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. 2013 Aug 20;64(14):4207–4224. doi: 10.1093/jxb/ert234

Fig. 6.

Fig. 6.

Total N concentration and δ15N in roots (A and B) and leaves (C and D) of P. popularis (Pp) and P. alba × P. glandulosa (Pg) exposed to 10, 100, or 1000 μM NH4NO3. Bars indicate mean ± SE (n = 6). Different letters on the bars indicate significant difference. P-values of the ANOVAs of species, N treatment, and their interaction are indicated. *P < 0.05; **P < 0.01; ***P < 0.001; ****P < 0.0001; ns, not significant. DW, dryweight (this figure is available in colour at JXB online).