Figure 4. Alteration of gas exchange after transfer from high CO₂ to ambient air.

Plants were grown in HC and transferred to LC exactly as described in the legend to Figure 1 (short day conditions). Net CO₂ uptake (A, at 380 µl L⁻¹ CO₂) and CO₂ compensation points (Γ₂₁) were measured before (HC control) and after (LC; 1, 3 and 5 days) transfer to normal air. Mean values ± SD (n = 5) are shown. Asterisks show significant alterations according to the two-tailed Student's t-test (p<0.05, * to wild-type, ** to hpr1, ⁺ to glyk1 and shm1 at the corresponding time points).