|Pinter Jr, Paul|
|Leavitt, S. - UNIV. OF ARIZONA|
|Webber, A. - ARIZONA STATE UNIV.|
Submitted to: Agronomy Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: November 19, 1998
Publication Date: N/A
Technical Abstract: Field-grown spring wheat (triticum aestivum L. cv. Yecora Rojo) was exposed to carbon dioxide (CO2) concentrations enriched to 200ppm above ambient (ca. 370ppm) control plots using free-air CO2 enrichment (FACE) apparatus (main plot). Half of each main CO2 plot received ample nitrogen levels of ~350 kg N ha-1, while the other half received ~70 kg N ha-1. Measurements of photosythesis (A) at a range of intercellular CO2 levels (Ci) were made throughout the season on the three uppermost, fully-exposed leaves of the main stem. Biochemical analyses were also conducted on these leaves. Treatment effects on activities of Rubisco and quantities of the large and small subunits of Rubisco protein were similar to treatment effects on the carboxylation efficiencies calculated from the A-Ci relationship. Leaves from both ample and low nitrogen treatments showed reductions in each parameter as a result of CO2 enrichment, indicating that tacclimation of the photosynthetic apparatus to CO2 enrichment occurred. Leaves lower in the canopy showed more pronounced changes in each parameter.