FIGURE 7.

Effects of LaCl₃ and external Ca²⁺ on steady Cd²⁺ and/or Ca²⁺ fluxes in roots of ectomycorrhizal (MAJ and NAU) and non-mycorrhizal (NM) Populus × canescens plants under Cd²⁺ stress. (A,B) Ectomycorrhizal (MAJ and NAU) and NM P. × canescens plants were subjected to 50 μM CdCl₂ for 24 h in the presence and absence of 5 mM LaCl₃. Control roots were well fertilized but treated without CdCl₂ or LaCl₃. (C) Ectomycorrhizal (MAJ and NAU) and NM P. × canescens plants were subjected to 50 μM CdCl₂ for 24 h prior to Cd²⁺ flux recordings in the presence of CaCl₂ (25 μM, 50 μM, or 100 μM; the ratio of Ca²⁺:Cd²⁺ was 1:2; 1:1, and 2:1). Ca²⁺ (A) and Cd²⁺ (B,C) fluxes were measured along root axes, 100–2,300 μm from the apex, at intervals of 200–300 μm. Each point is the mean of 4–5 individual plants and bars represent the standard error of the mean. Inserted sections show the mean flux rates and different letters, a, b, c, and d, indicate significant difference at P < 0.05 between treatments.