The Regulation of Potassium Absorption in Barley Roots

Abstract

The dynamics of changes in K+ influx across the plasmalemma and of internal K+ concentrations [K+]1 of intact barley (Hordeum vulgare) roots were examined as the roots were converted from `high-salt' to `low-salt' roots. Following the transfer of plants grown in 0.5 mm CaSO4 solutions plus various concentrations of KCl to 0.5 mm CaSO4 solutions, influx rates increased and internal K+ concentrations declined as a function of time and the initial K+ status of the tissue. The relationship between plasmalemma influx and [K+]1 was examined over a wide range of [K+]1 values by growing intact plants in various concentrations of KCl. Plasmalemma influx was inversely correlated with the square of [K+]1. A model for the regulation of plasmalemma influx by [K+]1 is considered.