Fig. 2.
The detailed electrical models (A, B, and C) and the corresponding simplified models (A1, B1, and C1) for willow in the three experimental set-ups (see Fig. 1). Rsa and Csa, the resistance and capacitance of the stem above the solution level; Rss and Css, the resistance and capacitance of the longitudinal interface of the stem with the solution; Rsc and Csc, the resistance and capacitance of the cross-sectional interface of the stem with the solution; Rr and Cr, the resistance and capacitance of the interface of roots with the solution; Rssa, Rsca, and Rra, the auxiliary resistances for the bulk resistance properties of the surface of the stem, the cross-section of the stem, and the root immersed in the solution, respectively. The superposition resistance, Rsup, combines the effects of the parallel interface resistances of stem (C) and roots (A) with the solution. E1 and E2 refer to the electrodes.