EVALUATION OF BIOLOGICAL EFFICACY OF TRICHODERMA SPECIES ISOLATES AGAINST ALTERNARIA LEAF SPOT DISEASE OF SESAME

摘要

Alternaria leaf spot disease is a major threat to sesame (Sesamum orientale L.) caused by Alternari asesami. Induced resistance is an alternative to systemic disease resistance response of plants. The present study aims to evaluate Trichoderma species efficacy as biocontrol via induction of resistance against A. sesami in sesame species. During in vitro bio control test, T. harzianum colonize and parallely inhibit the growth of the fungal pathogen. Expression of various defence related enzymes observed in sesame induce resistance against the pathogen infection in the host. T. harzianum coupled with inoculation of A. sesami enhance the remarkable induction of defence enzyme such as peroxidase (POX), polyphenol oxidase (PPO), phenylalanine ammonia lyase (PAL) and also the phenolic content compared with the control. The enzyme activity increased from 48 h of sampling and peaked at 72 h and then decreased after 72 h. In greenhouse and field experiments, soil treatment with a powder formulation of T. harzianum two weeks before planting or at the time of planting reduced significantly the incidence of diseases on both the wild and cultivar Thilarani.The results demonstrate that T. harzianumcan be successfully applied as a biological control against Alternaria leaf spot disease in sesame.