Table 4.
Selected parameters (mean ± s.d.) of temperature response curves of light-saturated rate of Rubisco carboxylation (VCmax) and light-saturated rate of photorespiration (RL) calculated for individual leaves of Fagus sylvatica and Picea abies grown at ambient (AC) and elevated (EC) CO2 concentration
| Parameter | Units |
F. sylvatica |
P. abies |
||
|---|---|---|---|---|---|
| AC | EC | AC | EC | ||
| VCmax,25 | µmol m−2 s−1 | 40·1 ± 3·9 | 34·4 ± 2·8 | 26·5 ± 1·4 | 22·6 ± 2·6 |
| VCmax at Topt | µmol m−2 s−1 | 82·6 ± 5·7 | 105·7 ± 10·6* | 37·2 ± 2·8 | 42·2 ± 3·1 |
| Topt(VCmax) | °C | 36·3 ± 0·9 | 40·0 ± 0·9** | 32·4 ± 0·3 | 35·8 ± 0·3** |
| RL,25 | µmol m−2 s−1 | 6·3 | 3·2 | 3·3 | 0·1 |
| RL at Topt | µmol m−2 s−1 | 6·9 | 6·4 | 3·3 | 3·6 |
| Topt(RL) | °C | 29·8 | 35·3 | 25·3 | 30·9 |
VCmax,25 and RL,25 are VCmax and RL rates at reference leaf temperature 25 °C; Topt(VCmax) and Topt(RL) are temperature optima of VCmax and RL. Measurements were performed at growth CO2 concentration and 2 % oxygen (RL) or at intercellular CO2 concentrations ranging between 50 and 250 µmol CO2 mol−1 (VCmax). Statistically significant differences between AC and EC treatments are indicated as follows: *0·01 < P < 0·05, **p < 0·01; n = 3. See Supplementary Table S2 for the complete list of parameters of the modified Arrhenius function (eqn 2) fitted to the VCmax and RL data.