Analysis of Cultural and Pathogenic Diversity in Bipolaris sorokiniana Causing Spot Blotch of Bread Wheat in North India

Present study was conducted to analyse the cultural and pathogenic diversity in different isolates of Bipolaris sorokiniana the causal organism of spot blotch in bread wheat. Six isolates of Biplorais sorokiniana (BS-F-5, BS-D-2, BS-K,4, BS-DWR-K-1, BS-V-6, and BS-P-3) were evaluated simultaneously for cultural and pathogenic variability on the basis of diverse characteristics against seven different genotypes of wheat grown in the region viz: BOW’S’, HS 375, HUW 234, PBW 343, PBW 443, K9107 and A9-30-1. The results indicated that isolates varied significantly among themselves for all the characters analysed. The isolate BS-F-5 exhibited the maximum colony diameter, maximum average dimension (length and width) of conidiophore, maximum number of septa in conidiophore and conidia. Variations were also observed in texture of the colony. Among the seven genotypes tested against six isolates, BOW’S’ showed resistance against three isolates (BS-D-2, BS-K,4, BS-DWR-K-1) and genotype A-9-30-1 showed high susceptibility against all isolates except BS-D-2. The isolates BS-F-5 and BS-P-3 exhibited maximum pathogenic virulence among the isolates analysed in the present investigation.