Morphological, Physical and Chemical Characteristics of Epicuticular Wax on Ornamental Plants Regenerated In Vitro

The morphological and physical characteristics of epicuticular wax of Maranta, Dieffenbachia, Chrysanthemum, Spathiphyllum, and Gerbera grown in a greenhouse, growth chamber, or in vitro, were determined by scanning electron microscopy (SEM) and gravimetric analysis. Morphological characteristics varied among the different species ranging from ridges in Dieffenbachia to smooth surfaces in Chrysanthemum and Gerbera. There was no consistent appearance of wax of plants grown in vitro. Gravimetric analysis was necessary to determine the amounts of wax accurately. Thin-layer chromatography and gas-liquid chromatography revealed chemical differences in the wax from different treatments within each species. There was no correlation between survival in the greenhouse or amount of leaf damage and the amounts of epicuticular wax present on plants at time of transfer. A comparison of results from gravimetric analysis and SEM indicated that SEM alone cannot be used with confidence in determining either the presence or the relative amounts of epicuticular wax present. In addition, morphological differences in epicuticular wax of greenhouse, growth chamber, and cultured plants cannot be predicted from the growth environment of plants and must be determined individually for each species under study.