Graham, E.A. and Nobel, P.S. 1996. Long-term effects of a doubled atmospheric CO2 concentration on the CAM species Agave deserti. Journal of Experimental Botany 47: 61-69.
What was done
The authors grew the CAM plant Agave deserti Engelm. in environmental chambers maintained at atmospheric CO2 concentrations of 370 and 750 ppm for 17 months to study the effects of elevated CO2 on gas exchange and biomass production in this succulent Sonoran Desert species.
What was learned
Twice-ambient CO2 concentrations increased plant daily net carbon uptake by nearly 50%, while reducing daily transpirational water loss by approximately 24%. Together, the two phenomena led to a 110% increase in plant water-use efficiency. At the same time, however, prolonged exposure to atmospheric CO2 enrichment induced measurable photosynthetic acclimation, as indicated by an 11% reduction in rubisco activity and a 34% reduction in the activity of PEP-carboxylase. Nevertheless, the plants grown in elevated CO2 produced 88% more biomass than the plants grown in ambient air.
What it means
As the air's CO2 content continues to rise, this desert succulent will likely exhibit increased rates of photosynthesis and growth while concomitantly displaying reductions in water-use. Thus, Agave populations native to the United States and Mexico should do well indeed in the years ahead.
Reviewed 20 November 2002