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Soil carbon dioxide venting through rice roots

Soil carbon dioxide venting through rice roots
Soil carbon dioxide venting through rice roots
The growth of rice in submerged soils depends on its ability to form continuous gas channels – aerenchyma – through which oxygen (O2) diffuses from the shoots to aerate the roots. Less well understood is the extent to which aerenchyma permits venting of respiratory carbon dioxide (CO2) in the opposite direction. Large, potentially toxic concentrations of dissolved CO2 develop in submerged rice soils. We show using X‐ray computed tomography (CT) and image‐based mathematical modelling that CO2 venting through rice roots is far greater than thought hitherto. We found rates of venting equivalent to a third of the daily CO2 fixation in photosynthesis. Without this venting through the roots, the concentrations of CO2 and associated bicarbonate (HCO3‐) in root cells would have been well above levels known to be toxic to roots. Removal of CO2 and hence carbonic acid (H2CO3) from the soil was sufficient to increase the pH in the rhizosphere close to the roots by 0.7 units, which is sufficient to solubilise or immobilise various nutrients and toxicants. A sensitivity analysis of the model showed such changes are expected for a wide range of plant and soil conditions.
flooding, respiration, X-ray computed tomography, biological models, biological transport
0140-7791
Kirk, Guy J.D.
72cf1b56-242e-4c9d-bcc9-3b3ccfe14584
Boghi, Andrea
54a72da6-c8a2-468c-9773-897efac0638f
Affholder, Marie-Cecile
645fd0d9-99fb-405a-a66b-6bb51ac14eae
Keyes, Samuel
ed3ee62b-e257-4b92-922c-023b232e8145
Heppell, James P.
1dd93015-2620-4a4f-8ded-754815f5663f
Roose, Tiina
3581ab5b-71e1-4897-8d88-59f13f3bccfe
Kirk, Guy J.D.
72cf1b56-242e-4c9d-bcc9-3b3ccfe14584
Boghi, Andrea
54a72da6-c8a2-468c-9773-897efac0638f
Affholder, Marie-Cecile
645fd0d9-99fb-405a-a66b-6bb51ac14eae
Keyes, Samuel
ed3ee62b-e257-4b92-922c-023b232e8145
Heppell, James P.
1dd93015-2620-4a4f-8ded-754815f5663f
Roose, Tiina
3581ab5b-71e1-4897-8d88-59f13f3bccfe

Kirk, Guy J.D., Boghi, Andrea, Affholder, Marie-Cecile, Keyes, Samuel, Heppell, James P. and Roose, Tiina (2019) Soil carbon dioxide venting through rice roots. Plant, Cell and Environment. (doi:10.1111/pce.13638).

Record type: Article

Abstract

The growth of rice in submerged soils depends on its ability to form continuous gas channels – aerenchyma – through which oxygen (O2) diffuses from the shoots to aerate the roots. Less well understood is the extent to which aerenchyma permits venting of respiratory carbon dioxide (CO2) in the opposite direction. Large, potentially toxic concentrations of dissolved CO2 develop in submerged rice soils. We show using X‐ray computed tomography (CT) and image‐based mathematical modelling that CO2 venting through rice roots is far greater than thought hitherto. We found rates of venting equivalent to a third of the daily CO2 fixation in photosynthesis. Without this venting through the roots, the concentrations of CO2 and associated bicarbonate (HCO3‐) in root cells would have been well above levels known to be toxic to roots. Removal of CO2 and hence carbonic acid (H2CO3) from the soil was sufficient to increase the pH in the rhizosphere close to the roots by 0.7 units, which is sufficient to solubilise or immobilise various nutrients and toxicants. A sensitivity analysis of the model showed such changes are expected for a wide range of plant and soil conditions.

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Accepted/In Press date: 31 July 2019
e-pub ahead of print date: 4 August 2019
Keywords: flooding, respiration, X-ray computed tomography, biological models, biological transport

Identifiers

Local EPrints ID: 433011
URI: http://eprints.soton.ac.uk/id/eprint/433011
ISSN: 0140-7791
PURE UUID: db7a9a82-5a14-41eb-8d84-0ef464ce7dea
ORCID for Andrea Boghi: ORCID iD orcid.org/0000-0002-9387-326X
ORCID for Samuel Keyes: ORCID iD orcid.org/0000-0002-4129-2228
ORCID for Tiina Roose: ORCID iD orcid.org/0000-0001-8710-1063

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Date deposited: 06 Aug 2019 16:30
Last modified: 07 Oct 2020 06:44

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