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Quantifying citrate-enhanced phosphate root uptake using microdialysis

Quantifying citrate-enhanced phosphate root uptake using microdialysis
Quantifying citrate-enhanced phosphate root uptake using microdialysis
Aims: Organic acid exudation by plant roots is thought to promote phosphate (P) solubilisation and bioavailability in soils with poorly available nutrients. Here we describe a new combined experimental (microdialysis) and modelling approach to quantify citrate-enhanced P desorption and its importance for root P uptake.
Methods: To mimic the rhizosphere, microdialysis probes were placed in soil and perfused with citrate solutions (0.1, 1.0 and 10 mM) and the amount of P recovered from soil used to quantify rhizosphere P availability. Parameters in a mathematical model describing probe P uptake, citrate exudation, P movement and citrate-enhanced desorption were fit to the experimental data. These parameters were used in a model of a root which exuded citrate and absorbed P. The importance of soil citrate-P mobilisation for root P uptake was then quantified using this model.
Results: A plant needs to exude citrate at a rate of 0.73 µmol cm-1 of root h-1 to see a significant increase in P absorption. Microdialysis probes with citrate in the perfusate were shown to absorb similar quantities of P to an exuding root.
Conclusion: A single root exuding citrate at a typical rate (4.3×〖10〗^(-5) µmol m-1 of root h-1) did not contribute significantly to P uptake. Microdialysis probes show promise for measuring rhizosphere processes when calibration experiments and mathematical modelling are used to decouple microdialysis and rhizosphere mechanisms.
method, modelling, nutrient uptake, phosphorus mobilisation, soil solution
0032-079X
1-21
McKay Fletcher, D.M.
60e9adeb-182b-4dfd-846a-b684f8e2358e
Shaw, R.
525a62b3-df9a-40fd-8b01-cca1c77b5a5d
Sanchez Rodriguez, A.R.
ba4ca685-5ecc-4f75-ae0a-5cfc2019f57a
Daly, K.R.
e28b1acf-cdde-4b52-8d83-cf314d7c3466
Van Veelen, A.
cb6f2c8b-4671-4836-88a0-3987fd2f2d67
Jones, D. L.
aa75a0d9-20c3-4c0e-a986-10bb4185321d
Roose, T.
3581ab5b-71e1-4897-8d88-59f13f3bccfe
McKay Fletcher, D.M.
60e9adeb-182b-4dfd-846a-b684f8e2358e
Shaw, R.
525a62b3-df9a-40fd-8b01-cca1c77b5a5d
Sanchez Rodriguez, A.R.
ba4ca685-5ecc-4f75-ae0a-5cfc2019f57a
Daly, K.R.
e28b1acf-cdde-4b52-8d83-cf314d7c3466
Van Veelen, A.
cb6f2c8b-4671-4836-88a0-3987fd2f2d67
Jones, D. L.
aa75a0d9-20c3-4c0e-a986-10bb4185321d
Roose, T.
3581ab5b-71e1-4897-8d88-59f13f3bccfe

McKay Fletcher, D.M., Shaw, R., Sanchez Rodriguez, A.R., Daly, K.R., Van Veelen, A., Jones, D. L. and Roose, T. (2019) Quantifying citrate-enhanced phosphate root uptake using microdialysis. Plant and Soil, 1-21. (doi:10.1007/s11104-019-04376-4).

Record type: Article

Abstract

Aims: Organic acid exudation by plant roots is thought to promote phosphate (P) solubilisation and bioavailability in soils with poorly available nutrients. Here we describe a new combined experimental (microdialysis) and modelling approach to quantify citrate-enhanced P desorption and its importance for root P uptake.
Methods: To mimic the rhizosphere, microdialysis probes were placed in soil and perfused with citrate solutions (0.1, 1.0 and 10 mM) and the amount of P recovered from soil used to quantify rhizosphere P availability. Parameters in a mathematical model describing probe P uptake, citrate exudation, P movement and citrate-enhanced desorption were fit to the experimental data. These parameters were used in a model of a root which exuded citrate and absorbed P. The importance of soil citrate-P mobilisation for root P uptake was then quantified using this model.
Results: A plant needs to exude citrate at a rate of 0.73 µmol cm-1 of root h-1 to see a significant increase in P absorption. Microdialysis probes with citrate in the perfusate were shown to absorb similar quantities of P to an exuding root.
Conclusion: A single root exuding citrate at a typical rate (4.3×〖10〗^(-5) µmol m-1 of root h-1) did not contribute significantly to P uptake. Microdialysis probes show promise for measuring rhizosphere processes when calibration experiments and mathematical modelling are used to decouple microdialysis and rhizosphere mechanisms.

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manuscriptPlantandSoilReviewersCommentsR4-ACCEPT - Accepted Manuscript
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Accepted/In Press date: 13 November 2019
e-pub ahead of print date: 5 December 2019
Keywords: method, modelling, nutrient uptake, phosphorus mobilisation, soil solution

Identifiers

Local EPrints ID: 435763
URI: http://eprints.soton.ac.uk/id/eprint/435763
ISSN: 0032-079X
PURE UUID: 8700dfd5-3638-4c95-9812-217b25d2f550
ORCID for T. Roose: ORCID iD orcid.org/0000-0001-8710-1063

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Date deposited: 20 Nov 2019 17:30
Last modified: 13 Nov 2020 05:01

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