06-08-2013, 04:37 PM
Effect of different media on the growth and sclerotial development of Rhizoctonia solani causing sheath blight of rice.
ABSTRACT
Effect of different media on growth and sclerotial development of Rhizoctonia solani showed that there was variation in radial growth, growth pattern and hyphal width of R. solani. Maximum growth was recorded in Potato Dextrose Agar (45.0 mm) followed by Oat meal agar (44.5 mm) where as the least growth was observed in Richard’s medium (26.0 mm). Mycelial colour of R. solani varied from creamish white to off-white in different media whereas, growth pattern also varied from fluffy to suppressed hypha. The maximum hyphal width of mycelium was found on PDA (8.14 µm) followed by Oat Meal Agar (7.00 µm) and the minimum hyphal width was found on Malt Extract Peptone Agar (5.60 µm). Similarly sclerotial position, size of sclerotia, number of sclerotia and shape of sclerotia on different media also varied considerably. The position of sclerotia on Potato Dextrose Agar, Richard’s medium, Host extract, Sabourand’s agar, Malt extract peptone dextrose agar and Asthana and Hawker agar were in centre and on Oat meal agar, Czpeck dox agar, Corn meal agar and Malt and yeast extract were towards the periphery of petri plates where as the maximum size of sclerotia was found on Potato Dextrose Agar (2.06 mm) which significantly differed from rest of the sclerotial size and the minimum sclerotial size was found on Host extract (0.31 mm). Maximum number of sclerotia were found on Potato Dextrose Agar (183) followed by Oat meal agar (160) where as the least number of sclerotia were found on Host extract (18). The shape of sclerotia varied from round and rough (PDA) through round and smooth (Oat meal agar, Czapeck dox agar, Richard’s medium, host extract Sabourand’s agar and Asthana and Hawker agar) to serrated (Corn meal agar, Malt and yeast extract and Malt extract peptone dextrose agar).