Role of ethylene in the initiation of fruit ripening

Abstract

The green-life of bananas has been shown to be reduced by short periods of exposure to ethylene, the length of exposure and ethylene concentration being such that ripening was not immediately intiated, but commenced several days or even weeks after fruit had been treated. This effect is proposed as evidence that endogenous ethylene is physiologically active throughout the preclimacteric life of a fruit, and that it is functional in determining when the climacteric will occur. The sensitivity to ethylene, defined as the proportional loss in green-life brought about by an exposure to the gas, is shown to vary exponentially with green-life at harvest, decreasing as fruit approach maturity. The sensitivity of harvested fruit is shown to increase with time after harvest, the rate of increase appearing to be dependent on the green-life at harvest. The concept that endogenous ethylene initiates ripening by exceeding a critical threshold
level is discussed and proposed to be inadequate.