Surface tension, rheology and hydrophobicity of rhizodeposits and seed mucilage influence soil water retention and hysteresis

M. Naveed, M. A. Ahmed, P. Benard, L. K. Brown, T. S. George, A. G. Bengough, T. Roose, N. Koebernick, P. D. Hallett (Lead / Corresponding author)

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Abstract

Aims: Rhizodeposits collected from hydroponic solutions with roots of maize and barley, and seed mucilage washed from chia, were added to soil to measure their impact on water retention and hysteresis in a sandy loam soil at a range of concentrations. We test the hypothesis that the effect of plant exudates and mucilages on hydraulic properties of soils depends on their physicochemical characteristics and origin.

Methods: Surface tension and viscosity of the exudate solutions were measured using the Du Noüy ring method and a cone-plate rheometer, respectively. The contact angle of water on exudate treated soil was measured with the sessile drop method. Water retention and hysteresis were measured by equilibrating soil samples, treated with exudates and mucilages at 0.46 and 4.6 mg g−1 concentration, on dialysis tubing filled with polyethylene glycol (PEG) solution of known osmotic potential.

Results: Surface tension decreased and viscosity increased with increasing concentration of the exudates and mucilage in solutions. Change in surface tension and viscosity was greatest for chia seed exudate and least for barley root exudate. Contact angle increased with increasing maize root and chia seed exudate concentration in soil, but not barley root. Chia seed mucilage and maize root rhizodeposits enhanced soil water retention and increased hysteresis index, whereas barley root rhizodeposits decreased soil water retention and the hysteresis effect. The impact of exudates and mucilages on soil water retention almost ceased when approaching wilting point at −1500 kPa matric potential.

Conclusions: Barley rhizodeposits behaved as surfactants, drying the rhizosphere at smaller suctions. Chia seed mucilage and maize root rhizodeposits behaved as hydrogels that hold more water in the rhizosphere, but with slower rewetting and greater hysteresis.
Original languageEnglish
Pages (from-to)65-81
Number of pages17
JournalPlant and Soil
Volume437
Issue number1-2
Early online date2 Feb 2019
DOIs
Publication statusPublished - Apr 2019

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mucilage
soil water retention
mucilages
surface tension
hysteresis
rheology
hydrophobicity
water retention
soil water
barley
seed
seeds
maize
viscosity
contact angle
corn
soil
rhizosphere
water
plant exudates

Keywords

  • Contact angle
  • Hysteresis
  • Root exudate
  • Seed exudate
  • Soil water retention
  • Surface tension
  • Viscosity

Cite this

Naveed, M. ; Ahmed, M. A. ; Benard, P. ; Brown, L. K. ; George, T. S. ; Bengough, A. G. ; Roose, T. ; Koebernick, N. ; Hallett, P. D. / Surface tension, rheology and hydrophobicity of rhizodeposits and seed mucilage influence soil water retention and hysteresis. In: Plant and Soil. 2019 ; Vol. 437, No. 1-2. pp. 65-81.
@article{0fd3d4574baa4c6daa7a68ae8ac9b0e6,
title = "Surface tension, rheology and hydrophobicity of rhizodeposits and seed mucilage influence soil water retention and hysteresis",
abstract = "Aims: Rhizodeposits collected from hydroponic solutions with roots of maize and barley, and seed mucilage washed from chia, were added to soil to measure their impact on water retention and hysteresis in a sandy loam soil at a range of concentrations. We test the hypothesis that the effect of plant exudates and mucilages on hydraulic properties of soils depends on their physicochemical characteristics and origin.Methods: Surface tension and viscosity of the exudate solutions were measured using the Du No{\"u}y ring method and a cone-plate rheometer, respectively. The contact angle of water on exudate treated soil was measured with the sessile drop method. Water retention and hysteresis were measured by equilibrating soil samples, treated with exudates and mucilages at 0.46 and 4.6 mg g−1 concentration, on dialysis tubing filled with polyethylene glycol (PEG) solution of known osmotic potential.Results: Surface tension decreased and viscosity increased with increasing concentration of the exudates and mucilage in solutions. Change in surface tension and viscosity was greatest for chia seed exudate and least for barley root exudate. Contact angle increased with increasing maize root and chia seed exudate concentration in soil, but not barley root. Chia seed mucilage and maize root rhizodeposits enhanced soil water retention and increased hysteresis index, whereas barley root rhizodeposits decreased soil water retention and the hysteresis effect. The impact of exudates and mucilages on soil water retention almost ceased when approaching wilting point at −1500 kPa matric potential.Conclusions: Barley rhizodeposits behaved as surfactants, drying the rhizosphere at smaller suctions. Chia seed mucilage and maize root rhizodeposits behaved as hydrogels that hold more water in the rhizosphere, but with slower rewetting and greater hysteresis.",
keywords = "Contact angle, Hysteresis, Root exudate, Seed exudate, Soil water retention, Surface tension, Viscosity",
author = "M. Naveed and Ahmed, {M. A.} and P. Benard and Brown, {L. K.} and George, {T. S.} and Bengough, {A. G.} and T. Roose and N. Koebernick and Hallett, {P. D.}",
note = "This work was funded by the Biotechnology and Biological Sciences Research Council (BBSRC) project ‘Rhizosphere by Design’ (BB/L026058/1, BB/J000868/1 and BB/J011460/1) with support from a Royal Society University Research Fellowship, EPSRC EP/M020355/1, BBSRC SARIC BB/P004180/1, NERC NE/L00237/1 and ERC Consolidator grant DIMR 646809. The James Hutton Institute receives funding from the Scottish Government.",
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Naveed, M, Ahmed, MA, Benard, P, Brown, LK, George, TS, Bengough, AG, Roose, T, Koebernick, N & Hallett, PD 2019, 'Surface tension, rheology and hydrophobicity of rhizodeposits and seed mucilage influence soil water retention and hysteresis' Plant and Soil, vol. 437, no. 1-2, pp. 65-81. https://doi.org/10.1007/s11104-019-03939-9

Surface tension, rheology and hydrophobicity of rhizodeposits and seed mucilage influence soil water retention and hysteresis. / Naveed, M.; Ahmed, M. A.; Benard, P.; Brown, L. K.; George, T. S.; Bengough, A. G.; Roose, T.; Koebernick, N.; Hallett, P. D. (Lead / Corresponding author).

In: Plant and Soil, Vol. 437, No. 1-2, 04.2019, p. 65-81.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Surface tension, rheology and hydrophobicity of rhizodeposits and seed mucilage influence soil water retention and hysteresis

AU - Naveed, M.

AU - Ahmed, M. A.

AU - Benard, P.

AU - Brown, L. K.

AU - George, T. S.

AU - Bengough, A. G.

AU - Roose, T.

AU - Koebernick, N.

AU - Hallett, P. D.

N1 - This work was funded by the Biotechnology and Biological Sciences Research Council (BBSRC) project ‘Rhizosphere by Design’ (BB/L026058/1, BB/J000868/1 and BB/J011460/1) with support from a Royal Society University Research Fellowship, EPSRC EP/M020355/1, BBSRC SARIC BB/P004180/1, NERC NE/L00237/1 and ERC Consolidator grant DIMR 646809. The James Hutton Institute receives funding from the Scottish Government.

PY - 2019/4

Y1 - 2019/4

N2 - Aims: Rhizodeposits collected from hydroponic solutions with roots of maize and barley, and seed mucilage washed from chia, were added to soil to measure their impact on water retention and hysteresis in a sandy loam soil at a range of concentrations. We test the hypothesis that the effect of plant exudates and mucilages on hydraulic properties of soils depends on their physicochemical characteristics and origin.Methods: Surface tension and viscosity of the exudate solutions were measured using the Du Noüy ring method and a cone-plate rheometer, respectively. The contact angle of water on exudate treated soil was measured with the sessile drop method. Water retention and hysteresis were measured by equilibrating soil samples, treated with exudates and mucilages at 0.46 and 4.6 mg g−1 concentration, on dialysis tubing filled with polyethylene glycol (PEG) solution of known osmotic potential.Results: Surface tension decreased and viscosity increased with increasing concentration of the exudates and mucilage in solutions. Change in surface tension and viscosity was greatest for chia seed exudate and least for barley root exudate. Contact angle increased with increasing maize root and chia seed exudate concentration in soil, but not barley root. Chia seed mucilage and maize root rhizodeposits enhanced soil water retention and increased hysteresis index, whereas barley root rhizodeposits decreased soil water retention and the hysteresis effect. The impact of exudates and mucilages on soil water retention almost ceased when approaching wilting point at −1500 kPa matric potential.Conclusions: Barley rhizodeposits behaved as surfactants, drying the rhizosphere at smaller suctions. Chia seed mucilage and maize root rhizodeposits behaved as hydrogels that hold more water in the rhizosphere, but with slower rewetting and greater hysteresis.

AB - Aims: Rhizodeposits collected from hydroponic solutions with roots of maize and barley, and seed mucilage washed from chia, were added to soil to measure their impact on water retention and hysteresis in a sandy loam soil at a range of concentrations. We test the hypothesis that the effect of plant exudates and mucilages on hydraulic properties of soils depends on their physicochemical characteristics and origin.Methods: Surface tension and viscosity of the exudate solutions were measured using the Du Noüy ring method and a cone-plate rheometer, respectively. The contact angle of water on exudate treated soil was measured with the sessile drop method. Water retention and hysteresis were measured by equilibrating soil samples, treated with exudates and mucilages at 0.46 and 4.6 mg g−1 concentration, on dialysis tubing filled with polyethylene glycol (PEG) solution of known osmotic potential.Results: Surface tension decreased and viscosity increased with increasing concentration of the exudates and mucilage in solutions. Change in surface tension and viscosity was greatest for chia seed exudate and least for barley root exudate. Contact angle increased with increasing maize root and chia seed exudate concentration in soil, but not barley root. Chia seed mucilage and maize root rhizodeposits enhanced soil water retention and increased hysteresis index, whereas barley root rhizodeposits decreased soil water retention and the hysteresis effect. The impact of exudates and mucilages on soil water retention almost ceased when approaching wilting point at −1500 kPa matric potential.Conclusions: Barley rhizodeposits behaved as surfactants, drying the rhizosphere at smaller suctions. Chia seed mucilage and maize root rhizodeposits behaved as hydrogels that hold more water in the rhizosphere, but with slower rewetting and greater hysteresis.

KW - Contact angle

KW - Hysteresis

KW - Root exudate

KW - Seed exudate

KW - Soil water retention

KW - Surface tension

KW - Viscosity

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U2 - 10.1007/s11104-019-03939-9

DO - 10.1007/s11104-019-03939-9

M3 - Article

VL - 437

SP - 65

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JO - Plant and Soil

JF - Plant and Soil

SN - 0032-079X

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