Fig. 3.

Stylo root growth was affected by different Al concentrations: (A) relative tap root growth; (B) roots stained with haematoxylin to visualize root Al content. Plants were grown in nutrient solution at three Al³⁺ levels: 0, 50 or 100 µm as AlCl₃. Relative tap root growth was calculated as the percentage of tap root growth for roots grown at different Al³⁺ levels at pH 4·2 relative to the tap root growth without Al addition at pH 5·8. Each column is the mean and s.e. of four replicates. F-values of ANOVA: 12·24 for genotype (P < 0·0001), 28·68 for Al treatments (P < 0·0001).