Photosynthetic acclimation of maize to growth under elevated levels of carbon dioxide |
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Authors: | João P Maroco Gerald E Edwards Maurice S B Ku |
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Institution: | (1) Department of Botany, Washington State University, Pullman, WA 99164-4238, USA, US |
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Abstract: | The effects of elevated CO2 concentrations on the photochemistry, biochemistry and physiology of C4 photosynthesis were studied in maize (Zea mays L.). Plants were grown at ambient (350 μL L−1) or ca. 3 times ambient (1100 μL L−1) CO2 levels under high light conditions in a greenhouse for 30 d. Relative to plants grown at ambient CO2 levels, plants grown under elevated CO2 accumulated ca. 20% more biomass and 23% more leaf area. When measured at the CO2 concentration of growth, mature leaves of high-CO2-grown plants had higher light-saturated rates of photosynthesis (ca. 15%), lower stomatal conductance (71%), higher water-use
efficiency (225%) and higher dark respiration rates (100%). High-CO2-grown plants had lower carboxylation efficiencies (23%), measured under limiting CO2, and lower leaf protein contents (22%). Activities of a number of C3 and C4 cycle enzymes decreased on a leaf-area basis in the high-CO2-grown plants by 5–30%, with NADP-malate dehydrogenase exhibiting the greatest decrease. In contrast, activities of fructose
1,6-bisphosphatase and ADP-glucose pyrophosphorylase increased significantly under elevated CO2 condition (8% and 36%, respectively). These data show that the C4 plant maize may benefit from elevated CO2 through acclimation in the capacities of certain photosynthetic enzymes. The increased capacity to synthesize sucrose and
starch, and to utilize these end-products of photosynthesis to produce extra energy by respiration, may contribute to the
enhanced growth of maize under elevated CO2.
Received: 30 April 1999 / Accepted: 17 June 1999 |
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Keywords: | : CO2 enrichment C4 photosynthesis Respiration Zea (CO2 enrichment) |
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