采前赤霉素处理对‘石硖’龙眼常温贮藏性的影响

Effects of Preharvest Gibberellin Treatments on the Room-temperature Storability of ‘Shixia’ Longan Fruit

摘要:

花后85 d+95 d以含50 mg/L GA3（T1）和150 mg/L GA3（T2）的赤霉素920、含50 mg/L (GA4+GA7)+0.33 mg/L EBRs（T3）和150 mg/L (GA4+GA7)+1 mg/L EBRs（T4）的2,4-表芸苔•赤霉酸及对照（清水）喷施处理‘石硖’龙眼，商业成熟后采收，于常温下（25±1 ℃，相对湿度85%）贮藏，分析各处理对生理、品质和贮藏性的影响。结果表明，T1、T2、T3可延缓龙眼腐烂、质量损失、内果皮褐变和果肉自溶，T1效果最显著。T1显著延缓果皮的色度L*、b*、h°和C*值下降、a*值的上升、相对电导率的升高、总酚和类黄酮含量的下降。T1组果皮的总抗氧化能力平行高于对照，贮藏后期的多酚氧化酶、漆酶和过氧化物酶活性显著低于对照，而过氧化氢酶和抗坏血酸过氧化物酶的活性高于对照。T1处理未显著影响果肉TSS、TA和维生素C含量。T1延缓果肉自溶的显著效果可能与其显著下调贮藏中后期多聚半乳糖醛酸酶和β-半乳糖苷酶的活性。因此，采前920（50 mg/L GA3）喷施有效延缓常温贮藏‘石硖’的果皮褐变和果肉自溶，可为采前激素处理提升龙眼贮藏性提供重要参考。

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.