ABSTRACT
A wide diversity of substances can be deposited on the aerial parts of plants either intentionally as with nutrients, growth regulators, herbicides, fungicides, and insecticides applications to promote, control, and protect plant development, or unintentionally as in the case of industrial pollutants. Therefore, the problem of foliar penetration and translocation of these chemicals is of major practical importance. Potassium nutrition of roots is also an important factor affecting the foliar translocation of this element. The cuticle represents the first barrier to the penetration of exogenous materials deposited on aerial plant surfaces, so cuticular penetration is an essential step to be considered in the analysis of the complex process of foliar absorption. The plant cuticle is a noncellular, nonliving, lipoidal covering composed of the biopolymer cutin with embedded wax and a layer of epicuticular waxes on the outer surface, the ultrastructure of which varies from amorphous to highly crystalline deposits.
