The effect of organic acids on the assimilation of nitrates by soybean plants and the adhesion of Bradyrhizobium japonicum to roots

The effect of malate, succinate, alpha-ketoglutarate, and citrate on the content of nitrates in roots and leaves, the nitrate reductase activity (NRA) in leaves, the pH of the external medium, and the adhesion of Bradyrhizobium japonicum 273 to the surface of soybean (Glycine max L.) roots was studied. When affected by organic acids, NRA and nitrate content slightly increased in the leaves of plants at the first leaf stage. In addition, the pH of the nutrient solution was shifted to neutral, promoting the adhesion of B. japonicum. These data confirm the importance of organic acids for the assimilation of nitrate-associated nitrogen and their role in the adhesion of B. japonicum 273 to the root surface.