Distribution of Stomata and Epicuticular Wax on Oranges as Related to Stem End Rind Breakdown and Water Loss1

Abstract

Abstract Upon microscopic examination, no stomata were found within 3 mm of the button in an area typically immune to stem end rind breakdown. Stomata outlined the oil glands 7 to 10 mm from the button in peel susceptible to this disorder. Heavy deposits of epicuticular wax were also found in the area void of stomata. Total epicuticular wax was inversely correlated to postharvest wt loss of ‘Valencia’ oranges (r2 = 0.94). A 1-min petroleum ether extraction of soft wax components increased wt loss 66% over washed-only fruit and resulted in etched patterns in the wax platelets suggesting that the soft and hard waxes are not uniformly mixed. A 1-min wax extraction with CCL4 : hexane (1 : 1 v/v) removed 85.6% of the surface wax and increased wt loss to 3 times that of the washed-only fruit over 24- and 48-hr time periods.