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Elevated carbon dioxide ameliorates the effects of ozone on photosynthesis and growth: species respond similarly regardless of photosynthetic pathway or plant functional group.
- Source :
-
New Phytologist . Feb98, Vol. 138 Issue 2, p315-325. 11p. - Publication Year :
- 1998
-
Abstract
- Due to their different physiological effects, elevated carbon dioxide and elevated ozone might have interactive Impacts on plants, and differentially so on plants differing in photosynthetic pathway and growth rate. To test Several hypotheses related to these issues, we examined the physiological, morphological and growth responses of Six perennial species grown at various atmospheric concentrations of carbon dioxide and ozone. The species involved (two C3 trees: <em>Populus tremuloides</em> Michx., <em>Quercus rubra</em> L.; two C2 grasses: <em>Agropyron smithii</em> Rybd., <em>Koeleria cristata</em>L.; two C4 grasses: <em>Bouteloua curtipendula</em> Michx., <em>Schizachyrium scoparium</em> Michx.) differed in growth form, stomatal conductance and photosynthetic pathway. <em>In situ</em> photosynthesis, relative growth rate (RGR) and its determinants (leaf area ratio, specific leaf area, leaf weight ratio and root weight ratio) were determined via sequential harvests of seedlings that were grown in all combinations of 366 or 672 μmol mol-1 CO2 and 3 or 95 nmol mol-1 O3 over a 101-d period. Elevated CO2 had minimal effect on either photosynthesis or RGR. By Contrast, RGR for all six species was lower in high O3 concentrations at ambient CO2, significantly so in <em>A. smithii</em> and <em>P. tremuloides</em>. Five of the six species also exhibited reductions in <em>in situ</em> photosynthesis at ambient CO2 in high-O3-grown compared with low-O3-grown plants. For all species, these O3-induced reductions in RGR and Photosynthesis were absent in the elevated CO2 environment. Root weight ratio was significantly reduced by elevated O3 in <em>A. smithii</em> and <em>P. tremuloides</em> in ambient but not elevated CO2. Species with high stomatal Conductance were the most susceptible to oxidant injury, while those with low stomatal conductance, such as the C4 species and <em>Q. rubra</em>, were not as detrimentally affected by O3. Elevated levels of CO2 will reduce stomatal Conductance and O3 uptake, and might therefore reduce the potential for oxidant damage. However, there wan Stronger relationship of the percent reduction in whole-plant mass due to O3, related to the ratio of photosynthesis to Stomatal conductance. In general, results of this study of six functionally diverse plant species suggest that O3 Pollution effects on carbon balance and growth are likely to he ameliorated by elevated concentrations of atmospheric CO2. [ABSTRACT FROM AUTHOR]
- Subjects :
- *CARBON dioxide
*OZONE
*PHOTOSYNTHESIS
*PLANTS
*HYPOTHESIS
*GROWTH rate
Subjects
Details
- Language :
- English
- ISSN :
- 0028646X
- Volume :
- 138
- Issue :
- 2
- Database :
- Academic Search Index
- Journal :
- New Phytologist
- Publication Type :
- Academic Journal
- Accession number :
- 13183811
- Full Text :
- https://doi.org/10.1046/j.1469-8137.1998.00100.x