Exploration of indigenous Trichoderma species for their use as biofertilizers, optimization of growth conditions and cultivation on cheap substrates

Members of the genus Trichoderma have substantially improved the agricultural economy through inhibitingthe phytopathogens, assimilating nutrients and inducing defensive metabolism against the environmental stresses.The major aim of this study was to isolate indigenous Trichoderma that can be used as a potential biocontrolagent (BCA). Currently, we isolated 14 native fungal isolates from vermicompost, agricultural soils and infectedsubstrates, and identified them as Trichoderma spp. based on their morphological characteristics. Isolatesdesignated V1D, V1F, V3D, V3F, W1, W2, KAL, NAR, BIOC, AG, RD and NIM resembled to T. viride, whileMUSH and RF resembled T. harzianum. The ability of these isolates to assimilate different forms of sugars,nitrogen source (N) and phosphates (PO4) were evaluated qualitatively. Isolates showed differing solubilizationzones (cm) in agar plates containing cellulose (1.8-9.5 cm), amylose (0.1-2.1 cm), tri-calcium phosphate (0.1-0.17cm) and di-calcium phosphate (0.33-0.53 cm), to substantiate their biofertilizer potentialities. Confrontation assaywith dual culture technique against seven phytopathogens (i.e. Rhizoctonia solani, Aspergillus niger, Sclerotiniasclerotiorum, S. rolfsii, Fusarium solani, F. oxysporum and Botryodiplodia theobromae) revealed promisingmycoparasitic activity. Three isolates (MUSH, BIOC and V3F) showed mycelial growth inhibition in the range of33-77%, compared to the control plate (without isolates). With respect to isolate MUSH, a significantly higher(P< 0.05) dry biomass weight (g) was obtained at pH 7 (0.66 ± 0.05) and pH 6 (0.55 ± 0.05), than at pH 3, pH 4and pH 5. Similarly, higher biomass significance (P< 0.001) was obtained in yeast mannitol broth (2.58 ± 0.11 g),compared to potato dextrose broth (PDB) and nutrient broth (NB). The production of spores by isolate MUSHwas tested on four locally available solid substrates (i.e. corn stalk, rice husk, jackfruit molasses and sugarcanebagasse) through solid state fermentation (SSF). Production of conidia (cfu/g) was higher in corn stalk (72.6×108), followed by rice husk (68.4×108), jackfruit molasses (18.6×108) and sugarcane bagasse (12.4×108). Highcounts of conidia production on these substrates render MUSH isolate efficient to be used as a BCA by thefarmers, to enhance their crop productivity.