Control of Ripening in ‘McIntosh’ Apples. II. Effect of Growth Regulators and CO2 on Fruit Ripening, Storage Behaviour, and Shelf Life.1,2

Fruit quality measurements and taste panel assessments indicated considerable latitude for programming harvest of ‘McIntosh’ apples. Ripening at 20°C was advanced by ethephon-auxin and delayed by succinic acid-2,2-dimethylhydrazide (SADH) and CO 2 . The rate of softening and acid catabolism at 0°C were not altered by the growth regulator treatments. SADH suppressed ethylene production and CO 2 suppressed both ethylene production and softening of ripening fruits held at 20°C. These effects were greatest in fruits not subjected to cold storage and declined linearly in fruits held 30, 60 or 90 days at 0°C. Neither SADH nor CO 2 influenced acid loss at 20°C.