The influence of environmental factors on apparent photosynthesis and respiration of the submersed macrophyte Elodea canadensis |
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| Authors: | P. S. SIMPSON J. W. EATON K. HARDWICK |
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| Affiliation: | Department of Botany, University of Liverpool, P.O. Box 147, Liverpool L69 3BX |
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| Abstract: | Abstract Oxygen effects on apparent photosynthetic and dark respiratory O2 exchange rates of detached leaves of Elodea canadensis Michx. (Hydrocharitaceae) were determined over a range of conditions which the submersed plant is likely to experience in shallow water. Apparent photosynthesis is inhibited by O2 under all the experimental regimes of light, temperature, CO2 concentration and pH. This inhibition is not caused solely by an accelerated rate of dark respiration, and the observed variations in O2 inhibition are comparable to O2 effects on photosynthesis and photorespiration of terrestrial C3 plants. Percentage inhibition of apparent photosynthesis is enhanced by high O2 and also by low CO2. These results indicate that high O2, high pH and low CO2 conditions could cause major losses in photosynthetic activity under field conditions. This may account for some of the losses in biomass that are observed under still water conditions. |
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