Valorization of Spent Oyster Mushroom Substrate with Trichoderma asperellum for Suppression of Sesame Root Rot In Vitro

Spent mushroom substrate (SMS) is an important by-product of the mushroom industry having tremendous potential as a bio-fertilizer, soil amendment, plant protectant, animal feed, and renewable energy source. An investigation was performed to examine its microbial diversity and potentiality in sesame root rot management in association with antagonistic microbial inoculants in vitro. The investigation revealed that SMS gathers different fungal genera such as Penicillium, Rhizopus, Aspergillus, Trichoderma, and Pleurotus which were found antagonists to Macrophomina phaseolina in dual culture. In pot culture, Trichoderma-enriched SMS promoted germination (86.67%), suppressed the disease severity up to an appreciable limit (68.86%), and promoted plant growth such as plant heights (45.67 cm), fresh weight (4.02 g), dry weight (1.18 g), number of capsules (9.0) as compared to others. In addition, GC-MS analysis of ethyl acetate fractions of culture filtrates of Trichoderma asperellum showed the abundant presence of antifungal volatile compound 6-Pentyl-2 H-pyran-2-one (22.02%). FTIR spectra of SMS in comparison to unused straw substrate revealed the presence of different functional groups like water, alcohols, phenols, alkynes, amide, amines, and alkyl halides having different stretching. These findings indicate that SMS has the potential to suppress root rot of sesame and augment plant growth in association with the fungal antagonist T. asperellum.