Transpiration and The Waxy Bloom in Brassica Oleracea L.

Abstract

The stomatal and cuticular transpiration rates and quantity of wax per unit area of leaf surface were determined for seven glaucous and non-glaucous sibling lines of B. oleracea. There were no statistically significant differences in the stomatal transpiration rates of the glaucous and non-glaucous lines, but there were highly statistically significant differences between the two classes of lines in terms of cuticular transpiration. Rubbing the surfaces of the leaves to remove lightly adhering wax deposits, such as the waxy bloom, significantly increased the cuticular but not the stomatal transpiration rates of both glaucous and non-glaucous plants. There was no appreciable correlation between the quantity of wax per unit area of leaf surface and the loss of water through cuticular transpiration among either the glaucous or nonglaucous lines. It was concluded that the function of cuticular waxes in limiting cuticular transpiration is a product of the architecture of the deposits and the quantity of wax per unit area of leaf surface.