Trichoderma spp. of west bengal tea cropping system: Study on cultural characteristics and conidia production potency

Fungi belonging to the genus Trichoderma possess a tremendous antagonism in managing the pathogens causing various diseases in crops. The rate of mycelial growth and the number of spores of antagonists have a direct impact on the control of phytopathogens. Six Trichoderma strains developed at Tea Research Association, North Bengal Regional Research and Development Centre, Nagrakata were evaluated for their rate of mycelial growth and sporulation under laboratory conditions through test tube and Petriplate culture methods. Investigations revealed that all the isolates were fast-growing, they started to grow after 6 hours of inoculation on an artificial medium (Potato dextrose agar). Isolates exhibited small variation in their growth rate, initiation of conidiation, and color of conidia. The mycelial growth rate of isolate KBN-24 and KBN-34 was very fast, however, it was slower in isolate KBN-29 and KBN-32. They produced light yellow, light green, and dark green conidia. Diffusion of yellow pigment was also noticed in isolate KBN-33. The earliest conidiation was observed in isolate KBN-33. Isolate KBN-32 and KBN-24 could produce conidia after 72 hours, however; isolate KBN-34, KBN-29 and KBN-35 produced after 96 hours of inoculation. In Petri plates, isolates produced dull-white, light cream, and white-colored mycelia and also showed variations in the number of concentric rings of conidia. Three isolates were found to be fast-growing and covered the entire surface area of the plate within 72 hours. All the isolates produced 78.6 to 310.7 × 10⁸/ mL conidia after a month of inoculation indicating their suitability as promising antagonists.

• Trichoderma strains could be applied to manage soil-borne fungal pathogens of tea plantations.