Variety-strain interaction specificity of <i>Bacillus subtilis</i> with salt-stressed <i>Phaseolus vulgaris</i> L. plants

The effectiveness of crop inoculation using growth-stimulating bacteria can depend on the plant variety and environmental conditions. The reactions of three-week-old plants of the Ufimskaya and Zolotistaya green bean varieties to inoculation with strains 26D and 10-4 in normal conditions and under stress (1% NaCl 48 h) were analysed. Although the Zolotistaya variety formed less biomass and leaf area, it surpassed the Ufimskaya variety in terms of chlorophyll and root water content, as well as reacting to stress by reducing the content of photosynthetic pigments and root water content. Inoculation contributed to the preservation of these indicators at the level of non–stressed plants: the positive effect of strain 26D was expressed in the effect on the composition of pigments, while that of strain 10-4 was expressed in the hydration of roots. Under stress, the Ufinskaya variety improved the water status of the roots, on which inoculation had a weak or negative effect; however, the decrease in the level of synthetic pigments under stress was compensated by inoculation with both strains. According to the biomass of three-week-old plants, the Zolotistaya variety was shown to respond positively to inoculation with both strains both normally and under stress, while the Ufimskaya variety tended to react negatively to inoculation with strain 26D; under stress, the effect of inoculation with both strains was positive. Compared with the stress-induced control, the malondialdehyde content in the roots of inoculated plants of both varieties decreased in comparison with that of the uninoculated control both in normal conditions and under stress. The revealed differences in plant reactions to inoculation serve as a basis for further analysis of the effectiveness of variety-strain combinations of symbiotic partners.