Cultural studies on Ustilaginoidea virens, the incitant of false smut of rice (Oryza sativa)

A study was carried out to find out the favourable culture media for mass multiplication and the effect of carbon sources and duration on chlamydospore germination of Ustilaginoidea virens (Cook.) Tak. Different synthetic and semi synthetic solid, liquid media, substrate media were evaluated for mass multiplication of U. virens. Potato sucrose broth was the best medium for fast mycelia growth (104.80 mg) and sporulation (6.78 x 10(5) spores/ml), potato dextrose broth also favored mycelial growth, whereas corn meal dextrose broth was not suitable. Out of four solid media tested, maximum colony diameter (68.74 mm) and sporulation (6.86 x 10(5) spores/ml) was produced by potato sucrose agar followed by potato dextrose agar. Maximum sporulation was produced on substrate media based on barley seeds (5.54 x 10(5) spores/ml) followed by rice seeds (3.72 x 10(5) spores/ml) whereas rice husk based media produced minimum sporulation. Higher concentration of sucrose and dextrose at 2 per cent supported maximum germination of spores of U. virens and sucrose was found superior in inducing germination than dextrose. The results of this study help to understand the physiological and biochemical requirements for the growth and development of the pathogen, which could serve as an input in disease management to minimize the effect of false smut disease on rice.