The Timing of Exogenous Ethylene Application Affects the Sugar Content and Quality of Early Harvested Melons

Melon (Cucumis melo L. var. Cantaloupe) is a climacteric fruit susceptible to postharvest damage. Early fruit harvesting can increase the shelf life of melon fruit, but early harvested fruit has low sugar content, and the color of the fruit flesh is less attractive. This study evaluated the effects of exogenous ethylene and its application time in increasing the sugar content and quality of early harvested melon during storage. Melon fruit was treated without exogenous ethylene application (control) and exogenous ethylene application (Ethrel) at a concentration of 100 ppm with application times of 0, 3, 6, and 9 (d0, d3, d6, and d9) days after harvesting (DAH). In the exogenous ethylene application, melon fruit was soaked in an exogenous ethylene solution for 1 minute and dried in air. Furthermore, melons were stored in an ambient room (28 ± 1 ◦C and 80 ± 5% RH) for 21 days. The results showed that 100 ppm ethylene treatment at 6 DAH (d6) accelerated the increase in sugar content (sucrose, fructose, and glucose) and color degradation in melon flesh. The d6 treatment also maintained the titratable acidity (TA) and vitamin C content. In addition, the shelf life of melons in the d6 treatment reached 12 days of storage. Therefore, exogenous ethylene treatment of 100 ppm at 6 DAH can be considered an appropriate treatment to improve the sugar content and quality of early harvested melons.