Efficiency of formation and functioning of the symbiotic soybean system with glyphosate treatment

Abstract

The efficiency of the formation and functioning of the soybean symbiotic system during the crops treatment with glyphosate and pre-sowing seed inoculation with different strains of Bradyrhizobium in the field studied. It is known, that glyphosate can affect symbiotic nitrogen fixation through direct action on rhizobia and symbiotic formations, we took plant samples for analysis after four weeks of glyphosate treatment and determined the aboveground mass of plants and symbiotic apparatus formation evaluated by the number of nodules, their mass and nitrogen fixation activity. It was shown that the late treatment (35 days after sowing) with glyphosate does not provide a sufficient level of weed control and under such conditions inhibits the development and growth of soybean plants, reduces the growth of aboveground and root mass. Treatment of plants with glyphosate before the formation of symbiotic apparatus (21 days after sowing) reduces nitrogen fixation activity by 3550%, but it does not have a significant effect on the formation of soybean yield. The obtained results confirmed the hypothesis of intensification of the nitrogen complex during late treatment of plants with glyphosate in plants inoculated with Bradyrhizobium japonicum strain EL-35 and the composition of strains of B. japonicum EM-24 and B. japonicum EL-35. The most effective for inoculation of soybean plants was a mixture of the studied strains of B. japonicum EM-24 and B. japonicum EL-35, which provides high nitrogen fixation activity and productivity. Therefore, to reduce the negative impact of glyphosate on the nitrogen fixation activity of symbiotic systems and to obtain high soybean productivity, it is necessary to select rhizobia strains with a high rate of symbiotic system formation, because even a slight decrease in nitrogen fixation can have long-term negative consequences.