接种根瘤菌和遮光对大豆固氮和光合作用的影响

【目的】研究光合和氮素互作对大豆生长和光合作用的影响。【方法】以大豆黑农37为供试材料，采用接种根瘤菌和遮光相结合的手段，测定了接根瘤菌大豆在非遮光、遮光和复光条件下的生长及光合指标。【结果】非遮光条件下，接种根瘤菌显著提高了大豆的生物量、叶绿素含量和光合能力；遮光条件下，根瘤菌发挥不出其优越性，受气孔导度和非气孔因素的影响，接菌大豆的光合速率比不接菌的对照低；恢复光照后，接种根瘤菌大豆的光合作用恢复程度也不如不接菌对照。【结论】大豆与根瘤菌的共生固氮需要在合适光照条件下才能发挥其促进生长和促进光合作用的正效应。

Effects of Rhizobial Inoculation and Shading on Nitrogen Fixation and Photosynthesis of Soybean

【OBJECTIVE】The interactive effects of light strength and nitrogen supply on soybean growth and photosynthetic physiology were studied. 【METHOD】Plant growth, photosynthetic gas exchange and chlorophyll fluorescence in soybean ( Glycine max (L.) cv. Heinong 37 ) were investigated after inoculated with Sinorhizobium fredii USDA191 under light-shaded and subsequent light-recovered conditions.【RESULTS】The results showed that, under non-shaded condition, plant biomass, chlorophyll contents and photosynthetic capacity were significantly increased in soybean following rhizobial inoculation as compared to those of the control plants; while under light-shaded condition, the photosynthetic rate of the rhizobia-inoculated soybean was markedly decreased compared to the non-inoculated control plants due to the influences of stomatal conductance and non-stomatal factors, showing that the inoculated rhizobia did not play the role in nitrogen fixation. Under light-recovered condition, the photosynthetic parameters were not recovered to the degree as that of the non-inoculated control plants. 【CONCLUSION】It is concluded that the positive effects of symbiotic nitrogen fixation can be attained only under suitable light condition.