冯波 刘开昌

摘要：本试验以夏玉米常规品种郑单958（ZD958）和耐密品种登海618（DH618）为试材，采用单株盆栽种植方式，设置种植密度为90 000 株/hm2，研究施氮量和种植密度对高产夏玉米氮素利用效率和光合作用的影响。结果表明，施氮显著增加玉米干物质积累量与氮素积累，提高氮素利用效率，且叶片净光合速率显著升高，两品种表现一致。对比不同品种，施氮条件下DH618氮肥利用效率和叶片气体交换参数改善幅度显著，最终表现在干物质积累量与产量增加上显著高于ZD958。可知，合理施用氮素可以显著改善光合特性和干物质与氮素积累的协调性，最终提高产量。在密植条件下，DH618对氮肥的施用与否反应更加敏感，在生产实践上，追求玉米高产在提高种植密度的同时不能忽视氮肥的作用，两者合理结合才能有效提高产量。

关键词：氮肥； 密植； 夏玉米； 氮效率； 光合特性

中图分类号：S513.01文献标识号：A文章编号：1001-4942（2018）05-0076-06

Abstract The pot experiments were carried out to study the effects of nitrogen application amount and planting density on photosynthesis and nitrogen utilization efficiency of summer maize cultivars DH618 and ZD958. The results indicated that dry matter accumulation and nitrogen accumulation were significantly increased， the net photosynthetic rate （Pn） was increased remarkably， and the nitrogen utilization efficiency was improved by increasing N fertilization. The two varieties showed consistent performance in the above characteristics. Between different cultivars， the nitrogen utilization efficiency and the net photosynthetic rate of DH618 were significantly higher than those of ZD958， and finally led to the increase of dry matter accumulation and yield. Consequently， rational application of nitrogen could significantly improve the photosynthetic characteristics and the coordination between dry matter and nitrogen accumulation， and eventually increase the yield. DH618 was more sensitive to nitrogen fertilizer depletion under high planting density. In practice， the effect of nitrogen fertilizer should not be ignored in high yield production under close planting in maize. Only combining the two factors above reasonably， the yield could be improved effectively.

Keywords Nitrogen fertilizer； Close planting； Nirogen efficiency； Photosynthetic characteristics

增加種植密度是玉米高产的关键措施之一[1，2]，夏玉米的耐密植特性是一个复杂的综合特性，是夏玉米个体间性状的相互制约、相互影响和群体与环境相适应、相协调的整体功能的体现。种植密度增加会提高植株群体的需氮量[3-5]，氮素的合理施入对提高夏玉米产量和氮肥利用率具有重要意义[6]。氮素是植物体内多种有机物的重要组分，是夏玉米最重要的营养物质[7]。合理施入氮素可以提高氮素利用率，增加植株叶片叶绿素含量、改善光合性能、延长叶片功能期，随施氮量的提高，净光合速率上升，光合产物的积累增加[8]。……