Effects of atmospheric CO2 concentration on wheat yield: review of results from experiments using various approaches to control CO2 concentration

Amthor, J S (2001) Effects of atmospheric CO2 concentration on wheat yield: review of results from experiments using various approaches to control CO2 concentration. Field Crops Research, 73 (1). pp. 1-34.

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Fifty studies (156 experiments) of effects of CO2 concentration ([CO2]) on wheat (Triticum aestivum L.) yield (grain mass at maturity) were analyzed (24 were out-of-doors studies). Only studies controlling [CO2] during all (or most) of the wheat life cycle were considered. Studies were divided into five categories based on the method of controlling [CO2]: laboratory-chamber, glasshouse (greenhouse), closed-top field chamber, open-top field chamber (OTC), and a free-air (chamberless) field CO2 enrichment (FACE) system. Only three studies, all conducted in glasshouses, included subambient-[CO2] treatments , with yield positively related to [CO2] in all three. In superambient-[CO2] experiments with ample water and nutrients and with favorable temperature, [CO2] up to about 2000 ppm increased yield, with a maximum effect (+37%) at about 890 ppm CO2 (according to curve fitting with data from all methods pooled). On average, doubling [CO2] from 350 to 700 ppm increased yield about 31%. Differences in effects of [CO2] on yield between methods of controlling [CO2] could not be judged (or did not exist) because of large variation in yield across chamber (including glasshouse) experiments and too few FACE experiments. Side-by-side comparisons of different methods of controlling [CO2] in which yield was measured were notably lacking. The large variation in effect of [CO2] on yield, even with ample water and nutrients, probably reflected interactions between [CO2] and other factors. With mineral nutrient limitations, effects of [CO2] on yield were small, and with severe nutrient limitations increased [CO2] sometimes reduced yield. With ample nutrients and [CO2] greater than 2000 ppm, yield was also reduced, but this may be of limited significance to field crops for at least the next 100 years. Elevated [CO2] stimulated yield of water-stressed wheat, but usually did not fully compensate for water shortage, though few data were available. Elevated [O3] sometimes reduced positive effects of elevated [CO2] on yield, though again, few data were available. Usually, modest warming (1–4°C) counteracted positive effects of doubled [CO2] on yield. Combinations of rising temperature, [CO2], and [O3] may result in positive or negative effects on wheat yield, though the [CO2]-effect per se will normally be positive. Predictions of effects of rising [CO2] on wheat yield carry with them intrinsic uncertainty.

Item Type: Article
Additional Information: Madhoolika Agrawal, Jeremy Barnes, Bruce Bugbee, David Connor, Marnie Goodbody, Mary Beth Kirkham, Baryy Mulholland, Paul Pinter, Steve Prior, and Seth Prithard are thanked for discussing their papers, providing unpublished data, and revieding manuscript drafts. Two anonymous reviewers are also thanked. Financial support was from the US Department of Energy's Office of Biological and Engironmental Research under conract DE-AC05-00OR22725 with University of Tennessee-Battelle, LLC.
Uncontrolled Keywords: Atmospheric CO2 concentration; Climate change; Grain; Wheat; Yield
Author Affiliation: Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
Subjects: Atmosperic Science
Divisions: Other Crops
Depositing User: Mr Siva Shankar
Date Deposited: 11 Apr 2012 06:04
Last Modified: 11 Apr 2012 06:04
Official URL: http://dx.doi.org/10.1016/S0378-4290(01)00179-4
URI: http://eprints.icrisat.ac.in/id/eprint/4624

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