Figure 5. Diel (24 h) leaf growth patterns in high CO₂ and thereafter in ambient air.

Grey (night) and white (day) areas mark the 10/14 h photoperiodic phases. Relative growth rates (RGR, left scale) of the Arabidopsis wild type (A) and photorespiratory mutants hpr1 (B), shm1 (C), glyk1 (D), and pglp1 (E) in HC conditions (1% CO₂, open circles) and after HC-to-LC transition in ambient CO₂ (closed circles). Each data point represents the mean RGR ± SE of one-hour average RGR values of the preceding hour individually measured with five leaves, each from another plant. Mean RGR values (RGR averaged over the preceding hour) over the day and night period are shown as horizontal lines (right scale; HC, dashed lines; LC, solid lines).