Salicylic acid induced systemic resistance on onion plants against Stemphylium vesicarium

Abstract

This study investigated the induced defense responses and protective effects against Stemphylium vesicarium by application of Salicylic Acid (SA). The effect of SA to induce resistance in onion plants against Stemphylium vesicarium was investigated in greenhouse conditions. Different doses of SA (1, 2 and 5 mM) were tested in vitro; growth of S. vesicarium was not affected by SA treatment, foliage sprays of 2 mM SA significantly suppressed disease development up to 40.39% by day 15 after inoculation under greenhouse conditions. Changes in the activities of peroxidase, polyphenoloxidase, SA and phenolic content on onion after application of SA and inoculation with S. vesicarium were studied. Onion plants treated by SA and inoculated with the pathogen showed significantly higher peroxidase, poly phenoloxidase, SA content and phenolic content than inoculated water-treated plants.