Some counteractive effects of antitranspirants.

Some previously unexpected effects of antitranspirants on stomata and plant growth are described, and their implications are discussed. Antitranspirant films increase the resistance to diffusion of water vapor from stomata. This increases leaf water potential and results in wider stomatal apertures immediately under the film, as well as on those parts of a partially treated leaf which are not covered by the film. Antitranspirants are expected to curtail growth via reduced photosynthesis. However, by increasing plant water potential they can enhance the growth of fruits and shoots.