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Atmospheric CO2 and Syrian Wheat Production
Reference
Kaddour, A.A. and Fuller, M.P.  2004.  The effect of elevated CO2 and drought on the vegetative growth and development of durum wheat (Triticum durum Desf.) cultivars.  Cereal Research Communications 32: 225-232.

What was done
The authors grew three commercial cultivars of durum wheat (Triticum durum Desf.) registered in Syria (Cham 1, Cham 3 and Cham 5) from seed in 10-liter pots in different compartments of a phytotron, half of which compartments were maintained at an atmospheric CO2 concentration of approximately 400 ppm and half of which were maintained at a concentration of approximately 1000 ppm.  Half of each of these treatments were further subdivided into two soil water treatments: well-watered, where available water content (AWC) was replenished to 90% of full capacity when it had dropped to 60%, and water-stressed, where AWC was replenished to 70% of full capacity when it had dropped to 45%.

What was learned
Averaged over the three cultivars, the extra 600 ppm of CO2 supplied to the CO2-enriched compartments led to total plant biomass increases of 62% in the well-watered treatment and 60% in the water-stressed treatment.  Also of interest was the fact that the extra CO2 led to increases in the nitrogen concentrations of stems and ears.  In the case of ears, nitrogen concentration was increased by 22% in the well-watered plants and by 16% in the water-stressed plants.

What it means
"These results," according to Kaddour and Fuller, "have important implications for the production of durum wheat in the future."  They state, for example, that "yields can be expected to rise as atmospheric CO2 levels rise," and that "this increase in yield can be expected under both water restricted and well irrigated conditions."  Hence, as they continue, "where water availability (irrigation) is a prime limiting economic resource, it can be distributed more effectively under higher CO2 conditions," and "for countries such as Syria where average national production is well below the physiological maximum due largely to drought stress, the predicted rise in atmospheric CO2 could have a positive effect on production."

Reviewed 12 January 2005