High alcohols as antitranspirants

The use of monomolecular films of high alcohols to reduce evaporation from open water surfaces has stimulated much work on the possibility of applying these materials to plants to reduce transpiration. The results of 17 such investigations indicate that at concentrations that reduce transpiration, these materials also reduce plant growth. The one study that reported reduction of plant transpiration and increase of growth was repeated, but with negative results. Analysis of the relative resistances of hexadecanol films to flow of CO₂ and water vapor and their relation to resistances to flow normally found in plant leaves indicates that these films should reduce photosynthesis more than transpiration. It is concluded that such materials are not suitable as antitranspirants. (Key words: Evapotranspiration; plants; vegetation)