Efficiency of inoculum types in evaluating sheath blight progression in rice by Rhizoctonia solani
2011
Lore, J. S. | Jain, J. | Hunjan, M.S.
Sheath blight caused by Rhizoctonia solani, is one of the most important rice diseases worldwide especially under irrigated agro-ecosystem. To detect quantitative differences in disease spread, lesion length, number of lesion and per cent disease severity on six rice genotypes, different inoculum types viz. single sclerotium, mycelial disc, and mycelial ball were compared using detached tiller test under control conditions. Liquid culture mycelial ball produced significantly longer lesion length, higher disease spread alongwith number of lesions and maximum per cent disease severity followed by the single sclerotium inoculum. However, all these parameters were least when mycelial disc inoculation was followed, though no significant differences were observed between single sclerotium and mycelial disc inoculum. Among the six genotypes i.e. Jasmine 85, Tetep, IR 64 (D256), IR 64 (D6766), PR 108 and PAU 201 evaluated, Tetep showed lesser number of lesion, lowest lesion length, lower disease spread and disease severity followed by Jasmine 85 and PR108. No significant difference was observed between Tetep and IR 64 (D256) in relation to number of lesion and disease severity. Highest lesion length, higher disease spread, higher number of lesions and maximum per cent disease severity were observed in susceptible mutant IR 64 (D6766) and cultivar PAU 201. Although, mycelial ball produced longer lesions, single sclerotium produced uniform-sized lesions as compared to the other types of inoculum. These results can provide a basis to design methods to evaluate quantitative resistance to sheath blight in rice.
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