Comment on: "neutron imaging reveals internal plant water dynamics"

Introduction: In a recent paper, Warren et al. (2013) illustrated the potential of neutron radiography to visualize water dynamics in soil and plants.Methods: After injection of deuterated water (D₂O) in soil, the authors could monitor the changes of D₂O concentration in roots.Results: Based on the radiographs, the authors concluded that D₂O was transported from roots growing in a wet soil region to roots in a dry region, proving hydraulic redistribution between roots. However, this interpretation depends on the correct estimation of D₂O concentration in soil.Conclusions: The experiments of Warren et al. (2013) could also be explained by diffusion of D₂O from soil to roots, without hydraulic redistribution within the root system.