Parameters of the photosynthesis model of Farquhar et al. (1980) fitted to the relationships shown in Figure 4 between net CO2 A and ci
Values of the parameters Γ* and K′ (photorespiratory compensation point and effective Km for Rubisco, respectively) were calculated from expressions given by Farquhar et al. (1980) using values of Rubisco Km and turnover rates for carboxylation and oxygenation given by de Pury and Farquhar (1997) for 25°C.
| Parameter | Symbol | Units | PFD/[O2] | |||
|---|---|---|---|---|---|---|
| 300/2 | 1,000/2 | 300/21 | 1,000/21 | |||
| μE m−2 s−1/% | ||||||
| Maximum velocity of carboxylation | Vc,max | μmol m−2 s−1 | 68 ± 6 | 90 ± 6 | 105 ± 38 | 109 ± 6 |
| Potential electron transport rate | J | μmol e− m−2 s−1 | 40 ± 1 | 84 ± 3 | 39 ± 7 | 105 ± 5 |
| Mitochondrial respiration rate | Rd | μmol m−2 s−1 | 0.7 ± 0.1 | 0.9 ± 0.1 | 1.0 ± 0.4 | 1.1 ± 0.1 |
| Intercellular CO2 mole fraction at transition point | ci | μmol mol−1 | 79 ± 10 | 145 ± 20 | 35.9 | 181 ± 33 |
| Photorespiratory compensation point | Γ* | μmol mol−1 | 3.4 | 35.9 | ||
| Effective Km for carboxylation | K′ | μmol mol−1 | 502.3 | 811.9 | ||