Table 1.
Effect of elevated (550 µmol mol–1) and ambient (390 µmol mol–1) [CO2] on some photosynthetic parameters of two coffee cultivars (Catuaí and Obatã) growing in a FACE trial during the growing season (February) and winter (August)
The following values were determined: mesophyll conductance (g m), estimated using two independent methods: the EDO curve-fitting technique and the method that was proposed by Harley et al. (1992); the maximum apparent carboxylation capacity (V cmax) and the in vivo maximum rate of carboxylation as limited by electron transport (J max), both on a chloroplast [CO2] basis; and the chloroplastic [CO2] (C c) and C c of transition (C c_trans). Data for J max and C c_trans were not obtained in August. V cmax, J max and g m were normalized to 25 °C using the temperature response equations from Sharkey et al. (2007). n=5–6±SE.
| Parameter | Catuaí | |||
|---|---|---|---|---|
| February | August | |||
| 390 µmol mol–1 | 550 µmol mol–1 | 390 µmol mol–1 | 550 µmol mol–1 | |
| g m_EDO | 0.067±0.012 | 0.102±0.015 | 0.072±0.012 | 0.072±0.015 |
| g m_Harley | 0.073±0.008 | 0.061±0.007 | 0.071±0.011 | 0.105±0.024 |
| V cmax | 61.0±1.8 | 54.8±2.8 | 57.3±5.4 | 58.3±3.3 |
| J max | 95.6±3.9 | 81.1±4.6 | - | - |
| C c | 152±15 | 205±15 | 107±9 | 182±19 |
| C c_trans | 268±15 | 231±13 | - | - |
| Obatã | ||||
| February | August | |||
| 390 µmol mol–1 | 550 µmol mol–1 | 390 µmol mol–1 | 550 µmol mol–1 | |
| g m_EDO | 0.060±0.015 | 0.083±0.017 | 0.088±0.021 | 0.063±0.010 |
| g m_Harley | 0.091±0.018 | 0.065±0.007 | 0.058±0.010 | 0.082±0.014 |
| V cmax | 55.2±3.3 | 54.8±2.7 | 59.9±5.6 | 52.3±1.9 |
| J max | 86.8±6.2 | 80.0±5.3 | – | – |
| C c | 173±15 | 253±31 | 104±19 | 165±23 |
| C c_trans | 303±10 | 231±9 | – | – |