Screening Of High-yield And High Nitrogen Use Efficiency Spring Maize Varieties And Their Accumulation And Distribution Of Dry Matter And Nitrogen

The development of more efficient N management strategies and more N-efficient maize variety is crucial to ensure national food security and protect resources and environment.In this study,the N requirement per t grain yield of maize in 5 provinces?Gansu,Ningxia,Shanxi,Shaanxi and Xinjiang provinces?of the Northwest of China was analyzed based on the literature survey.Field study was conduced at two sites?Yingxian in Shanxi province and Changwu in Shaanxi province?with two N levels(N225:225 kg N ha^-1and N0:0 kg N ha^-1)and 18 maize varieties.The goal was to evaluate yield components,dry matter production,and N accumulation among different yield categories,and to screen of high-yield and high N use efficiency varieties.The main results are as follows:?1?Based on the literature survey,the liner-plateau model had the best fit for the maize yield response curves to N rate.The optimal N rates were 197,260,240,203 kg/ha and 211kg/ha in Gansu,Ningxia,Shanxi,Shaanxi and Xinjiang,while the maximum yields were 10.6,13.1,10.0,10.2 t/ha and 16.2 t/ha,respectively.For the N requirement per t grain yield of maize,the average value was 21.1 kg.?2?To further compared the partitioning of dry matter production and N accumulation among different varieties,pooled yield data in N0 and N225 treatment were grouped into four categories:low yield at N0 and high yield at N225?L0HN?,high yield at both N0 and N225?H0HN?,high yield at N0 and low yield at N225?H0LN?,and low yield at both N0 and N225?L0LN?.The L0HN and H0HN varieties have the potential of increasing yield by 2.8%to6.9%and the potential of N fertilizer input reduction by 10.1%to 29.2%.At Yingxian,varieties with L0HN and H0HN were DF30,QS388,RP909,JN336,JY18,DH605,ZD9988and XY335,while the four varieties?DF30,JY18,DH605,and XY335?had the potential to increase production by more than 5%.?3?The difference of grain yield mainly depended on the total dry matter accumulation and the post-flowering dry matter accumulation.More total dry matter and post-flowering dry matter accumulation were observed for L0HN and H0HN varieties.There was no significant difference in the biomass of different types of maize varieties at the ten-leaf stage,but with the development of maize varieties,the biomass of L0HN and H0HN varieties increased gradually compared with the L0LN varieties,and reached the maximum at the filling stage.?4?Under the condition of N225,the L0HN and H0HN varieties had higher total nitrogen uptake and grain nitrogen accumulation than the L0LN varieties,while the average values were 35.7 kg/ha and 25.7 kg/ha,respectively.Compared with the L0LN varieties,86%more post-flowering N accumulation was uptake by the L0HN and H0HN varieties.?5?For the agronomic efficiency and the apparent recovery rate,the L0HN were significantly higher than the L0LN varieties.For the partial productivity of nitrogen fertilizer,the L0HN and H0HN varieties were significantly higher than the H0LN and L0LN varieties.