Action of Abscisic Acid on Ion Transport as Affected by Root Temperature and Nutrient Status

Abstract

Measurements were made of the transport of ions through excised barley roots. It is shown that addition of 10⁻⁵ M abscisic acid (ABA) may lead to inhibition or stimulation of transport. The effect of ABA depended on the conditions in which the plants had been grown and on the temperature at which the experiment was carried out. It is suggested that stimulation of transport is a direct effect of ABA, but inhibition may be an indirect effect due to disturbance of endogenous levels of plant hormones. The results are considered in relation to regulation of ion transport in the plant as a whole.