Effects of postharvest salicylic acid dipping on Alternaria rot and disease resistance of jujube fruit during storage

Background Considerable postharvest losses caused by Alternaria alternata often occur in Chinese jujube fruit, and synthetic fungicides have been widely used to protect the fruit from Alternaria rot. However, the potential harmfulness of fungicide residues to human health and the environment cannot be ignored. This study was conducted to develop an alternative approach for controlling postharvest disease by inducing fruit resistance with salicylic acid (SA) dipping. Results Disease incidence and lesion area in the jujube fruit inoculated with A. alternata were significantly inhibited by 2 and 2.5 mmol L-1 SA dipping. Naturally infected decay rate and index in jujubes were also significantly reduced by SA dipping during long-term storage at 0 degrees C. SA enhanced activities of the main defense-related enzymes including phenylalanine ammonia-lyase, peroxidase, chitinase and -1,3-glucanase in the fruit during storage. SA strongly decreased catalase activity but increased superoxide dismutase activity and ascorbic acid content in jujubes. Conclusion The beneficial effects of SA on fruit protection may be due to its ability to activate several highly coordinated defence-related systems in jujubes, instead of its fungicidal activity. The findings indicated that application of SA would offer an alternative approach that helps to control postharvest disease and maintain storage quality in fruits. (c) 2013 Society of Chemical Industry