Efficacy of Selected Bacterial Strains in the Protection and Growth Stimulation of Winter Wheat and Maize

The use of biopreparations currently plays a significant role in limiting the use of plant protection products and fertilizers. In this study, preparations based on <i>Bacillus velezensis_KT27</i>, <i>Paenibacillus polymyxa</i>, <i>Pseudomonas synxatha,</i> and a mixture of <i>Bacillus subtilis</i>, <i>Pseudomonas simiae</i>, and <i>Bacillus velezensis_S103</i>, used as seed dressings at doses of 0.5 L and 1.0 L × 100 kg^-1 grain, were tested to determine their efficacy. The prothioconazole preparation was used for comparison as a synthetic fungicide. The test microorganisms were prepared as standardized preparations diluted with sterile water to obtain a final cell concentration of 5 × 10⁸ CFU/mL for each bacterial strain. The ability of selected bacterial strains to solubilize phosphate was quantitatively evaluated as one of the factors influencing the stimulation of crop growth. The obtained results indicate that the microorganisms can reduce the infection in seedlings, and the health of those seedlings depends on the preparation used and its dose. The tested microorganisms had a positive effect on plant growth, which was confirmed by the analyses of plant height, fresh mass, and chlorophyll fluorescence. The results indicate that the selected strains of microorganisms <i>Bacillus</i> ssp., <i>Paenibacillus</i> ssp., and <i>Pseudomonas</i> ssp. may be used in the protection and growth stimulation of crop plants, but this needs to be verified by field tests prior to their practical application.