K+(Rb+) uptake by intact Taraxacum plants: effects of nutrient status on K+uptake

Abstract

Microspecies of the genus Taraxacum differ in mineral ecology, spanning a range from nutrient‐poor and undisturbed soils to heavily fertilized grasslands. In this study, the principal features of K+uptake in Taraxacum plants were surveyed in order to design an appropriate test for an ecological study of K+uptake kinetics. Mechanical stimuli induced transient K+efflux, combined with an alkalinization of the ambient solution; during this period, K+(Rb+) uptake was strongly inhibited. As a consequence, uptake experiments were conducted with intact plants in conditions of minimal disturbance. K+uptake was studied as a function of the internal K+status, which was manipulated by various (pre)treatments including cultivation at different temperatures and various types of K+deprivation. NO−3‐dependent K+uptake in ‘high‐salt’ plants was abolished by pretreatments in which K+uptake was inhibited (i.e. cultivation in CaSO4 solution, or in complete nutrient solution with K+omitted, or in K2SO4 solution). In K+‐starved plants, NO−3‐dependent K+uptake was replaced by K+/H+exchange. Copyright © 1990, Wiley Blackwell. All rights reserved