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通过气体交换和叶绿素荧光测定研究了缺铁对大豆叶片碳同化和光系统Ⅱ的影响。缺铁条件下大豆光合速率(Pn)大幅下降;最大光化学效率(po)下降幅度较小;荧光诱导动力学曲线发生明显的变化,其中电子传递活性明显下降,K相(VK)相对荧光产量提高。缺铁大豆的天线转化效率(Fv’/Fm’)、光化学猝灭系数(qP)和光系统Ⅱ实际光化学效率(ΦPSⅡ)降低,而非光化学猝灭(NPQ)则明显增加。此外,缺铁大豆的光后荧光上升增强。据此,认为铁缺乏伤害了光系统Ⅱ复合物供体侧和受体侧的电子传递;缺铁条件下光系统I环式电子传递的增强可能在维持激发能耗散和ATP供给方面起一定作用。
The effects of iron deficiency on carbon assimilation and photosystem Ⅱ in soybean leaves were studied by gas exchange and chlorophyll fluorescence measurements. Under the condition of iron deficiency, photosynthetic rate (Pn) of soybean decreased significantly; the maximum photochemical efficiency (po) decreased less; the fluorescence induced kinetic curve changed obviously, in which the electron transport activity decreased obviously, the relative fluorescence yield of K phase improve. The antenna conversion efficiency (Fv ’/ Fm’), photochemical quenching coefficient (qP) and photoperiod Ⅱ actual photochemical efficiency (ΦPSⅡ) of iron deficient soybean decreased, but non-photochemical quenching (NPQ) increased significantly. In addition, the iron-deficiency fluorescence of iron-deficient soybeans increased. Accordingly, the lack of iron is believed to impair the electron transport on the donor and acceptor sides of the photosystem II complex; enhancement of the I-ring electron transport of the photosystem under iron deficiency may play a role in maintaining excitation energy dissipation and ATP supply effect.