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研究了在缺氮条件下，CO_2倍增对大豆（GtycinemaxL.）Bragg及其等基因突变体超结瘤大豆nts382和不结瘤大豆Nod49生长和固氮的影响。结果表明在缺氮条件下CO_2倍增明显提高大生物量和根系结涵量，但对固氮酶活性的影响则随幼苗的生长而异。播种后25天取样结果显示CO_2倍增条件下，Bragg和nts382的固氮比活性和单株固氮活性都显著提高，而其后3天取样的结果没有表现出增加趋势，固氮比活性在nts382反而明显降低。两种CO_2浓度条件下，nts382单株固氮活性高于Bragg，但固氮比活性低于后者。两次测定结果的差异说明植物对CO_2倍增的反应具有很强的时效性;同时表明，CO_2倍增对植物生长和固氮的促进作用不能长期维持。这可能与生物固氮过程本身的复杂性有关。根据本研究结果推测，在未来全球环境变化、CO_2倍增条件下，共生固氮植物可能在生态系统氮素平衡中起到更为重要的作用;并有可能通过育种技术改良固氮农作物，提高农作物产量。
The effects of CO_2 doubling on the growth and nitrogen fixation of GtycinemaxL. Bragg and its isogenic mutant supernodular soybean nts382 and non-nodulated soybean Nod49 were studied under nitrogen deficiency conditions. The results showed that under the condition of nitrogen deficiency, CO 2 doubling significantly increased the biomass and the content of root junctions, but the effect on nitrogenase activity varied with seedling growth. The results of sampling at 25 days after sowing showed that under the conditions of CO_2 doubling, the nitrogen fixation specific activity and nitrogen fixation activity of Bragg and nts382 were significantly increased, while the results of sampling after 3 days did not show an increasing trend, but the nitrogen fixation specific activity was significantly reduced in nts382 . Under the two CO2 concentrations, the nitrogen fixation activity of nts382 was higher than that of Bragg, but the nitrogen fixation activity was lower than the latter. The difference between the two measurements indicates that the plant response to CO 2 doubling has a strong timeliness. At the same time, the promotion of plant doubling and nitrogen fixation can not be maintained for a long time. This may be related to the complexity of biological nitrogen fixation itself. Based on the results of this study, it is speculated that symbiotic nitrogen fixation plants may play a more important role in ecosystem nitrogen balance under future global environmental changes and CO 2 multiplication conditions. It is also possible to improve nitrogen fixation crops and increase crop yields through breeding techniques.