Foliar uptake and translocation of rubidium in bean plants as affected by root absorbed growth regulators

Abstract

The absorption and subsequent transport of foliar applied Rb86 labeled Rb Cl (10 mM) was studied on bean plants (Phaseolus vulgaris, L. cv. Black Seeded Blue Lake) exposed to physiologically tolerable levels of certain plant growth substances in the solution culture root media. Gibberellin A3 (10-5 M) increased Rb uptake but did not affect total translocation from the treated leaf. Translocation was directed to the upper vegetative parts and markedly reduced to the roots. Foliar influx of Rb and transport to the roots were greatly enhanced by 1-naphthaleneacetic acid (10-6 M) but mobilization of Rb into the leaves and upper stem was reduced. 2-Chloroethyltrimethylammonium chloride (10-3 M) and N,N-dimethylaminosuccinamic acid (3×10-4 M) decreased the mobility of Rb to the upper stem, increased it to the roots, and had no effect on initial uptake. Rb absorption was depressed by 2,4-dichlorobenzyltributylphosphonium chloride (10-5 M) with no effect on subsequent translocation. Both uptake and mobility were strikingly inhibited by N6-benzyladenine (10-6 M).