Studies on Leaf Surface Lipid of Tobacco III. Compositional Change in Alkane during Growth and Senescence of Tobacco Leaves

Alkane is the major constituent of epicuticular wax universally distributed in plants. Tobacco leaves contained 5–10 mg of alkane per 1000 cm². The content gradually increased with leaf age. Leaves on the upper stalk contained more alkane than those on lower stalk. Components with carbon numbers from 27 to 33 occupied more than 98 % of the total alkane content. In relative ratios of alkane components, anteiso-C₃₀ and normal-C₃₁ were most drastically and increased, respectively, with leaf age regardless of stalk position. On the other hand, normal-C₂₉ and normal-C₃₃ increased and decreased, respectively, from the upper to lower stalk positions without being affected by leaf age. These results suggest the possible use of alkane composition as an index of leaf maturity and stalk position, for example, the ratio of anteiso-C₃₀/normal-C₃₁ for maturity and normal-C₃₃/normal-C₂₉ for stalk position.