Effects of weak light on photosynthetic characteristics of peanut seedlings | 苗期弱光对花生光合特性的影响

Chinese. 【目的】探讨苗期不同弱光条件下花生（Arachis hypogaea L.）叶片光合特性的变化规律,为合理规划麦套花生布局提供理论依据。【方法】以丰花1号为供试材料,在花生苗期用不同透光率的黑色遮阳网进行遮光,设置不遮光(CK)、遮光27%、遮光43%和遮光77% 4个处理。测定遮光后花生功能叶片的叶绿素含量、净光合速率、光合曲线参数、荧光参数以及光合酶的活性,比较不同遮光处理间的差异。【结果】遮光后随遮光程度的增强,花生叶片净光合速率（Pn）显著降低,气孔导度（Gs）、细胞间隙CO2浓度（Ci）、光补偿点、光饱和点、CO2补偿点、CO2饱和点、羧化效率、RUBPCase和PEPCase活性显著降低;叶绿素含量、表观量子效率显著增加,实际光化学效率ФPSⅡ和最大光化学效率（Fv/Fm）升高;即时光强和长期遮光处理均能明显降低光合酶的活性。【结论】苗期遮光显著降低花生叶片的光合速率,原因是气孔限制、非气孔因素即叶肉细胞光合活性下降和光系统Ⅱ光能分配变化;提高了花生利用弱光的能力;遮光27%的影响较小,可据此合理规划麦套花生的种植规格。

English. 【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.