Responses of early, mid and late season apple cultivars to postharvest application of 1-methylcyclopropene (1-MCP) under air and controlled atmosphere storage conditions

The potential for commercial application of 1-methylcyclopropene (1-MCP) to maintain quality of 'McIntosh', 'Empire', 'Delicious' and 'Law Rome' apples under air and controlled atmosphere (CA) storage conditions was investigated. These cultivars represent early, mid and late season apples with ripening rates ranging from fast to slow. 1-MCP gas concentrations used were 0.5, 1 and 2 mu l l(-1), generated from measured amounts of Ethylbloc(TM) powder. Fruit of each cultivar were removed from storage at 6 week intervals during 30 weeks in air, or at 8 week intervals during 32 weeks in CA, and evaluated after 1 and 7 days at 20 degrees C. Effects of 1-MCP were greater in CA than air storage. A dose response of internal ethylene concentrations and flesh firmness to 1-MCP was found in 'McIntosh' and 'Law Rome', but 'Delicious' and 'Empire' ripening was generally prevented by all I-MCP concentrations. 1-MCP reduced superficial scald incidence, and accumulations of alpha-farnesene and conjugated trienols during air storage. The results indicate that the efficacy of 1-MCP is affected by cultivar and storage conditions, and that successful commercial utilization of the chemical will require understanding of these relationships. (C) 2000 Elsevier Science B.V. All rights reserved.