Figure 2: Alnus rugosa – Frankia alni sp. ACN14a symbiosis tolerance to tailing sand stressor agents. The amalgam consists of a mixture of NaCl, Na2SO4 and naphtenic acids where 1[x]=the concentrations found in tailing sands. Black bars: inoculated alders, hatched bars : non-inoculated alders. (a) Plant total weight; (b) Allocation of biomass to roots; (c) Nodules’ mass as a percentage of the total mass; and, (d) Specific Nodule Number (SNN). Each bar represents the average value obtained from alders exposed to the same treatment. SNN=number of nodule per mass of root. A two-way ANOVA with Bonferroni post-tests was performed on (a) and (b), and a one-way ANOVA with Tukey post-tests was performed on (c) and (d). Error bars represent the SEM. The significant P values are indicated as follows: *, P<0.05; **, P<0.001; and, ***, P<0.001.