Brassinosteroid-induced quality enhancement in ‘Flame Seedless’ grapevine: impact on harvest and post-harvest attributes under open and covered cultivation systems

Abstract

Early grape maturation is an important trait for Egypt’s grape export program to meet international market demands on time. A plastic-covering technique along with exogenous brassinosteroids (BR) treatments was used on ‘Flame Seedless’ grapes, in a two-year experiment to assess fruit quality at harvest and during storage. The results indicated that vines protected by plastic cover benefit from early maturation irrespective of BR treatment, with a mean harvest time two weeks earlier than that of grapes grown without the cover. However, this also resulted in a decrease in grape anthocyanin content. The application of BRs could partly compensate for this insufficiency, concurrently enhancing the grapes’ qualitative attributes and storage potential. The upregulation of selected anthocyanin biosynthesis-related genes such as chalcone synthase (CHS), flavanone 3-hydroxylase (F3H), and UDP-glucose-flavonoid 3-O-glucosyltransferase (UFGT) was confirmed to be in a linear and concentration-dependent relationship with BR treatments and associated with significantly increased anthocyanin content. Based on our research, it appears that the combined use of a plastic cover with elevated concentrations of brassinosteroids (0.8 ppm) is a potentially effective strategy for expediting the harvest season and preserving shelf life and the quality of grapes during cold storage.