Abscisic Acid transport coefficients of phaseolus root systems.

Diffusive and convective transport coefficients of Phaseolus vulgaris L. cv. Ouray root systems for abscisic acid for (ABA) were measured. The convective coefficient (reflection coefficient or osmotic efficiency factor) sigma was determined to be 0.96 for ABA while the diffusive coefficient, omega, was found to be 1.44 x 10(-11) mole per square centimeter per second per bar. Steady-state concentrations of ABA in the root system exudates were not achieved until at least three hours after the applications suggesting either a slow saturation of binding sites or equilibration with tissues surrounding the xylem.