The continuum model of radial mass transfer in plant roots we developed previously is used for processing the nonstationary experiments aimed at the determination of the root hydraulic conductivity. It is shown that in contrast to compartmental models our model allows to describe the observed shape of the relaxation curve and to obtain segments with different relaxation times. It is found that for correctly determining the hydraulic conductivity the data processing method should be modified. A method is also proposed for estimating the extracellular to intracellular conductivity ratio.
The model of a growing medium consisting of two phases, liquid and solid, is developed. Growth is treated as a combination of the irreversible deformation of the solid phase and its mass increment due to mass exchange with the liquid phase. The inelastic strain rate of the solid phase depends on the stresses in it, which are determined by the forces both external with respect to the medium and exerted by the liquid phase. In the liquid phase the pressure develops due to the presence of a chemical component whose displacement is hampered by its interaction with the solid phase. The approach developed makes it possible to waive many problems discussed in the theory of growing continua. Possible generalizations are considered.