Effects of Pre-harvest Salicylic Acid Treatment on Ripening and Softening of Muskmelon Fruits

The aim of this work was to study the mechanism for the delaying effect of pre-harvest salicylic acid treatment on the ripening and softening of muskmelon fruits. The Jin tian mi muskmelon fruit was sprayed with 1.0 mmol/L of salicylic acid for four times at different stages: young fruit stage(2 weeks after flowering), fruit enlarging stage(3weeks after flowering), netting stage(4 weeks after flowering) and 48 h before harvesting. The post-harvest muskmelon was stored at low temperature((7 ± 1) ℃, relative humidity 85 %). The fruit firmness, cellulose content, protopectin content,cellulase(Cx), polygalacturonase(PG), β-glucosidase activities related to the ripening and softening of muskmelon were determined at regular intervals during storage. The results showed that the pre-harvest salicylic acid treatment(1.0 mmol/L)could effectively inhibit the decrease of firmness and protopectin content, delay the increase of soluble pectin content, inhibit the PG, Cx, β-glucosidase activities of muskmelon during storage. The ripening and softening of muskmelon were delayed effectively. In conclusion, salicylic acid treatment significantly inhibited the PG, cellulase and β-glucosidase activities to effectively delay the decrease of the fruit firmness, and therefore delayed the ripening and softening of muskmelon fruits.