24-epibrassinolide enhanced the quality parameters and phytochemical contents of table grape.

Enhancing the nutritional quality of fruits using safe and environmental friendly methods has become of the most important targets in modern fruit production systems. Brassinosteroids, a new group of phytohormones with positive roles on human health, have been shown to modulate a wide range of plant activities and enhance fruit quality in some crops. This study was conducted to examine the effect of 24-Epibrassinolide (EBL), a synthetic brassinosteroid, on quality attributes and some active bio-compounds of “Thompson seedless” table grapes. Grape vines and bunches were sprayed with EBL (at 0, 3 and/or 6 µmol L-1) at three different stages (4 weeks after fool bloom, veraison stage and 1 day before harvest). As a novel finding in seedless grapes, exogenous EBL substantially enhanced soluble solids content, total organic acids, antioxidants, phenolics and ascorbic acid levels in treated berries. Also the activity of catalase and polyphenol oxidase enzymes was increased. There was no significant difference between the two brassinosteroid levels in most cases. EBL showed a good potential for enhancing table grape phytonutrients, nutritional quality and phytochemical contents and is introduced as a safe compound to be used in table grape production programs.