Efficacy of biopreparations on spring wheat under variable moisture conditions

The results of a three-year assessment of the effect of Bacillus-based preparations used to treat spring wheat seeds on the development of root rot and crop productivity are presented. The experiments were conducted in the northern forest-steppe of the Ob region in 2019 and 2021–2022 as field experiments. Of the three years of research, two years were moderately humid with a GTC according to Selyaninov of 1.02 and 0.91, while 2022 was dry with a GTC of 0.69. The effect of Fitop 8.67-9 based on B. subtilis and B. amyloliquefaciens bacteria with 109 CFU, as well as the bacterial-humic preparation AFG (a mixture of Fitop 8.67-9 and Cytogumate with a titer of 107 CFU), was studied on the Novosibirskaya 31 spring wheat variety, in comparison with a chemical fungicide based on difenoconazole and cyproconazole, and Cytogumate. Cytogumate is made from brown coal and contains potassium and sodium humic acids, N, P, K, Ca, Mg, S, and trace elements. It has been shown that bacterial Fitop 8-67.9 and bacterial-humic preparation AFG, used for seed treatment, reduced their infection with pathogens. It was shown that the bacterial preparation Fitop 8-67.9 and the bacterial-humic preparation AFG, used for seed treatment, reduced the infestation of seeds by the root rot pathogens Fusarium and Bipolaris sorokiniana to the threshold of harmfulness or lower, and reduced the disease incidence of the primary roots of plants by 1.6–3.5 times. In years with moderate moisture availability, the biological efficiency of biological products was comparable to that of a chemical fungicide based on difenoconazole and ciproconazole, but it was inferior in a dry year. The grain yield of spring wheat in years with GTC = 0.9–1.0 varied in the following order: products with Bacillus (approximately 20 % increase over the control) > Cytogumate (+10 %) > chemical reference (+5.5 %). In dry vegetation, the yield of spring wheat (the second crop after fallow) was 30–38 % higher on chemical seed treatment.