ACC oxidase activation by cold storage on ‘Passe-Crassane’ pears: effect of calcium treatment

Ethylene biosynthesis and respiration in untreated and in calcium-treated Passe-Crassane pear fruits during cold storage and during ripening at 20°C after removal from storage at 2°C was studied. Results suggest that the increase in ACC oxidase activity along with free-ACC availability for enzyme action is the most important limiting factor in the capacity of these fruits to produce ethylene and to ripen. A chilling period of at least 30 days was shown to be required for inducing the climacteric increase in ethylene biosynthesis. Calcium treatment partially prevented ethylene production and retarded the onset of the climacteric process in Passe-Crassane fruits. The role that calcium plays in preventing cellular wall and membrane degradation is probably responsible for this delaying effect on the ripening process of this pear cultivar. © 1998 SCI.