Author: Leakey, A.D.B.; Bernacchi, C.J.; Dohleman, F.G.; Ort, D.R.; Long, S.P.
Description: The C4 grass Zea mays (maize or corn) is the third most important food crop globally in terms of production and demand is predicted to increase 45% from 1997 to 2020. However, the effects of rising CO2 upon C4 plants, and Z. mays specifically, are not sufficiently understood to allow accurate predictions of future crop production. A rainfed, field experiment utilizing free-air concentration enrichment (FACE) technology in the primary area of global corn production (US Corn Belt) was undertaken to determine the effects of elevated CO2 on corn. FACE technology allows experimental treatments to be imposed upon a complete soil-plant-atmosphere continuum with none of the effects of experimental enclosures on plant microclimate. Crop performance was compared at ambient [CO2] (354 umol mol -1) and the elevated [CO2] (549 umol mol -1) predicted for 2050. Previous laboratory studies suggest that under favorable growing conditions C4 photosynthesis is not typically enhanced by elevated CO2. However, stomatal conductance and transpiration are decreased, which can indirectly increase photosynthesis in dry climates. Given the deep soils and relatively high rainfall of the US Corn Belt, it was predicted that photosynthesis would not be enhanced by elevated CO2. The diurnal course of gas exchange of upper canopy leaves was measured in situ across the growing season of 2002. Contrary to the prediction, growth at elevated CO2 significantly increased leaf photosynthetic CO2 uptake rate (A) by up to 41%, and 10% on average. Greater A was associated with greater intercellular CO2, lower stomatal conductance and lower transpiration. Summer rainfall during 2002 was very close to the 50-year average for this site, indicating that the year was not atypical or a drought year. The results call for a reassessment of the established view that C4 photosynthesis is insensitive to elevated CO2 under favorable growing conditions and that the production potential of corn in the US Corn Belt will not be affected by the global rise in CO2.
Subject headings: atmospheric change; climate change; elevated CO2; photosynthetic carbon gain; SoyFACE; maize; corn
Publication year: 2004
Journal or book title: Global Change Biology
Volume: 10
Issue: 6
Pages: 951-962
Find the full text:Â https://www.ideals.illinois.edu/bitstream/handle/2142/9595/Leakey%20et%20al%202004.pdf?sequence=2
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Type: Journal Article
Serial number: 1636