N contents [mmol g^-1 DW] in poplar plants exposed to normoxia or hypoxia for 14 days.

During harvest the trees were divided into leaf, petiole, bark, wood, fine roots and coarse roots. The shoot was separated into the top 40 cm, middle 40 cm and bottom 50 cm Data shown are means ± SD of 22–24 biological replicates. The differences between plants exposed to either hypoxia or normoxia were tested by Student’s t-test at p< 0.05; significant differences are indicated by bold. N contents [mmol g-1 DW] in poplar plants exposed to normoxia or hypoxia for 14 days.