关键词: 小麦, 氮效率, 低氮, 氮积累, 氮代谢, 产量, 品质

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