Growth and Zn content analyses.

Growth parameters and Zn concentration and content in roots, stem and leaves of Populus x canadensis clone I-214 subjected to 1 μM (control) and 1 mM Zn treatments. Data reported are the means ± s.d. (n = 5). Results of student t-test are shown. DW = dry weight. Shoot/root was calculated using the sum of leaf and stem DW/root DW. RGR was calculated using the root, stem and leaf DW determined at time t0 and after 3-week Zn treatments. RGR = Relative Growth Rate; SLA = Specific Leaf Area. The total biomass, the RGR and shoot/root ratio were calculated excluding woody cuttings.* = P ≤ 0.05** = P ≤ 0.01*** = P ≤ 0.001Growth and Zn content analyses.