Unveiling the regional variation in pathogenicity and aggressiveness of Bipolaris sorokiniana isolates on barley seedlings

Abstract Barley ( Hordeum vulgare L.), one of the earliest domesticated crops with essential uses in food, animal feed, and malt production. In many regions, is susceptible to seed-borne pathogens. This study assessed virulence and aggressiveness of twenty one Bipolaris sorokiniana isolates collected from different agroecological regions of Türkiye on barley seedlings under controlled conditions. Isolates were inoculated onto barley plants and evaluated for disease severity, seedling biomass, and plant length. Isolate 19 from Merkez Tokat caused the highest disease severity (86%), with more aggressive isolates from the Central-Inner Black Sea Region, while isolate 2 most severely reduced seedling fresh and dry weight by 29% and 37%, respectively. Isolates 12, 13, and 19 showed no significant differences from the control in fresh and dry weight measurements. All isolates except isolate 12 significantly reduced seedling length and increased disease severity compared to the control, with disease severity ranging from low to severe across treatments ( P < 0.05). The results demonstrated that B. sorokiniana inhibites barley seedling growth and biomass reduction, with significant variations in pathogenicity among regional isolates.