What was done
The authors grew winter wheat (Triticum aestivum L. cv. Hereward) in polyethylene tunnels maintained at atmospheric CO2 concentrations of 380 and 680 ppm from the time of seed germination to the time of plant maturity.  In addition, a temperature gradient of approximately 4°C was established in each tunnel.  In this paper, the authors report the effects of elevated CO2 and temperature on seed post-production survival and germination.

What was learned
Elevated CO2 increased seed yield per unit area, as well as mean seed weight; but it did not affect post-production seed survival and germination.  Increasing air temperatures, on the other hand, increased potential seed longevity across the entire range of temperatures investigated (14 to 19°C).

What it means
As the CO2 content of the air continues to rise, winter wheat seed production will likely increase without exhibiting any changes in seed viability.  And if air temperatures also rise, seed viability may actually increase.