THE ROLE OF ACTIVE WATER ABSORPTION IN AUXIN-INDUCED WATER UPTAKE BY AERATED POTATO DISCS

Abstract

On the assumption that the auxin-induced water uptake is due to active absorption, the amt. of energy required to produce the uptake is calculated. If the cell wall initially undergoes an elastic stretch which is then converted into a plastic stretch, the energy required is negligible. The exptl. evidence, however, indicates that it is not an active uptake for the following reasons: (1) The water absorbed is not lost on transfer to 0-2 C for 24 hrs. but continues to increase. (2) Respiratory loss of dry matter is markedly reduced by auxin at 21 - 24 C, though water uptake is increased. At 25 - 29 C respiratory loss is increased by auxin. (3) 10-4 [image] and 10-3 [image] KCN has no effect on auxin-induced water uptake. The evidence also indicates that neither a change in osmotic pressure nor an increase in protoplasmal hydration can account for the auxin-induced uptake.