In 1961, there were about 29 countries and/or important territories in Asia and rice was grown in 28 of them. In 1997, there were 50 countries and/or important territories and rice was grown in about 29 of them. Hong Kong, East Timor, Saudi Arabia, and Syria were reported to grow some rice in 1961. However, in 1997, no rice cultivation was reported in these countries. The new rice producing countries of the Asian continent are Azerbaijan, Kazakhstan, Kyrgyzstan, Tajikistan, Turkmenistan, and Uzbekistan.

Asia is the home of O. sativa and rice has been cultivated in this continent for several thousand years. Indica, Japonica, and Javanica (or Tropical Japonica) are the cultivated sub-species. Japonica is dominant in Japan, Korea, northern China, Iran, Turkey, Azerbaijan, Kazakhstan, Kyrgyzstan, Tajikistan, Turkmenistan, and Uzbekistan; whereas Indica is dominant in the rest of Asia. Javanica is found in Indonesia.

From 1961 to 1990, the harvested rice area in the continent had increased by about 30%, due to a combination of the expansion in cultivated area and crop intensification. In tropical climate and at low altitude areas, two or more rice crops could be grown on the same area in a year with irrigation water.  However, the growth in harvested rice area in the continent has remained more or less unchanged since 1990.

Most of the tall culm and long and droopy leaves varieties (or traditional varieties) have been replaced by the short culm and short and erect leaves varieties (or high yielding varieties) and hybrid rice varieties. In November 1966, the International Rice Research Institute (IRRI) released its first nitrogen responsive and high yielding variety, IR8, for tropical climate areas, whereas China, successfully developed and used hybrid rice in 1976.

The wide adoption of high yielding varieties in the continent and hybrid rice varieties in China coupled with the availability of irrigation water, and the intensive use of agro-chemicals, especially inorganic fertilizers have  led to a rapid increase in rice yield during 1961-1990 (from about 1.87 tons/ha in 1961 to about 3.61 tons/ha in 1990). The growth rate in rice yield, however, has been considerably slowed down since 1990. Rice yields in the continent, however, still vary widely from country to country. In 1997, yields varied from more than 6 tons/ha in China, Japan, and Korea to less than 2 tons/ha in Taijakstan, Afghanistan, Cambodia, etc…

In 1995, about 56 percent of the total harvested areas come from irrigated ecologies, 31.4% from rainfed lowland, 7.7 % from upland and 4.9% from other ecologies. Rice yields are much higher in irrigated ecologies.

As a result of the increases in both yield and harvested area, rice production in Asia has nearly tripled during 1961 to 1997 (from 198.75 M tons of paddy in 1961 to about 522.84 M tons in 1997). The growth in rice production was very high during the period from 1961 to 1985.

CONSUMPTION AND USE

    Rice is the staple food of the majority of Asian population which has grown from about 1.70 billion in 1961 to about 3.52 billion in 1997. Rice ranked as the first major food consumed in Bangladesh, Brunei Darussalam, Cambodia, China, Hong Kong SAR, India, Indonesia, Dem People's Rep of Korea, Republic of Korea, Laos, Macau, Malaysia, Myanmar, Nepal, Philippines, Singapore, Sri Lanka, Thailand, and Viet Nam. The total population of these countries in 1997 was 2.94 billion.

    To most of Asians, rice cultivation and post-production activities provide not only food but also incomes and employment opportunities. It is estimated that these activities provide main sources of income to about 200 million families or more in rural poor areas of Asia. In addition, rice straw, husks, and bran are major sources of cooking fuel, feeds to livestock, and substrates for the cultivation of mushrooms, vegetable crops, etc…

 CONSTRAINTS TO SUSTAINABLE RICE PRODUCTION

    There are several constraints to sustainable rice production in Asia. Following are the major ones:

• Water problems: Water availability is the primary factor determining the success of the rice crop. Water resources are being increasingly used by the industry and household sectors.
• Land constraints: Rapid urbanization, industrialization and demographic pressures have encouraged farmers to exploit marginal lands for increased rice production to meet family demands. Therefore, acid soils, tidal lands, forest lands, etc. have been reclaimed and put under cultivation, subsequently limiting crop yield potential.
• Biotic and abiotic stress: Pressures of pests and diseases in rice production, particularly in the tropics, have built up.
• Yield gaps: Yield gaps between rice farmers and research stations reach 40-50% in many countries.
• Yield plateau: The yield potentials of high yielding rice varieties have reached a plateau. In tropical climates, the yield per season of IR 8 has never been bettered.
• Decline in Productivity: Yield decline in rice has been found in various experimental farms where rice is grown two (2) or more times per year. The causes of the yield decline at the research stations are under investigation. At farmers’ fields, it has also been observed that farmers are now using higher levels of inputs than before in order to maintain rice productivity.
• Labor shortage: The shortage of labor is becoming increasingly critical in countries where the economy and urbanization are rapidly expanding. Farm mechanization is one solution to the labor shortage. However, the introduction of tractors, hand-powered tillers and other equipment has often encountered constraints such as lack of skilled personnel and spare parts and high cost of fuel.
• Gender issue: Women play an important role in rice production, processing and marketing. In particular they undertake the arduous tasks of transplanting, weeding and harvesting.
• Decline in investments for supporting rice production: Investments for the development of irrigation infrastructures in the continent have declined about 60 percent since the 1960s. Similarly, the growth rate in research expenditure in Asia declined from 7.4 percent in 1961 to about 4.6 percent during the 1980s.
• High costs of rice production: Cost of rice production in developed countries, e.g. Japan, are usually high. It is also reported that, in many developing countries, rice farmers are usually poorer than their counterparts who grow either fruit trees or vegetable crops or industrial crops. The challenge is how to increase the incomes of rice farmers.
• Low Efficiency of Nitrogen Fertilizers: It is estimated that more than 50% of the applied nitrogen are not taken up by rice crop.

TECHNICAL OPPORTUNITIES FOR SUSTAINABLE INCREASED RICE PRODUCTION

There are, however, considerable opportunities for maintaining sustainable rice production in the continent. Following are some main technical opportunities:

•  Hybrid Rice: Hybrid rice has a yielding advantage of about 15-20% over modern rice varieties. It has been commercially grown in China since 1976. Recently, it were commercially cultivated on large scale in India and Vietnam. Successful development and use of hybrid rice, however, require commitment from national policy makers, researchers, seed growers, extension workers, and farmers.
• New Plant Type Rice: Scientists at the International Rice Research Institute have been developing New Plant Type with yield potential of 25 to 50% over the yield potential of today IR high yielding varieties. It is hopeful that advances in biotechnology, definitely, will expedite the development of NPT with resistance to pests and diseases, low sterility and acceptable grain quality.
• Advances in Crop Management: In particular, the Integrated Pest Management concept and approach, Integrated Plant Nutrition Management, the Leaf Colour Chart for guiding the application of Nitrogen fertilizer.
  

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