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/Jmaxoptimal Vcmax/Jmaxpredicted 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 (%)
200938.521.300.630.4738342110
200938.521.33.50.720.5439944612
200958.521.300.630.4045352516
200958.521.33.50.660.4451359015
201138.527.200.790.6039744813
201138.527.23.50.810.723954114
201158.527.200.710.4854162315
201158.527.23.50.790.5755964014