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Does Elevated CO2 Cause Genotypic Selection in Perennial Grasses?
Reference
Roumet, C., Laurent, G., Canivenc, G. and Roy, J.  2002.  Genotypic variation in the response of two perennial grass species to elevated carbon dioxide.  Oecologia 133: 342-348.

What was done
The authors grew 14 genotypes of the perennial grasses Bromus erectus Huds. and Dactylis glomerata L. in competition with one another in soil monoliths placed within glasshouses maintained at atmospheric CO2 concentrations of 350 and 700 ppm for two years to determine whether or not elevated CO2 causes genotypic selection within these species common to Mediterranean rangelands.

What was learned
Over the two-year study, elevated CO2 elicited a large variety of shoot biomass growth responses in Bromus erectus, ranging from -37 to +38%.  However, none of these CO2 x genotype interactions was significant.  In Dactylis glomerata, elevated CO2 caused a similarly large variety of shoot biomass responses (-44 to +90%); and in this species, elevated CO2 caused one marginally significant CO2 x genotype interaction.  With respect to reproductive biomass, however, elevated CO2 did not significantly interact with genotypes of either species.

What it means
As the CO2 content of the air increases, it will likely have little to no impact on genotypic selection within these two perennial grass species.  Thus, future increases in the air's CO2 content will likely result in small to no changes in the genetic variability that currently exists within these grasses.


Reviewed 23 October 2002