The Effect of Abscisic Acid on the Uptake and Distribution of Ions in Intact Seedlings of <i>Phaseolus vulgaris</i> cv. Redland Pioneer

Abstract

Abstract Abscisic acid (ABA) was found to increase the accumulation of 36 Cl, total Cl, 22 Na and total Na + in roots of intact bean seedlings. After an initial promotion. ABA inhibited longdistance transport of these ions from the root to the shoot. However, it consistently inhibited both uptake and transport of 42 K and total K + in intact bean seedlings. A promotion of net 36 Cl influx (ψ oc ) and its accumulation in the root ( Q * v ) concomitant decrease in transport index (long‐distance transport as percentage of total influx) showed that ABA stimulates ‐ 36 Cl transport at the tonoplast. It inhibited H 4 extrusion and net 86 Rb influx which agrees with a cation exchange theory K + /Rb + transport.