Impact of Hydrogen Peroxide on Early Ripening of Thompson Seedless Grapes

Abstract

An experiment was conducted during 2023–2024 at the ICAR-National Research Centre for Grapes, Pune, to evaluate the effect of exogenous hydrogen peroxide (H₂O₂) on the ripening, yield, berry quality, and biochemical attributes of Thompson Seedless grape (Vitis vinifera L.). Twelve-year-old vines grafted on Dogridge rootstock were arranged in a randomised block design with five treatments and four replications. The vines received a single foliar spray of H₂O₂ at 0.1, 0.2, 0.4, or 0.8 ppm at veraison, while untreated vines served as the control. All H₂O₂ treatments advanced berry ripening compared with the control. The 0.8 ppm treatment produced the most favourable response, enabling harvest at 108 days after pruning and approximately 15–20 days earlier than the usual harvest period. At harvest, this treatment recorded the highest total soluble solids (20.20 °B), TSS/acidity ratio (32.41), bunch weight (393.03 g), 10-berry weight (39.27 g), and yield per vine (15.72 kg), together with the lowest acidity (0.62%). It also recorded the highest observed phenolic, tannin, proline, reducing-sugar, flavonoid, carbohydrate, protein, and chlorophyll values. Yield per vine was strongly correlated with bunch weight and 10-berry weight, whereas total soluble solids were inversely correlated with acidity. These results indicate that a single low-concentration H₂O₂ application at veraison can promote earlier ripening while supporting favourable yield, berry-quality, and biochemical responses in Thompson Seedless grapes under the conditions of this study.