1May 2011

2The rice plant (Oryza sativa species) was domesticated in Asia some 8,000 to 10,000 years ago. At the beginning of the 21^st century, it is still the leading cereal in human food systems, the main source of energy and represents a significant share of proteins consumed by almost three billion people. In certain Asian developing countries, the annual consumption per capita can reach 200 kg of white rice, but it falls to approximately 50 kg of high quality grains in rich and industrialised countries such as Japan. The annual global production of rice amounts to over 600 million tonnes of paddy rice (the whole grain rice before milling), 90% of which is located in Asia where the largest producing countries are China, India, Indonesia, Bangladesh, Vietnam and Thailand.

3The crucial production of the “grain of life” depends on a myriad of very small family holdings often managing less than one hectare of paddy fields per household, in China for example, compared to four hectares in Thailand where the availability of farmland is far higher. Rice lands occupy 150 million hectares worldwide, i. e. 15% of the global farm area and almost a quarter of the world’s cereal croplands. More than 200 million rice farmers are involved in this production, with a growing number of part-time farmers combining this activity with other economic ones, like in Japan in the past. This industry is therefore the most important human activity on earth. A large proportion of the production is from domestic rice farmers’ own consumption and the remaining rice ends up on the local and domestic markets. Only 6 to 7% of the rice harvest is exchanged between countries on the world market, with Thailand, Vietnam, the United States, India and Pakistan as leading exporters. Industrial countries import several million tonnes of high commercial value aromatic (Basmati or Thai) rice, but far greater volumes of lower quality rice are exported to tropical developing countries, particularly in sub-Saharan Africa and the Middle East. Rice growing is deeply rooted in Asian cultures and identities thus contribute to bringing Asian people together (the ASEAN [Association of South East Asian Nations] symbol is a bundle of rice panicles). Although lasting decades, small-scale rice farming is often unprofitable – a remarkable fact in this part of the world, accustomed to double-digit economic growth during the last decades. The Emperor of Japan is a sacred rice grower, while the royal ploughing ceremony continues to mark the start of the wet season rice-growing cycle across Thailand in early May. As S. Rushdie wrote, “even where paddy fields are under concrete blocks today, rice has left its mark on us.”

4This essential cereal crop can be produced in extremely different ecological conditions, from the large and flat coastal plains to mountainous terraces, reaching up to 2,700 m in the Himalayas, and from the Equator to 53 degrees north latitude in the Chinese province of Heilongjiang. In the irrigated rice ecosystem, double or triple cropping in the same field every year is possible thanks to the control of surface water, which is the best herbicide. With more than a half of the total rice-growing areas and three quarters of global production, these large “rice bowls” feed densely-populated deltas (more than ten inhabitants per hectare of rice land is common) and alluvial plains, dominating the Far East where China feeds a fifth of the world’s population on only 9% of arable lands. While the average paddy yields attain 5 to 6 tonnes per hectare and crop cycle in the wet season, they can reach up to ten or even twelve tonnes per hectare in the sunny dry seasons. This is the case in Chinese rice fields, planted in early-maturing super hybrids, which produce more than 100 kg of rice per hectare and per day in a crop cycle! In tropical Asia, the Green Revolution in rice (1965-1990) had a tremendous impact on this irrigated ecosystem through a combination of technological innovations (particularly the adoption of semidwarf varieties responding to nitrogen fertilizers and with high potential yields) and supportive policies (irrigation and drainage infrastructures, price and market policies, agricultural research and extension services). The physical productivity of land thus tripled during this period; most of the key cultivation practices were mechanized – with the all-round multi-purpose hand-tractor playing a major role – but farm employment increased, while the fall in the actual price of rice acted as an important engine, fuelling the economic take-off in many countries. This, however, led to an environmental degradation such as lower water quality, pesticide residues, a decrease in fresh water fisheries in rice areas, which needs to be corrected by designing and adopting new cropping systems. They still need to be very productive, but far less dependent on external inputs by relying more on useful ecological regulations available in rice lands. The challenge is impressive as these irrigated rice bowls will need to feed an increasing number of consumers with less land (due to urbanisation, soil salinity and crop diversification), less labour (as the industry and services sectors absorb a growing share of the labour force), less chemical inputs (due to the cost of mineral fertilisers and the need to stop the overconsumption of pesticides) and less agricultural water (because of increased competition with other users of this key, but increasingly scarce resource). Using up to five cubic metres of water to produce a kilogram of paddy rice, while releasing two thirds of the nitrogen applied to the crop in the environment, will simply not be possible anymore in most Asian rice-growing regions.

5The production of flooded rice accounts for a quarter of the total rice-growing areas. The fields are bounded, but flooding depends on rainfall in the absence of irrigation infrastructures, and most of the time the submersion control is not satisfactory. The risks of drought early in the crop cycle or during flowering, and floods during the peak of the monsoon, are common and sometimes both occur in the same season. With only one crop cycle per year, this system is still widespread in South and South-East Asia. It was bypassed by the Green Revolution in rice because the lack of control over the surface water level prohibited the adoption of semi-dwarf cultivars, resulting in major inter-regional inequalities. Tall traditional cultivars are still very common, yielding usually 2 to 3 tonnes of rice per hectare. Deep-water rice presents a more smaller and shrinking ecosystem, encompassing low-lying coastal and mangrove areas, including the production of floating rice (with stem-lengths reaching more than 5 metres in some cases). Soil productivity tends to be low (yields of 1 to 1.5 t/ha are common) and often these rice lands are converted to aquaculture (fish, shrimp, crab, etc.). Upland rice production presents another small ecosystem where rice is grown in non-flooded and non-bounded fields in sloping highlands and by relying on slash-and-burn techniques. The gradual integration of these remote areas into the market economy, combined with the increasing forest conservation pressure, lead to the frequent conversion of upland rice production into a diverse range of commercial crops (maize, fruit and vegetables, rubber, etc.).

6Rice was already cultivated during the upper Neolithic period in the middle of the Yangtze valley (where a 7,000-year-old irrigation and drainage system was uncovered in Chengtoushan) as well as in the upper valley of the Huai River in southern China, then later in Uttar Pradesh, northeast India. In those days, other staple crops were possibly barley, millet, buckwheat or tubers. Rice breeders admit that Oryza sativa was independently domesticated in China and India, from annual types of the O. rufipogon wild species, giving rise to the two main groups of indicas and japonicas. Their respective geographic origins, morphological and agronomic characteristics, as well as biochemical and molecular markers distinguish the two groups, and these differences make their recombination difficult. Recent research results have shown that genomes indicas and japonicas rice could have evolved differently, well before being domesticated, at least 200,000 years ago and probably 2 or 3 million years before, possibly in relation to the lifting of the Himalayan barrier. Indicas rice is widely cultivated in irrigated and flooded lowland rice areas of tropical Asia, whereas japonicas rice is mostly found in irrigated temperate, high-elevation and upland rice areas. In China, rice production at the bottoms of valleys and deltas with soil paddling and transplanting could have been in use before the production of upland rice, while the contrary could be said for South-East Asia. Beyond this simplistic bipolarity between the two groups, however, the current genetic diversity of rice is somewhat remarkable and is the result of cross breeding between species or internal to O. sativa by natural or man-made selection (particularly on-station breeding, which has been practised for more than a century in China, Japan and India). It has been estimated that some 150,000 rice varieties are currently known and the gene bank of the International Rice Research Institute (IRRI) in Los Baños, southern Luzon, in the Philippines, keeps 107,000 different types, including 5,000 wild ones in its quakeproof facilities.

7Owing to its relatively small genome, of which the complete sequence was published in 2005, rice was selected as a major model in crop genetics worldwide. From this extensive reservoir of natural diversity, new varietal selection techniques relying on molecular biology are currently used to build rice cultivars that are more resistant to water deficit, deep submersion, or salinity, in particular. The selection and promotion of such varieties in the flooded lowland ecosystem where widespread poverty remains, especially in South Asia, could contribute significantly to increasing rice production by 40% by 2030. This is needed to win the race that began half a century ago between production and demographic growth, and to be able to satisfy the needs of today’s 4 billion consumers, which is unsatisfactory in many developing regions. The political stability of the states will depend on the result of this challenge because, according to Deng Xiaoping: “without enough grains, it is chaos.” Beyond the volume of rice production, its annual stability must be guaranteed. More attention should be paid to strengthening the capacities of rice systems to buffer climatic strain (drought, flash floods, etc.) or economic crises, causing the price of rice to triple over the course of a few months in 2008. To achieve this, the deep anchoring of rice systems in Asian societies, and the fact that they are still dominated by flexible, adaptive and innovative small-scale family holdings are two strong comparative advantages.