Fig. 2

Aluminium-induced malate (a) and citrate (b) excretion from roots of E. grandis × E. urophylla G9 and E. urophylla W4 into growth media at the indicated times after initiation of Al treatment. Growth media containing root exudates was sampled at each time point after the addition of Al at the same time that the seedlings were harvested. Data are means ± standard error (n = 3). Different letters above the bars indicate a significant difference at P < 0.05. CK, non-Al-treated control; Al, aluminium treated