The absorption and translocation of ions in excised barley roots: A multi-compartment transport box experiment

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Abstract
The distribution of K and P absorbed at various regions along excised barley roots was investigated using a multi-compartment transport box. Subsequently, the effects of pH and sucrose addition on the absorption and translocation of K and P in barley roots were examined by the application of the same technique. The results are as follows: 1) The absorption rate of K and P was higher at the apical part than at the basal part of the excised roots. The translocation toward the apex of ions absorbed in the basal part of the roots was negligible. 2) The absorption of K and P by the apex of excised roots and the translocation of the ions through the roots were strongly inhibited when the pH of the test solution was low (pH 3.1). The inhibitory effect of the extremely low pH on the absorption and translocation of ions in the roots was hardly alleviated by the addition of Ca. At pH 4.9 and 4.0 Ca stimulated the absorption of P, while the absorption of K was lowered slightly in the presence of Ca at pH 4.9. 3) The addition of sucrose in the test solution inhibited the absorption of K and P by the apex of excised roots and the translocation of the ions through the roots, though the inhibition by sucrose was less conspicuous for P than for K.