Description

Rice farming is about 10,000 year old and largest single use of land for producing food. Rice is eaten by nearly half of the world's population. Rice fields cover 11% of Earth's entire arable land. Rice is synonymous with food throughout Asia. Two rice species are important cereals for human nutrition i.e. Oryza sativa, grown worldwide and O. glaberrima, grown in parts of West Africa. Varieties of growth duration ranging from 70 to 160 days exist in diverse environments. Flooding afflicts some 20 million ha in Asia each year and estimates indicate that submergence stress causes annual losses of $650 million to $1 billion in Asia.In India, about 16.1 million ha rainfed lowland rice are grown each year, of which 4.4 million ha are highly submergence-prone (intermediate rainfed lowlands.In addition, submergence might also occur in shallow rainfed lowlands and irrigated lowlands. Damage to plants caused by submergence could have several causes linked to floodwater conditions, particularly the interference in normal gas exchange and light interception. The adverse effects of flooding on rice vary by genotype, and of particular importance are the carbohydrate status of the plant.