Phosphate uptake by the component parts of cham hispida

Abstract

Mean daily rates of net phosphate uptake, as determined colorimetrically from phosphate depletion of the medium, were measured for Chara hispida shoots given 1 mmol m-3phosphate and isolated (split chamber technique) rhizoid-node complexes given 1-, 50-, 100-, 500- and 1000 mmol m-3phosphate. Under aerobic conditions phosphate uptake by the rhizoid-node complex expressed per g FW shoot increased with external phosphate concentration 1-100 mmol m-3. At external phosphate concentrations 100-1000 mmol m-3uptake rates by the rhizoid-node complex were two to three times greater than that for the shoot at 1 mmol m-3phosphate. Anaerobic conditions substantially reduced uptake by the rhizoid-node complex. It is concluded that in aerobic sediments, the rhizoid could play a substantial, possibly major role in phosphate uptake by the whole plant but, in aerobic sediments, this will be the case only when phosphate levels in the open water are extremely low. © 1987 The British Phycological Society.