Effects Of Rhizobia, NH₄～+-Fertilizer And Light Strength On Nitrogen Fixation And Photosynthesis Of Soybean

Biological nitrogen fixation and photosynthesis are two basic biological processes in the global ecosystems, which play important roles in nitrogen and carbon cycle, sustaining and succession of nature ecosystems, and crop production of artificial ecosystems. While great achievements have been made in both symbiotic nitrogen fixation and photosynthesis, the interaction and relationship between biological nitrogen fixation and photosynthesis were seldom concerned. In our study we tried to link them together based on following work: (1)To compare nitrogen fixation and photosynthesis in lower and higher photosynthetic soybean after inoculated with engineered rhizobia with extra copy of nifA or dctABD.(2) To compare photosynthetic parameters of soybean following inoculation of rhizobia and fertilization of ammonium sulfate.(3) To evaluate the effects of light intensity on nitrogen fixation and photosynthesis of soybean seedlings.(4) To try to get transgenic alfalfa containing C4 PEPC gene. The results are follows:1. It was indicated that, after inoculated with the nifA and dct engineered Sinorhizobium fredii USDA 191, both nitrogen fixation and photosynthesis of soybean plants were improved as compared with wild type of rhizobia. The effects of two genetic engineered rhizobia were also different in two soybean varieties. The nifA engineered bacteria played a better role than the dct ones in Heinong 37 (variety with lower photosynthetic rate), having better photosynthetic parameters, higher nitrogen fixation activities and biomass production. Contrarily, as for variety of Heinong 40 with higher photosynthetic rate, soybean plants inoculated with dct engineered rhizobia had better photosynthetic efficiency than the nifA ones although there were no significant differences in nitrogen fixation activities between them.2. Under condition of growth chamber, soybean growth and a series of its photosynthetic parameters were determined after treatment of inoculation with...