Fig. 3

Zinc and cadmium concentration in the apical, middle and basal parts of roots from plants grown under various Zn and Cd concentrations. 3.5-week old plants grown in the quarter-strength Knop’s medium were exposed to the control medium supplemented with pairwise combinations of Zn (0; 1 μM) and Cd (0; 0.25; 1 μM) concentrations for 17 days. Concentrations of metals were measured in the apical parts (2.5 cm) from the main and lateral roots; basal (proximal) parts (1/4 of the total length of the main roots); middle part (remaining parts of the main roots). The basal and the middle parts of the roots were collected from the main root only (adventitious roots were excised). Zinc concentration (a): at Zn-deficiency (a1), at 1 μM Zn (a2). Cadmium concentration (b): at Zn-deficiency (b1), at 1 μM Zn (b2). Values correspond to arithmetic means ±SD (n = 10). Significance of differences between all values were evaluated by Student’s t-test (P ≤ 0.05), and it has been determined that each pair of values is significantly different if the SD bars do not overlap. Significance has not been marked above the bars with the letters or arrows to keep the clarity of the graph