Responses Of Yield And Nitrogen Use Efficiency Of Summer Maize To Nitrogen Application And Density In Dongting Lake Region

In recent years,the planting area of cotton sharply decreased in Dongting Lake area because of the decline of domestic cotton planting benefit,and the planting area of maize increased year by year,and winter rapeseed-summer maize has become an important multicropping way in local area.In order to probe the response of summer maize yield formation and nitrogen utilization efficiency to nitrogen application rate and planting density in Dongting Lake region,and then to provide support for improving the high-yielding and high-efficiency cultivation techniques for machine-harvest summer maize,the field experiment was conducted out with Xiangnongyu No.27 as the material under three nitrogen application rates(300 kgN/hm~2,225 kgN/hm~2,150 kgN/hm~2)and three densities(60000plants/hm~2,75 000 plant/hm~2,90 000 plants/hm~2)in 2017-2018.The main results are as follows:(1)The whole growth duration of summer maize variety Xiangnongyu No.27 was not affected by the density,but it was prolonged by 2-4 days with the increase of nitrogen application rate,and proper early sowing could shorten the whole growth duration of summer maize.(2)Planting density had significant effect on summer maize yield,and nitrogen application rate should be appropriately reduced with the increasing planting density.Effect of interaction of density and nitrogen application rate on summer maize yield was significant,and the yield of Xiangnongyu No.27 was highest under the conditions of 90,000 plants/hm~2and 225 kgN/hm~2,it was 7252 kg/hm~2 and 10258.3 kg/hm~2 in 2017and 2018,respectively.(3)With the increase of density,the double ear rate of summer maize decreased and the empty stalk rate increased.The weather had great influence on the lodging rate and the collapse rate.The leaf area index of summer maize increased with the increase of nitrogen application rate and density.(4)Nitrogen absorption efficiency and nitrogen fertilizer utilization efficiency decreased with the increment of nitrogen application rate,while increased with the increment of density.The interaction of nitrogen application and density had significant effects on nitrogen uptake efficiency and nitrogen fertilizer utilization efficiency of summer maize.These results indicated that Xiangnongyu No.27 adapted to high density planting,proper control of nitrogen application rate and increase of planting density could improve nitrogen absorption efficiency and nitrogen fertilizer utilization efficiency,which was beneficial to the efficient absorption and utilization of nitrogen fertilizer in summer maize.Considered the high yield and nutrient utilization efficiency,Xiangnongyu No.27 should adopt the strategy of high-density and medium-nitrogen rate(90000 plants/hm~2+225kgN/hm~2).