中文摘要：

主要探讨了氮肥对不同耐低氮性玉米品种生育后期叶片叶绿素含量和氮代谢关键酶活性及籽粒蛋白质含量和产量的影响,以期为西南地区不同耐低氮性玉米品种的高产高效施肥技术提供依据。采用裂区试验设计,主区为前期筛选的不同耐低氮性玉米品种：耐低氮品种正红311（ZH311）和低氮敏感品种先玉508（XY508）,副区为不同施氮量：包括6个氮水平（0,90,180,270,360和450kg/hm~2）。结果表明,施氮可以显著提高玉米生育后期叶片叶绿素含量和氮代谢关键酶活性,并最终提高籽粒蛋白质含量和产量。增施氮肥对低氮敏感品种先玉508各生理指标的促进作用较耐低氮品种正红311更明显,但耐低氮品种正红311生育后期叶片叶绿素含量及氮代谢关键酶活性均显著高于低氮敏感品种先玉508,尤其是灌浆中后期和低中氮水平下,使其最终籽粒产量及籽粒蛋白质含量均显著高于先玉508,这可能是其较低氮敏感品种先玉508耐低氮能力强的重要生理机制。

英文摘要：

The aim of this study was to investigate the effects of nitrogen（N）fertilizer on the activity of N metabolism and growth of two maize（Zea mays）cultivars with contrasting tolerance to low N.An experiment was laid out in a split-plot design with three replicates.The main plot consisted of two maize cultivars with contrasting tolerance to low N（the low-N tolerant cultivar ZH311 and the low-N sensitive cultivar XY508）.The split plot consisted of six N treatments：0,90,180,270,360,and 450kg/ha.The chlorophyll content and the activities of enzymes involved in N metabolism（NR：nitrate reductase,GS：glutamine synthetase,GDH：glutamate dehydrogenase）at late growth stages were determined,as well as the seed protein content and yield.The results showed that N fertilizer increased chlorophyll content and enzyme activities at late stages,and promoted protein content and yield.As the amount of N fertilizer increased,these indexes increased to a greater extent in XY508 than in ZH311,while all indexes were higher in ZH311 than in YX508.Compared with the low-N sensitive cultivar,the low-N tolerant cultivar retained a higher chlorophyll content and higher activities of enzymes involved in N metabolism,especially at the mid to late grain-filling stage.In addition,the low-N tolerant cultivar required low to mid N levels to improve seed protein content and yield.These results provide information about the physiological mechanisms involved in tolerance to low-N conditions.