Effects of preharvest foliar applications of calcium chloride, boric acid and zinc sulfate on the postharvest quality of ‘Xuong’ longan (Dimocarpus longan L.) fruit

Longan (Dimocarpus longan Lour.) fruits are highly perishable and tend to lose their quality quickly after harvest due to peel browning, moisture loss and softening, which affect their marketability and storage life. Preharvest application of calcium, boron and zinc may help maintain fruit quality and extend storage life, but their effectiveness in 'Xuong' longan needs further investigation. Therefore, this study aimed to evaluate the effects of preharvest foliar applications of calcium chloride (CaCl₂), boric acid (H₃BO₃), and zinc sulfate (ZnSO₄) at 0.5% on the postharvest quality of ‘Xuồng’ longan fruit. The experiment was arranged in a randomised complete block design with four treatments: control (water foliar application) and foliar applications of 0.5% CaCl₂, H₃BO₃, and ZnSO₄, with five replicates. CaCl₂, H₃BO₃, and ZnSO₄ at 0.5% were applied twice, at 30 and 15 days before harvest. Longan fruits were harvested at 100 days after fruit set and subsequently stored for 7 days at 26 ± 2 °C for quality evaluation. The results showed that preharvest applications of 0.5% CaCl₂, H₃BO₃, and ZnSO₄ reduced the browning index and fruit weight loss while maintaining fruit water content, total soluble solids, and titratable acidity. In addition, preharvest application of 0.5% H₃BO₃ maintained vitamin C and flavonoid contents in the fruit.