EPICUTICULAR WAX ON JOHNSONGRASS (SORGHUM-HALEPENSE) LEAVES

Studies were conducted to investigate the uniformity of epicuticular w ax deposition on leaf blades of johnsongrass. Johnsongrass leaves grow n under drought stress had greatly increased epicuticular wax weights compared to leaves from plants with adequate moisture, but relative hu midity (95% vs. 40 +/- 5%) had little effect on wax deposition. Wax we ights decreased as leaves matured. Sections of lower leaf surfaces of young johnsongrass leaves tended to have more wax than sections of upp er leaf surfaces, but weights were nearly equal on upper vs. lower lea f surfaces of older leaves. The narrow side of asymmetrical johnsongra ss leaf blades often had more wax per unit area than the wide side. 'r he area over the midvein contained more wax per unit area than either the narrow or wide side of the leaf blade. Greatest wax concentrations on individual leaves were over the midvein area near the leaf apex. L eaf blades of johnsongrass had more wax per unit area than leaves of c orn or grain sorghum.