Morpho-cultural and biochemical characterization of Trichoderma isolates and their efficacy in controlling cotton root rot

Trichoderma species are essential for crop productivity, nutrient uptake, abiotic stress resistance and root growth and development. This study was conducted to evaluate the morpho-cultural, biochemical and biocontrol activities of different Trichoderma isolates against cotton root rot. It was observed that maximum mycelial growth (53.67 mm) was recorded by HST2, whereas the least (36.33 mm) was shown by HMT2 after 6 DAI (days after incubation). All the isolates had colonies that ranged in colour from light green to pale green to dark green. The native Trichoderma isolates showed reverse colony colours from creamish white and colourless to yellowish, accompanied by wavy to smooth colony edges. Conidia ranged in length from 2.69 to 4.66 µm. Among the isolates, HFtT produced the longest conidia, with an average length of 4.66 µm. The conidial width of the isolates ranged from 2.31 to 3.65 µm, with the maximum width (3.65 µm) recorded in HFtT. The native HST2 isolate showed positive results for all the biocontrol activities. The antagonistic potential of different native Trichoderma isolates against cotton root rot causing pathogens RB5 and RS2 was evaluated under both in vitro and in vivo conditions. In vitro dual-culture results revealed that HST2 exhibited the highest mycelial growth inhibition (72.78 % in RB5 and 72.50 % in RS2), followed by HMT2. Under in vivo conditions, minimum disease incidence and maximum disease control were shown by HST2 (10 % and 10 %) and (57.13 % and 57.13 %) respectively, in both Desi and American cotton. .