MOVEMENT OF GROWTH REGULATORS IN PLANTS

Abstract

S ummary Indoleacetic acid and 2,4‐dichlorophenoxyacetic acid, labelled with carbon‐14, were applied in agar blocks to one end of sections cut from the petioles of primary leaves of Phaseolus vulgaris at various stages in their development. The movement of 14 C by polar transport into agar blocks at the other end of the sections was measured and compared with the elongation of the sections. With both auxins there was a steady decline in the polarity of movement of 14 C—due mainly to a steady increase of movement in the acropetal direction—in petioles from successively older plants. This decreasing polarity was closely associated with a progressive decrease in the ability of the sections to grow in length.