Soil carbon dioxide venting through rice roots
Abstract The growth of rice in submerged soils depends on its ability to form continuous gas channels—aerenchyma—through which oxygen (O 2 ) diffuses from the shoots to aerate the roots. Less well understood is the extent to which aerenchyma permits venting of respiratory carbon dioxide (CO 2 ) in t...
| Published in: | Plant, Cell & Environment |
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| Main Authors: | , , , , , |
| Other Authors: | |
| Format: | Article in Journal/Newspaper |
| Language: | English |
| Published: |
Wiley
2019
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| Subjects: | |
| Online Access: | http://dx.doi.org/10.1111/pce.13638 https://onlinelibrary.wiley.com/doi/pdf/10.1111/pce.13638 https://onlinelibrary.wiley.com/doi/full-xml/10.1111/pce.13638 |
| Summary: | Abstract The growth of rice in submerged soils depends on its ability to form continuous gas channels—aerenchyma—through which oxygen (O 2 ) diffuses from the shoots to aerate the roots. Less well understood is the extent to which aerenchyma permits venting of respiratory carbon dioxide (CO 2 ) in the opposite direction. Large, potentially toxic concentrations of dissolved CO 2 develop in submerged rice soils. We show using X‐ray computed tomography and image‐based mathematical modelling that CO 2 venting through rice roots is far greater than thought hitherto. We found rates of venting equivalent to a third of the daily CO 2 fixation in photosynthesis. Without this venting through the roots, the concentrations of CO 2 and associated bicarbonate (HCO 3 − ) in root cells would have been well above levels known to be toxic to roots. Removal of CO 2 and hence carbonic acid (H 2 CO 3 ) from the soil was sufficient to increase the pH in the rhizosphere close to the roots by 0.7 units, which is sufficient to solubilize or immobilize various nutrients and toxicants. A sensitivity analysis of the model showed that such changes are expected for a wide range of plant and soil conditions. |
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