Dynamic variation of water deficit of winter wheat and its possible climatic factors in Northern China

Currently, it is widely recognized that the determination of water deficit for crop water requirement is a key part of design and operation of agricultural water resource systems. This paper analyzes the weather and crop data for the periods of 1971—1980 and 2001—2010, to assess the spatial dynamic variation of water deficit of winter wheat in different growth stages. The water deficit changes during jointing and heading stages were investigated considering the shapes of climate
parameters using sensitivity analysis model. The results indentified an increasing trend of total water deficit of winter wheat
in central Northern China where large part is arid land. Moreover the drought degree of winter wheat showed more aggravation during the period between sowing and returning green stages along the line of Xuzhou and Xuchang to the north. Water deficit had alleviated during the period between returning green and jointing stages, excluding central part of Northern China. The spatial pattern of water deficit of winter wheat showed an increasing trend during the period between jointing and heading stages except in the central part of Shanxi Province. Most part of the Northern China showed a decreasing trend of water deficit during the period between heading and maturity stages, where as in the south west of Northern China water deficit increased. During jointing and heading stages of winter wheat, the meteorological stations where water deficit changes are positively linked to sunshine duration account for the majority and the stations where water deficit changes is positive sensitive to sunshine duration are located in Hebei Province. The wind speed is followed, and the stations where water deficit changes are positive sensitive to mean air temperature account for the minority. The findings from this research provide an important information base for the regional studies of irrigation scheduling, water resources management to ease the tension of water resources supply and demand