What was done
Three winter wheat (Triticum aestivum L.) varieties commonly cultivated in Hungary - Martina (an early ripening variety with medium breadmaking quality and record productivity), Mezofold (a mid-early hard red variety with good agronomic characteristics), and Emma (similar to Mezofold with excellent breadmaking quality) - were grown in pots placed in growth chambers that were maintained at atmospheric CO2 concentrations of either 375 or 750 ppm, while being watered daily and supplied with essential nutrients on a weekly basis for one entire growing season.  In addition, half of the plants of each CO2 treatment were exposed to a significant heat stress during their respective grain-filling periods.

What was learned
The authors report that Martina "responded very positively to CO2 treatment, exhibiting an increase in the tiller and ear number and in the number of grains per plant, resulting in 38% higher yield without a deterioration in the grain quality."  They also state that "neither CO2 nor heat stress had a negative effect on the flour quality of this variety," noting that protein and gluten contents, as well as SDS sedimentation volumes, actually increased in both treatments.  Elevated CO2 had somewhat less positive influence on the yields of the other two varieties, while heat stress had a negative effect; but Bencze et al. note that this latter phenomenon "could be counterbalanced by elevated CO2."

What it means
Atmospheric CO2 enrichment typically increases the yields of nearly all wheat varieties, although some may experience decreases in some aspects of grain quality that may also be induced by heat stress.  Nevertheless, there are always varieties, such as Martina, that experience improvements in grain quality under elevated CO2 and temperature; and, therefore, as Bencze et al. conclude, "it is possible to produce genotypes with better adaptability to [predicted] changes in environmental conditions through plant breeding," not to mention genetic engineering, which can actually take advantage of, and benefit from, the "twin evils" (rising CO2 and temperature) of the climate-alarmist movement.