Epicuticular Wax Structure and Regeneration on Developing Juvenile Eucalyptus Leaves

Abstract

Eighteen species of Eucalyptus L'Hér. were studied for changes in wax morphology of juvenile foliage with leaf age using environmental scanning electron microscopy. Three species were studied for wax regeneration following removal from the adaxial surface of day 16 and day 30 leaves (16 and 30 days following lamina separation, respectively) while still attached to the tree. For each leaf age, four leaves per species were sampled at 0, 1, 3, 9 and 15 days after wax removal. All species had tube wax on juvenile leaves but there were differences between the species, in the length and conformation of tubes and percentage surface area covered by wax. Tube length was greatest in day 30 leaves, but tube diameter was narrower than day 0 leaves (unfolding leaves). There were significant differences in wax structure between the proximal and distal ends of day 0 leaves of 10 species, and tubes were observed crystallising from amorphous wax deposits in the proximal area only. Significant wax regeneration occurred more rapidly on day 16 leaves than day 30 leaves. Wax morphology was consistent across six species of the series Viminales. Thirteen species of Eucalyptus are recommended for the cut foliage industry.