Ethylene-releasing Compounds and the Laboratory Modeling of Olive Fruit Abscission vs. Ethylene Release

Abstract A laboratory system was developed to study olive ( Olea europaea L.) organ abscission (21). An improvement of the use of ethylene-releasing compounds in this system is described to provide a model for field abscission responses and characterization of ethylene release. Olive fruit began the separation process as early as 7 to 13 hr after treatment with CGA-15281 (CGA), but not until 19 to 25 hr after treatment with ethephon (ET). CGA is characterized by an immediate, substantial breakdown to ethylene, whereas ET reaches its maximum ethylene release at 12 to 18 hr after application. Ethylene release was much greater from CGA than from equimolar concentrations of ET throughout the abscission initiation period. The relation of ethylene release characteristics to control of olive fruit and leaf abscission is discussed, with the suggestion that fruit respond more rapidly to, and at shorter durations of applied ethylene than do leaves.