An Alternative Explanation for the Apparently Active Water Exudation in Excised Roots

A standing-gradient osmotic-flow model has been proposed by others to explain the apparently active water uptake in excised maize roots. An alternative model is proposed which incorporates electrogenic coupling between the fluxes of anions and cations and electro-osmotic coupling between the fluxes of cations and water in the cell walls of roots. This model does not exclude the contribution (positive or negative) of a standing-gradient osmotic flow.