Water movement through plant roots – exact solutions of the water flow equation in roots with linear or exponential piecewise  hydraulic properties

Meunier, Félicien; Couvreur, Valentin; Draye, Xavier; Zarebanadkouki, Mohsen; Vanderborght, Jan; Javaux, Mathieu

doi:https://doi.org/10.5194/hess-21-6519-2017

Articles | Volume 21, issue 12

https://doi.org/10.5194/hess-21-6519-2017

© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.

https://doi.org/10.5194/hess-21-6519-2017

© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.

Articles | Volume 21, issue 12

Research article

|

21 Dec 2017

Research article |

| 21 Dec 2017

Water movement through plant roots – exact solutions of the water flow equation in roots with linear or exponential piecewise hydraulic properties

Félicien Meunier, Valentin Couvreur, Xavier Draye, Mohsen Zarebanadkouki, Jan Vanderborght, and Mathieu Javaux

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Final revised paper (published on 21 Dec 2017)
Supplement to the final revised paper
Preprint (discussion started on 20 Dec 2016)

Interactive discussion

Status: closed

AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment

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- Supplement

RC1: 'Review of HESS-2016-633 « Water movement through plant roots -Exact solutions of the water flow equation in roots with varying hydraulic properties”', Anonymous Referee #1, 10 Mar 2017
- AC1: 'Response to Review of HESS-2016-633 « Water movement through plant roots -Exact solutions of the water flow equation in roots with varying hydraulic properties”', Anonymous Referee #1', Félicien Meunier, 25 Apr 2017
RC2: 'Review of hess-2016-633.', Anonymous Referee #2, 22 Mar 2017
- AC2: 'Response to Review of HESS-2016-633 « Water movement through plant roots -Exact solutions of the water flow equation in roots with varying hydraulic properties”', Anonymous Referee #2', Félicien Meunier, 25 Apr 2017

Peer-review completion

AR: Author's response | RR: Referee report | ED: Editor decision

ED: Reconsider after major revisions (further review by Editor and Referees) (30 Apr 2017) by Anas Ghadouani

AR by Félicien Meunier on behalf of the Authors (07 Jul 2017) Author's response Manuscript

ED: Referee Nomination & Report Request started (21 Jul 2017) by Anas Ghadouani

RR by Anonymous Referee #1 (23 Oct 2017)

Suggestions for revision or reasons for rejection

Review of « Water movement through plant roots : Exact solutions of the water flow equation in roots with linear or exponential piecewise hydraulic properties » by Meunier et al., 2017, 2nd revision
Submitted to HESS, N° hess-2016-633

General remarks:
I thank the authors for this revision of their initial manuscript where they accounted for most of my preceding comments. The incorporation of pressure probe derived root hydraulic conductance data is to me a very interesting added value to the paper, as is the simulation example coupling soil transfer – root uptake. Overall, this results in a very interesting, but “dense”, paper. To me, some minor revisions are required throughout the paper, but particularly in the new sections concerning pressure probe data inversion and root uptake in soil.
About root pressure probe data and inversion, it would be necessary to fix some scenarios (ie ~3) and explain them and their assumptions (ie why these conductance variations’ scenarios) to make the study easier to read. Presently, Figure 9 is not really understandable and is not coherent with text description (non-coherent lines colors..). What is a missing result from of this study is the fact that different solutions are possible for root radial conductance variations, even when axial conductance variation is known. This shows that more knowledge/measurement on local variations of root conductance is needed.
Concerning the root in soil water uptake simulations (sections 3.3 – 4.3), there is a need to present/recap how is calculated the soil root water potential, as well as the soil water transfer. Why you choosed this scenario (i.e including growth in your case) needs to be also better explained and shall be recalled in interpreting results of section 4.3, with regards to this scenario. Surprising results are found in Fig. 10, where water potential (at collar, but soil too) increases with time for the heterogeneous root case : this is unexpected, but may be false ? (check alos the inversion between psi_collar and psi_seq in Fig 10 – see annotated paper).
The new, added part, final part of the conclusion is unclear for me. It could be stated more simply. Finally the “root conductance” expression is not really precise, as we don’t know exactly which conductance it refers to (cf line 4, p22 for example). I would suggest that when author refer to Krs (and not kr or kx) they could call it “effective root conductance” because Krs is indeed an effective macroscopic property emerging from geometry and kx, kr variations.
Detailed comments
See annotated pdf which recap both typos/grammar and questions.

Referee Report: PDF

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ED: Publish subject to minor revisions (review by editor) (28 Oct 2017) by Anas Ghadouani

AR by Félicien Meunier on behalf of the Authors (09 Nov 2017) Author's response Manuscript

ED: Publish subject to minor revisions (review by editor) (10 Nov 2017) by Anas Ghadouani

AR by Félicien Meunier on behalf of the Authors (11 Nov 2017) Author's response Manuscript

ED: Publish as is (15 Nov 2017) by Anas Ghadouani

AR by Félicien Meunier on behalf of the Authors (15 Nov 2017) Author's response Manuscript

Short summary

To maintain its yield, a plant needs to transpire water that it acquires from the soil. A deep understanding of the mechanisms that lead to water uptake location and intensity is required to correctly simulate the water transfer in the soil to the atmosphere. This work presents novel and general solutions of the water flow equation in roots with varying hydraulic properties that deeply affect the uptake pattern and the transpiration rate and can be used in ecohydrological models.