Table I.

Gas exchange (at max PPFD), CA activity, and isotopic water data (average at all PPFDs) for tobacco, soy (n = 3 and 2), and oak (n = 3, at different O2%)

SpeciesEmax gs(max) Amax ci(min) Tmax CAassay CAleaf VPDδtδeδLW
     × 103
Tobacco 15.524414.127427.2n.d1,6231-a 1.37 (0.19)−6.3 (0.9)+12.0 (1.1)+11.0
Tobacco 24.818913.524029.354.8 (13)5981.48 (0.17)−5.5 (0.6)+15.6 (1.0)+11.9
Tobacco 35.024115.826528.571.3 (6.3)6701.27 (0.18)−2.3 (0.7)+16.4 (1.1)+13.6
Soy 14.320612.225529.325.3 (2.9)2941.51 (0.11)−4.7 (0.9)+11.0 (1.1)+11.0
Soy 25.130020.023728.537.1 (1.6)3421.32 (0.14)−5.1 (0.9)+12.7 (0.3)+11.9
Oak - 40%3.314211.823728.9n.d.1.62 (0.18)−5.6 (1.9)+13.4 (1.4)n.d
Oak - 20%4.216615.520729.2n.d.1.57 (0.17)−6.6 (0.6)+11.8 (0.8)n.d.
Oak - 2%4.117217.517427.8n.d.14.6 (2.2)−6.2 (0.7)+13.1 (1.3)n.d.

Units are: evaporation rate (E max, mmol m−2 s−1), stomatal CO2conductance (gs(max) , mmol CO2m−2 s−1), CO2 assimilation (Amax , μmol m−2s−1), sub-stomatal CO2 concentration (ci , μmol mol−1), leaf temperature (Tmax , °C), carbonic anhydrase CO2 hydration rate, under assay (CAassay , at 2°C and 35 mm[CO2], mean of three leaves), and in vivo conditions (CAleaf , at ccs andTleaf , μmol CO2 m−2s−1). For VPD (kPa) and isotopic data (‰), nos. are averages (+sd) during the entire light response. Symbols as in text.

    • F1-a In vivo CA hydration based on the meanCAassay of the other two tobacco plants.