低温、弱光及盐胁迫下辣椒叶片的光合特性

【目的】探讨低温(18℃/10℃,昼/夜)、弱光(80μmol·m-2·s-1)及盐胁迫(70mmol·L-1NaCl)下辣椒叶片光合特性的响应机制,为辣椒冬春设施生产中的温、光、肥管理提供理论依据。【方法】以‘中椒4号’幼苗为试材,测定了辣椒叶片叶绿素含量、光合参数及叶绿素荧光参数等指标。【结果】弱光、弱光和盐胁迫处理提高辣椒叶片叶绿素含量,降低叶绿素a/b比值,处理后15d叶绿素a、叶绿素b、叶绿素a+b含量分别比对照增加25.91%—35.75%、31.34%—44.78%、27.31%—38.08%,其他处理则降低叶绿素含量。低温、弱光和盐胁迫单一及复合逆境胁迫均导致辣椒叶片的净光合速率、气孔导度、蒸腾速率、光系统Ⅱ最大光化学效率、光合电子传递量子效率的下降及天线热耗散、反应中心过剩光能的增加,各指标变化幅度较大的是低温盐胁迫处理。【结论】低温、弱光和盐胁迫单一、双重或三重逆境下辣椒叶片净光合速率均降低,各逆境导致净光合速率下降的限制因子是不同的。低温盐胁迫对辣椒叶片光合参数、叶绿素荧光参数影响较大,其次为低温弱光及盐胁迫,影响较小的是弱光处理。

Photosynthetic Characteristics of Pepper Leaves Under Low Temperature,Weak Light and Salt Stress

Objective]The aim of this study was to investigate the response mechanism of photosynthetic characteristics in pepper(Capsicum annuum L.)leaves subjected to low temperature,weak light and salt stress,and to offer a theoretical basis for the pepper production in protected culture in winter and spring.Method]Chlorophyll content,photosynthetic parameters and chlorophyll fluorescence parameters in pepper leaves were determined.gesult] Compared with the control,contents of Chl a,Chl b and Chl(a+b)in leaves treated with weak light,weak light under salt stress increased by 25.91%-35.75%,31.34%-44.78%,and 27.31%-38.08%,respectively,while other treatments were reverse.Moreover,net photosynthetic rate,stomatal conductance,transpiration rate,the maximal efficiency of PS Ⅱ photochemistry(Fv/Fm),quantum yield of PS Ⅱ electron transport (ΦPSⅡ) decreased and antenna heat dissipation (D),excess light energy (E) of PS Ⅱ increased under single low temperature,weak light,salt stress or combined stress,especially low temperature under salt stress.Conclusion] Although net photosynthetic rate decreased under single or combined stress,the limited factor of different stresses leading to decreased net photosynthetic rate in pepper leaves is different.The effects of low temperature under salt stress on photosynthetic characteristics in pepper leaves are the greatest and the lowest is weak light.With the effect of low temperature,weak light and salt combined stress is the next to low temperature under salt stress.