Table 1.
The maximum rate of carboxylation by Rubisco (Vc,max), the PPF‐saturated rate of electron transport (Jmax), assimilation at saturating light and CO2 (Asat), and the apparent quantum efficiency (Q) in Pascopyrum smithii (C3) at three periods during the growing season
| Vc,max (µmol CO2 m–2 s–1) | Jmax (µmol e– m–2 s–1) | Asat (µmol CO2 m–2 s–1) | Q (CO2/photon) | |
| Early season | ||||
| Ambient CO2 | 63·3 ± 4 | 206 ± 20 | 32·8 ± 2·4 | 0·066 ± 0·01 |
| Elevated CO2 | 40·9 ± 4 | 121 ± 16 | 19·9 ± 2·4 | 0·076 ± 0·007 |
| Mid‐season | ||||
| Ambient CO2 | 43·4 ± 9 | 97 ± 21 | 15·5 ± 3·7 | 0·051 ± 0·009 |
| Elevated CO2 | 28·2 ± 3 | 57 ± 7 | 10·1 ± 1·3 | 0·053 ± 0·008 |
| Late season | ||||
| Ambient CO2 | 62·9 ± 6 | 155 ± 19 | 24·5 ± 3·3 | 0·053 ± 0·013 |
| Elevated CO2 | 39·2 ± 5 | 99 ± 15 | 16·2 ± 3·4 | 0·053 ± 0·004 |
| P | ||||
| CO2trt | 0·0001 | 0·0003 | 0·0006 | 0·4968 |
| Year | 0·8744 | 0·3395 | 0·2531 | 0·6905 |
| Season | 0·0132 | 0·0001 | 0·0001 | 0·1527 |
| CO2trt × year | 0·7552 | 0·5467 | 0·6649 | 0·8450 |
| CO2trt × season | 0·7006 | 0·4207 | 0·4028 | 0·9547 |
Plants were grown in open‐top chambers on native shortgrass steppe of Colorado, USA, with ambient or elevated (360 and 720 µmol mol–1) CO2. Data are averaged across three years and three replications ± s.e.