Table II.

Effect of temperature, Ci, and O2 on Pn and Rubisco activation in intact Antarctic hairgrass leaves

TemperatureO2CiPnRubisco activation
°Cmbarμbarμmol m−2 s−1%
1621029019.4 ± 0.5100
161027025.6 ± 2.377.8
3221023413.4 ± 0.4NDa
3621024111.4 ± 0.766.4
361021316.8 ± 1.050.3
361028422.1 ± 1.3ND
361039528.9 ± 2.3ND
361054936.1 ± 2.4ND
361070240.8 ± 2.537.1
  • 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.