WHERE IS THE MOST IMPORTANT AND EFFICIENT SITE FOR ABSORPTION AND TRANSLOCATION OF CATIONS IN EXCISED BARLEY ROOTS

Differences in the cation-absorption efficiency at various sites along the barley root axis were investigated using a combined technique of multi-compartment transport boxes and radioisotopes. Besides the peak site of cation absorption at the root apex, other peak sites of translocation for cations were detected. The peak sites for Ca2+, Na+, and K+ translocation were arranged in the order from younger to older root tissues. Judging from the response to 2,4-dinitrophenol (DNP) or to lower levels of cations, a considerable part of K+ translocation seems to be energy-dependent, whereas the Ca2+ and Na+ translocation from the peak sites showed a low dependence on metabolic energy.