Photosynthetic Capacity and Productivity of CO2-Enriched Rice (Oryza sativa L.) Under Field Conditions

Abstract

SUMMARY We studied the impacts of free-air CO2 enrichment (FACE), and the interaction with nitrogen (N) fertilization, on the photosynthetic capacity of the flag leaf, above-ground dry matter production and grain yield of rice (Oryza sativa L.). Plant were exposed to ambient or elevated [CO2] (ambient + 200 μmol mol−1) and 4, 9 or 15 g N mr 2 . We found no evidence of down-regulation of the photosynthetic capacity of the flag leaf in FACE. Although a reduction in N fertilization reduced the content of nitrogen and photosynthetic pigments, this hardly affected the photosynthetic capacity of the flag leaf. Both FACE and N enrichment stimulated the above-ground dry matter production and grain yield, however, the stimulation of grain yield by FACE was not significant at low N supply.