Effects of Calcium with and without Surfactants on Fruit Quality, Mineral Nutrient, Respiration and Ethylene Evolution of ‘Red Spur Delicious’ Apple

Calcium (Ca) plays an important role in apple fruit quality. Only portion of Ca spray that lands on the surface of apple fruit can penetrate in the tissue and influence fruit quality and maturity. Thus, selection of an appropriate surfactant in a spray solution would be extremely crucial in the success of Ca and other nutrient absorption. In this study, effects of Ca spray with or without Regulaid and KALO surfactants on fruit quality, ethylene and respiration of ‘Red Spur Delicious’ apple was studied. No significant difference in fruit quality attributes or mineral nutrients were found between the two surfactants. However, fruits receiving a combination of KALO surfactant and Ca had significantly lower respiration and ethylene evolution, suggesting that KALO could be a preferred surfactant if fruit growers wish to postpone fruit maturity. The reason of this phenomenon is not clear and deserves further investigation.