通过田间试验，连续4 a研究了不同施氮量对春小麦水分利用效率的影响。结果表明，在黄土高原黄绵土土壤中，随施氮量的增加，春小麦水分利用效率呈先增后降的趋势，连续4 a施氮105 kg/hm2时，春小麦的水分利用效率最高。春小麦产量与生育期降水量呈极显著线性相关水平，说明生育期降水极显著影响春小麦产量水平，并与降水年型有很大关系。

Field trials were conducted to study the effects of different nitrogen application rates on water use efficiency of spring wheat for 4 consecutive years. The results showed that the water use efficiency of spring wheat increased first and then decreased with the increase of nitrogen application rate in loess soil of the Loess Plateau. The water use efficiency of crops was the highest when the nitrogen application rate was 105 kg/hm2 for 4 consecutive years. The linear correlation between spring wheat yield and precipitation during growth period was very significant， which indicated that precipitation during growth period had a significant effect on yield of spring wheat and had a great relationship with precipitation pattern.

S512.1

国家自然科学基金(31460337、31660373、31761143004)；甘肃省教育厅项目(2017C-12)；“十二五”国家科技支撑计划(2012BAD14B03、2015BAD22B04-3)。