In-vitro antagonism of Trichoderma spp. against Sclerotium rolfsii and Rhizoctonia solani and their response towards growth of cucumber, bottle gourd and bitter gourd

In the current study we evaluated the production of potential growth-promoting metabolites (IAA, phosphate, siderophore) for 20 isolates of Trichoderma collected from different geographical locations of Chhattisgarh and assessed their growth response on cucumber, bottle gourd and bitter gourd. All the Trichoderma isolates were able to release inorganic phosphorus from tri-calcium phosphate and showed consistent ability to produce siderophores and indole-3-acetic acid (IAA). The production of these metabolites varied greatly within species. Using the same set of isolates we evaluated the production of potential cell wall degrading enzymes. Confrontation assays of Trichoderma isolates against two soilborne plant pathogens (Scelrotium rolfsii and Rhizoctonia solani) expressed varying degrees of antagonistic responses, in-vitro antagonism being more effective against R. solani than S. rolfsii. The production of metabolites in all the Trichoderma isolates did not correlate with enhanced growth on cucumber, bottle gourd and bitter gourd, and bio control efficacy. However, one of the Trichoderma viride isolate (T14) was identified as highest producer of inorganic phosphate, IAA and siderophore exhibited high antagonistic and plant growth promoting ability. A characteristic aromatic odour resembling coconut in T14 isolate was observed which we speculate is due to 6-Pentyl pyrone (one of the best studied secondary metabolites having both antifungal and plant growth-promoting activities).