The effect of method of treatment with petroleum ether on the drying rate of grass leaves measured in the laboratory

Excised S24 perennial ryegrass leaves were dried in controlled and measured conditions of temperature (28°C), relative humidity (22%) and airspeed (40 cm s−1), without treatment or after treatment with petroleum ether (4O–60°C boiling point) applied in various ways. Subsequent increase in the drying rate of the leaves varied greatly with method of application of petroleum ether, and the results indicate that the modification of the waxes on the leaf surfaces, which results in reduced cuticular resistance to water loss, requires the presence of liquid petroleum ether on the leaf surface. This effect increases with temperature, and the increase is due to the enhanced activity of the petroleum ether in dissolving waxes, rather than to direct thermal effect on tissue resistance. The practical implications of employing such a technique are discussed.