Effect of water deficit at different growth stages and nitrogen fertilizer on yield and water use efficiency of winter wheat.

【Objective】 This paper was to study the effect of water deficit at different growth stages and nitrogen fertilizer on yield and water use efficiency of winter wheat,and to discuss the sensitive period of water deficit and reasonable amount of nitrogen fertilizer during wheat growth.【Method】 With Xiaoyan 22 as test material,four nitrogen fertilizer levels and eleven water deficit treatments were provided to carry out pot experiments to study the effect of water deficit at different growth stages and nitrogen fertilizer on yield,yield component factors and water use efficiency of winter wheat.【Result】 There were some effects of soil water deficit at different growth stages and nitrogen fertilizer levels on yield and water use efficiency of winter wheat.Compared with no water deficit at whole growth stages(CK),water deficit at period of returning green significantly decreased the dry wheat matter by 7.70% and significantly increased the wheat yield and water use efficiency by 4.95% and 7.56%.Water deficit at jointing stage and tassel stage significantly reduced dry matter and yield by 13.69%,15.88% and 5.69%,8.06%,respectively.Moreover,it significantly reduced spikelet bearing number and grain number per spike,too.No significant yield reduction was found when water deficit was imposed at milky stage,but water consumption was reduced significantly by 5.44%,and the water use efficiency was significantly increased by 8.02%.Compared with CK,water deficit at seedling establishment+jointing stage,seedling establishment+tassel stage,seedling establishment+milky stage,jointing+tassel stage,jointing+milky stage and tassel+milky stage reduced the dry matter and the yield significantly.Winter wheat was sensitive to water deficit at turning green+jointing stage and jointing+milky stage,and its yield was reduced seriously by 11.60% and 14.52%,respectively.At the same time,water use efficiency was reduced significantly by 8.02% and 7.56%.Nitrogen fertilizer had significant promoting effect on yield and water use of winter wheat.The middle nitrogen treatment(0.3 g/kg,N2) obtained the highest yield,the lower water consumption and the higher water use efficiency compared with the other nitrogen fertilizer treatments.【Conclusion】 Winter wheat is sensitive to water deficit at jointing stage,tassel stage,returning green+jointing stage and jointing+milky stage,and the middle nitrogen treatment has the highest yield and higher water use efficiency.