The impact of mucilage on root water uptake - A numerical study

N. Schwartz*, A. Carminati, M. Javaux

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

29 Scopus citations

Abstract

The flow of water between soil and plants follows the gradient in water potential and depends on the hydraulic properties of the soil and the root. In models for root water uptake (RWU), it is usually assumed that the hydraulic properties near the plant root (i.e., in the rhizosphere) and in the bulk soil are identical. Yet a growing body of evidence has shown that the hydraulic properties of the rhizosphere are affected by root exudates (specifically, mucilage) and markedly differ from those of the bulk soil. In this work, we couple a 3-D detailed description of RWU with a model that accounts for the rhizosphere-specific properties (i.e., rhizosphere hydraulic properties and a nonequilibrium relation between water content and matric head). We show that as the soil dries out (due to water uptake), the higher water holding capacity of the rhizosphere results in a delay of the stress onset. During rewetting, nonequilibrium results in a slower increase of the rhizosphere water content. Furthermore, the inverse relation between water content and relaxation time implies that the drier is the rhizosphere the longer it takes to rewet. Another outcome of nonequilibrium is the small fluctuation of the rhizosphere water content compared to the bulk soil. Overall, our numerical results are in agreement with recent experimental data and provide a tool to further examine the impact of various rhizosphere processes on RWU and water dynamics.

Original languageAmerican English
Pages (from-to)264-277
Number of pages14
JournalWater Resources Research
Volume52
Issue number1
DOIs
StatePublished - 1 Jan 2016
Externally publishedYes

Bibliographical note

Publisher Copyright:
© 2015. American Geophysical Union. All Rights Reserved.

Keywords

  • hydraulic properties
  • modeling
  • mucilage
  • nonequilibrium
  • root water uptake

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