Proc. of
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,
F.G. Mitchell and G.
Mayer
Department of Pomology,
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.