In vitro efficacy of volatile and non-volatile metabolites of Trichoderma species on rice sheath blight pahogen, Rhizoctonia solani Kuhn

Three native Trichoderma spp viz., T. viride, T. harzianum and T. hamatum were screened for their efficacy in controlling the rice sheath blight pathogen, Rhizoctonia solani Kuhn. In- vitro dual culture studies revealed maximum inhibition of R. solani with T. harzianum (76.47%), followed by T. viride (65.03%) and T. hamatum (63.43%). An inhibition zone was noticed in case of T. harzianum and a yellow halo prevailed in dual culture studies for a period of one week, indicating antibiosis. Screening for production of non-volatile metabolites against the radial growth of R. solani revealed the increase in inhibition of the test pathogen with an increase in concentration of the culture filtrate. Among the three Trichoderma spp., T. harzianum was proved effective in inhibiting the growth of R. solani (44.50% inhibition) at 100% concentration of the culture filtrate, followed by T. hamatum (38.63% inhibition) and T. viride (35.37% inhibition). In case of volatile metabolite production, maximum inhibition of the test pathogen was obtained when the cultures were exposed to 15 and 25 day - old species of Trichoderma spp. Among the Trichoderma spp, maximum inhibition of the radial growth of R. solani was obtained when 25-day-old culture of T. harzianum (49.17% inhibition) was used, followed by T. viride (36.63%) and T. hamatum (36.37%).