Abstract
Colour enhancement in red table grapes is critical for consumer acceptance and market value. This study investigated the effects of Abscisic Acid (ABA) and Ethephon applications on berry colour development, anthocyanin accumulation, and biochemical parameters in ‘Red Globe’ seeded grapes. Research was conducted at the ICAR-National Research Centre for Grapes, Pune, during the 2022–2023 fruiting season. Twelve treatments comprising varying concentrations of ABA (200, 400, 600 ppm), Ethephon (100, 200 ppm), their combinations, and a control were applied at veraison and 10 days post-veraison in a randomized block design with three replications. Results demonstrated that ABA at 400 ppm (T2) produced optimal berry colour development (4.2 scale value) with significant anthocyanin accumulation (13.86 mg/100 g) and colour intensity (4.42%). While higher concentrations of ABA and Ethephon, particularly in combination, yielded more intense colouration, this exceeded the characteristic red hue desired in ‘Red Globe’ grapes. Significant increases in flavonoid content were observed across treatments (p < 0.01), with highest levels (46.56 mg/100 g) in T11 (ABA @ 600 ppm + Ethephon @ 200 ppm) compared to control (38.98 mg/100 g). Treatments showed non-significant effects on phenolic compounds, tannins, proteins, and carbohydrates. This research provides evidence-based recommendations for commercial grape production, suggesting ABA at 400 ppm as an optimal exogenous application for desirable colour development in ‘Red Globe’ grapes under subtropical conditions.