Rice in the Global Food Supply

Rice (Oryza sativa L.) has supported a greater number of people for a longer period of time than any other crop since it was domesticated between 8,000 to 10,000 years ago (Greenland, 1997). At present, rice is the staple food for more people than wheat, and 90 percent of total rice production is grown and consumed in Asia (Evans, 1998). Unlike maize or wheat, less than five percent of total rice production is traded on world markets, mainly within Asia and from Asia to Africa and Europe. Thus the emphasis in all rice economies is on self-sufficiency. In many Asian countries, rice selfsufficiency and political stability are interdependent issues. Wetland or paddy rice production has been sustained over millennia and can be considered one of the world’s most sustainable and productive farming systems. On an annual basis, irrigated rice is often 100 times more productive than upland rice, over 12 times more productive than deep-water rice, and five times more productive than rainfed rice (Table 1). Irrigated rice accounts for 55 percent of the global harvested area and contributes 75 percent of global rice production, which is about 410 million tonnes (M t) of rice per year (Dobermann and Fairhurst, 2000). Rice is now the staple food of 2.7 billion people, almost half the world’s population, and is grown by more than half the world’s farmers. The enormous productivity of intensified paddy rice systems accounts for the very high population densities and rich cultures that have developed alongside the major river systems of Asia. Rice culture is thus the cornerstone of cultural, social, and economic development in Asia. Until the middle part of the last century, yields increased slowly but steadily and crop failure became less frequent as improved methods to control water supply were developed and farmers selected varieties adapted to specific agroecological conditions. Rice was adapted to fit a wide range of growing conditions, from the equatorial tropics to the high altitudes of Japan, from the tropical lowlands to the mountain terraces of the Himalayas, and from deep-water swamps to the uplands. This explains why over the past 35 years it has been possible to collect more than 80,000 local varieties now T