Abnormal stomatal behaviour and ion imbalance in Capsicum scabrous diminutive

An attempt was made to explain the abnormal behaviour of stomata in Capsicum scabrous diminutive, a wilty pepper mutant. Stomatal movement in the pepper plant was found to be associated with changes in the ion content of the guard cells. These changes were smaller in the mutant than in the normal plants. In addition, total ion content was higher in the mutant under both control and NaCl treatments. Na⁺ substituted K⁺ in its function in stomatal movement under high salinity. This phenomenon was more pronounced in the mutant plants. Analysis of whole root systems and leaves of plants grown on solutions of high NaCl or KCl concentration confirmed that the regulation of K⁺ and Na⁺ uptake mechanisms was not functioning properly in the mutant. Evidence was presented that the difference in K⁺ staining between mutant and normal epidermal cells is an artefact resulting from the difference in leaf anatomy.