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Rice in human nutrition has been written to serve a wide range of readers in government, universities and industry as a general source on most aspects of rice production, processing, trade and consumption. We hope that this book, as well as complementary trade information on rice published by FAO, will successfully address many readers' questions about this important food and assist in development and training activities in all countries.
John R. Lupien
Food Policy and Nutrition Division
Rice (Oryza sativa is the most important cereal crop in the developing world and is the staple food of over half the world's population. It is generally considered a semi-aquatic annual grass plant. About 20 species of the genus Oryza are recognized, but nearly all cultivated rice is O. sativa L. A small amount of Oryza glaberrima, a perennial species, is grown in Africa. So-called "wild rice" (Zizania aquatica), grown in the Great Lakes region of the United States, is more closely related to oats than to rice.
Because of its long history of cultivation and selection under diverse environments, O. sativa has acquired a broad range of adaptability and tolerance so that it can be grown in a wide range of water/soil regimens from deeply flooded land to dry hilly slopes (Lu and Chang, 1980). In Asia, cultivars with resistance to aluminum toxicity and with tolerance to submergence by flood water (IRRI, 1975), (Figure 1), high salinity and cool temperatures at the seedling or ripening stage have been developed (Chang, 1983). In Africa, cultivars with tolerance to iron toxicity and heatconstraints have also been developed and cultivated. Rice is now grown in over 100 countries on every continent except Antarctica, extending from 50° north latitude to 40° south latitude and from sea level to an altitude of 3 000 m.
The geographical site of the origin of rice domestication is not yet definitely known. The general consensus is that rice domestication occurred independently in China, India and Indonesia, thereby giving rise to three races of rice: sinica (also known as japonica), indica and javanica (also known as bulu in Indonesia). There are indications that rice was cultivated in India between 1500 and 2000 B.C. and in Indonesia around 1648 B.C. Archaeological findings have shown that tropical or indica rice was being cultivated in Ho-mu-tu, Chekiang Province, China at least 7 000 years ago (Chang, 1983). Recently, remains of the temperate or sinica (japonica) rice of the same age were found at Lou-jia-jiao, also in Chekiang Province (Chang, 1985). Rice was rapidly dispersed from its tropical (southern and southeastern Asia) and subtropical (southwestern and southern China) habitats to much higher altitudes and latitudes in Asia, reaching Japan as recently as 2 300 years ago (Chang, 1983). It was introduced to points as far as West Africa, North America and Australia within the last six centuries.
FIGURE 1 The world's rice land classified by water regimes and predominant rice type
Rice growing became firmly established in South Carolina in the United States in about 1690 (Adair, 1972). Rice was cultivated in Europe from the eighth century in Portugal and Spain and by the ninth to the tenth century in southern Italy (Lu and Chang, 1980).
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