The Influence of Hydrogen Ion Concentration on Cation Absorption by Barley Roots.

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Abstract
Treatment of excised barley roots with pure HCl solutions below pH 5 resulted in a loss of potassium from the tissues which could be offset by the presence of the polyvalent cations: Ca++, Al+++, La+++, and Ce+++. Furthermore, the loss in absorption capacity resulting from pretreatment with HCl at low pH also was offset by the presence of small quantities of the polyvalent cations. The rate of K absorption from 0.001[image] KCl fell off rapidly below pH 6. Below pH 4.25 potassium was lost from the tissues. However, small concentrations of Ca++ and La+++ in the culture solution showed a pronounced stimulating effect on K absorption for the pH range 2 to 6. Al+++ and Ce+++ ions also had a large stimulating effect in the pH range 2 to 4. The observed interrelation of polyvalent cations and hydrogen ion is invoked as a possible explanation of this stimulating effect.