What was done
The authors grew well watered and fertilized spring wheat (Triticum aestivum L. cv. Gazul) plants from seed to maturity out-of-doors in Salamanca, Spain, in two different years (2004 and 2005) within temperature-gradient chambers -- made of transparent polycarbonate walls and polyethylene sheet roofing -- that were maintained at ambient (370 ppm) and elevated (700 ppm) atmospheric CO2 concentrations and ambient air temperature (TA) and elevated air temperature (TE = TA plus 4°C), during which time they measured several plant physiological properties and processes.

What was learned
Gutierrez et al.'s findings are perhaps best summed up by the title of their paper: "Acclimation to future atmospheric CO2 levels increases photochemical efficiency and mitigates photochemistry inhibition by warm temperatures in wheat." They report, for example, that net photosynthesis was increased by 62-72% in both years in the CO2-enriched chambers; while at the conclusion of the growing season, total plant biomass production in the CO2-enriched chambers was increased by 12-18%.

What it means
The six Spanish scientists conclude that "future increases in atmospheric CO2 and temperature may have a positive effect on photochemical efficiency" in wheat, and that their work "provides evidence that with air CO2 enrichment a reallocation of resources favoring light capture may occur."