Abstract: The risk degrees of drought during growing period of winter wheat and its impacts on winter wheat yield were analyzed by using the integrated moisture index and the meteorological data of 78 meteorological stations from 1971 to 2006 in Anhui Province.The results showed that in terms of spatial distribution of drought,the agricultural drought risk of winter wheat during growing period increased gradually from the South to the North in Anhui Province,while the most parts of the North Huai Rive were with serious risk of droughts and regions between Huai River and Yangtze River were no drought risk region.In terms of the temporal distribution of drought,the greatest drought risk was during grain filling and harvest stages,while the jointing-heading stage was with moderate drought risk and with low drought risk during overwintering and tillering stage.In terms of inter-annual variations,although tendencies of drought risks in different regions were different,the drought risks increased significantly since 2000 in all regions.The yield loss of winter wheat was closely related to drought occurrence period.The drought occurred during jointing and filling stage would lead to most significant yield loss.The longer the drought lasted and the greater the drought intensive was,the greater the yield loss was.

Key words: Winter wheat, Winter wheat, Growing stage, Agricultural drought, Occurrence risk