Effect of Nitrogen Application Rate on Physiological Characteristics in Flag Leaf of Spring Wheat under Water Stress

【Objective】The project aims to study the effect of nitrogen rate on flag leaf physiological characteristics by using Xinhan 688,a new variety of drought- resis tance in the field experiment after flowering under water stress. 【Method】Conventional irrigation was taken as the control and two times of irrigation as drought stress in the whole growth period,and others were nitrogen application rate with 0,150,300,450 kg / ha to study the effect of nitrogen fertilizer and irrigation on physiological characteristics in Xinhan 688 【Result】 The content of Chl(a + b),Chla,Chlb,total N of leaf varied with nitrogen rate under drought stress in certain nitrogen application rate,the ratio of Chla / Chlb gradually decreased with increasing amount of nitrogen. The net photosynthetic rate was increased,and the intercellular CO 2 concentration was decreased in the range of 0- 300 kg / ha nitrogen. When nitrogen rate reached to 450 kg / ha,the intercellular CO 2 concentration began to increase,but the photosynthetic rate decreased. The high nitrogen in drought were generally most effective in the accumulation of soluble sugar,and the accumulation of soluble sugar with 150 kg / ha nitrogen was higher than that of other treatments. 【Conclusion】The nitrogen application of different nitrogen levels had effect on the physiological characteristics of wheat flag leaf after anthesis under water stress.