Soil-plant hydraulic model to predict the onset of water stress

#Drought #irrigation #Root traits
The model predicts the hydraulic state of the plant for varying climatic condition and soil conditions. The actual transpiration is constrained by the onset of nonlinearity of the E(ψleaf) relationship – marked by the red line. Irrigation should be scheduled to maintain plants in the linear zone at potential transpiration.
Model predictions of the relation between transpiration rate E, soil water potential (ψsoil) and leaf water potential (ψleaf) in the three-dimensional space (a), from the soil perspective (b) and the leaf perspective (c). Irrigation should be scheduled to maintain plants in the linear zone at potential transpiration (below the red line, which is defined as the onset of nonlinearity of the E(ψleaf) relationship.

Within the German-Israeli Cooperation, a hydraulic model was developed, that allows accurate prediction of the onset of crop water stress as a function of climate, soil properties and plant traits. The model can be used to schedule irrigation and design optimal hydraulic phenotypes adapted to particular environmental conditions.

Water shortage is a major constrain for agriculture. There is urgent need to identify plant traits that improve root water uptake and irrigation technologies that maximize the efficient use of water.


In the project “Rhizosphere”, we developed a hydraulic model ( that allows to calculate the onset of plant water stress. The model has been tested across a broad selection of crops (including tomato, maize, barley, wheat and millet). The model demonstrates that stomata downregulate transpiration and photosynthesis when the relation between transpiration rate and leaf water potential becomes nonlinear due to a drop in soil hydraulic conductivity. This onset of water limitation can be predicted by the mechanistic model as a function of climatic conditions, soil hydraulic properties, and key and root traits such as length and hydraulic conductance.


The model has two practical applications:

1) To schedule irrigation: Optimally, irrigation should start at the critical soil moisture corresponding to the point when photosynthesis starts to drop. This critical point can be predetermined by the model.

2) To identify the optimal root traits for a given soil and climatic environment. Our model is able to determine three key hydraulic traits that largely control crop water use: maximum stomatal conductance, root length and root hydraulic conductance.

Water resource: Groundwater
Type of product:
  • Modelling & software tools
Application sector: Agriculture
Funding measure: DE-IL-WaTec
Project: Rhizosphere

Contact and partners

  • ETH Zürich,
  • Universitätstrasse 16,
  • 8092 Zürich, Switzerland
Prof. Dr. Andrea Carminati

University of Bayreuth, Department of Hydrology
The Hebrew University of Jerusalem - Faculty of Agriculture, Food and Environment, Department of Soil and Water Sciences,
Rehovot, Israel

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