Regulation Effect of Exogenous Salicylic Acid Treatment on the Softening of Postharvest Blueberry Fruit

To explore the regulatory effect of exogenous salicylic acid treatment on the softening of postharvest blueberry fruit and the optimal regulatory concentration, three different concentrations（0.5, 1.0, 1.5 mmol/L） of exogenous salicylic acid were used to treat the postharvest‘Lanfeng’ blueberry fruits. The regulatory effects of exogenous salicylic acid treatment on the softening of postharvest blueberry fruits were investigated by measuring the changes of fruit firmness, decay rate, weight loss rate and soluble solid content（SSC） and the changes in cell wall hydrolase activities such as pectin esterase（PE）, polygalacturonase（PG） and cellulase（Cx） during shelf life at room temperature. The results showed that exogenous salicylic acid treatment could effectively delay the decline of firmness of blueberry fruits. From the 2nd day of shelf life at room temperature, the firmness of blueberry fruits in1.0 mmol/L concentration of salicylic acid treatment group was significantly higher than that in control group, and on the 8th day of shelf life at room temperature, the firmness of the fruits in 1.0 mmol/L concentration of salicylic acid treatment group was 70% higher than that in control group. Compared with the control group, 1.0 mmol/L salicylic acid treatment could delay the occurrence of fruit decay for 2 days, effectively reduce the fruit weight loss rate,and maintain stable content of SSC. The 1.0 mmol/L concentration of salicylic acid treatment significantly inhibited the increase of PE and PG activities in blueberries, thereby delay fruit softening. In conclusion, exogenous salicylic acid treatment has a certain regulatory effect on the softening of postharvest blueberry fruit, among which 1.0 mmol/L was the optimal salicylate treatment concentration for inhibiting fruit softening, which can delay the softening of postharvest blueberry fruits by inhibiting the activities of PE and PG.