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Effects of Elevated CO2 on Canola Productivity in the Presence and Absence of UV-B Radiation
Qaderi, M.M. and Reid, D.M.  2005.  Growth and physiological responses of canola (Brassica napus) to UV-B and CO2 under controlled environment conditions.  Physiologia Plantarum 125: 247-259.

What was done
Well watered and fertilized plants were grown from seed to maturity in pots within controlled environment chambers maintained at either 370 or 740 ppm CO2 with and without a daily dose of UV-B radiation in the amount of 4.2 kJ m-2, while a number of plant parameters were measured at various times throughout the growing season.

What was learned
With respect to the bottom-line result of final seed yield, this parameter was determined to be 0.98 g/plant in the control treatment (ambient CO2, with UV-B).  Doubling the CO2 concentration increased yield by 25.5% to 1.23 g/plant.  Alternatively, removing the UV-B radiation flux increased yield by 91.8% to 1.88 g/plant.  Doing both (doubling the CO2 concentration while simultaneously removing the UV-B flux) increased final seed yield most of all, by 175.5% to 2.7 g/plant.  Viewed from a different perspective, doubling the air's CO2 concentration in the presence of the UV-B radiation flux enhanced final seed yield by 25.5%, while doubling CO2 in the absence of the UV-B radiation flux increased seed yield by 43.6%.

What it means
Qaderi and Reid note that "previous studies have shown that elevated CO2 increases biomass and seed yield, whereas UV-B decreases them (Sullivan, 1997; Teramura et al., 1990)."  Finding much the same thing in their study, they thus concluded that "elevated CO2 may have a positive effect on plants by mitigating the detrimental effects caused by UV-B radiation."

Sullivan, J.H.  1997.  Effects of increasing UV-B radiation and atmospheric CO2 on photosynthesis and growth: implications for terrestrial ecosystems.  Plant Ecology 128: 195-206.

Teramura, A.H., Sullivan, J.H. and Ziska, L.H.  1990.  Interaction of elevated UV-B radiation and CO2 on productivity and photosynthetic characteristics in wheat, rice, and soybean.  Plant Physiology 94: 470-475.

Reviewed 30 November 2005