Fig. 2. Dependence of log concentration of Cd in plant tissue on the log of (a) effective Cd concentration, C_E, before growth, (b) effective Cd concentration, C_E, after growth, (c) soil solution Cd, before growth, (d) soil solution Cd, after growth, (e) free Cd²⁺ activity, (f) CaCl₂–extracted Cd, (g) Cd E value, and (h) total soil Cd. The quadratic regression equations and regression coefficients are shown.