Photosynthetic Capacity and Productivity of CO2-Enriched Rice (Oryza sativa L.) Under Field Conditions: The Role of N Fertilization

We studied the impacts of free-air CO(2 )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 saliva L.). Plant were exposed to ambient or elevated [CO2] (ambient + 200 mu mol mol(-1) ) and 4, 9 or 15 g N m(-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. (C) 2005 by The Haworth Press, Inc.