title: The long-term resistance mechanisms, critical irrigation threshold and relief capacity shown by Eugenia myrtifolia plants in response to saline reclaimed water.
abstract: Salts present in irrigation water are serious problems for commercial horticulture, particularly in semi-arid regions. Reclaimed water (RW) typically contains, among others elements, high levels of salts, boron and heavy metal. Phytotoxic ion accumulation in the substrate has been linked to different electric conductivities of the treatments. Based on these premises, we studied the long-term effect of three reclaimed water treatments with different saline concentrations on Eugenia myrtifolia plants. We also looked at the ability of these plants to recover when no drainage was applied. The RW with the highest electric conductivity (RW3, EC = 6.96 dS m-1) provoked a number of responses to salinity in these plants, including: 1) accumulation and extrusion of phytotoxic ions in roots; 2) a decrease in the shoot/root ratio, leaf area, number of leaves; 3) a decrease in root hydraulic conductivity, leaf water potential, the relative water content of leaves, leaf stomatal conductance, the leaf photosynthetic rate, water-use efficiency and accumulated evapotranspiration in order to limit water loss; and 4) changes in the antioxidant defence mechanisms. These different responses induced oxidative stress, which can explain the damage caused in the membranes, leading to the death of RW3 plants during the relief period. The behaviour observed in RW2 plants was slightly better compared with RW3 plants, although at the end of the experiment about 55% of the RW2 plants also died, however RW containing low salinity level (RW1, EC = 2.97 dS m-1) can be effective for plant irrigation.
authors.affiliation: Irrigation Department, CEBAS-CSIC, Campus Universitario de Espinardo, Murcia, P.O. Box 164, E-30100, Spain.
authors.forename: José Ramón
authors.initials: JR
authors.lastname: Acosta-Motos
authors.affiliation: Fruit Tree Biotechnology Group, Department of Plant Breeding, CEBAS-CSIC, Campus Universitario de Espinardo, Murcia, P.O. Box 164, E-30100, Spain. Electronic address: jahernan@cebas.csic.es.
authors.forename: José Antonio
authors.initials: JA
authors.lastname: Hernández
authors.affiliation: Irrigation Department, CEBAS-CSIC, Campus Universitario de Espinardo, Murcia, P.O. Box 164, E-30100, Spain.
authors.forename: Sara
authors.initials: S
authors.lastname: Álvarez
authors.affiliation: Fruit Tree Biotechnology Group, Department of Plant Breeding, CEBAS-CSIC, Campus Universitario de Espinardo, Murcia, P.O. Box 164, E-30100, Spain; Department of Plant and Environmental Sciences, University of Copenhagen, Denmark.
authors.forename: Gregorio
authors.initials: G
authors.lastname: Barba-Espín
authors.affiliation: Irrigation Department, CEBAS-CSIC, Campus Universitario de Espinardo, Murcia, P.O. Box 164, E-30100, Spain.
authors.forename: María Jesús
authors.initials: MJ
authors.lastname: Sánchez-Blanco
mesh_terms: D057914:Agricultural Irrigation; D000975:Antioxidants / Q000378:metabolism; D000068856:Eugenia / Q000201:enzymology / Q000254:growth & development / Q000502:physiology*; D005740:Gases / Q000378:metabolism; D007477:Ions; D009747:Nutritional Physiological Phenomena; D063245:Plant Development; D018515:Plant Leaves / Q000201:enzymology / Q000502:physiology; D018517:Plant Roots / Q000502:physiology; D054712:Salinity; D013312:Stress, Physiological; D017392:Thiobarbituric Acid Reactive Substances / Q000378:metabolism; D013997:Time Factors; D014867:Water / Q000378:metabolism*
chemical_list: D000975:Antioxidants; D005740:Gases; D007477:Ions; D017392:Thiobarbituric Acid Reactive Substances; D014867:Water
keywords: Eugenia myrtifolia; Non-conventional water resource; Ornamental plant; Oxidative stress; Photosynthetic activity; Salinity; Water relations