The cuticles of Citrus species. Composition of leaf and fruit waxes



Seasonal changes in the surface waxes of the leaves and fruits of four species of Citrus have been examined. Leaf wax deposits ranging from 20 μg/cm2 in orange to 31 μg/cm2 in lemon were consistent during all except the most juvenile stages of growth whereas the surface waxes of the fruits showed considerable variation, the most pronounced being a 58% decrease in the wax deposits of lemon between July and October. Hydrocarbons (23–66%), primary alcohols (6–38%) and fatty acids (2–20%) were important constituents of the waxes of mature leaves and fruits but aldehydes present as major components of the fruit waxes (28–44%), were found only in trace quantities in the leaf waxes. n-Hentriacontane and n-tritriacontane, the dominant homologues of the hydrocarbon fractions were the major components of the leaf waxes which also contained n-hexacosanol and n-octacosonal as important constituents. n-Nonacosane, n-hentriacontane, n-tetracosanal, n-hexacosanal and n-octacosanal were present in the largest proportions in the fruit waxes.