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 CO 2 concentration (Ci), light compensation point, light saturation point, CO 2 compensation concentration, CO 2 saturation concentration, carboxylation efficiency, RUBPCase and PEPCase activities along with the shading degree but increased the chlorophyll content, apparent quantum yield, and Phi PS II 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 PS II), 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.
