Interaction of Daminozide, Harvesting Date, and Ethylene in CA Storage on ‘McIntosh’ Apple Quality1

Daminozide (butanedioic acid mono-(2,2-dimethylhydrazide)-treated ‘McIntosh’ apples ( Malus domestica Borkh.) harvested at the preclimacteric stage did not soften in 7-½ months of controiled-atmosphere (CA) storage with <1 ppm ethylene in the atmosphere. These apples were satisfactorily firm and of acceptable-to-good quality after storage plus 7 days at 21°C. Apples from all other treatments were softer and had inferior quality. Control fruit harvested at the preclimacteric stage and stored in CA with a low ethylene level (<2.6 ppm) was also slightly firmer than similar fruit stored in CA with high ethylene (10 or 500 ppm). With a high ethylene level (500 ppm) in CA, daminozide-treated fruit was not firmer than control fruit and had more ‘McIntosh’ breakdown during the 7-day holding period after storage.