Table 1.
Observed and optimal Vcmax/Jmax ratios for soya bean grown at elevated [CO2], air temperature or both and associated predicted reductions in canopy productivity. (Observed parameter values were obtained from [25]. Results are shown for two contrasting field seasons in Illinois: 2009 (cool) and 2011 (hot).)
| year | [CO2] (Pa) | monthly average T (°C) | ΔT (°C) | observed Vcmax/Jmax | optimal Vcmax/Jmax | predicted canopy productivity with observed Vcmax/Jmax ratio (kg CH2O m−2 d−1) | predicted canopy productivity with optimal Vcmax/Jmax ratio (kg CH2O m−2 d−1) | relative productivity difference optimal versus observed Vcmax/Jmax ratio (%) |
|---|---|---|---|---|---|---|---|---|
| 2009 | 38.5 | 21.3 | 0 | 0.63 | 0.47 | 383 | 421 | 10 |
| 2009 | 38.5 | 21.3 | 3.5 | 0.72 | 0.54 | 399 | 446 | 12 |
| 2009 | 58.5 | 21.3 | 0 | 0.63 | 0.40 | 453 | 525 | 16 |
| 2009 | 58.5 | 21.3 | 3.5 | 0.66 | 0.44 | 513 | 590 | 15 |
| 2011 | 38.5 | 27.2 | 0 | 0.79 | 0.60 | 397 | 448 | 13 |
| 2011 | 38.5 | 27.2 | 3.5 | 0.81 | 0.72 | 395 | 411 | 4 |
| 2011 | 58.5 | 27.2 | 0 | 0.71 | 0.48 | 541 | 623 | 15 |
| 2011 | 58.5 | 27.2 | 3.5 | 0.79 | 0.57 | 559 | 640 | 14 |