Proc. of Second World Avocado Congress 1992 p. 495

The Relationship of Flesh Softening to the Respiratory Climacteric, Ethylene Production and Ammonia Accumulation

M.L. Arpaia and C.J. Lovatt

Department of Botany and Plant Sciences, University of California, Riverside, CA 92521, USA

 

F.G. Mitchell and G. Mayer

Department of Pomology, University of California, Davis, CA 95616, USA

Abstract. In preparation for future studies to evaluate the relationship between the development of chilling injury and ammonia (NH3-NH4+ accumulation, we examined the relationship between flesh firmness (mesocarp tissue), respiration (CO2), ethylene production (C2H4) and NH3-NH4+ concentration during normal ripening at 20C.

The changes in CO2 and C2H4 content in two avocado cultivars, ‘Fuerte’ and ‘Hass’ relative to softening were comparable. The increase in CO2 and C2H4occurred gradually during the course of softening. The respiratory climacteric and the peak of ethylene production did not occur until the fruit were fully ripe (eating ripeness). There was no clear relationship between NH3-NH4+ levels and changes in flesh firmness although there was an apparent increase in NH3-NH4+ which roughly paralleled the rise in C2H4 and CO2 production.