Temperature-dependent micromorphology of epicuticular wax in cabbage (Brassica oleracea var. capitata)

Scanning electron microscopic examinations of epicuticular waxes in cabbage cultivars (Brassica oleracea var. capitata) showed that the growth temperatures of 24/24 degrees C (day/night) resulted in characteristic dendrite structures. In cv. "Akiou", "Kinsyun" and "Sousyu" the dendritic plates are comparatively small with dense texture, in cv. "Braunschweiger" they are notably increased in size, more complex and interwoven. Additionally, long wax filaments occur. At temperatures of 32/29 degrees C (day/night), in cv. "Akiou" and "Sousyu" much more elaborated and enlarged dendritic plates and filaments are found, the microsculpturing being now comparable to that of "Braunschweiger". In cv. "Kinsyun" only scattered rodlets and platelets are present. The epicuticular waxes contain ketones, secondary alcohols and alkanes as main fractions whilst esters, aldehydes, primary alcohols and free fatty acids occur only in small amounts. The clearly dominating chain length of the main fractions is C-29. Despite of the poor development of wax crystalloids in "Kinsyun" at the high temperatures, there are only small differences in composition and amount of the wax compared to the other cultivars.