中文摘要：

【目的】探究密度与氮肥用量对不同耐密型夏玉米品种籽粒产量及氮素利用效率的影响。【方法】以稀植大穗型品种鲁单981（LD981）和紧凑耐密型品种郑单958（ZD958）为供试材料,设置52 500和82 500株/hm~2两个种植密度,同时设置0、90、180、270和360 kg·hm~（-2） 5个施氮水平,研究密度与氮肥用量对不同耐密型夏玉米品种单株及群体干物质积累特性、氮素转运效率、氮素利用效率、产量及其构成因素的影响。【结果】增加种植密度,相同施氮水平处理的千粒重和穗粒数显著降低,单位面积穗数、空秆率、倒伏率显著提高,不耐密品种空秆率、倒伏率增加更显著。其中,ZD958与LD981各施氮处理的平均千粒重、穗粒数分别降低6.24%、6.77%和7.52%、18.09%,LD981空秆率、倒伏率高达17.0%、27.6%,显著高于ZD958。高密度条件下,籽粒产量随施氮量增加而增加,施氮270和360 kg·hm~（-2）处理的产量差异不显著;低密度条件下,随施氮量增加,籽粒产量先上升后下降,施氮量270 kg·hm~（-2）处理产量达到最大值。增加种植密度,夏玉米单株干物质积累量呈降低趋势,群体干物质积累量呈增加的趋势。随施氮量增加,单株和群体干物质积累量均显著增加,花后干物质贡献率呈上升趋势。相同氮素水平下,高密度处理显著提高夏玉米总氮素积累量、氮素转运量及其对籽粒的贡献率。增加种植密度,ZD958和LD981各施氮处理的平均总氮素积累量、氮肥农学利用率、氮肥利用率分别增加15.94%、39.01%、26.22%和1.96%、5.79%、14.92%。相同种植密度水平下,总氮素积累量和花后氮素同化量随施氮量增加呈上升趋势,而氮肥农学效率、氮肥利用率和氮肥偏生产力呈下降趋势。增加种植密度,营养器官氮素转运量和氮素转运对籽粒的贡献率显著增加。高密度种植条件下,氮素转运效率及贡献率随施氮量增加而增加,而低?

英文摘要：

[ Objective ] The objective of this experiment is to study the effects of close planting and nitrogen application rates on grain yield and nitrogen utilization efficiency of different density-tolerance maize hybrids. [Method] Two summer maize cultivars, density-resistant hybrid （ZD958） and non-density resistant hybrid （LD981）, were used as experiment materials to study the effects of different planting densities （ 52 500, 82 500 plant/hm2） and nitrogen rates （0, 90, 180, 270, 360 kg N.hm-2） on dry matter accumulation, nitrogen translocation efficiency, nitrogen use efficiency, yield and its components of different density-tolerance summer maize. [ Result ] The 1000-grain weight and kernels per ear were significantly decreased with the increase of planting density at the same nitrogen application level, but the ear number, barrenness and lodging rate were significantly increased. The barrenness and lodging rate of non-density resistant hybrid were increased more significantly. The average 1000-grain weight and kernels per ear of ZD958 and LD981 were decreased by 6.24% and 6.77%, 7.52% and 18.09%, respectively, and barrenness and lodging rate of LD981 were as high as 17% and 27.6%, significantly higher than ZD958. The grain yield increased with increase of N application rate under high density condition, but the difference between N application rate at 270 kg.hm2 and 360 kg.hm-2 was not significant. Under low density condition, the grain yield increased first and then decreased with increase of N application rate, and reached the maximum at N application rate of 270 kg＇hm-2. The dry matter accumulation per plant decreased with the increase of planting density, while the population dry matter accumulation increased. Both of them increased with increase of N application rate, and the dry matter contribution rate increased after anthesis. Under the same nitrogen level, the high density treatments significantly increased the total N accumulation, N translocation and its contribution rate to grain. Wi