钙对弱光亚适温下黄瓜光合作用的影响

Effect of Calcium on Photosynthesis of Cucumber Under Low Light Intensity and Sub-optimal Temperature

【目的】探讨钙对弱光亚适温下黄瓜光合功能的影响机理,为寻找缓解弱光亚适温逆境障碍的有效措施提供理论依据。【方法】10mmol·L-1CaCl2溶液喷撒黄瓜幼苗,清水处理作对照,连喷5d后利用光照培养箱模拟弱光亚适温条件对黄瓜幼苗进行处理。【结果】弱光亚适温胁迫使黄瓜幼苗的光合诱导时间延长,光合速率(Pn)、气孔导度(Gs)、胞间CO2浓度(Ci)、羧化效率(CE)、表观量子效率(AQY)、实际光化学效率(φPSⅡ)、光化学猝灭(qP)及电子传递速率(ETR)等降低,非光化学猝灭(NPQ)升高。胁迫前用10mmol·L-1CaCl2预处理,黄瓜幼苗的光合诱导时间缩短,Pn、Gs、Ci、CE、AQY、qP、ETR等都有不同程度的提高,NPQ有所降低。【结论】弱光亚适温下气孔与非气孔限制因素同时存在,气孔导度下降和碳同化降低都是引起黄瓜光合速率降低的重要原因。Ca2+对减轻弱光亚适温对黄瓜幼苗光合作用的影响发挥积极作用。

[ Objective] The purpose of this paper is to clarify the mechanism of calcium on the function of photosynthesis in cucumber under the combined stress of low light intensity plus suboptimal temperature and to provide some theoretic basis for searching an effective way to alleviate the resulted injuries. [ Method ] The stress condition of low light intensity （100 μmol·m^-1·s^-1） and suboptimal temperature （18℃/11℃） were simulated in a growth chamber, and the effect of 10 mmol·L^-1 CaCl2 on photosynthesis in cucumber seedlings were studied. [ Result ] The results showed that low light intensity and suboptimal temperature stress led to decline in the induction period of photosynthesis, photosynthetic rate （Pn）, stomatal conductance （Gs）, intercellular CO2 concentration （Ci）, carboxylation efficiency （CE）, apparent quantum yield （AQY）, actual photochemical efficiency of PS Ⅱ （φPS Ⅱ）, photochemical quenching （qP） and electron transport rate （ETR）, while increase in non-photochemical quenching （NPQ）. Pretreated with 10 mmol·L^-1 CaCl2 before exposure to stress condition, the induction period of photosynthesis of cucumber seedlings shortened, the Pn, Gs, Ci, CE, AQY, φPS Ⅱ, qP, ETR, etc. increased, while NPQ decreased.[ Conclusion ]There were stomatal and non-stomatal limitations simultaneously under low light intensity and suboptimal temperature condition, a decline in Gs and carbon assimilation led to a decrease in Pn. Ca^2＋, which played a positive role in alleviating the effect of low light intensity and suboptimal temperature on the photosynthesis of cucumber seedlings.