Fig. 6.

(A) The relationship between ambient PPFD above the canopy and the contribution of [CO₂] to the increase of GPP (ΔGPP) for a mature soybean canopy from the V10 stage to the V18 stage (207 to 264 DOY). Different points show data from different days and the R² of the linear fitting is 0.727. (B) Light response curves of leaf photosynthetic CO₂ uptake rates under elevated [CO₂] and ambient [CO₂] conditions on the 219 DOY. The curves were drawn based on the V_cmax and J_max measured on 219 DOY.