Differences In Photosynthetic Characteristics And Nitrogen Metabolism In Wheat Cultivars With Various Nitrogen Efficiency

Nitrogen is one of the essential nutrients in plant growth and development,and plays an important role in the formation of wheat yield and quality.There are many problems in wheat cultivation in China,such as low nitrogen use efficiency,increased production cost and a series of environmental pollution.Therefore,the cultivation of high nitrogen efficiency varieties is of great significance to improve the utilization rate of nitrogen fertilizer in crops.In this study,30 wheat varieties with different nitrogen efficiency were selected to analyze the differences of yield and nitrogen efficiency among different genotypes of wheat.Then,the nitrogen absorption efficiency,agronomic efficiency and nitrogen physiological utilization efficiency of different genotypes of wheat were used as screening indicators,and cluster analysis was carried out,which was divided into three categories:nitrogen efficiency,nitrogen intermediate efficiency and nitrogen inefficiency.The differences of photosynthetic characteristics,fluorescence characteristics,enzymes related to nitrogen metabolism and the expression of glutamine synthase isoenzymes TaGS Ⅰ and TaGS Ⅱ at flowering stage were analyzed in order to clarify the differences of nitrogen efficiency among wheat varieties with different nitrogen efficiency.1.30 Wheat Cultivars with different genotypes were classified into three types,i.e.N-efficient,N-moderate and N-inefficient.Nitrogen efficient varieties were Zhoumai 18,Huaimai 33,Zhengmai 9023,Ningmai 13,Yangmai 22,Zhoumai 27 and Yangmai 16.The middle-effective nitrogen varieties were Yumai 49,Yannong 19,Yumai 18,Zhengyin 1,Yangmai 158,Dwarf 58,Zhoumai 9,Xinong 979,Huaimai 18,Yangmai 20,Yangmai 5,Huaimai 20,Annong 0711,Annong 1124,Xumai 33,and the low-effective nitrogen varieties were Huosuotou,Zaoyangmai,Jiangdongmen,Abe,Afu,Wangshui Bai,Yangmai 1,Nanda 4219.The indices of N-efficient wheat varieties were significantly higher than those of N-efficient wheat varieties and N-inefficient wheat varieties.The correlation analysis showed that nitrogen efficiency was positively correlated with dry matter accumulation,total nitrogen content and nitrogen uptake rate after anthesis;the efficiency of nitrogen dry matter production was significantly correlated with total dry weight,and dry matter accumulation contributed a lot to the efficiency of nitrogen dry matter production.2.Photosynthesis and nitrogen metabolism are closely related to nitrogen efficiency.The photosynthetic capacity,chlorophyll content and nitrogen metabolism-related enzymes including nitrate reductase and glutamate synthase activity and GS isoenzyme expression of N-efficient wheat cultivars were significantly higher than those of N-efficient wheat cultivars and N-inefficient wheat cultivars.These indicators can be used to screen N-efficient wheat cultivars of different genotypes and provide scientific reference for high yield,high efficiency and sustainable development of wheat.