Abstract: Seasonal drought is one of the most serious disasters in rice production in Hunan province of China. On the basis of calibration and validation of rice model ORYZA2000, the characteristics of seasonal drought and its effect on growth and yield of double cropping rice under three types of water management with continued flooding (CF), alternative wet and dry (AWD), and rainfed (RF) conditions were simulated and analyzed with history weather data from 1960 to 2007. The results was as follows, (1) The soil seasonal drought of double rice gradually occurred from panicle initiation (PI) under AWD and RF conditions, and got more serious in the process of growth, especially under rainfed condition. The late rice tended to be more easily affected by seasonal drought than early rice, and the seasonal drought was more serious at late stage than early stage. The effect of drought on biomass and yield of rice was the severest at flowering stage. The characteristics between soil drought and crop drought showed differently. (2) There appeared seasonal drought for both early and late rice under the year types of normal and dry. The drought was serious for early rice from early PI to maturity under dry year type, and its strength and duration surpassed that of normal year type. The frequency and strength of drought for late rice excessed that of early rice under dry year type, especially from PI to maturity. (3) The seasonal drought caused different losses of yield in double rice. Higher yield of rice occurred under AWD, while the lowest yield occurred under RF. The yield of late rice was lower than that of early rice under rainfed condition. This quantitative study could provide a theoretical basis for the disaster mitigation of seasonal drought and sustainable water management in double rice production in Hunan.

Key words: Double cropping rice, Seasonal drought, Yield, ORYZA2000, Hunan Province