The Effects of Cytokinins and ABA on Stomatal Behaviour of Maize andCommelina

Abstract
Epidermal strips and leaf fragments of Commelina and leaf fragments of maize were incubated on solutions containing naturally-occurring or synthetic cytokinins and/or ABA. The effects of these treatments on stomatal behaviour were assessed. Cytokinins alone did not promote stomatal opening in either species but concentrations of both zeatin and kinetin from 10−3 to 10−1 mol m−3 caused some reversal of ABA-stimulated closure of maize stomata. The reversal of the ABA effect increased with increasing cytokinin concentration. Cytokinins had no effect on ABA-stimulated closure of Commelina stomata. When applied alone, at high concentration (10−1 mol m−3), to Commelina epidermis or leaf pieces both zeatin and kinetin restricted stomatal opening.