Copper is a substance that has been used in plant protection for years. Currently, however, more and more attention is being paid to the need to limit the amount of it that ends up in the natural environment. At the same time, it is necessary to partially replace synthetic fungicides with alternative preparations. It is therefore worth looking for forms of copper that will contain a smaller amount of the mentioned ingredient while being highly effective. This experiment assessed the effect of selected preparations on the development of mycelium of pathogens of the Fusarium genus and the germination parameters of winter wheat. The efficacy of copper lignosulfonate and copper heptagluconate in seed treatment was tested, comparing them to copper oxychloride, copper hydroxide, and tebuconazole. The obtained results indicate that the use of copper lignosulfonate and copper heptagluconate allows for the effective limitation of the development of the tested pathogens (mycelium development was inhibited by up to 100%). Most of the preparations had no effect on the energy and germination capacity of winter wheat (only in one combination were the values lower than 90%). The use of preparations containing reduced doses of copper is an effective solution when applied as seed dressings.

Preparations containing appropriate microorganisms stimulate plant growth and are increasingly used to alleviate plant stress, including water deficit stress. Despite the growing interest in PGPR, little is known about the post-emergence efficacy of formulations based on native strains under water stress. In this study, we tested the post-emergence efficacy of preparations based on Bacillus velezensis_KT27 and Bacillus subtilis + Pseudomonas simiae + Bacillus velezensis_S103 at doses of half a liter and one liter × 200 L × ha⁻¹ in culture fluid or oil dispersion each at a final microbial cell concentration of 5 × 10⁸ (CFU/mL) for the tested strains. Our hypothesis was that the different biostimulants may positively affect plants’ tolerance to water stress. To this end, analyses of plant height, fresh weight, dry weight, chlorophyll, flavonol and anthocyanin content, and chlorophyll fluorescence were conducted under greenhouse conditions for winter wheat, winter barley, and winter oilseed rape. The preparations promoted the growth and water-stress tolerance of the selected plants, with effectiveness depending on strain, plant, dose, and formulation. B. velezensis_KT27 (0.5 L in oil dispersion) increased the dry weight of winter wheat by 17% (optimal) and 14% (water deficit stress) and of winter barley by 17% and 28%. Bacillus spp. + Pseudomonas spp. (0.5 L in oil dispersion) increased winter oilseed rape dry weight by 13% in both conditions. These findings highlight the potential of Bacillus spp. and Pseudomonas spp. for post-emergence biostimulation under variable soil levels of moisture.

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 Bacillus velezensis_KT27, Paenibacillus polymyxa, Pseudomonas synxatha, and a mixture of Bacillus subtilis, Pseudomonas simiae, and Bacillus velezensis_S103, 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 Bacillus ssp., Paenibacillus ssp., and Pseudomonas 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.