Evaluation of the effect of different concentrations of active ingredients of modern seed dressings Imidocloprid and Imazalil on the viability of pure cultures of

This study examined the toxic effects of the active ingredients imidocloprid and imazalil, which are components of several fungicide seed treatments, on the viability of pure cultures of Bradyrhizobium elkanii rhizobia bred at the All-Russian Soybean Research Institute. The effects of three concentrations of these active ingredients (recommended/production, half the recommended/production, and double the recommended/production) on the streak growth rate of B. elkanii strains on mannitol yeast agar (MDA) on the fifth day after sowing were analyzed. It was found that imidocloprid and imazalil exert a suppressive effect on rhizobia, significantly reducing the growth of colonies of the strains on the nutrient medium. Despite the toxic effects of these chemicals, a third of the studied strains were resistant to recommended/production concentrations of imidocloprid and imazalil. The effect of the active components of imidocloprid and imazalil on the formation of the soybean symbiotic apparatus was studied in laboratory experiments. It was found that simultaneous treatment of soybean seeds with pure cultures of root nodule bacteria using these chemicals does not impair nodulation and even slightly increases virulence, and in some cases, these parameters even increase compared to control samples. It was determined that the inhibitory effect of imidocloprid and imazalil on collection strains of the rhizobia species B. elkanii varies and depends on the adaptive capabilities of the strain.