Genetic and Environmental Interactions in Spring Wheat Resistance to Bipolaris Sorokiniana Root Rot in Kazakhstan

Common root rot caused by Bipolaris sorokiniana represents a major constraint to wheat production in Kazakhstan. This study evaluated the resistance of 30 spring bread and durum wheat genotypes under diverse environmental and treatment conditions in two contrasting regions (Almaty and Aktobe) during 2024. The experimental design included three treatment regimes: fungicide application, artificial inoculation with the pathogen, and natural infection. Agronomic traits (stem length, spike characteristics, grain weight) and disease parameters (prevalence, severity, yield loss) were assessed using standard phytopathological methods, while molecular markers identified resistance genes Sb1 and Sb2. Results demonstrated that genotypes carrying resistance genes exhibited significantly lower disease incidence and severity under infectious conditions. Genotype №518/Serke, gord. (Sb2) showed stable performance with 87.38 cm stem length and 21.67 g grain weight per 50 plants, while line №575 (Sb1, Sb2) achieved the highest spikelet number (14.27) and grain weight (9.67 g). Fungicide application improved stem length (84.24 cm) and grain weight (16.96 g), whereas natural infection significantly reduced yield-related traits. Significant regional differences emerged: Aktobe plants exhibited higher tillering capacity (2.32) but shorter stems (77.07 cm), while Almaty plants showed longer stems (81.29 cm) and superior spike structure. These findings demonstrate that integrating genetic resistance, strategic fungicide application, and region-specific breeding strategies can effectively mitigate yield losses from common root rot. This research provides a framework for developing climate-resilient wheat varieties combining disease resistance with environmental adaptability, essential for food security in Kazakhstan's diverse agroecological zones.