中文摘要：

【目的】阐明玉米叶片衰老过程中叶片叶绿素降解与光合作用光反应活性的关系，为选育长效光合持续期的作物品种提供理论基础。【方法】本研究使用保绿型玉米品种“齐319”（Q319）和早衰型玉米品种“黄早4”（HZ4）为材料，在严格控制环境因素的条件下，用乙烯利诱导离体叶片衰老，通过快速叶绿素荧光诱导动力学曲线分析（0JIPtest）和820nm光吸收曲线技术，研究衰老过程中叶片叶绿素含量、光合速率、光系统1（PSI）和光系统2（PSII）光化学活性的变化，并分析光化学活性下降与叶绿素降解的关系。【结果】在衰老过程中，与保绿品种相比，早衰品种HZ4叶片的光能吸收能力、能量的转化效率以及PSI和PSII电子传递的活性均衰退较快。虽然早衰品种在衰老过程中光化学活性的衰退快于保绿品种，但是＇-3叶片的叶绿素含量下降相同程度时，保绿品种Q319叶片的光能的捕获、能量的转化以及电子传递活性都比HZ4叶片下降得更明显。【结论】光化学活性的快速衰退是导致早衰品种HZ4叶片在生育后期光合功能快速衰退的一个重要原因，但它在叶绿素降解时能维持较高的光化学活性。因此在长效光合持续期品种的选育中，应当同时重视两个典型性状：①衰老过程中维持较高的叶绿素含量；②在叶绿素降解时维持较高的单位叶绿素光能吸收、能量转换以及电子传递活性。

英文摘要：

[Objective] The purpose of this study is to explore the relationship between the photosynthetic performance and the decrease in chlorophyll content, and to provide a theoretical basis to breed long duration of active photosynthesis hybrids. [Method] By simultaneously analyzing chlorophyll a fluorescence transient and light absorbance at 820 nm as well as analyzing net photosynthetic rate and chlorophyll content, the photosynthetic behavior including light absorption, energy transformation and the photo-activities of PSII and PS I during senescence in the stay green inbred line of maize （Zea mays L.） Q319 and the quick-leaf-senescence inbred line of maize HZ4 was studied. [Result] Results showed that the net photosynthetic rate, light absorption, energy transformation, the activities of PS II acceptor side and donor side and the PS I activities decreased much slower in stay green inbred line Q319 than in quick-leaf-senescence inbred line HZ4 during the ethephon-induced senescence. Although the chlorophyll content decreased faster in HZ4 with decrease of chlorophyll content induced by ethephon, thephotosynthetic performance of Q319 deteriorated much more severely than that of HZ4. [ Conclusion ] The above results indicate that the retention of light absorption, energy transformation and activity of electron transfer contribute to the extended duration of active photosynthesis in the stay green inbred line. It was concluded that attention should be paid to two favorable characteristics in breeding long duration of active photosynthesis hybrids： 1） maintaining more chlorophyll content during senescence and 2） maintaining higher photosynthetic activity during the loss of chlorophyll.