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本文以苹果砧木平邑甜茶为实验材料,利用快速叶绿素荧光、延迟荧光及820nm光反射同步测量技术,研究了干旱胁迫对平邑甜茶叶片光合机构的光系统Ⅰ(PSⅠ)、光系统Ⅱ(PSⅡ)以及整个光合电子传递链的伤害机制。实验结果表明:干旱胁迫下平邑甜茶叶片的整个光合电子传递链都受到不同程度的影响。干旱2d,PSⅡ反应中心捕获的光能用于还原QA的能力低于电子从QA-向下游传递的能力,电子从QA-向下游传递给QB和PQ库等中间电子传递体的能力小于电子从QB和PQ库向PSⅠ受体侧传递的能力,但干旱5d上述变化则相反,且更加显著。由此可以得出,严重干旱胁迫下,沿着从PSⅡ到PSⅠ受体侧的光合电子传递链,电子传递的能力越来越低。此外,随着干旱胁迫,PSⅡ和PSⅠ反应中心色素的降解速率快于天线色素,且PSⅡ的捕光效率和PSⅠ反应中心的含量逐渐降低。快速荧光、延迟荧光及820nm光反射同步测量结果互相印证了上述结论。我们推测,这可能是平邑甜茶叶片对干旱的一种适应机制。
In this paper, apple rootstock Malus hupehensis was used as experimental material to study the effects of drought stress on photosystem Ⅰ (PSⅠ) and photosystem Ⅱ (PSⅡ) in the photosynthetic organs of Malus hupehensis Rehd., Using rapid chlorophyll fluorescence, delayed fluorescence and simultaneous measurement of 820nm light reflectance ) And the damage mechanisms of the photosynthetic electron transport chain. The experimental results showed that the photosynthetic electron transport chains of P. euphratica under drought stress all had different degrees of influence. In drought 2d, the ability of light captured by PSⅡ reaction center to reduce QA is lower than the ability of electrons to transfer from QA to downstream. The ability of electrons to transfer from QA-downstream to intermediate electron mediators such as QB and PQ pools is less than that of electrons from QB and PQ pools to the PS I receptor side, but the above changes were opposite and more significant at 5 days of drought. From this we can conclude that the ability of electron transfer is getting lower and lower along the photosynthetic electron transfer chain from PS Ⅱ to PS Ⅰ receptor under severe drought stress. In addition, with the drought stress, the degradation rate of PSⅡ and PSⅠreaction center pigment was faster than that of aerial pigment, and the light harvesting efficiency of PSⅡ and PSⅠ reaction center content decreased gradually. Fast fluorescence, delayed fluorescence and 820nm light reflectance measurements simultaneously confirm this conclusion. We speculate that this may be an adaptation mechanism of Malus hupehensis leaves to drought.