Effects of Gibberellin On Endogenous Hormone Status and Quality of “Dong” Jujube Fruit During Postharvest Storage

Fresh ''Dong" Jujube fruit rich in soluble sugars and vitamin C is commonly consumed in northern China. An experiment was conducted to evaluate endogenous hormone status and postharvest quality of fresh 'Dong" Jujube as affected by exogenous application of gibberellin. After harvest, fruits were spayed with gibberellin at different concentrations (40, 80, 120 and 160 mg/L) and then stored at 10℃. A plain water spay was used as control. Fruit samples were assessed at 1, 5, 9, 13, 17, and 21 days after the treatment. Gibberellin application caused significant changes in the contents of abscisic acid (ABA), gibberellic acid (GA), heteroauxin (IAA), and zeatin riboside (ZR) in the fruits. GA content in the control treatment reached the peak value on the 9^th day while in the 80 mg/L treatment it appeared on the 13^th day. Contents of IAA and ZR increased gradually and reached their maximum values on the 17^th day in the fruits treated with 80 mg/L gibberellin. In contrast, IAA and ZR levels were highest on the 13^th day in the control. In addition, the 80 mg/L treatment showed a lower ABA level compared with the control during storage. Firmness, soluble sugar, and vitamin C in the control fruits tended to decline during storage; however, the postharvest quality of fruits was improved by the gibberellin spray at 80 mg/L. For instance, firmness and contents of soluble sugar and vitamin C in gibberellin treated fruits were 36.5%, 16.7%, and 167.3% higher on average than that of control throughout the storage, respectively. Among all the concentrations tested, gibberellin at 80 mg/L demonstrated the greatest potential for its application in postharvest storage of “Dong” Jujube fruits. It was estimated that exogenous spray of gibberellin at 80mg/L could extend the fruit shelf life by 3 to 5 days at 10℃.