K+ uptake by root systems grown in soil under salinity: I. A mathematical model |
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Authors: | Moshe Silberbush Shaul Sorek Alex Yakirevich |
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Institution: | (1) J. Blaustein Institute for Desert Research, Ben-Gurion University of the Negev, 84990 Sede-Boker Campus, Israel |
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Abstract: | A novel theoretical model is proposed for K+ uptake by intact root systems from saline soil considering interactions with Na+, Ca2+ and Mg2+. The model assumes radial movement of ions towards the root governed by advection and diffusion flux mechanisms, and chemical exchange of the four cations according to Gapon isotherms, with Cl? as the accompanying anion. Influx of K+ to the root surface is assumed as a function of its concentration in the soil solution at the root. This influx is governed by a saturable-cooperative term and a linear term for low and high K+ concentrations, respectively. Influx of Na+, above a critical value of its concentration, increases linearly with its concentration in the soil solution at the root surface. Uptake of Ca+ 2+ is controlled by the balance between influxes of anions and cations, which induces efflux of H+ or HCO 3 ? , and interacts with calcite in a calcareous soil. The model may provide information about the behavior of ions at the root-soil interface which cannot be measuredin situ. |
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Keywords: | Cation exchange cation interaction Gapon isotherms K+ uptake H+ efflux mathematical model mineral nutrition soil salinity |
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