Fig. 4.

Photosynthesis and chlorophyll fluorescence response of aCO₂- and eCO₂-grown wheat cv. Scout measured before, during, after, and at the recovery stage of the heat stress cycle. CO₂ assimilation rates (a), of the F_v/F_m ratio in dark-adapted leaves (b), stomatal conductance (c), and of the F_v'/F_m' ratio in light-adapted leaves (d) measured at growth CO₂ (aCO₂-grown plants measured at 400 μl l⁻¹ and eCO₂-grown plants measured at 650 μl l⁻¹). Values are means ±SE (n=9–10). Ambient and elevated CO₂-grown plants are depicted in black and grey, respectively. Filled and open circles represent control and heat-stressed plants, respectively. The circle and star symbols depict CO₂ assimilation rates measured at 25 °C and 35 °C, respectively.