Previous Page Table of Contents Next Page



Rice is the staple food of Asia and part of the Pacific. Over 90 percent of the world’s rice is produced and consumed in the Asia-Pacific Region. With growing prosperity and urbanization, per capita rice consumption has started declining in the middle and high-income Asian countries like the Republic of Korea and Japan. But, nearly a fourth of the Asian population is still poor and has considerable unmet demand for rice. It is in these countries that rice consumption will grow faster. The Asian population is growing at 1.8 percent per year at present, and population may not stabilize before the middle of the next century. A population projection made for the year 2025 shows an average increase of 51 percent, and in certain cases up to 87 percent over the base year 1995. So far the annual growth rate for rice consumption in the Asia-Pacific Region over a period of 45 years (1950 to 1995) has kept pace with the demand, more through yield increase rather than area expansion. Improved varieties have made a significant impact (Khush, 1995) in an ever increasing order during this period. The world rice supply has more than doubled from 261 million tonnes in 1950 (with Asian production of 240 million tonnes) to 573 million tonnes in 1997 (including the region’s production of 524 million tonnes). Production has more than doubled overtaking the population growth of nearly 1.6 times in Asia. A measure of this success is reflected by the fall in the price of rice in the world markets.

The Asia-Pacific Region, where more than 56 percent of the world’s population live, adds 51 million more rice consumers annually. As a result of this the thin line of rice self-sufficiency experienced by many countries is disappearing fast. How the current 524 million tonnes of rice produced annually will be increased to 700 million tonnes by the year 2025 using less land, less people, less water and fewer pesticides, is a big question. The task of increasing substantially the current level of production will face additional difficulties as the avenues for putting more area under modern varieties and using more fertilizers for closing the yield gap, bringing in additional area under rice or under irrigation are becoming limited. The irrigated rice area currently occupies about 56 percent of the total area and contributes 76 percent of the total production. It would be hard to increase this area due to the problems of soil salinity, high cost of development, water scarcity, alternative and competing uses of water, and environmental concerns. Thus, increased productivity on a time scale has to make the major contribution across ecosystems by using more advanced technologies.


2.1 Production-Consumption Scenario

Rice is the crop of the Asia-Pacific Region. The projected demand by the year 2025 is mind boggling (Hossain, 1995), as in major Asian countries rice consumption will increase faster than the population growth. In summary, in Asia, the rice consumption by the year 2025, over the base year 1995, will increase by more than 51 percent (Table 1). Another significant change will be the development of many mega cities of the size of 10-15 million people over and above the general urbanization of the populace. Thus, the number of consumers will grow and the number of producers will be reduced dramatically. The current demand of 524 million tonnes is expected to increase to over 700 million tonnes. Rice will continue to supply 50-80 percent of the daily calories, and thus the average growth rate in production has to keep pace with the growth rate of the population.

Table 1. Projections of Population in Major Rice Producing and Consuming Countries in Asia, 1995 to 2025


(mill.) 1995

Annual Growth Rate
(% per year)

(mill.) in 2025


























































Rep. of Korea












Asia (excluding China)






Source: World Bank Population Projections, 1994-95 Edition
During 1997 the Region produced 91.37 percent of the world’s rice during the decade 1987-1997, with an average annual growth rate of 1.8 percent. In the last 3 decades, starting with the era of the green revolution triggered by IR 8, rice production in Asia increased by more than 100 percent outstripping the population growth of 80 percent. This increased the availability of rice and decreased the price, which fully justified the investments in research, thus creating a sense of social justice. Several countries like Cambodia, China, India, Indonesia and the Philippines achieved self-sufficiency, even though short-lived in some. Liberalization of economies, increasing consumer wealth and the proliferation of grey-channel trade ignited the demand for high quality rice imports. China’s imports are increasing steadily (Anon. 1998). In addition to Thailand, countries like Australia, India, Myanmar, Pakistan, Sri Lanka and Vietnam became rice exporters. During the year 1995, together they exported 17.1 million tonnes of rice (FAO, 1997) which accounted for 73.4 percent of the total world export in rice. The rice export grew during the 1985-1995 period by an average annual growth rate of 6.1 percent (FAO, 1997). This has been possible even in the light of the fact that the major producers like China increased their imports by an annual growth rate of 2.4 percent during this period. However, the number of rice farmers has been declining faster in proportion to the development stage of the countries, (4.3 percent on average in the Asia-Pacific Region). In addition, growth rate in fertilizer usage has leveled off in general and use of modern varieties is also plateauing with major producers. There has been almost no growth (0.4 percent) in the rice area but the production (1.8 percent) has grown due to the growth in the productivity (1.4 percent on annual basis) during the period of 1987-1997. In some countries like Bangladesh, Bhutan, China, DPR Korea, Fiji, and the Republic of Korea, the rice area decreased during this period.

2.2 Rice Balance in the Region

Aggregate rice output growth rate for Asia increased from 2.2 percent per annum during 1950-1965 to 2.9 percent during the 1965-1980 period, outstripping the annual population growth of 2.23 percent. This growth declined to 2.6 percent during 1980-1990 and to 1.8 percent during the 1987-1997 period. Despite an anticipated decline in per capita rice consumption, aggregate demand for rice is expected to increase by about 50 percent during 1990-2025. As income grows, per capita rice consumption is expected to decline as consumers substitute rice with high-cost quality food containing more protein and vitamins such as processed preparations of rice, vegetables, bread, fish and meat. Japan and the Republic of Korea have already made this transition, and rest of the Asia will be making it in proportion to the pace of their economic growth. But these declines will be offset by the population growth (Table 1) and additional income (Table 2), increasing the net demand of rice to over 700 million tonnes by 2025. It is frightening to note that the rice production growth rate of 1975-85 (3.2 percent) which declined to 1.8 percent during 1987-97 (Table 3) is declining further. As a result in the next 10 to 20 years most Asian countries will find it hard to be self-sufficient and in fact, helped by trade liberalization under the General Agreement on Tariff and Trade (GATT), will likely become net rice importers. Several countries that are now self-sufficient in rice may find it more profitable to import rice in exchange for diverting production resources to more remunerative activities. But who will produce this rice is yet another issue to be understood and answered.

Table 2. The Demand Response to Incomes and Prices for Rice (Estimates for Selected Asian Countries)


Percent Increase in Demand
from 1% Increase in Income

Percent Increase in Demand
from 1% Increase in Prices






















Rep. of Korea



Source: IRRI/IFPRI, 1995. Rice Supply and Demand Project

Table 3. Rice Production, Yield, Area and Growth Rates in Production (P), Yield (Y) and Area (A) in the Asia-Pacific Region (1987-1997)


Production (P)
(000 tonnes)
in 1997

Area (A)
(000 ha)
in 1997

Yield (Y)
in 1997

Growth Rate (%)







































DPR Korea













































































Papua New Guinea














Rep. of Korea







Sri Lanka




























Rest of World














Source: FAO/RAP Publication: 1998/21

The task of producing the additional rice to meet the expected demands of the year 2025 poses a major challenge. The danger is that stability in rice production is linked to social and political stability of the countries in the Asia-Pacific Region (Hossain, 1996). The scope of area expansion in some countries is offset by the reduction in rice lands in major rice producing countries. So far irrigated rice which occupies about 57 percent of the area and produces 76 percent of total rice has helped double the rice production. It will be easier to produce the necessary increases in productivity under irrigated conditions than under rainfed or other ecosystems. The question turns more problematic when we think that production increases have to be realized annually using less land, less people, less water and less pesticides. There are additional difficulties of putting more area under modern varieties and using more fertilizers for closing the yield gap, or bringing in additional area under rice or under irrigation. The irrigated rice area would be hard to increase as the problems of soil salinity, high cost of development, water scarcity, alternative and competing uses of water, environmental concerns of the emission of green house gases like methane (rice fields contribute 20 percent) and nitrous oxide (fertilizer contributes 19 percent). The difficulties are further amplified when potential consequences of increased cropping intensity are taken into account. Estimates of the Inter Centre Review instituted by the Consultative Group on International Agricultural Research (CGIAR) indicate that about 70 percent of additional production will have to come from the irrigated rice ecosystem and almost 21 percent from rainfed lowland. To achieve this, it was estimated that the yield ceiling of irrigated rice in Asia, for example, would need to be increased from its late 1980s level of about 10 tonnes/ha to around 13 tonnes/ha in 2030. Simultaneously the yield gap would have to be reduced from 48 to 35 percent to produce average yields of about 8.5 tonnes/ha or about double the current level. One of the several ways GATT will affect research will be through funding and comparative resource allocation. With the movement from subsistence to a market-oriented economy, rainfed rice production may bring additional changes in many countries which depend on this ecosystem heavily and have no resources to convert rainfed to irrigated systems (Pingali et al. 1997).

3.1 Germplasm Availability and Varietal Development

In the past agriculture, plant germplasm, and crop varieties were treated differently from the industry and industrial products with respect to Intellectual Property Rights (IPR). When the UPOV convention initiated a patenting right for the plant varieties and micro-organisms in 1961 (UPOV, 1991), only a few countries had become signatories. Most of the Asian countries that had not signed had sizeable public research investments for technology generation, which was seen as government support to feed the people. The IPR has its roots embedded in World Intellectual Property Organization (WIPO) established by a convention in 1967, enforced in 1970, and attached to the United Nations Organization (UNO) as a specialized agency in 1974 (WIPO, 1988; WIPO, 1990). It is generally argued that IPR and patenting will assure returns to research investment by providing product secrecy, and will attract private investment for agricultural research. In GATT, there is provision for patenting along the lines of IPR. Although, only a recommendation, it yet becomes binding for the signatory country to “provide some alternative means of protection for such plants”. The GATT provisions state: “The only types of inventions that countries can exclude from patentability are those whose exploitation would prejudice public order or morality, those involving diagnostic, therapeutic or surgical methods for the treatment of humans or animals, and inventions of plants and animals or essential biological processes for their production”. Countries taking advantage of this provision to preclude the grants of patents for new plants must, however, provide some alternative means of protection of such plants. In the absence of IPR and patenting, germplasm moved unrestrictedly and made contributions globally (Chaudhary, 1996), which can no longer be tolerated.

The historic discovery of the semi-dwarfing gene (sd1) of De-Geo-Woo-Gen variety in the district of Taichung in Taiwan ROC (province of China), revolutionized rice production in the world. Today varieties carrying this gene are cultivated in almost all the tropical rice growing countries. Can one imagine if the world has to pay Taiwan for this gene? Grassy stunt virus during the 1980’s threatened the cultivation of rice grown without the use of costly and hazardous pesticides. A single accession of Oryza nivara had the requisite gene later named as gsv. Ever since, all the IR varieties starting from IR 28 incorporating this gene were developed and released. Dr. G. S. Khush (personal communication) mentions that at its peak a single variety IR 36 carrying gsv gene was planted in 11 million ha in the 1980’s. IR 64, another variety carrying gsv gene is planted in about 8 million ha. There is no fair estimate available of the area under gsv gene but a rough guess is that in Asia alone it will be more than 100 million ha. One can very well imagine the production impact of a single freely available gene simply taken from a rice producing area in the eastern part of Uttar Pradesh in India. Can one imagine if this gene was patented by a private company? What if the world has to pay for this gene to the community from where the accession carrying this gene was collected?

3.2 Stagnation, Deceleration and Decline of Productivity

Yield decline is noticed when in order to get the same yield level, increased amounts of inputs are needed. This trend has been felt by farmers in irrigated rice systems, and reported by Cassman et al. (1997). Yield decline may occur when management practices are held constant on intensive irrigated rice systems, owing to changes in soil properties and improper nutrient balance. It also leads to a depletion of soil fertility when inputs do not replenish extracted nutrients. The need for designing regional programmes of action to enhance and sustain rice production and to attain durable food security and environmental protection in the Asia-Pacific Region was also recommended by an earlier FAO Expert Consultation (FAO, 1996). It was recommended that different countries should undertake systematic studies on the actual and potential downward yield trends (deceleration, stagnation, and decline), quantify these processes and delineate the affected areas as accurately as possible. These could find a place in the research agenda of the CGIAR institutions like IRRI, WARDA and other centres. The development of more location specific technologies for crop management, Integrated Pest Management, Integrated Nutrient Management, technology transfer to further reduce the yield gap, and manpower development in appropriate areas would have to be handled by NARS. The sharing, testing and utilization of technology and knowledge across national boundaries have to be facilitated by the CGIAR institutions and FAO through various networks supported by them (Tran, 1996). FAO’s work on agro-ecological zones (AEZs) and the CGIAR’s Eco-Regional approach have lots of common ground for this new paradigm in technology assessment and transfer.

3.3 Declining Production Resources

Rice land is shrinking owing to industrialization, urbanization, crop diversification and other economic factors. Under these pressures in China, the rice area declined from 37 million ha in 1976 to 31 million ha in 1996. A similar trend of negative growth is visible in many countries even over a relatively shorter period from 1986-1996 (Table 3). Similarly, the number of rice farmers is also declining fast in most countries. In the Republic of Korea during 1965-95, the numbers of rice farmers declined by 67.3 percent. It is estimated that by the year 2025, more than 50 percent of people will live in urban areas compared to 30 percent in 1990. Growing urbanization and industrialization will further reduce the agricultural labour, increase the labour wages and farm size, needing more mechanization.

The Green Revolution technologies used in irrigated and favourable rainfed lowlands, which stabilized rice production and reduced prices, are almost exhausted for any further productivity gains (Cassman, 1994). In fact, a net decline in the irrigated area may be expected if problems of salinization, waterlogging, and intensification-induced degradation of soil is not handled forthwith. It is predicted that quality and quantity of water for agriculture will be reduced. Water will become scarce and costly for agriculture (Gleick, 1993) and the next war may be fought over water. The water to rice ratio of 5,000 litres of water to 1 kg of rice has remained unchanged over the last 30 years, yet the availability has declined by 40 to 60 percent in Asia. In addition industrial and agricultural pollutants have degraded the water quality in most countries.

3.3.1 Declining factor productivity

A significant problem in Asia is the yield decline now noticeable in irrigated and rice-wheat rotation areas. Long-term experiments conducted at IRRI, the Philippines, have indicated that the factor productivity has gone down over the years. At the fixed level of fertilizer, the productivity has been going down, and to get the same yield a higher level of fertilizer has to be added. Cassman and Pingali (1995) concluded that decline in the productivity is due to the degradation of the paddy resource base. They analyzed that at any nitrogen level, the long term experiment plots at IRRI are giving significantly lower yields today than in the late 1960’s or and early 1970’s. The same may hold true for farmers’ fields. Productivity of rice has been declining faster in mono-crop rice areas as well as under rice-wheat rotation (Cassman et al. 1997). Sizeable areas in Bangladesh, China, India, Myanmar, Nepal, Pakistan and some in Vietnam and Thailand are under rice-wheat rotation. Thus, this problem needs attention soon without any sense of short-term complacency.

3.3.2 Deteriorating soil health

The continuous cropping of rice, either singly or in combination, has brought about a decline in soil health through nutrient deficiencies, nutrient toxicity, salinity and overall physical deterioration of the soil (Cassman et al. 1997). Saline and alkaline soils cover millions of hectares in several South and South-East Asian countries. Also upland rice cultivation has promoted soil erosion in the fields and clogged irrigation and drainage canals down stream. The over use or improper use of irrigation without drainage encouraged waterlogging, resulting in salinity build-up and other mineral toxicities. Proper technology backed by policy support and political will is needed for addressing these issues.

3.3.3 Low Efficiency of Nitrogen Fertilizers

Urea is the predominant source of nitrogen (N) in the rice fields. But its actual use by the rice plant is not more than 30 percent meaning thereby that 70 percent of the applied nitrogen goes either into the air or into the water, endangering the environment and human health. Further research is needed to understand and avert this situation. Related to nitrogen use efficiency is the area of proper use of nitrogenous fertilizer. Use of the chlorophyll meter and leaf colour chart to improve the congruence of N supply and crop demand is a good tool, for example, to save on fertilizer and optimize factor productivity. However, this knowledge intensive technology has its own hidden costs.

3.3.4 Ever-changing balance of rice and pests

Pests (including insect-pests and diseases) of rice evolved under the influence of host genes are changing the rice-environment. Thus, scientists are in a continuous war with ever changing races, pathotypes and biotypes of rice pests. New and more potent genes, being added continuously using conventional or biotechnological tools, fight a losing battle. But these efforts are essential to add stability to production and avoid the recurrence of the great Bengal famine of the Indian sub-continent, or brown plant hopper catastrophe of Indonesia and the Philippines, or blast and cold damage experienced in the Republic of Korea and Japan during 1996.

3.3.5 Aging of rice farmers

The average age of rice farmers is increasing in almost every country in proportion to rate of its industrialization. The younger generation is moving away from agriculture in general, and backbreaking rice farming in particular. The result is that only the old generation is staying with the rice farming, which has manifold implications. This also raises a serious socio-political issue.

3.3.6 Increasing cost of production

By the adoption of modern rice varieties and technologies, the unit cost of production and global rice prices came down. But since the beginning of the 1990’s, unit production costs are beginning to rise and rice farmers are facing declining profits. A stagnant yield frontier and diminishing returns to further intensification are the primary reasons for the reversal in profitability. Contemporaneous changes in market factors - especially land, labour and water - are driving up input prices. Rapid withdrawal of labour from the agricultural sector, diversion of land for other agricultural and non-agricultural purposes, increased competition for water, and withdrawal of subsidies for inputs have contributed to the current situation and may worsen it in the future. Politically, sound lower rice prices are welcome but who is losing?

3.4 Rice Trade and Price Incentive

Although less than 5 percent of the rice production is traded in the international market, yet it influences the local rice prices. GATT has increased pressure to liberalize trade and to open up rice markets in the middle and high-income countries. It has also an indirect effect on research priority setting and rice production by introducing a market-oriented decision making process. Though a modest expansion in rice trade can be expected due to opening of the closed markets of Japan and Republic of, yet due to a special “rice clause” the Philippines and Indonesia negotiated for tariff reductions. The tariff reduction by USA and EU may lead to additional exports of specialty rice and global trade may increase in general. Subsidies at input level by individual countries may reduce production costs marginally. The movement from subsistence to market-oriented rainfed production may bring in additional changes (Pingali et al., 1997). Given the long-term impact of GATT on increasing competitiveness among ecosystems, irrigated ecosystem may get 50 percent of the research share. Issues of intensification versus diversification, yield enhancement versus quality improvement, knowledge-intensive technologies versus farmers time, private sector versus public funded research need further investigation and alignment to set research priorities (Pingali et al., 1997).

3.5 Post-Harvest Losses

It is extraordinary that the tremendous efforts being made to lift rice productivity through modifications and manipulations of the rice plant and its environment, are not matched by corresponding efforts to address the dramatic post-harvest losses of 13 to 34 percent (Chandler, 1979) that continue to occur through much of the rice growing world. Part of the productivity gains that have been laboriously achieved through decades of research and development are simply thrown away after harvest in many cases.

3.6 Weeds

Weeds reduce rice yield by competing for space, nutrients, light and water, and by serving as hosts for pests and diseases. Under farmers’ conditions, weed control is not generally done properly or timely, resulting in severe yield reduction. In Asia, losses run up to 11.8 percent of potential production. Effective weed control requires knowledge of the names, distribution, ecology, and biology of weeds in the rice-growing regions. One or another form of weed control has been used during the last 10,000 years (De Datta, 1981), but no single weed-control measure gives continuous and best weed control in all the situations. Various weed control methods including complementary practices, hand weeding, mechanical weeding, chemical weeding, biological control, and integrated approaches are available (De Datta, 1981). As mentioned earlier, these methods need to be fine-tuned for specific regions, ecosystems, cropping systems, and economic groups.

It is worth mentioning also that red or wild rice has become a major problem of rice production in Malaysia, the Central Plain in Thailand and the Mekong Delta in Vietnam where direct seeding has been increasingly practiced.

3.7 Biotic and Abiotic Stresses

Rice has been under cultivation over thousands of years and in 115 countries. As a result, it has served as a host for a number of diseases and insect-pests, 54 in the temperate zone, and about 500 in tropical countries. Of the major diseases, 45 are fungal, 10 bacterial, 15 viral (Ou, 1985), and 75 are insect-pests and nematodes. Realizing the economic losses caused by them, efforts have been directed to understand the genetic basis of resistance and susceptibility. The studies directed to understand the host-plant interaction in rice have given rise to specialized breeding programs for resistance to diseases and insect-pests. Ten major bacterial diseases have been identified in rice (Ou, 1985). The major ones causing economic losses in any rice growing country are bacterial blight, bacterial leaf streak, and bacterial sheath rot. Many of the serious rice diseases are caused by fungi. Some of the diseases like blast, sheath blight, brown spot, narrow brown leaf spot, sheath rot and leaf scald are of economic significance in many rice growing countries of the world. Twelve virus diseases of rice have been identified but the important ones are tungro, grassy stunt, ragged stunt, orange leaf (in Asia), hoja blanca (America), stripe and dwarf virus (in temperate Asia). Brown plant hoppers, stem borers and gall midges are among the major insect-pests in rice production.


4.1 Raising the Yield Ceiling

The yield barrier of about 10 t/ha set by IR 8 (140 days) has been broken on a per day productivity front only by the shorter duration varieties (110 - 115 days). But to raise the yield ceiling by breaking the yield barrier set by IR 8, new approaches need to be implemented vigorously. These could be feasible by using the concepts of hybrid rice and the New Plant Type (“super rice”). However, the New Plant Type is not yet available to the farmers, and hybrid rice remains the only viable means to increase yield potential in rice at present.

4.1.1 New Plant Type rice

In narrowing the yield gap it is also necessary to raise the ceiling of yield potential for further increase in rice yield, where applicable. The yield potential of rice is 10 t/ha under tropical conditions and 13 t/ha under temperate conditions. The present technology of hybrid rice can increase the yield ceiling by 15-20 percent compared to the best commercial varieties. The New Plant Type of rice, which has been developed by IRRI, may raise the present yield potential by 25-30 percent (Khush, 1995). Rice biotechnology, which has recently made considerable progress, may also provide an opportunity to increase the rice yield in a more effective and sustainable manner.

To break the current yield potential barrier, IRRI scientists proposed New Plant Type (NPT) rice, referred to in the media as “Super Rice”. The basic architecture of the plant has been redesigned to produce only productive tillers (4-5 per plant), to optimize the allocation of assimilates to the panicles (0.6 harvest index), to increase nutrient and water capture by roots (vigorous roots), and thicker culm to resist lodging under heavy fertilization. Reduced tillering is thought to facilitate synchronous flowering, uniform panicle size, and efficient use of horizontal space (Janoria, 1989). Low-tillering genotypes are reported to have a larger proportion of high-density grains. A single semi-dominant gene controlled the low tillering trait, and this gene has a pleiotropic effect on culm length, culm thickness, and panicle size. The future rice plant (NPT) is also expected to have larger panicle (200-250 grains) as compared to 100-120 of current varieties, sturdy stems to bear the weight of larger panicles and heavy grain weight, and give high (13-15 t/ha) yields (Khush, 1995). The NPT rice will be amenable to direct seeding and dense planting and, therefore, would increase land productivity significantly. While architecturally, the design is virtually complete, it has not been possible to realize the full potential (15 t/ha) of the New Plant Type. One of the principal limitations is the inability to fill all of the large number of 200-250 spikelets. Addressing this problem will require further intensive research into the physiology of photosynthesis, source - sink relationships, and translocation of the assimilates to the sink. Incorporation of better disease and insect-pest resistance and improvement of grain quality would be highly desirable, which are also being currently addressed.

4.1.2 Hybrid rice

Hybrid rice has become a reality over a period of 30 years. The rice area in China (Virmani, 1994; Yuan, 1996) under hybrid rice has reached more than 60 percent. Countries like India, Vietnam, Myanmar and the Philippines have a strong interest in this direction. The Government of India has set a target of putting 2 million ha under hybrid rice by the year 2000. All the rice hybrids grown in India, Vietnam, the Philippines, and most in China are indica hybrids. In the northern part of China, japonica hybrids are under cultivation. Now it is proven beyond doubt that indica x tropical japonica hybrids give higher yields than indica x indica hybrids. It is apparent that the next breakthrough in yield may be set in motion by the use of indica x tropical japonica and indica x NPT rice (Virmani, 1994). Currently the three-line system of hybrid rice production is being followed. But it is known that the two-line system, based on the Photosensitive Genetic Male Sterility System (PGMS) or the Thermosensitive Genetic Male Sterility System (TGMS) are more efficient and cost effective. NARS must re-orient their hybrid rice breeding programmes accordingly. The one-line system using the concept of apomixis is under active research at IRRI and NARS will benefit the moment any system becomes available.

4.1.3 Transgenic rice

Over the last two decades humanity has acquired biological knowledge that allows it to tamper with the very nature of creation. We are only at the beginning of a process that will transform our lives and societies to a much larger extent than all inventions of the last decades. Ownership, property rights, and patenting are terms now linked to living matter, and tools to create them. No global code of conduct is yet in sight. Biotechnological developments (James, 1997) are poised to complement and speed up the conventional rice improvement approaches in many areas (Khush, 1995), which could have immediate and long term impacts on breaking the yield ceiling, stabilizing the production and making rice nutritionally superior. In summary, the tools of genetic engineering will help to increase and stabilize rice yields under varied situations of its growing, and thereby reducing the yield gap. These tools could be used to introduce superior kinds of plant resistance through wide hybridization, anther culture, marker aided selection, and transformation. These tools, and tagging of quantitative trait loci would help enhance the yield potential. Rice transformation enables the introduction of single genes that can selectively perturb yield-determining factors. Approaches like differential regulation of a foreign gene in the new host for partitioning sucrose and starch in leaves, the antisense approach as used in potato, and transposable elements Ac and Ds from maize have opened up new vistas in breaking yield barriers (Bennett et al. 1994). Identifying the physiological factors causing differences in growth rate among rice genotypes seems fundamental to success in germplasm development for greater yield potential. Increasing the rate of biomass production, increasing the sink size, and decreasing the lodging susceptibility would enhance these efforts (Cassman, 1994).

4.1.4 Stable performing variety

Superior yielding varieties are available (Chaudhary, 1996), which can take farmers’ yield to 8.0 tonnes/ha if grown properly. But their performance is variable due to higher proportion of Genotype X Environment (G X E) interaction. G X E interaction is a variety dependent trait (Kang, 1990; Gauch, 1992; Chaudhary, 1996). While the genetic reasons of stability in the performance may be difficult to understand, resistance to biotic and abiotic stresses, and insensitivity to crop management practices are the major reasons. There is a need to identify and release stable yielding varieties even on a specific area basis, as against relatively less stable but on a wide area basis. There are strong genotypic differences among varieties for this interaction, providing opportunities for selecting varieties which are more stable across environments and methods are available to estimate these (Kang, 1990; Gauch, 1992). Thus, two varieties with similar yield may have different degrees of stability. During the final selection process, before release, it is possible to select varieties which are more stable and thus giving stable performance even in poorer environments or management regimes.

4.2 Agronomic Manipulation

Other than using genetic means of raising yield ceiling, avenues of agronomic manipulation need to be explored. The success story of Bangladesh in becoming a self-sufficient country with stable yield by using Boro rice instead of deepwater rice is a case in point. This is a case of matching a technology in its proper perspectives.

4.2.1 Improving nitrogen (N) recovery efficiency, resourcing and management

Nitrogen being the major nutrient and in demand, it is applied in every crop season. Thus, efforts in improving the N recovery-efficiency will save quantity and cost, and reduce the cost of rice production. Avenues exist to enhance the recovery further, and also to augment its supply (Table 4).

Nitrogen is the nutrient that most frequently limits rice production. At current levels of N use efficiency, the rice world will require at least to double the 10 million tonnes of N fertilizer that are annually used for rice production. Global agriculture relies heavily on N fertilizers derived from petroleum, which in turn, is vulnerable to political and economic fluctuations in the oil market. N fertilizers, therefore, are expensive inputs, costing agriculture more than US$45 billion annually (Ladha et al., 1997).

Rice suffers from a mismatch of its N demand and N supplied as fertilizer, resulting in a 50-70 percent loss of applied N fertilizer. Two basic approaches may be used to solve this problem. One is to regulate the timing of N application based on needs of the rice plant, thus partly increasing the efficiency of the plant’s use of the applied N. The other is to increase the ability of the rice root system to fix its own N (Table 4). The latter approach is a long-term strategy, but it would have enormous environmental benefits while helping resource-poor farmers. Although N use has increased, still a large number of farmers use very little of it, primarily due to non-availability, lack of cash to buy it, and poor yield response or high risk. Furthermore, more than half of the applied N is lost due to de-nitrification, ammonia volatilization, leaching and runoff. It is in this context that biologically fixed N assumes importance. Furthermore, farmers more easily adopt a genotype or variety with useful traits than they do with crop and soil management practices that may be associated with additional costs.

Table 4. Conventional and Future Biological Nitrogen Fixation (BNF) Systems, their Potential and Feasibility


N supply

Rice Yield



and Adoption

Conventional BNF systems


50-100 kg/ha

3-6 t/ha


3-5 years


Green manure (Azolla, Sesbania)

100-200 kg/ha

5-8 t/ha




Future BNF systems




Endo+ fix+ NUE

3-5 years


Induced symbiosis (Rhizobia, Frankia etc.)

> 200 kg/ha

> 8 t/ha

Nod+ fix+ NUE

> 5 years


Nif gene transfer

> 200 kg/ha

> 8 t/ha

nif + fix+ NUE

> 5 years


ANFS = associative N2 fixation stimulation; NAE = nitrogen acquisition efficiency; nod = nodulability; NUE = nitrogen utilization efficiency; Endo = Endophytic; fix = N2 fixation ability; nif = N2 fixation gene
Recent advances in understanding symbiotic rhizobium-legume interaction at the molecular level, the discovery of endophytic interactions of N fixing organisms with non-legumes, and the ability to introduce genes into rice by transformation have stimulated researchers world-wide to harness opportunities for N fixation and improved N nutrition of rice. The development of symbiotic N2 fixation between legumes and Rhizobia is a multi-step process in which genes from both host plant (nodulin genes) and bacterium (nod, nif, exo, lps, and ndv genes) play essential roles (Khush and Bennett, 1992). Small signal molecules pass between the two organisms, activating genes and eliciting developmental responses which culminate in the formation of a cluster of bacterial cells rich in nitrogenase and protected from external O2 by a complex molecular barrier. Nodules take sucrose from phloem, convert it to succinate, and through bacterial respiration generate the ATP and reduced ferredoxin required for conversion of N2 to ammonia. The plant component of the nodule takes up the ammonia and assimilates it into glutamine and asparagine in temperate legumes or into the ureids, allatonic acid and allantoin in tropical legumes. The assimilate is then taken to the rest of the plant via the xylem. The engineering of plants capable of fixing their own nitrogen is an extremely complex task, requiring the coordinated and regulated expression of 16 nif genes; 8 core genes (B, E, D, H, M, N, K, V), and 8 housekeeping genes (S, T, Q, U, W, X, Y, Z) assembled in an appropriate cellular location (Dixon et al., 1997). Additional genes to maintain nitrogenase in an active form may also be needed. Dixon et al. (1997) suggested that plastids may provide a favourable environment for nif gene expression and the damage of nitrogenase enzyme can be protected from oxygen by regulating that nif genes function only in the dark.

Once incorporated, these genes can become part of the seed-based input in rice with high potential of adoption. This becomes more significant when it is realized that every tonne of rice harvested contains about 12 kg N, half of which comes from soil N and biologically fixed N2. The share of biologically fixed can be increased to suffice the entire need of rice plant. In that case the yield gap due to nitrogen may be reduced a to bare minimum. Currently, it appears a dream but is reasonable and realizable, as nodule formation is a reality (Reddy et al., 1998).

4.2.2 Integrated fertilizer use and balanced use of fertilizers

In addition to chemical fertilizer, there are avenues to augment it through organic manure, biological nitrogen fixation, and the adoption of Integrated Plant Nutrition Systems (IPNS). Recent efforts of IRRI in transferring the nodulating genes to rice roots is an innovative approach which may help rice plant fix atmospheric nitrogen for its own and future use. While this is recognized as a breakthrough using biotechnological tools, future research should be based on the current gains to create a nodulation rice plant in the near future. Until that is accomplished, the addition of a legume crop either in rice - wheat rotation or in a rice - rice system would be imperative.

Soil degradation and quality deterioration limit crop yields in many intensively cultivated farms in Asia. Changes in organic matter and soil nutrient supplying capacity, nutrient imbalance and multi-nutrient deficiency, waterlogging and iron toxicity, soil salinity and alkalinity, and development of hard pans at shallow depths are some of the major indicators of deteriorating soil quality. A lot of yield gaps can be attributed to knowledge gaps. Techniques (Balasubramanian et al., 1998; Cao et al., 1984) which can be used to handle the soil degradation, include the chlorophyll meter (SPAD) and leaf colour chart (LCC), N placement methods, use of modified coated urea materials, phyto-availability soil tests, nutrient-efficient rice varieties, periodic deep tillage to exploit the subsoil N reserve, catch crops to tap pre-rice accumulated soil nitrate, and use of biofertilizers.

Phosphorus, potassium, sulfur and zinc deficiencies in rice production have been increasingly observed in Asia. Therefore, more attention is needed in this direction. A balanced use of fertilizers is equally as important as other issues.

4.2.3 Water and irrigation

Water is essential to rice cultivation. Adequate water supply is one of the most important factors in rice production. In Asia, the rice crop suffers either from too little water (drought) or too much of it (flooding, submergence). Most studies on constraints to high rice yield indicate water as the main factor for yield gaps and yield variability from experiment stations to farms. A recent study conducted by the International Water Management Institute (IWMI), estimates that by the year 2020 a third of the Asian population will face water shortages. The next wars may be fought over water (Gleick, 1993). The growth rate in the development of irrigation has already declined (Barker et al. 1998). Even the existing irrigation systems are labeled as inefficient based on the irrigation efficiency calculated as the ratio of requirement to the percentage of water used. With the growing scarcity and competition for water there is an increased demand for research to identify potential areas for increasing the productivity of water in rice-based systems. The major challenge for research in the coming decade lies in identifying specific situations for the optimum combination of improved technologies and management practices that can raise water productivity at farm, system, or basin level.

Improved water use at the systems and farm levels are important considerations. Development of on farm water reservoirs for water harvesting, selection of drought tolerant varieties, land leveling, subsoil compaction, and need based irrigation scheduling may play a major role in increasing water use efficiency and decrease yield gaps.

4.2.4 Integrated crop management (prescription farming)

Based on the extensive and critical testing of rice varieties and the crop management technology, it is possible to develop a “prescription rice farming” for individual farmers and each situation. The concept was tested on a limited scale in Indonesia during 1996-1997.

It is essential, therefore, that crop management practices should not be applied in isolation but be holistically integrated in Integrated Crop Management Packages (ICMPs) with flexibility for adjustment to fit to prevailing environmental, socio-economic and market factors. The development of ICMPs, which are similar to the Australian Rice Check package, and their transfer could effectively assist farmers in many countries to narrow the yield gaps as well as to reduce rural poverty. The ideal ICMP, however, must aim to improve farmers’ knowledge not only on crop production and protection but also on the conservation of natural resources and market dynamics. This requires substantial improvement to the system of collection and dissemination of information on rice, its production factors, and its technologies as well as the modification of the extension systems in many countries.

4.3 Bridging the Yield Gap

A gap between the potential yield that can be achieved at farmers’ field level and what they actually get is very wide (Table 5). Bridging this yield gap offers a very lucrative opportunity to produce additional rice even by using the available technologies.

Table 5. Rice Yield Gap (kg/ha) in Different Agro-Ecological Zones and Rice Eco-Systems in Asia (Evenson et al. 1996)



Best Farm
Average Yield

Actual Farm
Average Yield


Southern India

Warm and semi tropics/irrigated




Eastern India

Warm and sub-humid tropics/irrigated, rainfed, lowland, flood-prone, upland





Warm humid tropics/irrigated, rainfed, lowland, flood-prone, upland




Northeastern China

Warm arid and semi-arid/irrigated




Central China

Warm and sub-humid subtropics/irrigated, rainfed, lowland, upland





Warm and sub-humid subtropics/irrigated, rainfed, lowland, upland




Northern China

Warm cool humid subtropics/irrigated




Western China

Cool subtropics/irrigated




4.4 Reversing Yield Decline

The yield decline appears real even at farm level. To reverse this trend, a strong research base is essential on an area specific basis, rather than on factors cutting across the continents. Setting up of a joint FAO/IRRI/NARS programme to identify causes, and arrest the decline was recommended by Cassman et al. (1997).

4.5 Policy Support to Increase Production

Government policies provide the environment to benefit from research investment, improve productivity, alleviate poverty, ensure systems’ sustainability, protect the environment, and provide food security. It is therefore imperative that through appropriate policies, socio-economic adjustments should be effected in terms of input-output pricing, institutional support, and to redress the needs of rice farmers in order to complement the technological gains.

4.5.1 Credit

Drastic policy changes are needed in making credit facilities available to small and marginal farmers. The interests of these producers and rice policy makers are inter-linked.

4.5.2 Input availability

Fertilizers, especially nitrogen, play an important role in rice production and productivity. Farmers need adequate amounts of fertilizer at the right time for obtaining high yields in rice cultivation. The supply of fertilizers needs to be decentralized to village markets and the quality of fertilizers should be assured. Small farmers are usually unable to buy sufficient quantity on time for application; hence, the provision of village credit could greatly help them. The Bangladesh Grameen Bank is an interesting example of providing rural credit to landless and resource-poor farmers. The loan proposals are received by the bank only on a group basis (at least 5 persons), focusing on technology loan, housing loan, joint loan and general loan (Dadhich, 1995). The principle of the Grameen bank could be deployed in other developing countries, with some modification for adaptation to local conditions. The problems of credit and input supply cannot be quickly resolved unless there is strong government intervention. The issue of village credit and input supply is being tackled where FAO and Governments are implementing Special Programmes for Food Security (SPFS).

4.5.3 Institutions

Availability of agricultural credit, inputs (seeds, fertilizers, pesticides) supply, availability and quality of contract services and machinery for different farm operations, and repair and maintenance services in rural areas will influence the rate of adoption of knowledge intensive technology (Price and Balasubramanian, 1998). The government and private institutions associated with credit, input and pricing directly influence the adoption and level of the use, and thereby the yield level. The kind of production environment provided by these agencies must be harmonious as any one of these factors is capable of becoming a bottleneck factor.

4.6 Quality Seed

Use of quality seed is the first and foremost way of realizing the yield potential of the recommended technology. High quality pure seed ensures proper germination, crop stands, freedom from weeds and seed borne pests and diseases. It is recognized in general, that quality seed ensures 10 to 15 percent higher yields under the same set of crop management practices. In the case of superior quality rice, it even ensures higher price and profit. Unfortunately, in most countries sufficient quantities of certified seed are not available from all the seed sources put together. As a result more than 80 percent of the area is cultivated using farmers’ own seed. Thus, there are several issues associated with the use of good quality seed. While the private seed producers need to be encouraged to produce more seed of the released varieties and hybrids, governments have to come up with proper legislation where the seed industry can prosper. Even an ambitious programme cannot stop the use of self-grown seeds (now that CGIAR system and most countries have rejected Terminator Technology) by the farmers, thus knowledge can play its part.

4.7 Post-Harvest Loss Reduction

Introduction of more efficient technologies for handling, drying, storage and milling rice at the village level is essential to reduce post-production losses (PPL). The present impressions are that post-production is labour intensive, as the operations involve harvesting hand-reaping, field sun-drying before threshing, threshing by trampling, and wind winnowing. This results in poor quality milled rice including grain discoloration. The physical losses are more in wet season harvests, with problems in drying, and the use of antiquated mills. Basic beliefs are that people in communities whose livelihood is affected are likely to provide their own motivation for change to ensure increased benefit for themselves. It is also believed that the local farmers and entrepreneurs are, therefore, to be given the opportunity to define their post-production needs and to be consulted in the selection of appropriate technologies. But one must also bear in mind that community organizations are required to make concerted efforts in the introduction of new technologies.

4.8 Research and Knowledge Transfer

The support of research and extension can ensure the effective bridging of yield gap of rice. Farmers’ adoption of the above-mentioned improved technologies depends on the capability of national agricultural research centres and extension services, which need more government resource allocation and training. The research scientists should understand well the farmers’ constraints to high rice productivity and provide them with appropriate technological packages for specific locations to bridge the gap under participatory approaches (IRRI, 1998; Price and Balasubramanian, 1998). The extension service should ensure that farmers use correctly and systematically recommended technological packages (ICMPs) in the rice fields, through effective training and demonstrations. For example, only relevant application of nitrogen fertilizers from seeding to heading, in terms of quantity and timing, will make significant contributions to narrow the yield gap of rice while avoiding unnecessary losses of nitrogen, which increase the cost of production and pollute the environment. The transfer of knowledge based on scientific principles aimed at altering farming practices requires a good fit between the knowledge system of the farmers and that of scientists (Price and Balasubramanian, 1998). If new components were added to the knowledge system and if these were couched in familiar terms, there would be latitude for experimentation at the local level that could eventually develop into a functional fit. The current “blanket recommendation approach” gives farmers information without understanding it, and provides information but not the knowledge.


· Rice is the life-blood of the Asia-Pacific Region where 56 percent of humanity lives, producing and consuming more than 90 percent of the world’s rice. The demand for rice is expected to grow faster than the production in most countries. How the current level of annual production of 524 million tonnes could be increased to 700 million tonnes by the year 2025 using less land, less water, less manpower and fewer agro-chemicals is a big question. Alternative ways to meet the challenge by horizontal and vertical growth have their own prospects and limitations. Based on this scenario, the bridging of the yield gap for producing more rice appears to be promising.

· Development of more location specific technology for crop management as well as technology transfer and adoption, coupled with manpower development in appropriate areas, has to be handled by the countries themselves. The sharing, testing and utilization of technology and knowledge across the national boundaries have to be facilitated by Regional and International bodies through various networks supported by them.

· The Integrated Crop Management approaches, including available location-specific technologies coupled with active institutional support from governments, particularly for input and village credit supplies as well as stronger research and extension linkages, can expedite the bridging of yield gaps and thus the increase in production. Location specific packages of technologies moving towards “prescription farming” could be made available and popularized. However, there is a need for better understanding of the yield gaps and national policies on this issue.

· The yield deceleration, stagnation and decline observed in high-yield environments must be arrested, first by systematic studies to understand the causes and then by the development of new varieties and crop management practices. As the phenomenon affects the most productive ecosystem - the irrigated rice, and the permanent asset - the soil, it is of great concern in which Eco-Regional Initiatives and AEZs networks may help.

· Technical knowledge is an important factor in determining the adoption of improved crop management practices and increased yields. Transfer of knowledge intensive technologies has to receive priority. The bridging of knowledge gaps can bridge yield gaps. New paradigms need to be added to transfer and use newer seed and knowledge based technologies under new policy environments.

· Yield variability is driven primarily by variability in the natural environment, and the challenge to research workers is to confront such variability in productivity by genetic and input manipulations. On the genetic side, there is ample evidence that considerable progress has been made (and can be further expanded) in exploiting natural tolerance to both biotic and abiotic stresses, which are polygenically controlled. But the diversion of resources towards risk reduction in phenotypic expression must be traded off against more direct progress in terms of mean yield performance. Thus, one has to consider the trade-off between high yield and yield stability. Development of varieties with high stability may therefore be considered.

· The efforts to break the rice yield ceiling (NPT rice, hybrid rice, and agronomic manipulation) need to be geared-up to attain higher yields. The technology must be made available through IRRI and FAO operated networks for testing and deployment by NARS. However, hybrid rice is the only technology available at present for raising the ceiling of rice yield potential.

· Technologies to decrease the cost of production and increase profitability must be considered very seriously at the same time. Issues in poverty alleviation, social justice and diversification in agriculture are inter-linked and should be handled at that level. The Asia-Pacific Region has the resilience to meet its future demand and remain a net exporter of rice, provided concerted efforts are continued with greater vigor and thrust.

· The trade globalization provided by GATT, WTO and COMESA, and geographic comparative advantages of producing a crop, can provide major incentive for farmers to strive hard and bridge the yield gap. The Region may also focus on other continents to answer questions. Africa can be a promising “Future-Food-Basket” for Asia, but concrete policy framework and support background under the South-South Co-operation and NAM must be added. The combined strength and synergistic links between Asia and Africa can work wonders. This can be a boost and provide a solid platform for a shared prosperity for both continents.


Anon. 1998. A strategic review of Chinese rice imports. 3rd Asian International Rice Conf., Phuket, Thailand, 29 - 30 October 1998, 32 pp.

Balasubramanian, V.; Morales, A. C.; Cruz, R. T.; and Abdul Rachman, S. 1998. On-farm adaptation of knowledge-intensive nitrogen management technologies for rice systems. 1-12. In: Nutrient Recycling in Agroecosystems; Kluwer Acad. Publ. Netherlands.

Barker, R.; Dae, D.; Tuong, T. P.; Bhuiyan, S. I.; and Guerra L. C. 1998. The outlook for water resources in the year 2020: Challenges for rice research on water management in rice production. 2 pp. IRRI, Los Baños, Philippines.

Bennett, J.; Brar, D. S.; Khush, G. S.; and Setter, T. L. 1994. Molecular approaches. In: 63-75 pp. Breaking the Yield Barrier. IRRI, Los Baños, Philippines.

Cao, Z. H.; De Datta, S. K.; and Fillery, I. R. P. 1984. Nitrogen-15 balance and residual balance of urea-N in wetland rice fields as affected by deep placement techniques. Soil Sci. Am. J. 48: 203-208.

Cassman, K. G. (ed.) 1994. Breaking the Yield Barrier. 141 pp. IRRI, Los Baños, Philippines.

Cassman, K. G. and Pingali, P. L. 1995. Extrapolating trends from long-term experiments to farmers’ fields: the case of irrigated rice ecosystem in Asia. IN: Barnett et al. (eds.) Agricultural Sustainability: Economic, Environmental and Statistical considerations, John Wiley & Sons Ltd. NY.

Cassman, K. G.; Olk, D. C.; and Doberman, A. 1997. Scientific evidence of yield and productivity declines in irrigated rice systems of tropical Asia. IRC Newsletter 46: 7 -27.

Chandler, R. F. 1979. Rice in the Tropics: A Guide to the development of National programmes. West Press, Boulder, Col. USA, 256 pp.

Chaudhary, R. C. 1996. Internationalization of elite germplasm for farmers: Collaborative mechanisms to enhance evaluation of rice genetic resources. In: New Approaches for Improved use of Plant Genetic Resources; Fukuyi, Japan; pp. 26.

Dadhich, C. L. 1995. Grameen bank: The pros and cos. In: Proc. New deal for Self Employed: Role of Credit, Technology and Public Policy. 30; 1-22.

De Datta, S. K. 1981. Principles and Practices of Rice Production. John Wiley & Sons, New York, USA; 618 pp.

Dixon, R.; Cheng, Q.; Shen, G.; Day, A.; and Day, M.D. 1997. Nif gene transfer and expression in chloroplasts: Prospects and problems. Plant and Soil, 194: 193-203.

Evenson, R.; Herdt, R,; and Hossain, M. 1996. Rice Research in Asia: Progress and Priorities. CAB International, Oxon, U.K. - IRRI, Los Baños, Philippines, 418 pp.

FAO 1996. Report of expert consultation on the technological evolution and impact for sustainable rice production in Asia and Pacific; FAO-RAP Publ. No. 1996/14, 20 pp. FAO-RAP Bangkok, Thailand.

FAO 1997. Selected indicators of food and agricultural development in the Asia-Pacific Region, 1986-96; FAO-RAP Publication No. 1997/23, 206 pp. Regional Office for the Asia and the Pacific, FAO Bangkok, Thailand.

Gauch. H. G. 1992. Statistical Analysis of Regional Yield Trials: AMMI Analysis of factorial Designs. 278 pp. Elsevier Publ. Co.

Gleick, P. H. (ed.) 1993. Water in Crisis: A Guide to the World’s Fresh Water Resources. Oxford University Press, New York.

Hossain, M. 1995. Sustaining food security for fragile environments in Asia: Achievements, challenges, and implications for rice research; 3 - 23 pp. In: Fragile Lives in Fragile Ecosystems. IRRI, Los Baños, Philippines.

Hossain, M. 1996. Recent developments in Asian rice economy: Challenges for rice research. 17 - 34 pp. In: Rice Research in Asia: Progress and Priorities. CAB International, Oxon, U.K. - IRRI, Los Baños, Philippines.

IRRI 1998. Bridging the Knowledge Systems of Rice Scientists and Farmers. CREMNET-IRRI Los Baños, Philippines. 19 pp.

James, C. 1997. Global status of transgenic crops in 1997. ISAA Briefs No. 5-1997.

Janoria, M. P. 1989. A basic plant ideotype for rice. Int. Rice Res.Newsl.14 (3):12-13.

Kang, M. S. 1990. Genotype-by-Environment Interaction in Plant Breeding. Louisiana State University, Agricultural Centre, Baton Rouge, Louisiana, USA.

Khush, G. S. 1995. Modern varieties - their real contribution to food supply and equity. Geojournal 35 (3): 275 - 284.

Khush, G. S., and Bennett, J. (eds.) 1992. Nodulation and Nitrogen Fixation in Rice: Potential and Prospects. 135 pp. IRRI, Los Baños, Philippines.

Ladha, J K.; de Bruijn, F. J.; and Malik, K. A. 1997. Introduction: Assessing opportunities for nitrogen fixation in rice - a frontier project. Plant & Soil 194: 1-10.

Muralidharan, K.; Rao, U. P.; Pasalu, I. C. P.; Reddy, A. P. K.; Singh, S. P.; and Krishnaiah, K. 1998. Technology for Rice Production. 31 pp. Directorate of Rice Research, Hyderabad, India.

Ou, S. H. 1985. Rice Diseases. 2nd edition. Commonwealth Mycological inst., Kew, Surrey, UK. 380 pp.

Papademetriou, M. K. 1998. Current issues of rice production in Asia and the Pacific. International Rice Commission, 19th Session, Cairo, Egypt; 18 pp.

Pingali, P. L.; Hossain, M.; and R. V. Gerpacio. 1997. Asian Rice Bowls: The Returning Crisis? IRRI-CAB International, 341 pp.

Price, L. M. L.; and Balasubramanian, V. 1998. Securing the future of intensive rice systems: A knowledge-intensive resource management and technology approach. In: Sustainability to Rice in the Global Food System. 93-204 pp. Pacific Basin Study Centre, Davis, California USA - IRRI, Los Baños, Philippines.

Reddy, P. M.; Ladha, J. K.; Ramos, M. C.; Maillet, F.; Hernandez, R. J.; Torrizo, L. B.; Oliva, L. P.; Datta, S.; and Datta, K. 1998. Rhizobila lipochitooligosaccharide nodulation factors activate expression of the legumes early nodulin gene ENOD12 in rice. The Plant Journal 14(6): 693-702.

Singh, R.B. 1996. Sustainable Rice Production in Asia and the Pacific: New Research and Technology Development Paradigms. Paper presented at the Expert Consultation on Technological Evolution and Impact for Sustainable Rice Production in Asia and the Pacific, Bangkok, Thailand, 29-31 October 1996.

Singh, R.B. and Paroda, R.S. 1994. Sustainability and Productivity of Rice-Wheat Systems in the Asia-Pacific Region: Research and Technology Development Needs. In: Sustainability of Rice-Wheat Production Systems in Asia. FAO/RAP Publication No. 1994/11.

Singh, R.B. 1992. Research and Development Strategies for Increased and Sustained Production of Rice in Asia and the Pacific. FAO/RAP Publication No. 1992/17.

Tran, D. V. 1996. Evolution of rice yield in Asia and the Pacific. Expert Consultation on Techn. Evol. & Impact for Sustainable Rice Prod. In Asia-Pacific. FAO, Bangkok, Thailand. 18 pp.

UPOV 1991. International convention for the protection of new varieties of plants of December 2, 1961 as revised at Geneva on November 10, 1972, on October 23, 1978, and on March 19, 1991; Final Draft Doc. DC/91/138.

Virmani, S. S. (ed.) 1994. Hybrid Rice Technology: New Developments and Future Prospects, IRRI, Los Baños, Philippines, 296 pp.

Yuan, L. P. 1996. Hybrid rice in China. In: Hybrid Rice Technology, Directorate of Rice Research, Hyderabad, India; 51 - 54 pp.

Previous Page Top of Page Next Page