The influence N and P supply on the short-term responses to elevated CO2 in faba bean (Vicia faba L)

In this study the effects of the inorganic nutrients carbon dioxide, nitrogen and phosphorus on light-saturated photosynthetic rates (Pmax) and quantum yield (α) were investigated in faba bean. Both Pmax and α increased asymptotically in response to increasing N supply. However the maximums that were achieved for the asymptotic Pmax and α values in relation to N depended on both P and CO2 supply. Also, the short-term photosynthetic responses to the increasing concentrations of CO2 were observed to be co-limited by both N and P supply. These findings support the proposal that the N:P supply ratio controls the plant's photosynthetic capacity in response to elevated CO2 concentrations.