The Effects of Cytokinins and ABA on Stomatal Behaviour of Maize and<i>Commelina</i>

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.