THE PHYSIOLOGY OF ETHYLENE FORMATION IN APPLES

Abstract

The production of ethylene by sections of apple tissue has been investigated by a new and precise method. The optimal temperature for the process is 32[degree]C, and above this ethylene production falls off rapidly. The heat inactivation slowly disappears when the tissue is exposed to lower temperatures. Ethylene production and O2 consumption show almost identical dependence upon O2 tension, the half minimum value for both being reached at 1.5-2.0% O2. Although the synthesis of ethylene ceases almost immediately under anaerobic conditions, a precursor accumulates which can be rapidly oxidized in air with the procedure of ethylene. Tritiated water transfers its label to ethylene in such a manner as to indicate that 1 of the terminal steps in the process is a reversible dehydration. The final reaction leading to ethylene does not require the participation of 02- A scheme for ethylene production is proposed in which 1 or more reductions are followed by a rapid oxidation, a reversible dehydration, and a nonoxidative terminal step.