氮肥后移对玉米冠层内物质分配及氮素利用的影响

研究不同施氮量、不同施肥时期对玉米产量与氮素利用的影响,对玉米干物质生产、氮素积累与分配进行分析。结果表明,施氮量为180 kg/hm2时,产量表现为基施处理最高,较拔节期、大喇叭口期施肥处理分别提高1.17%、7.69%;施氮量为75 kg/hm2时,拔节期施肥处理产量最高,较基施、大喇叭口期施肥处理分别提高10.31%、4.61%。大喇叭口期施肥处理的干物质积累与氮素积累量少,氮肥利用效率低,说明氮肥后移需考虑植株前期对氮素的需要。拔节期施肥处理产量与基施处理产量和氮素积累量相当或提高,植株干物质积累增加,冠层内茎叶干物质比例协调,生育后期穗下层茎叶干物重下降缓慢,氮素利用效率高。施氮量为75 kg/hm2,氮肥适当后移可提高氮肥利用率。

Effects of Postponing N Application on Dry Matter Accumulation and Nitrogen Utilization in Maize Canopy

A field experiment was conducted to investigate the effects of postponing N application on nitrogen absorption, use efficiency of nitrogen fertilizer and grain yield in maize. The results showed that, N180A achieved the most yield, with 1.17% and 7.69% higher compared with N180B and N180; while N75B was 10.31% and 4.61% higher in yield compared with N75A and N75C. Applying nitrogen at 12-leaf stage had decreased the dry matter accumulation, CGR at critical stage and nitrogen accumulation, thus leading to a low grain yield and use efficiency of nitrogen fertilizer. The grain yield of postponing N application at the 8-leaf stage was similar with that or higher than that of applying nitrogen as base fertilizer. Postponing N application at the 8-leaf stage improved the nitrogen efficiency, slowed down the decrease of dry matter of stalk and leaf below the ear layer. Therefore, based on summer maize N uptake at different growth stages, postponing N application especially when N applying amount 75 kg/ha was a feasible N management practice.