Article

Wetlands

, Volume 13, Issue 1, pp 10-15

First online:

Influence of soil oxidation-reduction potential and salinity on nutrition, N-15 uptake, and growth ofSpartina patens

  • B. K. BandyopadhyayAffiliated withWetland Biogeochemistry Institute, Louisiana State University
  • , S. R. PezeshkiAffiliated withWetland Biogeochemistry Institute, Louisiana State University
  • , R. D. DeLauneAffiliated withWetland Biogeochemistry Institute, Louisiana State University
  • , C. W. LindauAffiliated withWetland Biogeochemistry Institute, Louisiana State University

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Abstract

Nutrition, photosynthesis, and growth responses ofSpartina patens to various intensities of sediment reduction (redox potentials, Eh) ranging between — 115 mV to +475 mV and/or salinity of < 1 and 6 ppt were evaluated under controiled environmental conditions. Reduction in soil Eh to — 115 mV seemed to have little effect on net photosynthesis, but 6 ppt salinity combined with low Eh significantly decreased net photosynthesis, indicating the adverse effects of combined low Eh and salinity on gas exchange functioning. The treatments showed striking differences in concentration of nutrients in the plants. In each Eh treatment, N content in the plants was low under 6 ppt salinity compared to the < 1 ppt treatment. N content and N-15 concentration in the plant also decreased as the soil Eh decreased. Data indicated that uptake of N was inhibited by low Eh due to reduced ability of roots to take up nitrogen and/or poor physical growth of roots. Plant Fe and Mn content increased considerably at low Eh treatments. However, salinity did not show consistent influence on Fe and Mn content of tissue. Concentration of K, Ca, Mg, Zn, and Cu in plant tissue was not influenced by Eh or salinity. Root dry weight was significantly decreased in response to lowering of Eh. Within each Eh treatment, root dry weight was not influenced by salinity except in the aerated (high Eh) treatment. This finding indicates that under salinity concentrations tested, soil hypoxia is the dominant factor controlling nutrient uptake and growth ofSpartina patens. Results suggest that in submerged coastal environments, such as the Mississipppi River deltaic plain, increased flooding and soil redox conditions seem to be the primary stress factors affecting productivity ofSpartina patens unless salinity levels substantially exceed the present levels. Another primary reason for vegetation stress is the reduced uptake of nitrogen as a result of reduction in soil Eh.

Key words

Flood-stress salt-stress nitrogen uptake plant gas exchange photosynthesis stomatal conductance hypoxia