Avocado (Persea americana Mill. cv Hass) discs (3 mm thick) ripened in approximately 72 hours when maintained in a flow of moist air and resembled ripe fruit in texture and taste.
Ethylene evolution by discs of early and midseason fruit was characterized by two distinct components, viz.
wound ethylene, peaking at approximately 18 hours, and climacteric
ethylene, rising to a peak at approximately 72 hours. A commensurate respiratory stimulation accompanied each
ethylene peak. Aminoethoxyvinyl
glycine (AVG) given consecutively, at once and at 24 hours following disc preparation, prevented
wound and climacteric respiration peaks, virtually all
ethylene production, and ripening. When AVG was administered for the first 24 hours only, respiratory stimulation and softening (ripening) were retarded by at least a day. When AVG was added solely after the first 24 hours, ripening proceeded as in untreated discs, although climacteric
ethylene and respiration were diminished.
Propylene given together with AVG led to ripening under all circumstances.
2,5-Norbornadiene given continuously stimulated
wound ethylene production, and it inhibited climacteric
ethylene evolution, the augmentation of
ethylene-forming enzyme activity normally associated with climacteric
ethylene, and ripening.
2,5-Norbornadiene given at 24 hours fully inhibited ripening. When intact fruit were pulsed with
ethylene for 24 hours before discs were prepared therefrom, the respiration rate,
ethylene-forming enzyme activity buildup, and rate of
ethylene production were all subsequently enhanced. The evidence suggests that
ethylene is involved in all phases of disc ripening. In this view,
wound ethylene in discs accelerates events that normally take place over an extended period throughout the lag phase in intact fruit, and climacteric
ethylene serves the same ripening function in discs and intact fruit alike.