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. 【Result】 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 PSⅡ photochemistry (Fv/Fm),quantum yield of PSⅡ electron transport (ΦPSⅡ) decreased and antenna heat dissipation (D),excess light energy (E) of PSⅡ 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.