Plant Antitranspirants

Antitranspirants are substances deliberately applied to plants to slow down transpiration, ideally without interfering with the gas exchange (CO2 and O2) that the plant still needs to carry out. They work in one of two ways. The first approach places a physical barrier directly above the stomata - a thin film of a substance such as colourless plastic, silicone oil, or a low-viscosity wax is sprayed onto the leaf surface, blocking water vapour while, ideally, still letting CO2 and O2 pass through, though in practice this kind of physical barrier has only limited success. The second approach chemically induces the stomata themselves to close: CO2 itself acts as a natural antitranspirant by triggering stomatal closure, with the added benefit of suppressing photorespiration; Phenyl Mercuric Acetate (PMA), applied as a foliar spray, induces partial stomatal closure lasting two weeks or more with no toxic side effects; abscisic acid strongly promotes stomatal closure directly; and dodecenyl succinic acid also has a measurable closing effect on stomata. Antitranspirants have real practical uses in agriculture - reducing the large water losses transpiration causes in crop plants …