种植密度和施氮量耦合对夏玉米干物质积累及氮肥利用率的影响

以郑单958和中单909为试验材料,设4.5万、6.75万、9.0万株/km~2 3个种植密度和0、100、300、500 kg/km~2 4种施氮水平,分析种植密度与施氮量对夏玉米干物质积累量和氮肥利用率的影响。结果表明,玉米在种植密度9.0万株/hm~2,其叶面积指数、群体干物质积累量、总氮素积累量以及产量均显著高于4.5万株/hm~2密度处理。增施氮肥可显著增加玉米叶面积指数、单株干物质积累量、群体干物质积累量、总氮积累量和子粒产量。当施氮量为300~500 kg/hm~2时,叶面积指数、群体干物质积累量及产量不再提加,氮肥利用率和氮肥偏生产力大幅降低。结果表明,郑单958和中单909种植适宜模式为施氮量300~500 kg/hm~2、种植密度9.0万株/hm~2。

Effects of Planting Density and Nitrogen Rate on Dry Matter Accumulation and Nitrogen Utilization Efficiency of Summer Maize

The dry-matter accumulation and nitrogen utilization of summer maize were investigated with the varieties of Zhengdan958 and Zhongdan909 under the different planting densities(45 000, 67 500 and 90 000 plant/ha) and different nitrogen rates(N 0, 100, 300 and 500 kg/ha). The results showed that compared with the 45 000 plant/ha, the leaf area index(LAI), total dry matter accumulation, total nitrogen accumulation and grain yield under 90 000 plant/ha treatment were significantly improved. The increase of nitrogen rate could effectively increase the LAI, dry matter accumulation amount per plant, biomass, total nitrogen accumulation and grain yield. LAI, total dry matter accumulation and grain yield were no more increased when nitrogen rate reached 300-500 kg/ha, and the nitrogen partial factor productivity and nitrogen partial factor productivity were significantly decreased. The most optimal nitrogen rate and plant density of Zhengdan958 and Zhongdan909 were both N 300-500 kg/ha and 90 000 plant/ha in this experiment.