Effects of Calcium Fertilizers and 1-MCP On Cantaloupe Fruit Firmness

California and Arizona produce over 80% of all cantaloupe (Cucumis melo) produced in the United States.  Shipments of cantaloupe from CA and AZ to the east coast of the USA and Canada are very common and take about 4 days.  Long transportation time could reduce shelf-life or result in soft fruit, which is the most common reason for shipment rejection by distributors.  Calcium has been shown to play a significant role in maintaining cantaloupe fruit firmness and extending shelf-life.  This study investigated the potential of applying calcium fertilizers through berried drip tape to mitigate the effect of high sodium/calcium ratio in soil and irrigation water to increase fruit firmness.  Four compounds were used to increase calcium supply to cantaloupe variety “Olympic Gold” in a grower’s field at Harquahala Valley, AZ: CaCl₂, an EDTA-chelated calcium carbonate (Agri-Cal), a micro-encapsulated calcium carbonate (Mainstay Calcium), and a carboxyllated organic compound to reduce salt and sodium in the soil (Soilex).  The compounds were supplied every 10 days for 3 times through drip tape starting from the first female flower.  After harvest, half of the sampled cantaloupe fruits that were full slip and full color were treated with 1-methylcyclopropene (1-MCP) in a refrigerated trailer for 12 hours to test its effects on fruit storage quality.  The 1-MCP treated fruits and control were then stored in 3.5C cooler for 10 and 20 days.  There were no significant interactions between calcium fertilizer and 1-MCP treatments.  Calcium fertilizer treatments did not significantly affect firmness and Brix of fruits that were full slip but not full color and fruits that were full slip and full color.  After 10 days’ storage, fruit firmness decreased 17% in the 1-MCP treatment and 37% in the control treatment.  The difference in fruit firmness between 1-MCP and control treatment was similar after 20 days storage.  The Brix was not affected by 1-MCP treatment during the storage.  Calcium fertilizers did not change fruit firmness in this particular study, but fruits in the 1-MCP treatment maintained significantly higher fruit firmness during the 20-day storage time.