Fig. 1.

Root elongation rate (A) and Al content of 1 cm root tips (B) of four common bean genotypes under osmotic (200 g l⁻¹ PEG) and Al stress (25 μM Al). Plants were pre-cultured in a simplified nutrient solution containing 5 mM CaCl₂, 1 mM KCl, and 8 μM H₃BO₃ for 48 h for acclimation and pH adaptation, then treated without or with 25 μM Al in the absence or presence of 200 g l⁻¹ PEG in the simplified nutrient solution for 24 h, pH 4.5. Bars represent means ±SD, n=12 for (A) and n=4 for (B). Means with the same small letter and capital letter are not significantly different at P <0.05 (t test) for the comparison of PEG treatments within Al supplies and comparison of Al treatments within PEG supplies, respectively. For the ANOVA, **^, *** denote significant differences at P <0.01, P <0.001, respectively; ns, not significant.