From Fruit Development to Harvest: Impact of Exogenous Sorbitol on Physico-Chemical Traits and Yield of Pomegranate Fruit

The ‘Mollar de Elche’ pomegranate cultivar is highly valued for its organoleptic properties, yet it often suffers from inadequate fruit pigmentation, reducing its commercial competitiveness. This study, carried out in a mature commercial orchard located in Spain (Alicante), evaluated the impact of preharvest applications of sorbitol at different concentrations (0, 0.1, 0.5, and 1% in 2023, and 2.5 and 5% in 2024) and three application periods: S1 (nine applications from fruit set), S2 (six applications from seed hardening), and S3 (three applications at the onset of colour change) over two consecutive growing seasons (2023 and 2024). Treatments were applied via foliar spraying from the time of fruit set until the onset of external colour change. The results showed that sorbitol acted as an effective metabolic ‘vector’, significantly increasing fruit weight and total yield, particularly at concentrations of 1 and 5%. Furthermore, sorbitol treatments enhanced fruit firmness by stabilizing cell wall structures and significantly improved exocarp red pigmentation by reducing the hue angle. While the highest doses (1, 2.5, and 5%) enhanced biomass accumulation, they also triggered a potential negative feedback loop in sugar sensing that could interfere with secondary metabolism at excessive thresholds. These findings suggest that preharvest sorbitol applications, particularly at concentrations between 1 and 5% starting from early application period (S1), serve as an effective strategy for improving yield and external pigmentation in ‘Mollar de Elche’ pomegranate fruit.