Cuticular Waxes of Developing Leaves and Fruit of Blueberry, Vaccinium ashei Reade cv. Bluegem1

Abstract

An ultrastructural and chemical study of the cuticular waxes from leaves and fruits of rabbiteye blue-berry was conducted in North Central Florida between March and November 1977. Leaf epicuticular wax con-centration was relatively constant (75-83 µ g/cm 2 ) for the 40 days of leaf expansion following leaf emergence. Epicuticular wax reached a peak of 136 µ g/cm 2 in mid-May, 3-4 weeks after full leaf expansion. Levels declined thereafter to less than 70 µ g/cm 2 by October. The concentration of fruit surface wax increased from 159 µ g/cm 2 , 24 days after full bloom, to 295 µ g/cm 2 at maturity. β -Diketones, the dominant leaf surface wax fraction for the first 100 days (34-54% of total wax) declined to less than 9% in October. Acidic triterpenoids increased from 10-12% to more than 40% of total wax and primary alcohols increased from 10% to 20-30%. Secondary alcohols, initially 22% of total leaf wax, were not detected after the first month. Fruit surface wax was chemically similar to the leaf surface wax with β -diketones increasing to 50-60% of the total. The surface wax on leaves and fruit was made up of a dense network of interlocking branched rodlets (closed tubes). Disappearance of rodlet struc-ture on the leaves coincided with the decline of total wax and β -diketones. These data are discussed with respect to leaf and fruit water relations.