Fig. 3.

Relationships between uptake parameters. Maximum uptake rate per gram of dry root mass for (A) ${\text{NH}}_{\text{4}}^{+}$ and (B) ${\text{NO}}_{\text{3}}^{–}$, affinity for (C) ${\text{NH}}_{\text{4}}^{+}$ and (D) ${\text{NO}}_{\text{3}}^{–}$ and the co-ordinates of individuals along the first axis of the PCA. R² values for significant linear regression between variables (P-value <0.05) are indicated.