Submitted to: Agronomy Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: October 28, 1997
Publication Date: N/A
Field-grown spring wheat (Triticum aestivum L. cv. Yecora Rojo) was exposed to CO2 concentrations enriched to 200 umol/mol above ambient (ca. 370 umol/mol) using free-air CO2 enrichment (FACE) apparatus (main plot). Half of each main CO2 plot received ample nitrogen at levels of ca. 350 kgN/ha while the other half received ca. 70 kgN/ha. Measurements of photosynthesis (A) at a range of intercellular CO2 levels (Ci) were made throughout the season (5-leaf to grain ripe). The range in parameter estimates derived from the A/Ci curves (Vcmax, carboxylation efficiency) was broadcast in FACE-high N (FH) and narrowest in FL. Both CH (Control-High N) and CL were intermediate in their response, but the range in Vcmax and carboxylation efficiency was broader in CH than in CL. This CO2xN interaction effect occurred because of a larger proportionate change in the range of Vcmax and carboxylation efficiency under FACE compared with Control. Although inconclusive, preliminary results suggest that acclimation of the photosynthetic apparatus to elevated CO2 may have occurred for this cool season annual C3 grass grown under N deficiency.