Effect of biotic and abiotic inducers on induction of defense enzymes in sunflower

The present study explores the ability of biotic and abiotic agents as inducers to stimulate the plant immunity assessed through bio chemical estimations and to control the spread of fungal pathogen Alternariaster helianthi (Hansf.) E.G. Simmons in infected plants. Three chemical inducers α-Amino Butyric Acid (AABA), Ɣ-Amino Butyric Acid (GABA) and Salycilic Acid (SA) and two biological agents Trichoderma harizanum and Pseudomonas fluorescens as biological inducers on eight sunflower genotypes were studied. Bio chemical estimations of known plant defense enzymes viz., total phenols, peroxidases, total sugars, Phenyl Annine Lyase (PAL) and catalase were done spectro photo metrically at different intervals to understand the efficacy of inducers in developing resistance in plants. Among all the inducers tested GABA has shown effective response in systemic induction of resistance, followed by T. harizanum. All treated plants has shown high release of components at 18hours after inducer application. Observed defensive response of sunflower plants against the pathogen is different in inducer treated plant from untreated plant. In conclusion, chemical inducer GABA should be considered excellent and the results indicate that a comprehensive evaluation of inducers is advisable as they combine both direct antifungal activity against the targeted pathogen and the ability to develop prime plant immunity against various infections.