The plant root as an osmo-diffusive converter of free energy

Abstract

This work focuses on the maize root as a one-membrane osmo-diffusive converter of free energy. Energy expenditures of the root on water transport by radial route as well as on xylem water uptake, occurring according to the principle of osmotic root pressure, are analyzed. The so-called practical method of osmo-diffusive energy conversion (Kargol 1990, 1993) and experimental data taken from the work by Steudle et al. (1987) were employed, including coefficients of filtration ((L) over bar(pr)), reflection (<(sigma)over bar>) and permeation (<(omega)over bar>)) of the maize root treated as a one-membrane model system. It is shown a.o. that the energy efficiency of the root does not depend (within a certain concentration interval) on the concentration of a given solute in solution into which the root is placed. This suggests a certain independence of environmental conditions. The efficiency is different for different dissolved substances contained in the solution.