Nitrogen Efficiency Evaluation Of Selected Maize Inbred Lines From Shann A Group And Shann B Group

Application of nitrogen fertilizer can increase the yield of corn,but with the increase of nitrogen application causing a large number of nitrogen waste and environmental pollution.Breeding the nitrogen efficient varieties can improve the utilization rate of nitrogen fertilizer,the varieties from environment stress is particularly important to improve the efficiency of nitrogen.The resistance of maize varieties was from the parental inbred lines.Therefore,to evaluate the genetic diversity of maize germplasm and excavate the high efficiency germplasm resources of maize,then cultivate high efficiency varieties of corn is an effective way to improve nitrogen utilization.Inorder to explain the differentials of nitrogen efficiency in different maize inbred lines and screen the nitrogen high-efficient maize inbred lines.In 2015 and 2016,thirty maize inbred lines including twenty-six lines breeding from Shaan A and Shaan B groups under high stress environments as materials and four elite inbred lines(zheng58,chang7-2,PH6 WC,PH4CV)were planted under no nitrogen(N0)and normal nitrogen(N180)level and measured the SPAD-value,leaf area,dry matter accumulation and nitrogen conent of each tissue.At the same time screeing the 2 nitrogen efficient and 2 nitrogen inefficient inbred lines from field as a material to analyze the physiological indicater and gene expression of carbon and nitrogen under high and low nitrogen levels,the conclusion as following:1.Using yield as the primary indicator,the thirty maize inbred lines was divided into thirteen high-yield of nitrogen high-efficiency,two low-yield of nitrogen high-efficiency,eleven low-yield of nitrogen low-efficiency and four high-yield of nitrogen low-efficiency2.Using integrated D value as indicator,the thirty maize inbred lines was divided into three types,including ten(D-value?0.5)strongest ability of resistance to low nitrogen,fourteen(0.35?D-value<0.5))stronger ability of resistance to low nitrogen and six(D-value<0.35)have poor resistance to nitrogen.3.Using the optimum regression model,the results showed that the leaf area,post-silking nitrogen accumulation and N uptake in grain could as the secondary indicators.4.Through nanlysis the yield and other traits,KA015,2012KA-34,KB215,2013KB-37,2013KB-47 have the characteristics withlarge green area at silking,high yield,high dry matter weight of stem and leaf,high N content in grain,the strong resistance to low nitrogen.5.The dry matter accumulation and transport and nitrogen accumulation of two types of maize inbred lines were analyzed,which indicated that the dry matter of the two types of inbred lines was mainly derived from the accumulation of dry matter after silking,and the higher nitrogen accumulation after silking was the main source of nitrogen efficient inbred lines.6.According to the SPAD value,dry matter and nitrogen content of two maize inbred lines at seedling stage,it was shown that the nitrogen efficient inbred lines had more chlorophyll content and strong topsoil and root system.7.The enzyme activity results showed that the nitrogen-efficient inbred lines could maintain high activity at low nitrogen level,promote nitrogen metabolism,and have strong resistance.8.Seeding stage gene expression results show that the nitrogen efficiency materials under nitrogen stress can incress resistance to low nitrogen through improving the quantity of gene expression.