Pathogenic variability in Bipolaris sorokiniana population obtained from cereal hosts

Thirty isolates of Bipolaris sorokiniana were obtained from infected leaf samples of bread wheat, durum, barley, triticale and rye leaves collected randomly from Abohar, Gurdaspur, Ludhiana and Fazilka areas of Punjab state. Pathogenic variabilty was studied on fourteen different hosts including commercial and susceptible varieties of bread wheat, durum wheat, barley, triticale as well as rye and Phalaris minor at seedling stage and flag leaf stage. On the basis of multivariate cluster analysis of data of host response, the isolates were grouped into 8 and 12 clusters at seedling stage and flag leaf stage, respectively. Maximum variability was observed in isolates obtained from bread wheat and barley whereas isolates from triticale and rye exhibited maximum relatedness. Isolates from Abohar and Ludhiana were most variable followed by isolates obtained from Gurdaspur and Fazilka. The host-pathogen interactions of B. sorokiniana population studied indicated that the moderate resistance to moderate susceptible reactions predominated. On an average the proportion of moderately resistant response on all the test hosts was 36.19% and moderately susceptible response was 32.86% whereas resistant response was 19.52% and the susceptible was 11.43%.