EFFECTS OF SUGARS ON POTASSIUM TRANSLOCATION IN EXCISED BARLEY ROOTS

Effects of treatment with twelve sugars on potassium translocation in excised barley roots were studied using a multi-compartment transport box. Some sugars were found to be effective in potassium translocation at low concentrations. Though xylose and ribose were no effective in total absorption, they considerably inhibited xylem exudation. In cont rast, mannose and sucrose remarkably stimulated the total absorption o f potassium. The increase in xylem exudation was the most conspicuous phenomenon in the stimulation of potassium translocation. The stimulat ory effect on potassium translocation appeared 12 h after treatment. T he effect showed a different specificity for exogenous sugars from res piration. The optimum concentration of sucrose was considerably low (0 .2 mol m-3). These evidences indicate that sucrose may not act as a su bstrate for the energy metabolism supplying energy for the potassium t ranslocation system in barley roots.