Abstract
Low concentrations of long-chain alkenylsuccinic acids and certain of their derivatives inhibit stomatal opening in a tobacco-leaf disk assay, and when used as a spray. The monomethyl ester of decenylsuccinic acid is presently the most effective of this class of compounds. Stomatal closure induced with this substance is accompanied by a significant reduction in the rate of transpiration. These inhibitors probably close stomata by altering the permeability of the membranes of the guard cells.