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

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Abstract

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.

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