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通过PEG-6000和NaCl模拟试验研究了干旱和盐胁迫对白榆幼苗叶片光系统Ⅱ(PSII)活力的影响,结果显示:盐分和干旱胁迫诱导白榆叶片PSII快速荧光上升曲线在300μs处K点的出现,造成放氧复合体OEC的损伤,同时也引起PSII有活力反应中心密度(Rc/Cso)、最大量子产量(Fv/Fm)、分配进入电子传递链能量流(ETo/AB,S)等的下降,导致效能指数(PI)显著降低,从而全面抑制了白榆叶片PSII的活力。2类胁迫的作用点都位于PSII电子传递链供体侧和受体侧,但比较2类胁迫,盐胁迫对白榆叶片PSII活力的破坏程度显著高于干旱胁迫,盐离子对白榆叶片PSII活力具有显著的负效应。
The effects of drought and salt stress on the photosystem Ⅱ (PSII) activity of Ulmuspum L. seedlings were studied by PEG-6000 and NaCl simulations. The results showed that the PSII fluorescence peak of Ulmus pumila leaves at the K point of 300μs induced by salt stress and drought stress Resulting in the damage of the OEC and the PSII reactive center density (Rc / Cso), the maximum quantum yield (Fv / Fm), the energy distribution into the electron transport chain (ETo / AB, S) , Leading to a significant decrease in potency index (PI), thus completely inhibiting the activity of PSII in Ulmus pumila leaves. However, compared with the two types of stress, the destructive degree of PSII activity of Ulmus pumila leaves was significantly higher than that of drought stress, while the salt ions had the highest PSII activity Significant negative effect.