Linking transpiration reduction to rhizosphere salinity using a 3D coupled soil-plant model

Schröder, Natalie; Lazarovitch, Naftali; Vereecken, Harry; Javaux, Mathieu; Vanderborght, Jan

doi:10.1007/s11104-013-1990-8

Journal Article

FZJ-2014-03048

Linking transpiration reduction to rhizosphere salinity using a 3D coupled soil-plant model

Schröder, N. (Corresponding Author)FZJ* ; Lazarovitch, N. ; Vanderborght, J.FZJ* ; Vereecken, H.FZJ* ; Javaux, M.FZJ*

2014
Springer Science + Business Media B.V Dordrecht [u.a.]

Plant and soil 377(1-2), 277 - 293 (2014) [10.1007/s11104-013-1990-8]

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Please use a persistent id in citations: doi:10.1007/s11104-013-1990-8

Abstract: Aims: Soil salinity can cause salt plant stress by reducing plant transpiration and yield due to very low osmotic potentials in the soil. For predicting this reduction, we present a simulation study to (i) identify a suitable functional form of the transpiration reduction function and (ii) to explain the different shapes of empirically observed reduction functions.MethodsWe used high resolution simulations with a model that couples 3D water flow and salt transport in the soil towards individual roots with flow in the root system.ResultsThe simulations demonstrated that the local total water potential at the soil-root interface, i.e. the sum of the matric and osmotic potentials, is for a given root system, uniquely and piecewise linearly related to the transpiration rate. Using bulk total water potentials, i.e. spatially and temporally averaged potentials in the soil around roots, sigmoid relations were obtained. Unlike for the local potentials, the sigmoid relations were non-unique functions of the total bulk potential but depended on the contribution of the bulk osmotic potential.ConclusionsTo a large extent, Transpiration reduction is controlled by water potentials at the soil-root interface. Since spatial gradients in water potentials around roots are different for osmotic and matric potentials, depending on the root density and on soil hydraulic properties, transpiration reduction functions in terms of bulk water potentials cannot be transferred to other conditions, i.e. soil type, salt content, root density, beyond the conditions for which they were derived. Such a transfer could be achieved by downscaling to the soil-root interface using simulations with a high resolution process model.

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