The aim of our study was to determine the effect of fungicide formulation, brand of fungicide, its concentration in the solution, holding time and temperature regime of the solution on the number of survivors of nodule bacteria of soybean, lupine, peas and lentils in a solution. Bacterial suspensions of soybean nodule bacteria (Bradyrhizobium japonicum 634b), lupine (Bradyrhizobium lupini 367a), pea (Rhizobium leguminosarum 261b), and lentils (Rhizobium leguminosarum 712) were studied. Wetting powders Benomil (active substance benomil 500 g/kg, LLC “Soyuzagrohim”, Russia), Benorad (active substance benomil 500 g/kg, JSC “August”, Russia) and Fundazol (active substance benomil 500 g/l, LLC “Agro-Kemi”, Russia) and concentrates of suspension Maxim KS (active substance fludioxonil, 25 g/l; “Syngenta International AG”, Switzerland), Protect KS (active substance fludioxonil, 25 g/l; LLC “Agro Expert Group”, Russia), Protect Forte VSK (active substance fludioxonil, 40 g/l + flutriafol, 30 g/l; LLC “Agro Expert Group”, Russia) were studied as fungicidal disinfectants. Compatibility was determined after the preparation of tank solutions of biological products and fungicides, followed by an assessment of the percentage of surviving rhizobia depending on the brand of fungicide, its concentration (10 and 20%), the holding time of the solution (2, 4, 8 h) and the temperature regime of the solution (2-5, 16-18, 27 °C).

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.