Comparison of resistance of soybean nodule bacteria strains to pesticide and osmotic stresses

Abstract

The increasing areas under leguminous crops and the general increase in the intensification of production force agricultural producers to combine seed inoculation and dressing in one step, carrying it out a few days before sowing. In this regard, it is of practical interest to study the resistance of rhizobia strains of inoculants to osmotic and chemical stresses, i.e. the nature of the dynamics of their viability on seeds and in contact with pesticides. The stability of two strains of soybean nodule bacteria (B. japonicum 634 and B. japonicum H9) to osmotic and chemical stresses (fungicidal mordants) was studied. According to the results of the study, pesticidal protectants had different toxicity degrees for the studied strains, which allowed them to be arranged in order of increasing toxicity for rhizobia: Baisad, VSK; Tirada, SK; Oplot, VSK). Soybean rhizobium strain B. japonicum H9 is defined as more osmotically and chemically stable, i.e., more adapted to modern agricultural technologies of soybean cultivation, which ensures the presence of at least 2·104CFU per 1 seed 9 days after inoculation, while the number of viable cells of strain B. japonicum 634b per 1 seed drops to 0 within 3 days after inoculation. Osmotic resistance of the strain allows for effective inoculation of seeds at least 9 days before sowing, and chemical resistance allows for effective combination of an inoculant based on this strain and all the pesticide protectants studied in this work into one working solution.