摘要:光系统Ⅱ（PSⅡ）的光反应与作物光合能力密切相关。为了获得更多关于叶片衰老过程中PSⅡ状态的详细信息并快速筛选出具有不同叶片光合功能持续时间的棉花基因型，本试验利用快速叶绿素荧光技术研究了生产上报道叶片衰老快慢不同的3种棉花基因型倒一叶衰老过程中的PSⅡ的光化学反应。结果显示，基于光吸收的性能指数（PIABS）将‘百棉1号’ ‘百棉5号’和‘DP99B’分为晚衰型、中间型和早衰型。3种基因型棉花品种叶片衰老过程中电子传递受抑制情况遵循同样的规则。放氧复合体（OEC）在生育后期大量降解；PSⅡ受体侧的抑制情况要大于供体侧；叶片衰老显著限制光系统Ⅱ-光系统I间的电子传递；随着叶片衰老，用于热耗散和还原初级醌受体（QA）的能量增加，而用于PSⅡ电子传递链中QA还原（QA-）之后电子传递的能量下降。但是叶片衰老过程中，电子传递受抑制程度（除荧光开始到荧光最大时间段之间的QA还原次数之外）为‘DP99B’ > ‘百棉5号’ > ‘百棉1号’。由此可知，不同棉花基因型的叶绿素荧光特征可快速、无损地反映叶片衰老的快慢及内在生理机制。
关键词:棉花/
叶片衰老/
叶绿素荧光/
光系统Ⅱ(PSⅡ)/
快速叶绿素荧光参数
Abstract:The light reactions of photosystem Ⅱ (PSⅡ) is greatly associated with the photosynthetic capacity. In order to capture more detailed information describing the status of PSⅡ during leaf senescence and rapidly screen cotton (Gossypium L.) genotypes with different duration of photosynthetic capacity, the PSⅡ photochemistry of the first leaves counted from the stem top of three cotton genotypes ('Baimian1' 'Baimian5' and 'DP99B') presented different leaf senescence progresses in production were examined by chlorophyll a fluorescence (Chl F) analysis during leaf senescence. The results showed that 'Baimian1' 'Baimian5' and 'DP99B' were late, intermediate and early aging types, respectively, based on the performance index of light absorption (PIABS). The three genotypes complied with the similar patterns in electrical transferring inhibition accompanying leaf senescence. The depletion of oxygen-evolving complex (OEC) was obvious at the late growth stage. The inhibition of the acceptor side of PSⅡ was greater than that of the donor side. The electron flow that through the light reactions of photosystem Ⅱ and photosystem Ⅰwas significantly limited accompanying leaf senescence. With the duration of leaf senescence, the energy distributed to thermal dissipation and the primary quinone electron acceptors of PSⅡ (QA) restoration increased, and correspondingly the energy used to transport an electron into the electron transport chain beyond QA- (the reduction state of QA) declined. However, three cotton genotypes showed greater and greater electron transferring inhibition, except the number of QA reduction events between time=0 and time to reach maximal fluorescence, in the order of 'DP99B' > 'Baimian5' > 'Baimian1' with the duration of leaf senescence. It can be seen that the chlorophyll fluorescence characteristics can quickly and noninvasively reflect the senescence and the internal physiological mechanism of leaf senescence among different cotton genotypes.
Key words:Cotton/
Leaf senescence/
Chlorophyll a fluorescence/
Photosystem Ⅱ/
Rapid chlorophyll a fluorescence parameter
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