REACTION OF FREE-LIVING AND SYMBIOTIC BRADYRHIZOBIUM JAPONICUM ON THE USE OF SUCCINIC ACID

Abstract

Objective. Find out the influence of different concentrations of succinic acid on the intensity of growth of Bradyrhizobium japonicim and the activity of symbiotic systems created with their participation. Methods. Microbiological, physiological, statistical, gas chromatography. Results. It was found that the T21-2 strain had a more pronounced reaction to the use of succinic acid than the PC08 strain, regardless of its concentration. Addition of succinic acid to the culture medium of rhizobia at a concentration of 0.01 and 0.02 g/L led to an increase in the titre of bacterial cells of T21- 2 and PC08 strains, while at a concentration of 0.2 g/L it had a toxic effect on the studied strains. Succinic acid at a concentration of 0.01 g/L, both during seed treatment and as a component of the inoculation suspension, significantly activated the processes of formation and functioning of soybean symbiotic systems formed by the T21-2 rhizobia strain. At a concentration of 0.02 g/L, it provided the highest rate of growth of bacterial cells among the studied variants and led to an increase in their titre relative to rhizobia without adding acid, both on day three and four of cultivation. At the same time, regardless of the method of application, this concentration of succinic acid partially inhibited the nodulation activity of T21-2 strain and the nitrogen-fixing activity of the symbiotic systems formed with their participation. Conclusion. Based on the revealed effect of succinic acid on the growth of Bradyrhizobium japonicum in pure culture and on the formation and functioning of symbiosis, we recommend adding succinic acid at a concentration of 0.01 g/L, both as a component of the inoculation suspension, and for pre-sowing seed treatment to increase the activity of soybean-rhizobia symbiotic systems.