Journal of Research

The wheat varieties cultivated to date in the state were evaluated against mixture of prevalent pathotypes of Puccinia striiformis in one set and inoculated with Tilletia indica at the boot stage in another set. The disease response was analyzed on the basis of disease score. Thirty six varieties were grouped in to four clusters on the basis of yellow rust and the resistant varieties PBW 343, PBW 373, PBW 502 and Raj 3765, were included in cluster IV which were least affected on the basis of Karnal bunt incidence, varieties were grouped into 3 clusters, cluster I and II differed by 100 and 92 per cent from successive clusters. In cluster III, there were sub groups with variations in susceptibility level. Varieties PBW 343, PBW 373 and PBW 502 in cluster III-b were least infected. This variation in susceptibility to Karnal bunt was an important finding, particularly in the varieties PBW 343, PBW 373 and PBW 502, which indicates that mobility of the other rust resistant genes across genotypes over the years with the introduction of dwarf wheat from late sixties has also helped in introducing traits which made these varieties less affected by another important disease.