Source-sink balance affects reproductive development and fruit quality in cantaloupe melon (Cucumis melo L.)

Competition for assimilates affects fruit quality in many species, while seed content is reported to influence only fruit weight. Our study was aimed at determining whether and/or how source-sink balance and seed content in cantaloupe (Cucumis melo L.) could affect flowering, fruit set, growth and fruit quality including the physiological disorder water-soaking which is important for the market-value of this fruit. We followed standard cultivation practices for early cantaloupe production under greenhouse conditions and studied fruit and flower removal over 2 years with two Charentais cantaloupes cultivars, and limited hand-pollination treatment for 1 year on one cultivar, and recorded the quality attributes of the fruit. Reproductive development in both cultivars was characterised by the production of a large number of female flowers on plants bearing a single fruit. Fruit set and fruit growth rate were affected by the intensity of pollination, probably by the ability of fertilisation to promote cell division and increase the sink strength of the young ovary. Fruit load did not affect the average number of seeds per fruit, yet individual seeds were lighter under high fruit load. A significant difference in final fruit weights obtained with similar cultivars and treatments between the 2 years is discussed. Fruit quality was affected by source-sink balance. Seed content within a fruit correlated with individual fruit weight, affected flesh firmness, the sweetness of the flesh and slightly affected the occurrence of water-soaking. Competition for assimilates within a plant decreased the sweetness of the flesh and dramatically increased the occurrence of water-soaking in both years and in both cultivars. Climacterium also increased with a low source-sink balance, and an ethylene burst was confirmed to be closely-related to flesh firmness.