ABSTRACT
Paddy (Oryza sativa) is grown over a total area of 159 million ha [5]. It is the largest consumer of irrigation water [20]. The contribution of paddy yield as a percentage of global paddy yield from irrigated, rainfed, upland and food prone ecosystems is 76%, 17%, 4% and 3%, respectively [9]. About 25-33% of world’s fresh water is used for irrigation exclusively in paddy cultivation. In Asia, more than 80% of the developed freshwater resources are used for irrigation of which, paddy cultivation consumes more than 90% of irrigation water. By 2025, it is expected that 2 million ha of Asia’s irrigated dry-season rice and 13 million ha of its irrigated wet season rice will experience physical water scarcity, and most of the approximately 22 million ha of irrigated dry season rice in South and Southeast Asia will suffer economic water scarcity [19]. Drought is one of the main constraints to high yield in rainfed rice production systems in both the lowlands and the uplands. In India, paddy is grown over an area of 43 million ha with an annual production of 124 million tons [10] and average productivity is only 2-3.5 tons/ha [24].
