Fig. 2.

Carbon isotope discrimination (∆) during net CO₂ exchange (A, B) and bundle sheath leakiness (C, D) of Cleistogenes squarrosa leaves in response to short-term variation of intercellular CO₂ (C_i). Plants were grown under low (N1, circles; A, C) or high N supply (N2, triangles; B, D) combined with low (V1, open symbols, dashed lines) or high VPD (V2, filled symbols, solid lines). Operating conditions of gas exchange measurements were the same as conditions in growth chambers (leaf temperature 25 °C, PPFD 800 μmol m⁻² s⁻¹, VPD 0.8 kPa for V1 and 1.6 kPa for V2). Data are shown as the mean±SE (n=5–6). The regressions were fitted using a function of y=y₀+aln(x); all regressions have r²>0.8.