中文摘要：

本文在棕壤长期定位实验的基础上，测定了不同水平氮肥处理下灌浆期玉米（郑单958）穗位叶气体交换和叶绿素荧光等光合参数以及SPAD值。结果表明，施用氮肥可以引起荧光诱导曲线（OJIP曲线）显著变化，其中K、J和I点的荧光强度值明显降低；施用氮肥显著提高捕获的激子将电子传递到电子传递链中QA下游的其他电子受体的概率（ψ0）和以吸收光能为基础的性能指数（PI-ABS），显著降低K点的可变荧光Fk占振幅F0-Fj的比例（Wk）和J点的可变荧光Fj占振幅F0-Fp的比例（Vj），说明PsⅡ反应中心电子传递链综合性能以及供体侧和受体侧的电子传递能力均明显提高，并且可以看出受体侧性能的改善大于供体侧；随着施氮量的增加，PsI的最大氧化还原活性△I／I0呈先升后降的趋势变化，说明适量施氮可以增强P700的最大氧化还原能力，并可以显著提高叶片PSI与PSⅡ两个光系统之间的协调性φ（PSI/PSⅡ）。

英文摘要：

On the basis of a long-term experiment in brown soil, the photosynthetic characteristics of maize （cuhivar, Zhengdan 958） ear leaves at the filling stage, SPAD value, gas exchange and chlorophyll fluorescence parameters were measured under different levels of nitrogen treatments. The results show that the OJIP Fluorescence induction curve is affected significantly by nitrogen fertilization, and the fluorescence intensity of K, J and I steps are significantly decreased. The probability that a trapped exciton moves an electron into the electron transport chain beyond QA （ψ0） and the performance index on absorption basis （PIABs ） are significantly increased under the nitrogen fertilization, while the relative variable fluorescence intensity at the K-step （Wk ） and the relative variable fluorescence intensity at the J-step （Vj） are significantly reduced. It is shown that the comprehensive performance of electron transport chain in PS Ⅱ reaction center as well as the electron transport capacity both in the donor side and the receptor side are improved obviously. The performance of the receptor side is greater than that of the donor side. With nitrogen fertilizer levels increasing, the maximal oxidation-reduction activity of PS I （△I/Io） is increased first and then decreased, which indicates a moderate amount of nitrogen fertilizer could enhance the maximal oxidation-reduction ability of P70o, and could significantly improve coordination between PS I and PSⅡ optical systems φ（PSi/PSⅡ） in maize leaves.