title: Impact of treated wastewater on growth, respiration and hydraulic conductivity of citrus root systems in light and heavy soils.
abstract: Roots interact with soil properties and irrigation water quality leading to changes in root growth, structure and function. We studied these interactions in an orchard and in lysimeters with clay and sandy loam soils. Minirhizotron imaging and manual sampling showed that root growth was three times lower in the clay relative to sandy loam soil. Treated wastewater (TWW) led to a large reduction in root growth with clay (45-55%) but not with sandy loam soil (<20%). Treated wastewater increased salt uptake, membrane leakage and proline content, and decreased root viability, carbohydrate content and osmotic potentials in the fine roots, especially in clay. These results provide evidence that TWW challenges and damages the root system. The phenology and physiology of root orders were studied in lysimeters. Soil type influenced diameter, specific root area, tissue density and cortex area similarly in all root orders, while TWW influenced these only in clay soil. Respiration rates were similar in both soils, and root hydraulic conductivity was severely reduced in clay soil. Treated wastewater increased respiration rate and reduced hydraulic conductivity of all root orders in clay but only of the lower root orders in sandy loam soil. Loss of hydraulic conductivity increased with root order in clay and clay irrigated with TWW. Respiration and hydraulic properties of all root orders were significantly affected by sodium-amended TWW in sandy loam soil. These changes in root order morphology, anatomy, physiology and hydraulic properties indicate rapid and major modifications of root systems in response to differences in soil type and water quality.
authors.affiliation: Institute of Soil, Water and Environmental Sciences, ARO Volcani Center, Bet Dagan 50250, Israel The Robert H. Smith Faculty of Food Agriculture and Environment, The Hebrew University of Jerusalem, Rehovot 76100, Israel.
authors.forename: Indira
authors.initials: I
authors.lastname: Paudel
authors.affiliation: Institute of Soil, Water and Environmental Sciences, ARO Volcani Center, Bet Dagan 50250, Israel vwshep@volcani.agri.gov.il.
authors.forename: Shabtai
authors.initials: S
authors.lastname: Cohen
authors.affiliation: Department of Environmental, Water and Agricultural Engineering, Faculty of Civil and Environmental Engineering, Technion-Israel Institute of Technology, Haifa 32000, Israel.
authors.forename: Avi
authors.initials: A
authors.lastname: Shaviv
authors.affiliation: Institute of Soil, Water and Environmental Sciences, ARO Volcani Center, Bet Dagan 50250, Israel.
authors.forename: Asher
authors.initials: A
authors.lastname: Bar-Tal
authors.affiliation: Institute of Soil, Water and Environmental Sciences, ARO Volcani Center, Bet Dagan 50250, Israel.
authors.forename: Nirit
authors.initials: N
authors.lastname: Bernstein
authors.affiliation: Institute of Soil, Water and Environmental Sciences, ARO Volcani Center, Bet Dagan 50250, Israel.
authors.forename: Bruria
authors.initials: B
authors.lastname: Heuer
authors.affiliation: Jacob Blaustein Institutes for Desert Research, French Associates Institute for Agriculture and Biotechnology of Drylands, Ben-Gurion University of the Negev, Sde Boqer 849900, Israel.
authors.forename: Jhonathan
authors.initials: J
authors.lastname: Ephrath
mesh_terms: D002957:Citrus / Q000378:metabolism*; D009997:Osmotic Pressure / Q000502:physiology; D012987:Soil; D062065:Wastewater
chemical_list: D012987:Soil; D062065:Wastewater
keywords: irrigation; membrane leakage; minirhizotron; osmotic stress; proline; water quality