氮肥与密度对夏玉米生理特性、产量及氮肥偏生产力和抗倒性的影响

曹冰 朱紫薇 单娟 姚国旗 朱英华 沈军辉 黄令军 王成雨

摘要：以夏玉米品种隆平206为试验材料，采用裂区设计，设置2个氮肥水平（180、240 kg/hm2）和3个种植密度（每公顷6万株、7.5万株、9万株），研究氮肥与密度对夏玉米生理特性、产量及氮肥偏生产力和抗倒性的影响。结果表明：适当密植（每公顷7.5万株）有利于增加夏玉米产量;在低密度（每公顷6万株）条件下提高氮肥水平可以改善光合作用，有利于干物质的积累，增产显著;中高密度时增氮对光合作用的改善不明显，干物质积累增加也不显著，因此，增产效果不显著。增密降低穗位叶的光合速率，有利于大喇叭口期干物质的积累;散粉期和收获期，增至中密度有利于干物质积累，继续增密干物质积累增加不显著。低氮水平下增密可以有效提升氮肥偏生产力，而氮肥水平过高即使增加密度提升氮肥偏生產力的效果仍然不佳。密度过高降低植株的抗倒能力导致玉米田间倒伏率增加，适当增密不会导致抗倒能力显著减弱并保持较低的倒伏率。在本试验条件下，每公顷氮肥施用量180 kg、种植7.5万株是适合试验地夏玉米高产高效的栽培模式。

关键词：夏玉米;氮肥;密度;光合速率;氮肥偏生产力;抗倒性

中图分类号：S513.01  文献标识号：A  文章编号：1001-4942（2019）06-0097-06

Abstract In this experiment， the summer maize variety Longping 206 was used as experimental material. The split plot design was set with two nitrogen fertilizer levels （180 and 240 kg/hm2） and three planting densities （60 thousand， 75 thousand and 90 thousand plants per hectare） to study their effects on the physiological characteristics， yield， nitrogen partial factor productivity and lodging resistance of summer maize. The results showed that rational close planting （75 thousand plants per hectare） was beneficial to increase the yield of summer maize. Increasing nitrogen fertilizer rate under low density could improve the photosynthesis and dry matter accumulation， so it increased yield significantly. But the effects of increasing nitrogen fertilizer under medium or high density on photosynthesis and dry matter accumulation were not significant， so the yield did not increase significantly. Increasing density decreased the photosynthetic rate of ear leaves and was beneficial to the dry matter accumulation at large trumpet stage. At powder and harvest stages， increasing density to the intermediate density was beneficial for dry matter accumulation， while continuing to increase the density did not increase the dry matter accumulation significantly. Increasing planting density at low-nitrogen level could effectively improve the partial factor productivity of nitrogen fertilizer， but the effect was not better when the nitrogen fertilizer level was too high. Excessive density decreased the lodging resistance of plants and led to an increase of lodging rate of corn in field. A suitable increase of planting density would not lead to the significant weakness of lodging resistance but could keep lower lodging rate. Therefore， in the test conditions， 180 kg/hm2 nitrogen fertilizer and 75 thousand plants per hectare were suitable for high-yield and high-efficient production of summer maize.

Keywords Summer maize; Nitrogen fertilizer; Planting density; Photosynthetic rate; Nitrogen partial factor productivity; Lodging resistance

氮素是叶绿素的主要成分，而叶绿素含量的高低在很大程度上和光合速率密切相关并决定了光合产物的形成，因而氮肥用量和作物产量密切相关[1-3]。为了提高产量，农民往往过量施肥，导致近30年来我国化肥用量持续增长以及环境恶化[4，5]。……