缺磷条件下低分子量有机酸对大豆氮积累和结瘤固氮的影响

Effects of low molecular organic acids on nitrogen accumulation,nodulation,and nitrogen fixation of soybean(Glycine max L.) under phosphorus deficiency stress

采用砂培方法在温室条件下研究了低分子量有机酸柠檬酸、草酸、苹果酸及3种酸的混合物对大豆植株氮素积累、结瘤和固氮的影响.结果表明：低分子量有机酸对大豆植株氮素积累有显著的抑制作用,使大豆地上部各时期氮素积累量的降低幅度分别为：苗期17.6%-44.9%,花期29.8%-88.4%,鼓粒期9.18%-69.6%,成熟期2.21%-41.7%;低分子量有机酸对大豆根瘤生长和固氮能力也有显著影响,表现为使根瘤数量、根瘤固氮酶活性和豆血红蛋白含量显著降低,降低幅度分别为11.4%-59.6%,80.5%-91.7%和11.9%-59.9%,从而使大豆的固氮效率降低,最终导致大豆的固氮量较对照显著降低（降低幅度9.71%-64.5%）.低分子量有机酸对大豆氮积累、根瘤生长和固氮能力的抑制作用随浓度的增加而增加.3种有机酸中,草酸的抑制作用相对大于柠檬酸和苹果酸,3种有机酸混合后,抑制作用加强.

A greenhouse sand culture experiment was conducted to study the effects of citric acid, oxalic acid, malic acid, and their mixture on the nitrogen accumulation, nodulation, and nitrogen fixation of soybean. After the application of test low molecular weight organic acids, the nitrogen accumulation in the aboveground part of soybean decreased by 17.6%-44.9% at seedling stage, 29. 8%-88.4% at flowering stage, 9. 18%-69.6% at podding stage, and 2.21%-41.7% at maturing stage）. In the meanwhile, the nodule number, nitrogenase activity, and leghemoglobin content decreased by 11.4%-59.6% , 80. 5%-91.7% , and 11.9%-59.9% , respectively, resulting in a significant decrease （9.71%--64.5 % ） of nitrogen fixation of soybean, compared with the control. The inhibitory effect of test low molecular weight organic acids increased with their increasing concentration. Oxalic acid had a higher inhibitory effect than citric acid and malic acid, and the mixture of the three organic acids had an enhanced inhibitory effect.