Correlations between Potassium Uptake and Hydrogen Efflux in Barley Varieties

Rates of hydrogen ion secretion and potassium ((86)Rb) absorption by intact roots of twenty-four barley varieties were measured in solutions containing K(2)SO(4) (1 x 10(-4) to 1 x 10(-3) molar) plus 5 x 10(-4) molar CaSO(4), 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).