Fig. 2From: The influence of nitrogen availability on anatomical and physiological responses of Populus alba × P. glandulosa to drought stressLeaf N concentration (a) and N uptake (b) under drought and well-watered conditions with low nitrogen (LN) or adequate nitrogen (AN). The bars indicate means ± SE (n = 12). Different letters on the bars indicate significant differences (P < 0.05) based on multiple comparisons (Tukey’s HSD test) in ANOVA. P-values of the two-way ANOVA of water (W), nitrogen (N) and their interactions (W × N) are indicated. *P < 0.05; **P < 0.01; ns, not significantBack to article page