Effects of Preharvest Gibberellin Treatments on the Room-temperature Storability of ‘Shixia’ Longan Fruit
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Abstract:
At 85 and 95 days after flowering, ‘Shixia’ longan fruits were treated with four treatments (T1-4): gibberellin 920 containing 50 mg/L GA3 (T1), gibberellin 920 with 150 mg/L GA3 (T2), 2,4-epibrassinolide combined with gibberellic acid consisting of 50 mg/L (GA4+GA7) + 0.33 mg/L EBRs (T3), and 2,4-epibrassinolide combined/gibberellic acid with 150 mg/L (GA4+GA7) + 1 mg/L EBRs (T4)]. A control group was established by spraying the fruits with water. The commercially mature fruits were harvested and stored at room temperature (25±1 ℃, relative humidity of 85%) to evaluate the effect of each treatment on the physiology, quality, and storability of the fruits. The results showed that except T4, the other three treatments reduced the rotting rate, weight loss rate, endocarp browning, and pulp breakdown of longan during storage and T1 exhibited the most significant effects. T1 significantly delayed the decrease in L*, b*, h°, and C* values; increase in a* values and relative electrical conductivity; and decrease in total phenolic and flavonoid contents during storage. The total antioxidant capacity of the pericarp of the T1 group was consistently higher than that of the control group. Additionally, the activities of polyphenol oxidase, laccase, and peroxidase in the T1 pericarp were significantly lower than those in the control at the late storage stages. However, the activities of catalase and ascorbate peroxidase were higher in the T1 pericarp. T1 did not significantly affect the contents of total soluble solids, titratable acidity, and vitamin C in longan pulp. The remarkable effects of T1 on delaying pulp breakdown may be related to its significant reduction of activities of polygalacturonase and β-galactosidase in the middle and late storage stages. Therefore, preharvest 920 (50 mg/L GA3) spraying delays the pericarp browning and pulp breakdown of ‘Shixia’ longan during room-temperature storage. These results provide an important reference for improving the storability of longan by preharvest hormone treatments.
