Measuring and Modeling Poplar Root Water Extraction After Drought Using Neutron Imaging

 poplar seedling
Composite images of 16 radiographs of 11-week-old poplar seedling in sand. Intensity indicates water content. [Reprinted with permission of Springer from Dhiman, I., et al. “Quantifying Root Water Extraction After Drought Recovery Using Sub-mm In Situ Empirical Data.” Plant Soil 47, 1–17 (2017). [DOI:10.1007/s11104-017-3408-5]. © U.S. Government (outside the USA) 2017.]
Neutron radiography was used to measure soil water movement and water uptake by individual roots in situ. Root water uptake was linked to root traits; smaller-diameter roots had greater water uptake per unit surface area than larger-diameter roots. Model analysis based on root-free soil hydraulic properties indicated unreasonably large water fluxes among the vertical soil layers during the first 16 hours after wetting. These results suggest problems with common soil hydraulic or root surface area modeling approaches, indicating the need to further investigate and understand the impacts of roots on soil hydraulic properties. This work highlights the team’s ability to link root water uptake to characteristic root traits, thus enabling performance assessment of common water uptake models

Dhiman, I., et al. “Quantifying Root Water Extraction After Drought Recovery Using sub-mm In Situ Empirical Data.” Plant Soil 417, 1–17 (2017). [DOI:10.1007/s11104-017-3408-5].

Instruments and Facilities Used: Sequential neutron radiography using CG1-D beam line using cold neutrons, at High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory. Neutron attenuation by plant samples was detected with a 25-μm lithium fluoride / zinc sulfide (LiF/ ZnS) scintillator linked to a charge coupled detector (CCD) camera system (iKon – L 936, Andor Technology plc., Belfast, U.K.). Roots scanned and dimensions measured using WinRhizo software (Regent Instruments Inc., Quebec, Canada.