FIGURE 2.

(A–C) Leaf net CO₂ assimilation rate (A; μmol CO₂ m^–2 s^–1), (D–F) stomatal conductance (g_s; mol H₂O m^–2 s^–1), (G–I) transpiration rate (E; mmol H₂O m^–2 s^–1), (J–L) intrinsic water-use efficiency (WUE) (A/g_s; μmol CO₂ mol H₂O^–1), and (M–O) instantaneous WUE (A/E; mmol CO₂ mol H₂O^–1) on days 1, 3, 5, 7, and 14 of the drought/re-watering treatment in C. virgata (annual C₄), H. altissima (perennial C₄), and L. chinensis (perennial C₃). Different lower-case letters and capital letters indicate significant differences among the measuring dates under the unfertilized (N0) treatment and the fertilized (N10) treatment, respectively. “^*” represents significant differences between the N treatments (P < 0.05). Data are reported as the arithmetic mean ± 1 standard error (n = 6). Vertical dashed lines denote the separation of drought and re-watering period.