Microanalytical Studies of Potassium and Chloride Fluxes and Stomatal Movements of Two Species: Vicia faba and Pelargonium x hortorum

Potassium and chloride exchange kinetics in guard cells were found to be related to stomatal opening and closing kinetics in Pelargonium × hortorum and Vicia faba by simultaneously measuring ion contents and degrees of opening with an electron probe and a hydrogen diffusion porometer. Large shifts between both kinetics occur during opening and closing. These results show that maximal potassium content is delayed, which seems to question the primary role of potassium in stomatal opening