slowly increased during 1985-89 to 6.8 t/ha and further to 8.4 t/ha during 1995-99. Earlier, farmers complained of low profitability as their yields fluctuated widely. There was a big gap between “top” and “bottom” farmers. The widely used technology transfer model failed to spread the message across the board, and thus a new extension model called “Rice Check” was developed. This new approach uses the findings and experiences from farmers’ fields also, in addition to the information generated from research plots.

Rice Check is the crop management and collaborative learning system based on crop checking that has been used in the Australian Rice Industry to improve yields and the grain quality. The checking and measuring of high yielding crops identified seven key recommendations or checks conducive to high yields. Earlier, most farmers did not adopt these checks resulting in lower yields.

Most important feature of the Rice Check is to encourage farmers to monitor and check their crops to see how it compares with the seven key checks. The checks are described simply and objectively to reduce information overloads, and aid understanding of the Rice Check recommendation package. To help learning, farmers are encouraged to record their management practices by completing crop record sheets.

Between 500 to 600 field (paddock) records are received by the extension agency each season. These records are analyzed to compare management practices and yield to understand how high yields were obtained. Farmers receive individual Rice Check Crop Evaluation Reports, which compare their management style vis a vis rice check to let them learn how they can improve it further.

The 45 farmer discussion groups organized by extension agronomists play a key part in the delivery of the Rice Checks. Rice Check has provided a framework, which has improved the collaboration and team work between farmers, researchers, extensionists, commercial agronomists, and the rice industry. Rice Check has changed the management practices in rice growing where farmers learn by critically observing and checking their crops. Rice Check continues to evolve and remain dynamic with annual updates of the recommendations, development of key yield checks and incorporation of environmental and grain quality checks.

Rice Check has changed the culture and management of rice growing from distance management to walking in and checking the crop. An independent evaluation of Rice Check, done in 1997 by interviewing 124 randomly chosen farmers, revealed that 83% found it very useful in producing high yields.

Bangladesh

Dr. S.M.A. Sattar mentioned that in spite of a twofold increase in rice production in Bangladesh, per capita availability has gone down. As a result, the country has to import 1.5 million tonnes of rice annually. The shortage and rice import will grow if the production is not increased, although it means a 60% increase is required by the year 2020. There is no possibility of horizontal expansion by bringing more new area under rice. Therefore, options available for increasing rice production are: a) breakthrough in present yield potential; b) full exploitation of the yield potential of currently grown modern varieties; and c) utilization of unfavorable but potential rice ecosystems.

Elsewhere, varieties with high yield potential (8.6 t/ha) are available, but locally yields of only 6.5 t/ha in Boro and 6.0 t/ha in Aman season, mostly at experimental stations, are recorded. The gap between farmers’ yield and experiment stations’ yield is much wider, 2.53 t/ha under Boro, 3.39 t/ha in Aman, and 2.62 t/ha in Aus. Physical and socio-economic factors such as low level of crop management, lack of price control, hesitation of farmers to invest in field improvement due to land tenure problems and others are responsible for such gaps.

Management factors that pull down farm-level rice yields include growing a variety in a season not appropriate for that particular variety, use of poor quality seed, imbalance in use of fertilizers and other inputs, failure to control weeds, and ineffective control of pests and diseases. Relative contribution (%) of fertilizer, weed and insect control to grain yield is 0.42, 0.27 and 0.05 respectively in upland Aus, 0.52, 0.53 and - 0.05 in transplanted Aus, 0.77, 0.46 and - 0.23 in transplanted Aman, and 0.52, 0.44 and 0.04 in Boro. Soil related factors associated with low farm-level yields are reduced organic matter content, particularly in the North and North-Western Zone of the country, and deficiency of sulphur and zinc. Among the other physical factors that often affect rice yield are unfavorable temperatures, floods and droughts.

To meet the food requirements for the growing population, Bangladesh agriculture has been subjected to 180% cropping intensity. Farmers often find it hard to plant on time due to lack of draft power and labour shortage. Delayed planting results in yield losses of 66.0, 55.4, and 9.6 kg per day of delay in Boro, Aus and Aman rice respectively. Fertilizer contributes the maximum, followed by weed management and insect control in all the ecosystems. Moreover, the rice yield decline due to over-mining of soil nutrients, organic matter depletion, floods and drought, and use of poor quality seed, has not been analyzed systematically. Therefore, an in-depth assessment of the effects of these factors on rice yield is yet to be understood clearly.

Providing permanency to farm-level irrigation structures may assure irrigation water to Boro as well as T. Aman crops, and thereby help bridge the yield gap. Strong extension programmes to popularize the Mini-Watershed technology developed by BRRI for providing supplemental irrigation need to be carried out. However, this has to be backed by government policy. Policy issues relating to import and distribution of fertilizers as well as promotion of a balanced use of nutrients need to be reviewed.

Although the farm-level rice yield remains below the attainable yield because of the factors described above, yet there are many other socio-economic factors which affect rice yields. A systematic study of these factors is needed for all the ecosystems.

China

Dr. Zhu Defeng stated that rice is the main staple food crop in China. About 60% of the Chinese population live on rice. Over the recent decade, rice accounted for less than 30% of the grain-crop area, but contributed more than 40% of grain production with the highest yield of all grain crops and nearly 40% of calorie intake.

The average annual growth rate of rice production from 1961 to 1997 was 3.5%. The main reason of increase in rice production has been the increase in yield, which was made possible through use of modern varieties, better cultivation technology and more input use. However, since 1976 the rice planting area has decreased.

Irrigated rice is the main type of rice ecosystem, covering 93% of rice area and with 95.5% of rice production. There are few areas of rainfed rice in the limited water resource environment and of upland rice in the mountain and hilly areas.

Low profit from rice production, which is partly due to small size of the farms, affects the enthusiasm of farmers engaged in rice production. Deficiencies in nitrogen, phosphorus, potassium, trace elements and organic matter content in soil are major constraints. In the intensive rice cropping systems, soil fertility has been depleted and cannot be recovered by natural processes. The highly fertilizer responsive varieties used in farmers’ fields give higher yield by increasing the fertilizer application. Water-logged soils and acidity of soil are also constraints to rice yield. Low and high temperatures in the various growth phases of rice, floods, lodging caused by wind and storm, and drought often threaten rice production. Sheath blight and blast are major diseases that cause yield losses. Striped stemborer, planthopper and stemborer are important insects affecting rice production.

The yield gap between actual farmer yield and attainable yield is 1358 kg/ha for early rice, 1487 kg/ha for single rice and 2074 kg/ha for late rice. Compared with actual farmer yield, attainable yield increases are 24% for early rice, 21% for single rice and 37% for late rice. New varieties and hybrids can give about 7.1% of yield difference. The improved cultivation technology contributes 14% to 30% of yield difference between actual farmer yield and attainable yield.

To narrow the yield gap between potential and actual farmer yields, new varieties and hybrids as well as improved cultivation technologies are being popularized in farmers’ fields. In the implementation of the program to narrow the yield gap, extension workers and farmers are trained, and information on technology is transferred to the rice growing areas. The research program can further bridge the yield gap through the development of new varieties and cultivation technologies. Inter-country cooperation for the exchange of information and experience can be very helpful and needs to be strengthened.

India

Prof. E.A. Siddiq pointed out that since its attainment of self-sufficiency in rice by early eighties, India is successfully sustaining the same, besides building its bufferstock to 12-15 million tonnes and entering the export market with 2-5 million tonnes, largely on account of the impressive yield growth in the predominantly irrigated south and north zones. To sustain this status, it is estimated that the country would require about 160 million tonnes of rice by the year 2006-7 assuming population growth of around 1.9% and income at 5%. This would require a minimum compound growth of 2.4%, which amounts to yield increase from 1.85 to 2.45 t/ha. In the absence of some and shrinking of many of the favorable growth factors of the 80’s, achieving the target would not be easy, especially in the wake of declining productivity growth in the productive ecologies. As against the overall production and productivity growth of 3.63 and 3.25 in the eighties, it is now 1.84 and 1.54 respectively. Zone-wise analysis reveals the growth decline to be drastic in the north and south zones (2.68 and 1.72 as against 5.30 and 4.20 of the 80s). The trend of production growth by ecosystem suggests interestingly higher growth (2.4%) in rainfed and semi-irrigated rainfed ecologies as compared to irrigated ecology (1.1%).

Yield gap analysis by region and ecosystem, which enables precise assessment of the untapped quantum of yield and identification of key factors contributing to the gap, is a prerequisite for consolidating the potential yield. In the present study, mean yield of the best test entry over test locations and years in the irrigated or semi-irrigated medium duration yield nurseries under the All India Co-ordinated Project was taken as the potential yield, while the state average yield as the actual farmers’ yield and the percentage difference was taken as the yield gap for a given state/ecology. In respect of rainfed ecologies, which are yet to have ideal HYVs, yield gap has been computed based on yield difference between improved varieties now being popularized through Front Line Demonstrations (FLD) and state average yields.

The findings relating to irrigated ecosystems reveal bridgeable yield level to be still sizeable, the national average gap being 52.3%. In the predominantly irrigated south and north zones with the exception of Tamil Nadu (15.6%) and Punjab (22.0%), the yield gap is moderate, while it is large in the west and N.W. Hill Zones. Comparison of the present pattern with that of 1987 reveals little improvement, possibly due to productivity advance, outpacing the efforts to narrow the gap. In the case of rainfed ecosystems, the gap has been found to vary with sub-ecology and region, the maximum being in shallow water and minimum in semi-deep water lowlands. With the exception of Eastern Uttar Pradesh (34.8%), the gap in the shallow lowland is in the range of 53-60%, while in upland (excluding Bihar) the gap is moderate (30 and 50%) and low in the semi-deep water ecology (25 and 30%). Under saline/alkaline conditions the yield gap is in the range of 40 to 48%.

In the irrigated south and north zones, faulty irrigation causing salinity/alkalinity, late planting due to uncertainty of canal water release, imbalanced fertilizer use, widespread zinc deficiency and high incidence of pests and diseases constitute the major constraints. In the semi-irrigated coastal areas with saline/acid sulphate soils, low adoption of HYVs and low fertilizer use, late planting, salinity and deficiency of P, Ca, S, Zn, lack of ideal varieties, low fertilizer use and moisture stress are limiting factors. Whereas in the rainfed lowlands in eastern India, acid soils of poor fertility, saline soils deficient in N, P and Zn, lack of ideal HYVs, low fertilizer use, submergence, dry spells, disease/pest pressure and ineffective transfer of technology form the yield limiting factors. In acid and poor soils of rainfed uplands, lack of ideal HYVs and slow adoption of improved varieties, limited use of quality seed, very low fertilizer use, severe weed infestation, blast disease, moisture stress and ineffective technology transfer component constrain the yield.

To narrow the yield gap, especially in the irrigated ecology, various research/development/policy measures are on since 1965. Whereas development of varieties insulated with desired level of resistance to major pests and diseases and of improved varieties for rainfed ecologies are the major research inputs in this direction, centrally sponsored Special Rice Development Programmes promoting massive production and supply of quality seed, management of essential inputs, technology transfer through extensive on-farm demonstration, and training of extension personnel and farmers are considered essential. The developmental programmes launched between 1965 and 1995 which included National Demonstrations, Rice Seed Mini-Kits, Rice Production Training, Special Rice Production Programmes, Special Food Grain Production Programmes, Front Line Demonstrations, Integrated Programmes for Rice Development and the ongoing Integrated Rice-based Cereals Development Programme are important. The impact of these efforts largely confined to low productive environments is evident through various indicators. In Eastern India for instance, rice productivity has increased from 1887 to 2508 kg/ha registering higher productivity growth (2.05%) than other zones (0.75-1.75%). Its share is 13.4 million tonnes of the 32.5 million tonnes added during the last 10 years. This positive trend is attributable to increased acreage of HYVs (44% to 63%) and fertilizer consumption (18-24 kg/ha). Declining factor productivity in rice-wheat and rice-rice systems, yield plateauing, imbalanced use of fertilizer nutrients in high productivity areas, shrinking labour availability, and increasing area under low yielding high value varieties are the key problems.

Micro-level constraint analysis should precede before launching research/development programmes. The ‘time-bound crop management activities’, which account for 20% of the harvestable yield is far from satisfactory. ‘Technology dissemination’, the third component, needs innovation and augmentation. The suggested action plans for irrigated ecology are development and use of technology packages for reversing the declining factor productivity, breaking yield stagnation and selective mechanization for timely crop management operations in intensively cropped areas, varietal improvement for saline/alkaline soils, development and adoption of technological and social devices for enhanced water use efficiency, ensuring adequate power/fuel supply for effective ground water utilization in Boro areas and modernization of drainage systems in the deltas. In respect of rainfed ecology, micro-level constraints analysis and development of location specific production packages, development of mechanism and infrastructure for production and supply of quality seed and buffer stocking of seed of short duration varieties for unforeseen situations and development of facilities for life saving irrigation are needed. Cross ecology measures should include timely supply of all essential inputs, subsidy on essential fertilizers, promotion of eco-friendly IPM/INM, improvement of credit facilities in areas of low productivity and continued support to all the ongoing extension programmes. Favorable policy support is vital for giving a pragmatic approach to the foregoing research/development strategies.

Indonesia

Dr. Abdul Karim Makarim reported that rice production in Indonesia is predominantly influenced by factors that are common to the entire Asian region. Being a country comprising of thousands of islands spread over a vast area, edaphic and climatic conditions play a prominent role in crop production activities. In addition, several socio-economic factors influence the rice production sector. Based on physical and environmental factors, the country can be broadly demarcated into three major rice growing regions which show varying levels of production and productivity. In like manner, these three regions show a wide disparity in yield gaps in major rice growing eco-systems when compared with potential yields that are achievable under research/experimental conditions.

In 1996, Indonesia had a grown rice extent of 10, 251,393 ha with a total production of 48,188,255 tonnes of grain and a national average yield of 4.70 t/ha. With the available rice varieties, potential yields under well managed conditions ranged from 5.78 to 7.08 t/ha. Of the three regions mentioned, Java and Bali showed the highest yield with an average of 5.36 t/ha followed by Sulawesi, Sumatra and Nusa Tenggara which recorded a yield of 4.1-4.6 t/ha. Kalimantan, Maluku and Irian Jaya showed the lowest yield with less than 3.0 t/ha.

Many factors appear to contribute to this disparity in actual yields obtained by Indonesian farmers. Natural resources such as rainfall, temperature, solar radiation and soils seem to vary from region to region. Availability of irrigation water and its distribution, drainage problems with attendant soil salinity and alkalinity, soil fertility and salt intrusions are other abiotic factors that influence rice production. Other factors that affect rice production include agronomic constraints such as pest and disease stresses, seed quality and suitable varieties. The rate of adoption of ‘prescription farming’ for specific locations and rate of adoption of other inputs such as fertilizer, tools and machinery are some other factors which are determined by costs. Water management skills, price fluctuations of finished rice, availability of credit and labor costs have also affected rice production in Indonesia. Other factors include farmer’s response to new technologies and their adoption, technology generation and transfer and information sharing and dissemination systems. Government policies that influence rice production are price support schemes and import controls.

Yield gaps in rice production are brought about by the interaction of the above factors in each rice growing region. In Java and Bali (Group 1), most factors are conducive to higher production giving rice yields ranging from 5.28 to 5.61 t/ha. However, socio-economic factors such as high cost of production and low prices for produce compared to other commodities seem to affect rice production. Farmers in this region, therefore, resort to production of high quality rice with increased profit margins than increasing inputs to optimize yields. In Sulawasi, Sumatra and Nusa Tenggara (Group II) rice yields vary from 3.18 to 4.77 t/ha and reduction in the yield gap is dependant upon water availability as frequent droughts limit production. Bridging rice yield gaps in Sumatra is mainly dependant upon improvement in drainage systems, reducing soil acidity and iron toxicity, reclamation of acid sulphate soils, etc. In Kalimantan, Maluku and Irian Jaya (Group III) rice yields vary from 2.63 to 3.10 t/ha. Yield gaps in this region are highly influenced by soil problems, socio-economic factors such as low technical capability of extension officers as well as poor management skills of farmers and difficulties faced by many growers in procuring reliable inputs. The strategy for this region would be to improve production skills of farmers and introduce simple but effective technologies such as good varieties, better quality seed and other production inputs.

Strategies for bridging yield gaps are supply of quality seed of varieties with high yield potential, increasing water availability and improving delivery systems, adoption of soil amelioration technologies, pest and disease control measures, training manpower and introduction of mechanization (for Maluku, Irian Jaya and Kalimantan). Other thrusts under the new strategies are economic measures to stabilize prices, reduce costs, develop marketing, improve transport and facilitate capital and credit to farmers, traders and marketing systems. Motivation of farmers and providing a better policy environment are also pre-requisites for increasing production and productivity of rice in the years to come.

Philippines

Dr. L.S. Sebastian explained that rice contributes 13% to the consumer price index, 16% to gross value added, and 3.5% to the gross domestic product. Recent trend analyses show that rice production growth due to area devoted to rice has drastically declined and that the growth of the rice sector has become completely dependant on yield improvements.

Because of this, the only remaining source of output growth is yield improvement, which can come in either of two ways: a) by shifting the yield frontier, which can be done by breeding varieties that have higher yield potential than the current varieties, e.g. new plant type; or b) by narrowing the existing yield gaps between the experimental station yields and farmers’ yields.

Evidence from research stations suggests that substantial productivity gains are technically possible for rice. Yet, farm-level increased output continued very slowly, if not stagnated in the past decades. At present, the average farmer’s yield ranges from 50 to 70% of the on-farm experimental yield, and only very few farmers have yields that are comparable to the demonstrated potential in on-farm experiments. The yield gap that currently exists is a result of biological, technical, physical, and socio-economic constraints.

Analysis shows that the average yield in on-farm experiments from 1991 to 1995 was 5.7 t/ha during the wet season and 7.5 t/ha during the dry season, while the respective average yield of farmers was only 3.7 t/ha and 3.9 t/ha. This corresponds to a yield gap of 2 t/ha during the wet season and 3.6 t/ha during the dry season. The Government of the Philippines, through the Philippine Rice Research Institute (Phil Rice), is implementing various RD&E activities aimed at bridging the yield gap. These activities include: a) making RD&E more effective; b) improving the long term yield stability of varieties through breeding; c) improving crop protection/pest management; d) efficient use of fertilizer; e) use of quality seeds; f) expansion of irrigated areas; and g) intensified technology promotion.

Although there are available technologies for increased productivity, there is still a need for policy measures that will help maximize the potential of these technologies. The development of location-specific technologies must be vigorously pursued to suit the needs of the farmers. Policy makers should consider the need for a timely delivery of seeds, water, fertilisers, and other inputs to farmers. Current RD&E activities must be further strengthened to ensure that the technologies developed reach the intended beneficiaries.

Sri Lanka

Dr. M.P. Dhanapala said that Sri Lanka has 0.73 million ha of rice lands. Of this extent, 0.56 million hectares are cultivated during the major rice growing season (Maha) and about 0.31 million ha during the minor season (Yala). Therefore, the total annually cultivated area is around 0.87 million ha at a cropping intensity of 119%. The rice lands are distributed in 18 out of 22 different agro-ecological regions. About 36% of the total land extent is rainfed and the balance is irrigated through major or minor irrigation systems.

Sri Lanka will have an estimated population of 20.01 million by the year 2005. With an estimated annual per capita consumption of 96 kg of milled rice, the country will need around 1.92 million tonnes of milled rice, which in rough rice equivalent will be 3.10 million tonnes needed to feed the population.

The semi-dwarf cultivars introduced since 1970 replaced almost all other cultivars from the field within a decade of their introduction. Though the rate of adoption was significant, the increase in productivity did not substantiate the effort made to attain self-reliance. After an initial improvement in productivity, the rice yields remained almost stagnant despite the introduction of more new cultivars. Though the semi-dwarf cultivars recommended from time to time were having yield potential of 6-8 t/ha, the average yields remained well below 5 t/ha even in irrigated high potential rice ecosystems.

Initial attempts made to understand the reasons for the yield disparity confined primarily to the crop management practices. A substantial yield gap was observed in the preliminary studies due to confounded effects of deficiencies observed in seed quality, crop stand establishment, weed control, nutrient management (inorganic) and, pest and disease control. When such effects were quantified by controlled experiments, ineffective weed control appeared to be the major reason for yield disparity in many instances. Poor pest (insect) control and nutrient management too appeared to play a major role in widening the yield gap in some isolated instances. Subsequent analysis indicated that bridging the yield gap was economically viable, but very soon it was realized that crop management deficiencies were not the sole contributors limiting productivity in semi-dwarf cultivars.

A long term declining trend in soil fertility and ill effects of climatic parameters in the late planted crops were gradually understood to play a significant role in the observed yield disparities. Upsurge of insect pests due to overlapping crops by staggered planting as a result of unorganized farming also played a major role in the yield gap.

In subsequent investigations, the interaction between the genotype and environment (G x E) was closely examined. The climatic, edaphic and biotic parameters of the environment and their influence on productivity through long term studies were analyzed. The institutional and socio-economic constraints affecting management decisions of the farmer were also studied. Subsequently, a technological package was developed for adoption to enhance productivity while organizing the farming community for timely and seasonal cultivation on a tract (yaya) basis. Demonstrations of the package of practices were done on large tract basis (>40 ha tracts) and gradual dissemination of technology to the peripheral areas was encouraged. More and more effort was made to improve cropping intensity by inducing farmers to cultivate neglected paddy lands and resort to double cropping in favourable areas.

The key components of the technological package to bridge the yield gap are:

- Use of appropriate cultivars
- Use of quality seed
- Collective and timely (seasonal) cultivation
- Improvement and sustenance of soil fertility
- Intensive crop management practices
- Minimising post-harvest losses

Thailand

Dr. T. Kupkanchanakul indicated that rice is the most important food crop in Thailand. The total area under rice is estimated to be about 11 million ha representing approximately 40% of the cropped land area. Average rice yield in Thailand is relatively low, often less than 2 t/ha. Several attempts had been made to improve rice yield in the past two decades through varietal and cultural practices improvement and the development of water resources for rice production. Yield improvement through these efforts was small and further improvement is needed.

Rainfed lowland and irrigated areas are the most predominant rice production ecosystems in Thailand. In the 1997/98 crop year, rainfed lowland accounted for 66% of the area and 49% of production while irrigated rice accounted for 32% of the area and 49% of production. The area planted to deepwater and upland rice is very small and contributes very little to national rice production. Average yield is relatively low, about 3.55, 1.87, 1.95 and 1.75 t/ha in irrigated, rainfed lowland, deepwater and upland ecosystems, respectively.

In irrigated ecosystems most environmental factors are favorable for rice production and development. Narrowing the rice yield gap in this ecosystem should be done through the application of improved agricultural practices for rice production at all growth phases. The development of HYVs will contribute greatly in narrowing the yield gap in irrigated environments. Hybrid rice production with acceptable grain quality is also possible. The utilization of good and healthy seed can play an important role in increasing rice yields. Good land preparation with appropriate planting methods such as the wet seeded rice cultivation method will guarantee good crop stand establishment. Appropriate water management and correct fertilizer application for the crop are also needed in narrowing the yield gap. Adoption of integrated crop protection technology to control pests and weeds can significantly increase rice yield in irrigated ecosystems. Harvesting the crop at proper stage of maturity and reducing grain moisture to about 14% after harvesting can further reduce yield losses and maintain good grain quality, especially in the dry season rice cropping.

Rice production in the rainfed lowland environment, being dependant on rainfed conditions, is subjected to climatic variability, which may cause low yield. Major production constraints are related to unfavorable environmental factors such as rainfall variability and drought, inherent low soil fertility and poor field infrastructure. To narrow the yield gap in such environments, improvement of farm infrastructure such as land levelling, irrigation and drainage facility modifications, and farm road construction should be done before the introduction of improved production technologies. Technology components to improve rice yield in rainfed ecosystems are: the adoption of improved varieties, use of healthy and good seed, appropriate field preparation and planting methods, optimum planting date and proper crop management, soil fertility improvement and correct fertilizer application, good water control and integrated crop protection, proper harvesting stage and adoption of post-harvest technologies.

Vietnam

Dr. Bui Ba Bong reported that Vietnam grows rice on 7.5 million ha with a production of 30 million tonnes, which made it the world second largest exporter in 1998. Rice is grown under irrigation with yields of 6 to 7 t/ha in the dry season and 4 to 5 t/h in the wet season. Under rainfed lowland conditions yields of 2 to 4 t/ha are obtained. In the upland areas (0.45 million ha) yields range from less than 1 to 2 t/ha.

To meet the growing rice demand internally and of others dependant on Vietnamese rice exports, production would have to be increased from its present level of 4 t/ha to 5 t/ha in the next 10 years, as there is no additional land available for rice.

In the irrigated ecosystem, yields of varieties and hybrids tend to stagnate as biotic and abiotic stresses take their toll. Also, there is scarcity of superior yielding early duration varieties. Available varieties have poor grain quality and are susceptible to various biotic and abiotic stresses. Available rice hybrids have low seed yield, and are inferior in grain quality. Breeding of varieties and hybrids with higher yield potential, particularly for the Red River and Mekong River deltas, is of paramount importance. The solution to these problems lies in developing superior hybrids and inbreds with better grain quality. The crop yield and also the seed yield of the hybrids will have to be improved. To reverse the trends in yield decline, durable resistance to pests and diseases is another needed approach.

Rainfed lowland and flood prone ecosystems were prevalent in the Mekong River delta but since 1983 most of it has been converted into irrigated rice. Deficiency and excess of water causes unpredictable losses. Also, in rainfed lowlands especially the acid sulphate soils, nutritional disorders (iron and aluminium toxicity, inundation with sea water, and rising salinity) hold down and de-stabilize yields. Traditional varieties are grown in this ecosystem which are photoperiod sensitive and low yielding (2.5 to 4.5 t/ha). The average yields need to be raised by 0.5 to 1.0 t/ha. The solution to the problems of rainfed ecosystems and yield gaps lies in breeding varieties with tolerance to abiotic stresses, better management strategy for acid sulphate soils, identifying phosphorous efficient lines, etc.

In upland ecosystems, soil degradation and erosion, infertile soil, subsoil acidity, and lack of organic matter are the major bottlenecks. Also, lack of improved varieties keeps the production down. Traditional varieties also need to be evaluated for resistance to drought, phosphorous efficiency, resistance to blast and nematodes, tolerance to soil acidity, and weed competitiveness. New tools of ecosystem management are needed like hedgerow, cover crop systems, and crop residue management. These strategies are expected to stabilize and increase the yields by 1.0 t/ha across the ecosystems.