Effects of Weak Light on Photosynthetic Characteristics of Peanut Seedlings

【Objective】 The aim of this study was to investigate the effects of weak light on the photosynthetic characteristics of peanut leaves at the seedling stage and to offer a theoretical basis for the programming of peanut intercropped with wheat. 【Method】 Fenghua 1 was grown in an experiment with four shading treatments (CK,in which the plants were grown under natural light,and 27% shading,43% shading,77% shading) and the investigation was carried out at seedling stage using black sunshade net. The chlorophyll content,net photosynthetic rate,photosynthetic curve,fluorescence parameters and photosynthetic enzyme activities were tested. 【Result】 Shading treatment significantly reduced the net photosynthetic rate (Pn),stomatal conductance(Gs),intercellular CO2 concentration(Ci),light compensation point,light saturation point,CO2 compensation concentration,CO2 saturation concentration,carboxylation efficiency,RUBPCase and PEPCase activities along with the shading degree but increased the chlorophyll content,apparent quantum yield,and ФPSⅡ and Fv/Fm. Real-time low light intensity and long-term shading treatment depressed photosynthetic enzyme activities jointly. 【Conclusion】 Shading at seedling stage depressed Pn significantly,which induced by stomatal limitation and non-stomatal factors (such as decline of photosynthetic ability of mesophyll cell,changes of absorbed light allocation of PSⅡ),improved the capacity of utilization of weak light. Shading of 27% had less influence,and therefore can program plant the standards of intercropping system of wheat and peanut.