Susceptibility of Two Grape Varieties to Berry Abscission

Berry abscission is a serious problem in table grape during postharvest storage and transport, causing significant economic losses. To explore the mechanism of berry abscission, we compared the abscission-susceptible grape genotype 'Hutai No. 8' with the abscission-resistant grape genotype 'Xiangfei' during post-harvest storage. Compared with 'Xiangfei', in 'Hutai No. 8', the berry detachment force was lower and the berry abscission percentage was higher; the contents of auxin and gibberellin in the berries, rachis and abscission zone were lower, and the contents of abscisic acid and ethylene were higher. Compared with 'Xiangfei', 'Hutai No. 8' had higher activities cell wall-degrading enzymes in the abscission zone; lower contents of total pectin and intact pectin fractions, and higher contents of degraded pectin. The activities of antioxidant enzymes in the abscission zone were lower in 'Hutai No. 8' than in 'Xiangfei', resulting in higher contents of reactive oxygen species and malondialdehyde, and higher relative conductivity. The distribution of calcium in different fractions differed between the two varieties. Ultimately, these differences resulted in softer berries and higher berry weight loss percentage and decay percentage in 'Hutai No. 8' than in 'Xiangfei' during storage. These results shed light on the mechanism of grape berry abscission during storage.