What was done
The authors grew potato (Solanum tuberosum cv. Kennebec) plants from "seed tubers" planted in a 75:25 mix of coarse sand and vermiculite within soil-plant-atmosphere research chambers that were maintained at daytime atmospheric CO2 concentrations of either 370 or 740 ppm at well-watered and progressively water-stressed conditions until they were harvested when canopy photosynthetic rates dropped to below 50% of their seasonal peak values, before and after which they measured a variety of plant physical properties and physiological parameters.

What was learned
Fleisher et al. report that "proportionately more dry mass was partitioned to belowground organs for elevated CO2 as irrigation decreased," so that "tuber yields were larger for elevated CO2 plants at the lower irrigation amounts."

What it means
Noting that "CO2 enrichment helped mediate negative effects of drought stress on potato productivity," the three researchers concluded their results indicated that "CO2 interaction with water stress will compensate, to some extent, for anticipated decreased water supply available for potato production under future climate change scenarios," and that "water stress predicted by climate change models will be mediated somewhat under CO2 enrichment."