ABSTRACT
It was shown that changes in stomatal conductance can affect transpiration rate more than the rate of assimilation (see the chapter ‘‘Antitranspirants: FilmForming Types’’). Compounds that artificially decrease stomatal conductance, by inducing partial closure, may also be used to reduce transpiration. Whereas films are always located outside the leaf tissue, these compounds must be inside the leaf. They are either taken up by roots, transported to the leaves, and finally reach the epidermis, or absorbed directly by the leaf. It is expected that these compounds will affect metabolic reactions responsible for changes in the osmotic potential of guard cells or change the permeability of guard cell membranes or rigidity of cell walls. It is also expected that these compounds will have no significant side effects, mainly harmful effects; natural compounds such as plant hormones were thus more acceptable as antitranspirants.
