Abstract: Based on precipitation data between May and August in 1980-2011,considering water demand at each growth stage,the drought and flood grades of cotton was classified.The results showed that drought stress had not occurred during the cotton growth season in last 32 years in Jingzhou,but waterlogging stress occurred commonly Precipitation was currently beyond water demand of cotton at seedling stage,the bud stage and boll opening stage,so waterlogging stress was more frequently than droughtDrought and waterlogging stress were evenly coexisted at the blossoming and boll forming stage.Further more,ginned cotton yield per unit area was divided into trend yield and meteorological yield,for analyzing the correlation between drought and flood grades at each growth stage and meteorological yield.There was significant negative correlation between meteorological yield and water demand deviation during the whole growth season and at blossoming boll forming stage (P＜0.01),and negative correlation with water demand deviation of boll opening stage(P＜0.05).The meteorological yield decreased when precipitation was beyond water demand of cotton during whole growth periodThe results could provide basic evidence for field water management and high efficient utilization in Jianghan plain.

Key words: Drought and flood grade, Cotton, Growth period, Water demand, Meteorological yield, Waterlogging stress