Characterization of Rhizoctonia oryzae associated with sheath blight complex of rice from Haryana

Abstract

Sheath Blight Disease of rice is a complex biotic stress, caused by three Rhizoctonia speices namely, Rhizoctonia solani, R. oryzae and R. oryzae-sativae. to determine the extent of distribution of these pathogen species, infected samples showing sheath blight symptoms were collected from different rice cultivars grown in three agro-ecological zones of Haryana, India during August, 2016. The isolations attempted from 67 sheath blight infected samples yielded R. solani from 66 samples and R. oryzae from one sample indicating that R. oryzae was associated with sheath blight complex only to the extent of 1.5 per cent. none of the samples was found to be infected with R. oryzae-sativae. R. oryzae was found less pathogenic with 41.97 per cent relative lesion height (RLh) and 57.5 per cent tiller infection as compared to representative isolate of R. solani which produced 52.74 per cent RLh and 100 per cent tiller infection. R. oryzae had a growth rate of 1.82 mm/h, the mycelial width of 6.74 μm with appressed type of growth texture on PDa. the mean number sclerotia produced by R. oryzae were 201.33 per plate that were found immersed in PDa agar medium with peripheral arrangement. the rDna sequence of R. oryzae isolate of haryana has been submitted to nCBI with accession number Mk249694.1.