Effect of Zn<sup>2+</sup> on water and K<sup>+</sup> fluxes in detopped maize plants

Abstract

Water and K+ fluxes were examined in detopped plants ofZea mays L. (cv. White Horse Tooth), which were grown and exuded on half-strength Long Ashton nutrient solution containing the appropriate concentration of Zn2+ at 20 °C. In light-grown plants, 100 and 500 μM Zn2+ increased both water and K+ fluxes in detopped maize plants whereas 1 000 μM Zn2+ inhibited both fluxes. In the dark-pretreated plants, 1 000 μM Zn2+ in the medium stimulated K+ flux. The fluxes of K+, Zn2+, Ca2+ and Mg2+ were usually higher in detopped plants than in intact ones. At 1 000 μM Zn2+ in the exudation medium, Zn2+ concentration was higher in the xylem exudate of dark-pretreated plants than in roots of plants maintained in light. The results are discussed in relation to the influence of Zn2+ on the membrane permeability and transport in plants.