Study on characteristics of winter wheat water deficit in Longdong of Gansu Province

Using the meteorological data of 15 stations in Longdong area,the reference crop evapotranspiration(ET0),crop water requirement of main crops(ETc),and crop water deficit index(CWDI) of each station were calculated.The temporal and spatial distribution characteristics of winterwheat water deficit at different growth stages in Longdong area were studied to provide science gist for mastering law of drought and making rational distribution to avoid disadvantages in agricultural production.The results indicated that the drought especially severe drought occurred frequently in the growth period of winter wheat in Longdong area.The drought frequency was higher in vegetative growth stage while lower in reproductive growth stage.In space,drought occurred with the highest frequency in north Longdong,followed by west and north middle parts,and the lowest area located in south and east parts.In annual changes,the CWDI of winter wheat in critical period of water fluctuated with a slight increase in recent 40 years generally,and increased obviously in the years after 2005.