Comparative evaluation of native Trichoderma species from groundnut rhizosphere against stem rot caused by Sclerotium rolfsii Sacc.

Sclerotium rolfsii Sacc. is one of the important soil borne pathogen causing stem rot of groundnut prevalent in all growing area worldwide. The present study aimed on the identification of native Trichoderma isolates, and its efficacy against the stem rot pathogen in groundnut at field level. Thirty-five isolates of Trichoderma spp. isolated from the groundnut rhizosphere were comparatively evaluated for their biocontrol potential against S. rolfsii Sacc. and growth promoting traits in groundnut. The morphological studies of the 35 isolates were supported molecularly by amplifying of ITS region and classified into four species namely , T. asperellum , T. citrinoviride, T. longibrachiatum and T. harzianum which were further subjected to biocontrol efficacy tests. The highly efficient representative isolates namely, T. harzianum Thar23, T. asperellum Tasp49, T. longibrachiatum Tlongi5 and T. citrinoviride Tcitri2 were evaluated to produce lytic enzymes and growth promoting traits. The comparative study of these isolates revealed that, T. harzianum Thar23 produced significant (P < 0.05) amount of lytic enzymes viz., chitinase (31.36 U/ml), β 1, 3 glucanase (4.1 U/ml) and protease (2.76 U/ml). T. harzianum Thar23 promotes plant growth traits namely germination efficacy (31.48%), increase in the shoot length (42%) and root length (42.43%), improved vigor index, and increased relative water content (25.56%). Soil application, seed treatment and drenching with the powder formulation of Thar23 in field for the years 2019 and 2020 significantly (P < 0.05) reduced stem rot disease incidence to 59.45% and 53.79% and increased pod yield to 2.85 t/ha and 2.68 t/ha respectively. T. harzianum isolate Thar23 will help the groundnut growers for eco-friendly management of stem rot disease and increased yield.