Table I.

Effect of temperature, Ci, and O2 on Pn and Rubisco activation in intact creosote bush leaves

TemperatureO2CiPnRubisco activation
°Cmbarμbarμmol m−2 s−1%
2821026129.0 ± 0.6100
281024343.9 ± 1.179.4
4021025823.3 ± 1.684.7
42.521026219.3 ± 1.660
42.51024132.8 ± 1.1NDa
42.51033539.8 ± 1.4ND
42.51048949.5 ± 0.7ND
42.51068756.4 ± 0.7ND
42.51084459.0 ± 0.339.1
  • 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 28°C, 210 mbar O2, and 261 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.