遮荫对刺五加叶片光合特性及光系统Ⅱ活性的影响

Effect of Shading on Photosynthetic Characteristics and Activity of Photosystem Ⅱ in Leaves of Acanthopanax senticosus

以刺五加为试材,研究了全光照(对照)和遮荫条件下(30%遮荫)刺五加叶片光合特性及光系统II活性。结果表明:刺五加全光照条件下较遮荫净光合速率(Pn)和气孔导度显著降低,而细胞间隙CO2浓度(Ci)显著升高。JIP分析发现,全光照条件下叶片的单位反应中心光能吸收(ABS/RC)和热耗散(DI0/RC)较遮荫处理显著升高。然而全光照条件下叶片的最大光化学效率(Fv/Fm)、单位面积用于电子传递的光能(ET0/CS)较遮荫显著降低。全光照条件抑制了刺五加叶片PSⅡ电子供体侧、受体侧电子传递,最终导致光合作用能力下降。

Taking Acanthopanax senticosus as material, the changes of photosynthetic characteristics and activity of photosystem II in leaves of Acanthopanax senticosus under natural condition （control） and under continuous shading condition（30%shading）were studied respectively. The results showed that net photosynthetic rate （Pn） and stomatal conductance （Gs） decreased significantly,but intercellular CO2 concentration （Ci） increased under natural condition. JIP- test protocol revealed that the specific energy fluxes （per RC） for absorplion （ABS/RC） and dissipation （DIo/RC） under natural condition increased significantly compared shading, however, the maximal quantum yield of PSII photochemistry （Fv/Fm） and the phenomenological energy fluxes （per excited cross-section, CS） for electron transport （ET,,/CS） decreased. Donor side and acceptor side of PSⅡ in leaves of Acantkopanax senticosus under natural condition could cause the inhibition of electron transportation significantly,which finally result in the decrease of photosynthesis.