黑龙江省不同年代玉米杂交种产量对种植密度和施氮水平的响应

明确不同年代春玉米生产力对种植密度和氮肥水平的响应特征及其趋势，对高产高效的耐密品种选育和密植抗倒栽培具有重要的理论参考和技术指导意义。本文以黑龙江近50年来第一积温带大面积种植的8个典型春玉米品种为材料，于2009和2010年进行密度和施肥的田间试验，比较不同年代主栽品种生产力演变特征。结果显示，黑龙江省1970s—2000s玉米品种更替过程中，单株生产力与群体产量均明显提高，平均增幅分别为16.96 g 10年^-1和790 kg hm^-2 10年^-1；植株空秆率和倒伏率显著下降，株高、穗位、单株叶面积、穗粒数、千粒重显著提高。随着密度的提高，各年代玉米的单株产量呈显著下降趋势，群体产量呈抛物线形上升，群体最高产量的理论密度增幅为3 507株 hm^-2 10 年^-1；空秆率显著提高，但倒伏率仅1970s和1980s的品种呈递增趋势；株高、单株叶面积、棒三叶面积、穗粒数与千粒重均呈现下降趋势，穗位随密度增加呈显著上升趋势。各年代品种株高、穗位、单株叶面积和千粒重随氮肥水平提高呈增加趋势。在150~450 kg hm^-2的施氮水平范围，随着氮肥水平的提高，各年代品种增产效果不明显。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。对照东北玉米现有的品种特性、种植密度和施肥现状表明，选育耐密品种和实施密植抗倒栽培的增产潜力大，在现在的施肥水平上进一步提高种植密度是东北春玉米高产增效耕作栽培的技术创新方向。

Response of Grain Yield to Plant Density and Nitrogen Application Rate for Maize Hybrids Released from Different Eras in Heilongjiang Province

Eight typical maize hybrids released over 1970s to 2000s in Heilongjiang province were selected to investigate the productivity response to nitrogen fertilizer and plant density in 2009 and 2010. During the variety improvement period from 1970s to 2000s, the yield gains per plant and per unit area were 16.96 g 10 yr-1 and 790 kg ha-1 10 yr-1 , respectively, while the rates of lodging and barren plant decreased significantly. The plant height, ear height, leaf area per plant, kernel number per ear and 1000-kernel weight of newer hybrids were higher than those of older varieties. For all hybrids released in each era, grain yield per plant decreased with increasing plant density, while grain yield per unit area showed a parabolic shape response. The theoretical optimal density for the highest yield rose by 3 507 plants ha-1 10 yr-1 . The barren plant rates of all hybrids increased with the density increasing, and the lodging rates rose only for the older hybrids released in 1970s and 1980s. Higher plant population led todecreases in the agronomic indicators of plant height , leaf area per plant, kernel number per ear and 1000 kernel weight and the increase in the ear height. Higher nitrogen application rate tended to promote the agronomic indicators of plant height, ear height, leaf area and 1000-kernel weight. However, at the nitrogen application rate ranging from 150 kg ha -1 to 450 kg ha -1 , no significant increase was found in the yields for all hybrids released in the same era. There were significant interactions among density, nitrogen and era on the yield and agronomic traits. Compared with the present situations of maize variety and cropping technique, the above results indicated that there are great potentials in yield gains from new variety breeding and cultivation technique innovation for higher-yield with higher-efficiency through increasing plant density with unchanged nitrogen application rate in Northeast China.