EFFECTS OF O2 ON AMMONIUM UPTAKE AND ROOT RESPIRATION BY SPARTINA ALTERNIFLORA |
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Authors: | James T. Morris John W. H. Dacey |
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Affiliation: | 1. Department of Biology, University of South Carolina, Columbia, South Carolina, 29208;2. Woods Hole Oceanographic Institution, Woods Hole, Massachusetts, 02543 |
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Abstract: | Previously the growth of Spartina alterniflora has been found to be limited by nitrogen and correlated with sediment redox potential. In this study we have investigated a possible connection between these two factors. We have found that internal O2 transport is insufficient to saturate NH4+ uptake in short S. alterniflora in hydroponic culture. Rates of NH4+ uptake and root respiration were very sensitive to O2 concentration in the rhizosphere, saturating at about 5% O2. Ammonium uptake continued at a reduced rate for at least 4 hr under anaerobic conditions. Plant to plant variations in anaerobic rates of NH4+ uptake and root respiration were significantly correlated to the diffusion rate of CH4 tracer gas from the leaves to the roots of individual plants. |
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