Preharvest sorbitol application modulates phytohormone profiles and enhances nutraceutical quality of extra-early...

Foliar sorbitol applications (1, 2, and 5%) at different developmental stages were assessed in extra-early nectarines. Early, high-dose treatments (5% E1) acted as potent metabolic modulators, shifting the hormonal balance by increasing abscisic acid (ABA), indole-3-acetic acid (IAA), and ethylene signaling, promoting advanced ripening and concentrated harvest. This hormonal regulation was associated with enhanced accumulation of high-value phytochemicals: significantly enhancing peel anthocyanins (e.g., cyanidin-3-glucoside), total phenolics (chlorogenic acid, flavan-3-ols), and carotenoids, leading to superior antioxidant activity. Flesh quality was improved by increases in ascorbic acid (Vitamin C) and total organic acids (citric and malic), enhancing flavor chemistry. However, 5% E1 also caused the lowest firmness and elevated oxidative markers (MDA), potentially compromising postharvest life. Conversely, late, low-dose applications (E3) preserved firmness and reduced respiration/ethylene, suggesting potential for extended stability. Overall, sorbitol represents a practical agronomic tool to modulate fruit quality and harvest dynamics, increasing marketable yield and grower returns.