黑龙江省不同年代玉米杂交种氮肥利用效率对种植密度和施氮水平的响应

以黑龙江省近50年来第I积温带大面积种植的8个典型春玉米品种为材料，于2009-2010年进行密度和施肥的田间试验，比较不同年代主栽品种氮肥偏生产力(PFP)、氮肥农学效率(NAE)、氮肥吸收利用率(NRE)及主要器官氮含量对密度和氮素的响应差异。结果显示，1970s-2000s品种更替过程中，PFP和NRE呈递增趋势，增幅分别为3.41 kg kg^-1 10年^-1和2.26个百分点10年^-1。NAE在1970s-1990s呈显著递增趋势，之后呈下降趋势。氮收获指数随年代递增呈显著下降趋势，平均每10年下降1.51个百分点；茎、叶和籽粒氮积累量随年代推进呈显著递增趋势，平均每10年分别递增0.09、0.07和0.12 g株^-1；上述各主要指标在年代、密度和氮肥水平之间存在显著的互作效应。各年代品种的氮肥利用效率均随氮肥水平的提高而显著下降，随密度的增加呈抛物线形变化趋势，最高效率值出现在50 000-70 000株 hm^-2范围内，现代品种的最高氮效率的种植密度高于老品种。各年代品种籽粒、叶片、茎氮素积累量和氮收获指数随密度增加呈显著递减趋势。各年代品种籽粒、茎和叶片氮素积累量随施氮量增加呈增加趋势，施氮量对氮收获指数影响各年代品种表现不同。上述结果表明，品种改良的氮肥增效潜力较大。在现有的品种状况下，增密不仅可以增产，而且可以显著提高肥料效率。

Response of Nitrogen Use Efficiency to Plant Density and Nitrogen Application Rate for Maize Hybrids from Different Eras in Heilongjiang Province

n this study, eight typical maize hybrids released from 1970s to 2000s in Heilongjiang Province were selected to investigate the responses of grain yield, Nitrogen (N) partial factor productivity (PFP), N agronomic efficiency (NAE) and N recovery efficiency (NRE) to N application rate and plant density in 2009 and 2010. During the variety improvement period of 1970s–2000s, PFP and NRE increased significantly by 3.41 kg kg^-1 10 yr^-1 and 2.26 per cent 10 yr^-1, respectively. NAE increased significantly from 1970 to 2000 and descended after 2000. N harvest index decreased significantly by 1.51 per cent 10 yr^-1. Grain N, stem N and leaf N accumulations rose significantly by 0.09, 0.07, and 0.12 g plant^-1 10 yr^-1. There were significant interactions among eras, plant densities and N application rates for above indicators. Nitrogen use efficiency exhibited decline trends with increasing N application rate and parabolic shape response to increasing plant density, and got the maximum in the population range of 50 000–70 000 plants ha^-1. The theoretical optimal plant density for the maximal NUE was higher in newer hybrids than in the older ones. Higher plant population led to decrease N accumulation and N harvest index in grain, stem and leaf for all hybrids from different eras. Higher N application rate tended to promote N accumulation in grain, stem and leaf, but had different effects on N harvest index for hybrids from different eras. Compared to the varieties released abroad, there is a great potential in maize variety improvement for high-yield and higher-NUE in Northeast China. According to the existing variety’s traits, increasing plant density can enhance not only maize yield but also NUE.