Abstract: The effects of low nitrogen stress on net photosynthetic rate，nitrogen accumulation，nitrogen metabolic enzyme activity，root traits，yield and quality of Zhengmai 0943 with nitrogen use efficiency index of 1.557 and Zhoumai 18 with nitrogen use efficiency index of 0.895 were analyzed，so as to provide reference for high nitrogen efficiency breeding and cost⁃saving cultivation technology research.The results showed that under normal nitrogen and low nitrogen treatments，the net photosynthetic rate at 7，14 and 21 days after anthesis，net photosynthetic rate at 10：00—15：00 at 14 days after anthesis，activities of nitrate reductase and glutamine synthetase，nitrogen accumulation of straw and grain at maturity，and yield of Zhengmai 0943 were significantly higher than those of Zhoumai 18. Under low nitrogen treatment，the above indexes were significantly lower than those under normal nitrogen treatment，and the reduction rates of Zhengmai 0943 were lower than those of Zhoumai 18，among which the yield of Zhengmai 0943 decreased by 21.40%，and Zhoumai 18 decreased by 24.87%.Under low nitrogen treatment，the total root length，root surface area and root activity of Zhengmai 0943 were significantly higher than those of Zhoumai 18.The root traits of the two wheat varieties under low nitrogen treatment were significantly higher than those under normal nitrogen treatment，and the increase rates of Zhengmai 0943 were higher than those of Zhoumai 18.Low nitrogen stress significantly affected the quality of the two wheat varieties，but Zhengmai 0943 was less affected. Compared with normal nitrogen treatment，the decrease rates of protein content，wet gluten content，stability time，maximum tensile resistance and tensile area of Zhengmai 0943 under low nitrogen treatment were lower than those of Zhoumai 18.All parameters of Zhengmai 0943 reached the standard of medium⁃strong gluten wheat，except for the tensile area. In summary，Zhengmai 0943 is more tolerant to low nitrogen than Zhoumai 18，low nitrogen has less influence on its photosynthetic rate，nitrogen accumulation，nitrogen metabolic enzyme activity，root，yield and quality，and it has better photosynthetic characteristics，higher nitrogen absorption and assimilation ability，and more developed root system，so obtains higher yield and better quality under low nitrogen treatment.

Key words: Wheat, Nitrogen efficiency, Low nitrogen, Nitrogen accumulation, Nitrogen metabolism, Yield, Quality

摘要： 以氮效率不同的2个小麦品种郑麦0943（氮利用效率指数为1.557）和周麦18（氮利用效率指数为0.895）为试验材料，研究低氮胁迫对2个小麦品种净光合速率、氮积累量、氮代谢酶活性、根系性状、产量和品质的影响，以期为小麦氮高效育种和节本高效栽培技术研发提供参考。结果表明，在正常供氮和低氮处理下，郑麦0943花后7、14、21 d的净光合速率，花后14 d 10：00—15：00的净光合速率、硝酸还原酶和谷氨酰胺合成酶活性，成熟期秸秆和籽粒氮积累量，产量均显著高于周麦18；低氮处理下，上述指标均显著低于正常供氮处理，且郑麦0943的降低幅度低于周麦18，其中，郑麦0943产量降低21.40%，周麦18降低24.87%。低氮处理下，郑麦0943的总根长、根表面积和根系活力均显著高于周麦18；2个小麦品种根系性状均显著高于正常供氮处理，且郑麦0943的提高幅度高于周麦18。低氮胁迫显著影响2个小麦品种的品质，郑麦0943的品质受影响较小，低氮处理下郑麦0943的蛋白质含量、湿面筋含量、稳定时间、最大拉伸阻力、拉伸面积等指标较正常供氮处理的降幅均低于周麦18，除拉伸面积外，其余指标均达到了中强筋小麦标准。综上，郑麦0943较周麦18更耐低氮，低氮对其光合速率、氮积累量、氮代谢酶活性、根系、产量和品质的影响更小，低氮下其具有更好的光合特性、更高的氮吸收和同化能力、更发达的根系，进而获得更高的产量和较优的品质。

关键词: 小麦, 氮效率, 低氮, 氮积累, 氮代谢, 产量, 品质