From experiments to simulations: tracing Na+ distribution around roots under different transpiration rates and salinity levels

Abstract

From experiments to simulations: tracing Na+ distribution around rootsunder different transpiration rates and salinity levelsAdi Perelman (1), Helena Jorda (2), Jan Vanderborght (2,3), Andreas Pohlmeier (2), and Naftali Lazarovitch (1)(1) French Associates Institute for Agriculture and Biotechnology of Drylands, Jacob Blaustein Institutes for Desert Research,Ben-Gurion University of the Negev, Midreshet Ben-Gurion, Israel ([email protected]), (2) Institute of Bio- andGeoscience, Agrosphere Institute, IBG-3, Forschungszentrum Jülich GmbH Jülich, Germany, (3) Department of Earth andEnvironmental Sciences, Faculty of Bioscience Engineering, KU Leuven,Leuven, BelgiumWhen salinity increases beyond a certain threshold it will result in reduced crop yield at a fixed rate, according toMaas and Hoffman model (1976). Thus, there is a great importance of predicting salinization and its impact oncrops. Current models do not consider the impact of environmental conditions on plants salt tolerance, even thoughthese conditions are affecting plant water uptake and therefore salt accumulation around the roots. Different fac-tors, such as transpiration rates, can influence the plant sensitivity to salinity by influencing salt concentrationsaround the roots. Better parametrization of a model can help improving predicting the real effects of salinity oncrop growth and yield. The aim of this research is to study Na+ distribution around roots at different scales usingdifferent non-invasive methods, and study how this distribution is being affected by transpiration rate and plantwater uptake. Results from tomato plants growing on Rhizoslides (capillary paper growth system), show that Na+concentration is higher at the root- substrate interface, compared with the bulk. Also, Na+ accumulation around theroots decreased under low transpiration rate, which is supporting our hypothesis. Additionally, Rhizoslides enableto study roots’ growth rate and architecture under different salinity levels. Root system architecture was retrievedfrom photos taken during the experiment and enabled us to incorporate real root systems into a simulation. Toobserve the correlation of root system architectures and Na+ distribution in three dimensions, we used magneticresonance imaging (MRI). MRI provides fine resolution of Na+ accumulation around a single root without disturb-ing the root system. With time, Na+ was accumulating only where roots were found in the soil and later on aroundspecific roots. These data are being used for model calibration, which is expected to predict root water uptake insaline soils for different climatic conditions and different soil water availabilities