Effect of temperature, Ci, and O2 on Pn and Rubisco activation in intact Antarctic hairgrass leaves
| Temperature | O2 | Ci | Pn | Rubisco activation |
|---|---|---|---|---|
| °C | mbar | μbar | μmol m−2 s−1 | % |
| 16 | 210 | 290 | 19.4 ± 0.5 | 100 |
| 16 | 10 | 270 | 25.6 ± 2.3 | 77.8 |
| 32 | 210 | 234 | 13.4 ± 0.4 | NDa |
| 36 | 210 | 241 | 11.4 ± 0.7 | 66.4 |
| 36 | 10 | 213 | 16.8 ± 1.0 | 50.3 |
| 36 | 10 | 284 | 22.1 ± 1.3 | ND |
| 36 | 10 | 395 | 28.9 ± 2.3 | ND |
| 36 | 10 | 549 | 36.1 ± 2.4 | ND |
| 36 | 10 | 702 | 40.8 ± 2.5 | 37.1 |
The Pn of each of three sets of leaves was measured under all of the conditions listed below by continuously changing the O2, temperature, and Ci after first achieving a steady-state rate at 16°C, 210 mbar O2, and 290 μbar Ci. Rubisco activation was measured by rapid extraction and assay of freeze-clamped leaves. By necessity, separate sets of leaves were used for determining Rubisco activation.
a ND, Not determined.