title: Variable response of three Trifolium repens ecotypes to soil flooding by seawater.
abstract: OBJECTIVE
  Despite concerns about the impact of rising sea levels and storm surge events on coastal ecosystems, there is remarkably little information on the response of terrestrial coastal plant species to seawater inundation. The aim of this study was to elucidate responses of a glycophyte (white clover, Trifolium repens) to short-duration soil flooding by seawater and recovery following leaching of salts.
  
  
  METHODS
  Using plants cultivated from parent ecotypes collected from a natural soil salinity gradient, the impact of short-duration seawater soil flooding (8 or 24 h) on short-term changes in leaf salt ion and organic solute concentrations was examined, together with longer term impacts on plant growth (stolon elongation) and flowering.
  
  
  RESULTS
  There was substantial Cl(-) and Na(+) accumulation in leaves, especially for plants subjected to 24 h soil flooding with seawater, but no consistent variation linked to parent plant provenance. Proline and sucrose concentrations also increased in plants following seawater flooding of the soil. Plant growth and flowering were reduced by longer soil immersion times (seawater flooding followed by drainage and freshwater inputs), but plants originating from more saline soil responded less negatively than those from lower salinity soil.
  
  
  CONCLUSIONS
  The accumulation of proline and sucrose indicates a potential for solute accumulation as a response to the osmotic imbalance caused by salt ions, while variation in growth and flowering responses between ecotypes points to a natural adaptive capacity for tolerance of short-duration seawater soil flooding in T. repens. Consequently, it is suggested that selection for tolerant ecotypes is possible should the predicted increase in frequency of storm surge flooding events occur.
authors.affiliation: School of Biological Sciences, University of Plymouth, Plymouth PL4 8AA, UK.
authors.forename: Anissia C
authors.initials: AC
authors.lastname: White
authors.affiliation: School of Plant Biology, The University of Western Australia, 35 Stirling Highway, Crawley, 6009, WA, Australia.
authors.forename: Timothy D
authors.initials: TD
authors.lastname: Colmer
authors.affiliation: School of Plant Biology, The University of Western Australia, 35 Stirling Highway, Crawley, 6009, WA, Australia.
authors.forename: Greg R
authors.initials: GR
authors.lastname: Cawthray
authors.affiliation: School of Biological Sciences, University of Plymouth, Plymouth PL4 8AA, UK mehanley@plymouth.ac.uk.
authors.forename: Mick E
authors.initials: ME
authors.lastname: Hanley
mesh_terms: D060146:Ecotype; D004553:Electric Conductivity; D055868:Floods; D035264:Flowers / Q000502:physiology; D007477:Ions; D018515:Plant Leaves / Q000378:metabolism; D012492:Salts / Q000378:metabolism; D012623:Seawater; D012987:Soil; D013312:Stress, Physiological; D013997:Time Factors; D029921:Trifolium / Q000254:growth & development / Q000502:physiology*
chemical_list: D007477:Ions; D012492:Salts; D012987:Soil
keywords: Climate change; Trifolium repens; flooding; glycophyte; osmotic stress; saline soil waterlogging; salinity; salt ions; sea level rise; storm surge; stress metabolites; white clover