Figure 1.

Effect of Al on the exudation of organic acid anions from 5-mm root apices of intact maize seedlings. Root apices were incubated in a solution containing 200 μm CaCl₂ and 0, 100, or 200 μm AlCl₃ (pH 4.3) for 2 h. a, Total exudation rate of organic acid anions. b, Exudation rate of citrate (black bars) and malate (gray bars). Values are means of three independent replicates ± sd. Results shown are representative of two independent experiments. Different letters indicate significant differences at P < 0.05 (Tukey test). Small letters display treatment effects, and capital letters depict genotypical differences.