Table II.
Gas exchange and isotopic characteristics for R. communis leaves
| Parameter | Experiment 1: Dark Respiration at Low CO2 Concentration | Experiment 2: Dark Respiration at Atmospheric CO2 Concentration | Experiment 3: Photosynthesis at Atmospheric CO2 Concentration |
|---|---|---|---|
| n | 11 | 10 | 8 |
| gs (mol m−2 s−1) | 0.28 (0.04 to 0.55) | 0.13 (0.03 to 0.28) | 0.50 (0.18 to 0.77) |
| E (mmol m−2 s−1) | 4.4 (1.2 to 7.8) | 2.7 (1.3 to 4.0) | 8.8 (5.7 to 15.1) |
| Tleaf (°C) | 29.3 (27.3 to 31.2) | 30.2 (29.3 to 30.8) | 27.2 (24.0 to 30.1) |
| Ca (μbar) | 47 (24 to 66) | 347 (324 to 365) | 363 (328 to 395) |
| Ci (μbar) | 63 (27 to 125) | 357 (328 to 401) | 285 (250 to 317) |
| Cc (μbar) | 66 (28 to 128) | 360 (330 to 403) | 249 (207 to 287) |
| ea/ei | 0.53 (0.13 to 0.92) | 0.41 (0.11 to 0.73) | 0.51 (0.30 to 0.78) |
 (‰) |
6.6 (5.4 to 8.4) | 5.9 (3.7 to 8.3) | 6.0 (5.0 to 7.5) |
| δa (‰ versus VSMOW) | 51.6 (43.8 to 59.0) | 43.5 (37.7 to 51.2) | 42.3 (40.1 to 45.4) |
| δe (‰ versus VSMOW) | 16.9 (5.0 to 29.2) | 20.5 (10.8 to 29.8) | 17.5 (9.4 to 23.9) |
| δL (‰ versus VSMOW) | 12.4 (4.3 to 26.5) | 17.2 (8.4 to 27.4) | 9.5 (4.1 to 16.4) |
| δc (‰ versus VSMOW) | 53.3 (44.8 to 63.2) | 51.4 (44.6 to 60.7) | 59.6 (50.4 to 70.7) |
| δR (‰ versus VSMOW) | 51.6 (43.8 to 59.0) | 277 (233 to 324) | |
| Modeled δR | 51.9 (34.0 to 64.4) | 291 (149 to 476) | |
| ΔA (‰ versus VSMOW) | 44.6 (32.4 to 78.5) | ||
| Modeled ΔA | 43.4 (30.6 to 62.9) |
Values are given as the mean, with the total range in parentheses, for the three experiments conducted. Symbols are as defined in Table I. Modeled δR values were calculated using Equation 2 and the empirically determined coefficients for θ and δc0 for experiments 1 and 2. Modeled ΔA values were calculated using Equation 13 and assuming Δca = Δea; the term Δea was calculated as in Equation 15.