Effect Of Increasing Density And Decreasing Nitrogen Rate On Yield And Nitrogen Use Efficiency Of Different Density Tolerance Spring Maize Hybrids

Reasonable density and nitrogen fertilizer are effective way to increase of maize yield and improving the nitrogen use efficiency.There was a difference in response to increasing density and decreasing nitrogen rate by density-tolerance spring maize.In this experiment,we conducted the density×fertilizer rate×variety three factor split test,and under three density 60000plant/hm~2(PD6.00),82500plant/hm~2(PD8.25)and105000plant/hm~2(PD10.5),and three rate of N application 0(N0),150(N1)and300kgN/hm~2(N2),comparative analysis the physiological characteristics of the different density-tolerance maize were Huamei NO.1 Zhendan958,KeheNO.8 and Nongda108.The results show:(1)Increasing planting density and decreasing nitrogen rate significantly affects the yield of different spring maize varieties.Huamei No.1 achieved the highest output at15.1t/hm2 under PD10.5 and N2 conditions,Zhendan958,KeheNO.8 and Nongda108achieved the highest output at 16.51 t/hm~2,14.89 t/hm~2 and 13.75 t/hm~2 under PD8.25and N2 conditions.After increasing the planting density,the yield reduction of non-density resistant hybrid is more serious,under the same nitrogen application rate,density-resistant hybrid can obtain higher yields.In the high-density conditions,the two nitrogen application rates had no significant effect on the change of 1000-grain weight,and had a greater impact on the kernel number of grains per in all varieties of maize.(2)Increasing the density is conducive to dry matter accumulation in density-resistant hybrid.The dry matter accumulation of the non-density resistant hybrid increased first and then decreased with the density,under high-density conditions,the reduction in dry matter per plant is greater than the increase in population,over-application of nitrogen affects stem and leaf dry matter transport to Grain,excessive nitrogen application even causes a decrease in dry matter accumulation;density-resistant hybrid show more efficient nitrogen transport and contribution to kernels.(3)The photosynthetic capacity of weakly-tolerant spring maize varieties was superior under medium and low density conditions.Compared with non-density resistant hybrid,densification has less effect on the photosynthetic capacity of dense varieties,excessive nitrogen application under high-density conditions does not significantly improve the photosynthetic capacity of dense varietiesand,under the appropriate amount of nitrogen,it can still maintain relatively high photosynthetic performance in post-silking stage,which is beneficial to the assimilation of dry matter and provide guarantee for high yield.(4)Reduced nitrogen fertilizer can significantly improve the variety of NUE,after the densification of non-density resistant hybrid,the NUE decreased significantly.Under the PD10.5 and N1 conditions,the NUE of Huamei NO.1 was 14.87kgkg,Zhengdan958was 11.32kg/kg,Kehe8 was 9.86kg/kg,Nongda108 was 7.28kg/kg;and the PFP_N of density-resistant hybrid remained at about 100 kg/kg under the PD10.5 and N1 conditions,however the PFP_N of non-density resistant hybrid was maintained at about 80kg/kg.Therefore,under the dense planting conditions,the selection of density-resistant hybrid can achieve a synergistic increase in yield and NUE.