本文全面综合地分析了南阳冬小麦和夏玉米各生育期的水分条件,发现冬小麦拔节期和抽穗期、夏玉米抽穗——灌浆期水分供需矛盾最大,夏玉米产量低而不稳的原因是7月下旬到8月上旬降水年际变化太大的缘故. This paper comprehensively and comprehensively analyzed the moisture conditions of winter wheat and summer maize in Nanyang. The results showed that the water supply and demand of summer maize at jointing stage and heading stage were the biggest, and the reason of low and unstable summer maize yield was July Precipitation in late August to early interannual changes in the reason too much.