What was done
The authors grew eight ancestral and one modern soybean (Glycine max L.) genotype in glasshouses receiving atmospheric CO2 concentrations of 400 and 710 ppm to determine the effects of elevated CO2 on seed yield in these cultivars.

What was learned
Elevated CO2 increased photosynthetic rates in all cultivars by an average of 75%.  This enhancement in photosynthetic sugar production lead to CO2-induced increases in seed yield that averaged 40% for all cultivars, except for one ancestral variety that exhibited an 80% increase in seed yield.

What it means
As the CO2 content of the air rises, it is likely that the photosynthetic rates of soybeans will also rise, leading to significant increases in seed yield.  In addition, if plant breeders utilize the highly CO2-responsive ancestral cultivar identified in this study in their breeding programs, it is possible that soybean seed yields could be made to rise even faster in the days and years ahead.