Effect of humic acid, seaweed extract and essential oils as antioxidants on pre-and post-harvest quality of red radish plants

Abstract

This study was carried out to assess the effect of certain biomodulators, namely seaweed extract, humic acid, peppermint and thyme oils, on quality-related metabolites during both pre- and post-harvest of Red radish. For this purpose, plants were sprayed with tested biomodulators twice, 20 and 30 days after sowing, and chosen biochemical constituents affecting quality were estimated before harvest, and again in roots of harvested plants after storage in standard cold storage. In addition, to evaluate the involvement of each tested parameter in post-harvest quality of stored roots, a correlation matrix between biochemical constituents after storage and quality parameters of stored roots represented by weight loss and post-harvest decay percentage as well as stored root‘s dry matter percentage. Results indicated that the adopted biomodulators affected the metabolism of treated plants in a way that persisted after storage, hence positively affected roots post-storage quality attributes. Invariably, stored roots of biomodulators-treated plants contained higher concentrations from total anthocyanins, ascorbic acid, total phenols, nutrients concentration as well as flavonoids compared with those of control plants. Moreover, activity of both peroxidase and polyphenol oxidase was higher in stored roots of biomodulators-treated plants. In addition, all applied biomodulators decreased weight loss and post-harvest decay percentage, thus roots of biomodulators-treated plants contained higher dry matter compared with roots of untreated plants. The metabolic and physiological bases of biomodulators-induced quality parameters of roots after storage were discussed.