中文摘要：

以玉米自交系齐319（Qi 319）为试材，利用叶绿素荧光快速诱导动力学曲线，研究了喷施外源激素6-苄氨基嘌呤（6-BA）对不同氮素水平下玉米花后叶片光系统Ⅱ（PSⅡ）性能的调控效应。两年研究结果表明，花后穗位叶叶绿素含量和净光合速率（Pn）均呈降低趋势。在不施氮条件下，外源喷施6-BA，可提高叶绿素含量及后期Pn，但对PSⅡ反应中心的活性无显著改善。施氮可显著提高Pn和PSⅡ的性能，6-BA可显著增强其效果。二者互作条件下，叶绿素含量显著提高，R显著增加（P〈0．05），PSⅡ供体侧和受体侧的活性得到有效改善，其中对PSⅡ供体侧性能的改善幅度大于对受体侧，花后10dPSⅡ反应中心的活性提高最显著。光合性能的提高使单株生物量和籽粒产量显著增加（P〈0．05）。因此，在适量施用氮肥的条件下结合喷施6-BA可以显著改善叶片光合性能。

英文摘要：

A two years experiment was conducted using maize inbred line Qi 319 with different nitrogen fertilization levels and exogenous hormone 6 benzyl adenine （6-BA） treatments. The results demonstrated that the chlorophyll content and net photosyn- thetic rate （Pn） were gradually decreased after anthesis. In treatments of 6-BA without nitrogen fertilizer, chlorophyll contents were increased significantly, but Pn showed no significant increase, and the activity of PSII reaction center was not increased. Under the condition of applying nitrogen fertilizer, Pn and the activity of PSII reaction center were increased significantly, and based on nitrogen fertilizer used, the 6-BA could improve the response of Pn and performance of PSⅡ to nitrogen fertilizer effec- tively. Under the nitrogen fertilizer and 6-BA interaction conditions, the chlorophyll content and Pn were increased significantly （P〈0.05）, the activities of donor site and acceptor site of PSII were increased significantly, and the donor site was improved more than that of acceptor site. The most obvious improvement of the activity of PSⅡ reaction center was appeared at the 10th day after anthesis. The improvement of photosynthetic performance significantly improved the single plant dry matter accumulation and grain yield （P〈0.05）. In conclusion, spraying plant with 6-BA under suitable application of nitrogen fertilizer can significantly improve the photosynthetic performance of maize leaf.