Figure 1.

Steady-state temperature dependencies of net CO₂ assimilation and dark respiration rates (A), photosynthetic electron transport rate from chlorophyll fluorescence (Eq. 1) and from gas exchange (Eq. 2; B), and stomatal conductance to water vapor and intercellular CO₂ concentration (C) in hybrid aspen leaves at ambient CO₂ concentration of 380 μmol mol⁻¹ and oxygen concentration of 210 mmol mol⁻¹. Data for the net assimilation rate (A) and photosynthetic electron transport (B) were fitted by Equation 3, and the optimum temperatures (T_opt) were calculated by Equation 4. Error bars show sd of five replicate experiments.