Fig. 2

Zn and Cd xylem loading. Rice plants were hydroponically grown and exposed for a 10-day period to increasing Zn external concentrations (from 0.1 to 10 μM), in the absence or presence of 0.1 μM Cd²⁺ (a and b), or to different Cd concentrations (from 0 to 1 μM) in the presence of 1 μM Zn²⁺ (c and d). At the end of the exposure period, shoots were separated from roots and the xylem sap exuded from the cut (root side) surface was collected over a 45 min period. a Zn ions loaded and transported in the xylem sap in the absence (white circles) and in the presence (grey circles) of a steady amount of Cd. b Cd ions loaded and transported in the xylem sap in the presence of a steady amount of Cd. c and d Zn and Cd ions loaded and transported in the xylem sap in the presence of a steady amount of Zn. Data are means and SE of three experiments run in triplicate (n = 9). Different letters indicate significant differences between treatments (P < 0.05). Asterisks indicate significant differences between plants exposed or not to 0.1 μM Cd²⁺ (P ≤ 0.001)