Activities of Defensive Antioxidant Enzymes and Biochemical Compounds Induced by Bioagents in Indian Mustard Against Alternaria Blight

In the present investigation, Trichoderma harzianum Rifai and Pseudomonas fluorescens Flügge alone, and in various combinations were evaluated in field conditions for their efficacy to induce resistance related enzymes viz., peroxidase (POD), superoxide dismutase (SOD), polyphenol oxidase (PPO), phenylalanine ammonia lyase (PAL), lypoxigenase (LOX), catalase (CAT), ascorbate peroxidase (APX) and other biochemical compounds viz., proline, melondialdehyde content, total phenolic and hydrogen peroxide against Alternaria blight and to promote plant vigour. Results indicated that combination of two Trichoderma isolates increased the plant vigour and reduced the disease severity by 50.9% as compared to control (84.3%). Mustard seeds treated with bioagents, followed by inoculation with Alternaria brassicae showed enhanced activities of defense enzymes such as POD, SOD, PPO, PAL, LOX, CAT, APX and other defense related compounds as compared to control bioassay. The authors conclude that biotic induced resistance can be an ecofriendly alternative to fungicides in managing Alternaria blight and also to promote plant vigour in Indian mustard.