Abstract
This field study evaluated the effects of microbial seed treatments on field emergence, plant growth, yield components, and root rot development in spring wheat under the agro-climatic conditions of southeastern Kazakhstan. Two spring wheat cultivars, Diva and E-1, were used to assess microbial performance across locally adapted genetic backgrounds. Seeds were treated with selected strains of Bacillus, Lysinibacillus, and Trichoderma, as well as a Bacillus + Lysinibacillus consortium. Root rot incidence and severity were assessed at tillering, heading, and maturity. Microbial seed treatments significantly influenced field emergence and several yield-related traits. Bacillus mobilis E-bac1 produced the highest thousand-grain weight (43.2 g compared with 22.4 g in the untreated control). Lysinibacillus fusiformis D-bac4 showed the lowest numerical root rot incidence and severity (7.4% and 3.2%, respectively). However, these disease differences were not statistically significant (P = 0.696 and P = 0.670) and should therefore be considered seasonal trends rather than confirmed suppression. Root rot increased significantly during crop development and reached its highest level at maturity, with no significant differences between cultivars. Overall, the results suggest strain-specific effects, with some strains mainly improving productivity and others showing potential for disease reduction. Multi-year field trials are needed to confirm stable efficacy under natural pathogen pressure.