外源钙对干旱胁迫下烤烟幼苗光系统Ⅱ功能的影响

以叶绿素快相荧光动力学曲线(OJIP)为探针,研究了外源钙对干旱胁迫下烤烟幼苗光系统Ⅱ(PSⅡ)功能的影响.结果表明:干旱胁迫降低了烤烟幼苗PSⅡ原初光能转换效率(Fv/Fm)和电子传递速率(ETR),抑制了光合作用的原初过程,烤烟幼苗叶片发生了明显的光抑制.叶面喷施10.0 mmol·L-1CaCl2溶液后烤烟叶片的光合电子传递能量比例(ФEo)在干旱胁迫下的降低幅度明显小于对照(喷施清水),电子转运效率(ET0/RC)在干旱胁迫下明显高于对照.叶面喷施CaC12溶液增加了PSⅡ捕获光能用于光合电子传递的比例、剩余有活性反应中心的效率和电子传递链中的能量传递,使烤烟叶片的光系统Ⅱ在干旱胁迫下保持相对较高的活性,从而提高了烤烟幼苗的抗旱能力.

Effects of exogenous CaCl2 on the functions of flue-cured tobacco seedlings leaf photosystem II under drought stress

Taking chlorophyll a fluorescence transient OJIP as the probe, this paper studied the effects of foliar spraying 10 mmol x L(-1) of CaCl2 on the functions of photosystem II (PS II) in tobacco seedling leaves under drought stress. Drought stress decreased the conversion efficiency of PS II primary light energy (F(v)/F(m)) and electron transport rate (ETR), and inhibited the primal process of photosynthesis, resulting in an obvious photoinhibition. After the spraying of CaCl2, the decrement of quantum yield for electron transport (phiE(o)) under drought stress was obviously lower, and the increment of electron transport efficiency of per reaction center (ET(o)/RC) was obviously higher, compared with those after the spraying of water. Foliar spraying CaCl2 increased the amount of PS II -captured light energy used for photosynthesis electron transport, the efficiency of surplus active reaction center, as well as the energy transport in electron transport chain, making the PS II remain relatively high activity under drought stress, and accordingly, the drought resistance of the tobacco seedlings was improved.