S.S.AdiverVirupaksa.H.Prabhu2016-07-232016-07-232009http://krishikosh.egranth.ac.in/handle/1/69510Charcoal rot of sorghum caused by Macrophomina phaseolina, is a severe disease particularly in rabi season grown crop. Thirty five infected sorghum stalk samples were collected from Karnataka, Maharashtra and Andhra Pradesh to assess the variability. Based on colony pigmentation, the cultures were assigned to four major groups on PDA and three groups on Czapek’s medium. Studies on toxin variability showed the symptoms such as drooping of leaves, blackening of leaves which was initiated at four hours and continued upto fourteen hours, thus revealing the existence of variation among the isolates. The sensitivity of isolates to copper sulphate at three different levels of concentrations found to differ to various concentrations tested. But with Carbendazim, the growth of all isolates were completely inhibited. Highest growth was observed in 7.0 pH, closely followed by 6.5 pH indicating preferential range to be between 6.5 and 7.00 pH. Peroxidase and Polyphenoloxidase enzyme analysis indicated that there was significant variation among the 35 isolates of M. phaseolina. RAPD data distinguished the 35 isolates into three major clusters. Management of charcoal rot of sorghum revealed that the seed treatment with carbendazim and seed treatment with T. harzianum + P. fluorescens showed superior results. Sixty four germplasm lines of sorghum screened. Charcoal rot was least in Dagadi Solapur, followed by GRS-1 and BCR-9. None of the genotypes showed resistant reaction. Employment of new source of resistance sources like local genotypes mentioned above can be effectively employed in resistance breeding programme to manage charcoal rot of sorghum.Thesis