Characterization of Trichoderma species from vegetable and spice rhizospheres of Andaman Islands for broad spectrum antagonism and plant growth promotion

Trichoderma isolates from different spice and vegetable rhizosphere niche areas of Andaman Islands were characterized for their in vitro antagonism, lytic enzyme production and plant growth promotion. The in vitro antagonistic results against soil borne pathogens, by dual culture assay revealed that isolates TDK2, TRV 1, TRC 3 showed highest inhibition against S. oryzae (63.3%), F. oxysporum (40.6%) and P. aphanidermatum (40.6%), respectively. In volatile assay the isolate TDK 2 showed highest antagonistic activities against all the three tested pathogens viz., S. oryzae (90%), F. oxysporum(63.3%) and P. aphaidermatum (60%) which was followed by TRV1, TNB6 and TRC3 Trichoderma isolates. Lytic enzyme tests revealed that isolates TRC3 and TDK 2 were rich in cellulase (0.485±0.10 U ml^sup -1^ and 0.702±0.07 U ml^sup -1^), chitinase (3.561±0.34 U ml^sup -1^ and 0.400±0.03 U ml^sup -1^) and protease (0.400±0.03 U ml^sup -1^ and 0.626±0.02 U ml^sup -1^) activities respectively. Growth promotion studies, using paper towel method, revealed that four isolates showed good antagonistic and lytic enzyme activities were also found to increase germination percentage, root length and shoot length when treated with tomato and chilli seeds. The molecular characterization of ITS1 region showed prevalence of four different species viz., T. harzianum, T. asperellum, T. koningiopsis and T. aureoviride among the isolates. The overall results from the above studies revealed that four Trichoderma isolates (TDK2, TRV1, TRC3 and TNB6) belonging to T. aureoviride and T. harzianum from Andaman Islands had better potential for their utilization as broad spectrum bio agents and plant growth promoters either alone or as consortia.