Rice (Oryza sativa L.) is the world’s most important staple food for more than two billion people in Asia and hundreds of millions in Africa and Latin America (Ladha et al., 1997). Within Southeast Asia, rice provides about 60% of the human food consumption.
About 55% of the Asian rice is produced in irrigated areas, whichaccounts for about 75% of Asia’s total rice production with an estimated 2.2 billion Asian rice farmers and consumers depending upon the sustainable productivity of the irrigated lowland rice
ecosystem for their food supply (Buresh et al., 2005).