Effects of Preharvest Boron, Calcium Sulfate Treatment and Postharvest Calcium Chloride Peduncle Infiltration on Chilling Injury Alleviation of Queen Pineapple Cv. Sawi Fruit

The aim of this study was to determine the incorporative effects of preharvest boron (B) or calcium sulfate (CaSO₄) application and postharvest calcium chloride (CaCl₂) peduncle infiltration on chilling injury (CI) alleviation of Queen pineapple during commercial cold storage (13°C). Pineapple fruits were sprayed with 0.25% B four times a month after one month of anthesis, or CaSO₄ (100 kg per 400 m²) was applied during fruit development. The fruits were harvested after 135 days of flower induction. Both preharvest B and treated fruits were then peduncle-infiltrated with 2% CaCl₂ for 3 days and stored at cold temperature (CT) for 14 days. Control fruits were not peduncle-infiltrated with CaCl₂.Visual appearance of half cut fruit, CI score, the amount of fruit having CI, colour attributes, browning index (BI) value and electrolyte leakage (EL) of tissue adjacent to the core were determined after storage at CT for 7 or 14 days, followed by leaving at room temperature (RT), 28 ± 1°C, for 2 days. The results show that the incorporative application of preharvest CaSO₄ with CaCl₂ peduncle infiltration (CaSO4+CaCl2) alleviated CI, delayed decrease in lightness (L*) and chroma values, and also increased BI and total colour difference (∆E*) values during storage compared with control and the incorporative application of preharvest B with CaCl₂ treatment (B + CaCl₂). The treatment with CaSO₄ + CaCl₂ lowered CI severity and the amount of fruit having CI when compared to B + CaCl₂ and control treatments, respectively. Both treatments had no effect on the hue value over the storage period. Therefore, CaSO₄ + CaCl₂ treatment is an alternative method for alleviating CI of Queen pineapples.

Keywords: Queen pineapple; CaSO₄; boron; CaCl₂; chilling injury

*Corresponding author: E-mail: suriyan.su@kmitl.ac.th