Stimulation of volume flow and ion flux by abscisic acid in excised root systems of Phaseolus vulgaris L. cv. Redland Pioneer

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Abstract
Abscisic acid (ABA) caused a 7–8-fold increase in volume flow in excised bean root systems and this was coupled with an increase in 42K, 36Cl and 24Na flux into the xylem. The transport of 42K and 36Cl increased by a factor larger than the stimulation of volume flow, resulting in an increase in the concentration of those ions in the xylem exudate. Carbonyclcyanide-m-chlorophenyl hydrazone, on the other hand, eliminated ABA-stimulated 42K transport and caused a further inhibition of 42K flux, thus providing additional support for the proposition that ABA stimulation may involve an energised process of ion transport. ABA also increased the accumulation of 24Na and 36Cl in bean root tissue, but not that of 42K.