Correlations between Potassium Uptake and Hydrogen Efflux in Barley Varieties

Abstract
Rates of hydrogen ion secretion and potassium (86Rb) absorption by intact roots of twenty-four barley varieties were measured in solutions containing K2SO4 (1 × 10−4 to 1 × 10−3 molar) plus 5 × 10−4 molar CaSO4, at initial pH values in the range 5.3 to 5.5. Fluxes of H+ and K+ were strongly correlated in short-term experiments (up to 15 minutes) as well as in long-term experiments (lasting 24 hours). The observed correlations provide the basis for a preliminary screening method, designed to segregate varieties with high rates of potassium uptake by the use of an acid-base indicator (methyl red).