Effects of Al and B interactions on Chl (A), Chl a (B) and Chl b (C) concentrations and Chl a/b ratio (D) of leaves, and total soluble protein concentration of roots (E) and leaves (F) in Citrus grandis seedlings. Diagonal cross area quantifies the Al effect under different B supply. Each point is mean of 4 – 5 replicates with standard error. Difference among eight treatments was analyzed by 2 (Al levels) × 4 (B levels) ANOVA. P values for Al, B, and the interaction between the two were < 0.0001, 0.0016 and 0.0557 (A); < 0.0001, 0.0076 and 0.0311 (B); < 0.0001, 0.0339 and 0.2040 (C); 0.0314, 0.0255 and 0.0164 (D); < 0.0001, 0.0001 and 0.2386 (E); 0.0236, 0.6780 and 0.5181 (F), respectively. Different letters indicate significant differences among eight treatments at P < 0.05.