Uptake of Phosphate by White Clover

Abstract

Uptake of phosphate from flowing solution and cell membrane electrical potential differences (PD) have been followed simultaneously in the roots of Trifolium repens L. Intact plants were used and it was found that uptake and PD were strongly influenced by the shoot. They were reduced by excision of the root, defoliation of the plant, and lowering the light intensity at the leaf surface. 2, 4-Dinitrophenol caused the PD to decline by approximately 40 mV. A close correlation between phosphate uptake and PD was obtained over a wide range of conditions and removal of phosphate from the solution resulted in a decline in PD of about 35 mV. It was concluded that there is an electrogenic phosphate pump in T. repens roots which is closely dependent on the carbohydrate supply from the shoot.