Relative Bio-Efficacy And Shelf-Life of Mycelial Fragments, Conidia and Chlamydospores of Trichoderma harzianum

Fungal biocontrol agent Trichoderma harzianum developed mycelium and chlamydospores in liquid medium (potato dextrose broth) at 28°C in 4 and 10 days, respectively, while on solid media (PDA, grains, wheat bran, etc.) it produced conidia. When chlamydospores were inoculated on solid medium they produced profuse conidia. Lower sugar concentration of growth medium supported chlamydospore development but at higher concentrations maximum mycelial growth and conidia were developed. Higher temperature (>30°C) and pH (>7.0) resulted maximum sporulation (specially chlamydospores). Chlamydospores based formulation exhibited comparatively long shelf-life than that of conidia and mycelial fragments, by >75% viability after 9 month of storage at room temperature, while at low temperatures it retained similar viability for more than 12 months. When applied as seed bio-priming, all propagules resulted similar results on seed germination and post emergence seedling mortality. In field experiments, mycelial fragments based formulation exhibited better results than other propagules when applied as normal seed treatment (sowing of seeds just after treatment).