What was done
The authors grew spring wheat (Triticum aestivum L. cv. Gaoyuan 602) in open-top chambers receiving atmospheric CO2 concentrations of 350 and 700 ppm and three levels of soil moisture (40, 60 and 80% of field capacity) to study the interactive effects of these environmental variables on productivity and growth in this important agricultural crop.

What was learned
Elevated CO2 increased rates of net photosynthesis by 48, 120 and 97% at low, medium and high soil water capacities, respectively, while it reduced rates of transpiration by 56, 53 and 63% in the same order.  Consequently, these physiological changes lead to CO2-induced increases in plant water-use efficiency of approximately 25, 15 and 30% under low, medium and high soil moisture conditions, respectively.

What it means
As the air's CO2 content rises, this spring wheat cultivar (and others) will likely display enhanced rates of photosynthesis, decreased rates of transpirational water loss, and increases in water-use efficiency, even under less-than-optimal soil moisture conditions.  Thus, it should be able to better cope with periods of water stress in a future CO2-enriched world than it does currently.  In addition, this important crop should be able to be grown in areas where low soil moisture conditions presently preclude its cultivation.