Postharvest Application of Calcium to Whole Muskmelon Fruits

Abstract

Fully mature, abscised, hybrid netted- and honey dew-muskmelon fruits submerged in amino acid-calcium (AA-Ca) chelate solutions, vs. non-calcium treated fruits, were less senescent and had little or no surface decay following 21 days at 10 °C (honey dew) or 4C (netted) plus 3 days at 21 °C. Honey dew fruits submerged in either AA-Ca or AA-Ca plus AA-Mg, and netted fruits in AA-Ca plus AA-Mg, had hypodermal-mesocarp tissue [Ca2+] of 6.0 mg per g dry mass or higher 10 days postharvest, which is statistically similar to [Ca2+] in freshly harvested fruits. Non-calcium treated vs. calcium treated fruits, 10 days postharvest, had significantly less 6.0 mg per g dry mass [Ca2+]. Maintaining muskmelon hypodermal-mesocarp tissue [Ca2+] at 6.0 mg per g dry mass or higher maintained membrane integrity as evidenced by low free sterol: total phospholipid ratio (mol:mol), low electrolyte leakage, high total and specific H+- ATPase activities, and low lipoxygenase activity; maintained fruit firmness; and extended fruit storage life 2.4-fold (i.e., to 24 days) vs. non-calcium treated fruits. Application of calcium to abscised, fully ripe honey dew and netted muskmelon fruits should reduce fruit senescence rate in storage and should promote extended market-life and a higher quality product.