Sharma, ManjuSingh, Priya2019-07-222019-07-222019-06http://krishikosh.egranth.ac.in/handle/1/5810116119The Trichoderma species are of great economic importance due to their ability to control a wide array of plant pathogens. In the present investigation fifteen isolates of Trichoderma were isolated from the rhizospheric soils of soybean, rice and mungbean from various locations of Pantnagar and Dehradun. The isolates were characterized based on their cultural and morphological characteristics. The cultural characteristics included linear growth, colony colour, formation of concentric rings, pigmentation and time taken for sporulation. The morphological characters studied were shape, disposition of phialides, conidial shape, colour and formation of chlamydospores. The isolates were incubated at different temperature regimes ranging from 5 to 40°C to study the effect of various temperatures. There was no growth at 5°C and 40°C. However at temperatures 10, 15, 20, 30 and 35°C, the isolates PT-7, PT-7, DDNT-4, DDNT-4 and PT-10 respectively showed the maximum average linear growth rate (ALGR). While at 25°C, the maximum ALGR (29.83 mm/day) were recorded for the isolates PT-1, PT-8, PT-9, DDNT-4 and DDNT-5. Significantly maximum growth of all the isolates were recorded at 25°C followed by 20°C and 30°C. However, the isolates DDNT-4 and 5 respectively showed 54.60 mm and 54.27 mm colony diameter in three days. The isolates were tested in lab as well in glasshouse for the evaluation of their antagonistic potential against Rhizoctonia solani. They were tested in lab by dual culture, volatile assay and culture filtrate assay. It was observed that in dual culture method isolates PT4, PT-5, PT-8 and DDNT-5 showed complete mycelial parasitization of R. solani at 5 DAC. However in case of volatile compounds maximum inhibition per cent was shown by DDNT-2 (60.74%) while in case of culture filtrate the maximum inhibition per cent was exhibited by isolate PT-10 (71.11%). The glasshouse results revealed that PT-10 (63.67%) was significantly most effective over other treatments in suppressing the aerial blight of soybean. These isolates of Trichoderma were further evaluated for their growth promotion activity under lab and glasshouse conditions. The results obtained from lab studies clearly indicated that PT-2 (15.50 cm) recorded maximum plumule length while DDNT-4 (15.50 cm) showed highest radical length. However, under glasshouse condition DDNT-4 (34.50 cm) recorded maximum shoot length and PT-5 (19.00 cm) showed maximum root length. On the basis of the molecular identification PT-10 and DDNT-4 were identified as Trichoderma harzianum. Overall, PT-10 was found best isolate and can be exploitated in future for enhancing crop yield and suppressing aerial blight of soybean.ennullThesis