title: Salinization of the soil solution decreases the further accumulation of salt in the root zone of the halophyte Atriplex nummularia Lindl. growing above shallow saline groundwater.
abstract: Water use by plants in landscapes with shallow saline groundwater may lead to the accumulation of salt in the root zone. We examined the accumulation of Na+and Cl-around the roots of the halophyte Atriplex nummularia Lindl. and the impacts of this increasing salinity for stomatal conductance, water use and growth. Plants were grown in columns filled with a sand-clay mixture and connected at the bottom to reservoirs containing 20, 200 or 400 mM NaCl. At 21 d, Na+and Cl-concentrations in the soil solution were affected by the salinity of the groundwater, height above the water table and the root fresh mass density at various soil depths (P < 0.001). However, by day 35, the groundwater salinity and height above the water table remained significant factors, but the root fresh mass density was no longer significant. Regression of data from the 200 and 400 mM NaCl treatments showed that the rate of Na+accumulation in the soil increased until the Na+concentration reached ~250 mM within the root zone; subsequent decreases in accumulation were associated with decreases in stomatal conductance. Salinization of the soil solution therefore had a feedback effect on further salinization within the root zone.
authors.affiliation: Department of Biological Sciences, Faculty of Science, King Abdulaziz University, Jeddah, 21589, Saudi Arabia.|School of Agriculture and Environment, Faculty of Science, The University of Western Australia, 35 Stirling Hwy, Crawley, WA, 6009, Australia.
authors.forename: Hesham F
authors.initials: HF
authors.lastname: Alharby
authors.affiliation: School of Agriculture and Environment, Faculty of Science, The University of Western Australia, 35 Stirling Hwy, Crawley, WA, 6009, Australia.
authors.forename: Timothy D
authors.identifier: http://orcid.org/0000-0002-3383-9596
authors.initials: TD
authors.lastname: Colmer
authors.affiliation: School of Agriculture and Environment, Faculty of Science, The University of Western Australia, 35 Stirling Hwy, Crawley, WA, 6009, Australia.|Department of Agriculture and Food of Western Australia, 3 Baron-Hay Court, South Perth, WA, 6051, Australia.
authors.forename: Edward G
authors.identifier: http://orcid.org/0000-0001-9945-1044
authors.initials: EG
authors.lastname: Barrett-Lennard
mesh_terms: D027466:Atriplex / Q000254:growth & development*; D018533:Biomass; D005740:Gases / Q000378:metabolism; D060587:Groundwater; D018515:Plant Leaves / Q000502:physiology; D018517:Plant Roots / Q000187:drug effects / Q000254:growth & development* / Q000502:physiology*; D018520:Plant Shoots / Q000187:drug effects / Q000254:growth & development / Q000502:physiology; D054712:Salinity; D055051:Salt-Tolerant Plants / Q000187:drug effects / Q000254:growth & development* / Q000502:physiology; D012964:Sodium / Q000378:metabolism; D012965:Sodium Chloride / Q000494:pharmacology*; D012987:Soil; D012996:Solutions; D014867:Water
chemical_list: D005740:Gases; D012987:Soil; D012996:Solutions; D014867:Water; D012965:Sodium Chloride; D012964:Sodium
keywords: growth; heterogeneous soil salinity; salinity; salt accumulation; stomatal conductance; water relations