Limits...
O2 dynamics in the rhizosphere of young rice plants (Oryza sativa L.) as studied by planar optodes.

Larsen M, Santner J, Oburger E, Wenzel WW, Glud RN - Plant Soil (2015)

Bottom Line: At onset of darkness, oxia in the rhizosphere was drastically reduced, but subsequently oxia gradually increased, presumably as root and/or soil respiration declined.The study demonstrates a high spatio-temporal heterogeneity in rhizosphere O2 dynamics and difference in ROL between different parts of the rhizosphere.The work documents that spatio-temporal measurements are important to fully understand and account for the highly variable O2 dynamics and associated biogeochemical processes and pathways in the rice rhizosphere.

View Article: PubMed Central - PubMed

Affiliation: Institute of Biology and Nordic Center for Earth Evolution (NordCEE), University of Southern Denmark, 5320 Odense M, Denmark ; Scottish Marine Institute, Scottish Association for Marine Science, Oban, Scotland PA37 1QA UK ; Greenland Climate Research Centre (CO Greenland Institute of National resources), Kivioq 2, Box 570, 3900 Nuuk, Greenland.

ABSTRACT

Background and aims: Radial O2 loss (ROL) strongly affect the O2 availability in the rhizosphere of rice. The ROL create an oxic zone around the roots, protecting the plant from toxic reduced chemical species and regulates the redox chemistry in the soil. This study investigates the spatio-temporal variability in O2 dynamics in the rice rhizosphere.

Method: Applying high-resolution planar optode imaging, we investigated the O2 dynamics of plants grown in water saturated soil, as a function of ambient O2 level, irradiance and plant development, for submerged and emerged plants.

Results: O2 leakage was heterogeneously distributed with zones of intense leakage around roots tips and young developing roots. While the majority of roots exhibited high ROL others remained surrounded by anoxic soil. ROL was affected by ambient O2 levels around the plant, as well as irradiance, indicating a direct influence of photosynthetic activity on ROL. At onset of darkness, oxia in the rhizosphere was drastically reduced, but subsequently oxia gradually increased, presumably as root and/or soil respiration declined.

Conclusion: The study demonstrates a high spatio-temporal heterogeneity in rhizosphere O2 dynamics and difference in ROL between different parts of the rhizosphere. The work documents that spatio-temporal measurements are important to fully understand and account for the highly variable O2 dynamics and associated biogeochemical processes and pathways in the rice rhizosphere.

No MeSH data available.


Related in: MedlinePlus

Temporal development of ROL in the rhizosphere of a single rice root during a ~5.5 d period. a, b, c, d and e represent a close up of the root “a” in Fig. 4. The position of the root is indicated with the dashed line in panel a. From the time series it can be observed how ROL from the main root gradually disappears, presumably due to a formation of a barrier to ROL. Simultaneously it can be observed how multiple fine lateral roots are starting to leak O2
© Copyright Policy - OpenAccess
Related In: Results  -  Collection


getmorefigures.php?uid=PMC4495287&req=5

Fig5: Temporal development of ROL in the rhizosphere of a single rice root during a ~5.5 d period. a, b, c, d and e represent a close up of the root “a” in Fig. 4. The position of the root is indicated with the dashed line in panel a. From the time series it can be observed how ROL from the main root gradually disappears, presumably due to a formation of a barrier to ROL. Simultaneously it can be observed how multiple fine lateral roots are starting to leak O2

Mentions: The spatial extent of the oxygenated rhizosphere zone was dynamic, as the rhizosphere evolved; older roots ceased to leak O2, while young, newly grown roots exhibited high O2 release. We observed root growth rates of up to 2.6 mm d−1. One example of the temporal development is depicted in Fig. 4, where an emerging root begins leaking O2 into previously anoxic soil (root ‘a’ in Fig. 4), while concurrently the O2 levels around a neighbouring root drastically diminish (root ‘b’). Interestingly it could be observed that as O2 leakage from the main part of root ‘a’ diminishes with time, leakage from its laterals roots could be observed (Fig. 5). In contrast, O2 release from the neighbouring roots remained virtually unchanged during this ~5.5 day period.Fig. 4


O2 dynamics in the rhizosphere of young rice plants (Oryza sativa L.) as studied by planar optodes.

Larsen M, Santner J, Oburger E, Wenzel WW, Glud RN - Plant Soil (2015)

Temporal development of ROL in the rhizosphere of a single rice root during a ~5.5 d period. a, b, c, d and e represent a close up of the root “a” in Fig. 4. The position of the root is indicated with the dashed line in panel a. From the time series it can be observed how ROL from the main root gradually disappears, presumably due to a formation of a barrier to ROL. Simultaneously it can be observed how multiple fine lateral roots are starting to leak O2
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4495287&req=5

Fig5: Temporal development of ROL in the rhizosphere of a single rice root during a ~5.5 d period. a, b, c, d and e represent a close up of the root “a” in Fig. 4. The position of the root is indicated with the dashed line in panel a. From the time series it can be observed how ROL from the main root gradually disappears, presumably due to a formation of a barrier to ROL. Simultaneously it can be observed how multiple fine lateral roots are starting to leak O2
Mentions: The spatial extent of the oxygenated rhizosphere zone was dynamic, as the rhizosphere evolved; older roots ceased to leak O2, while young, newly grown roots exhibited high O2 release. We observed root growth rates of up to 2.6 mm d−1. One example of the temporal development is depicted in Fig. 4, where an emerging root begins leaking O2 into previously anoxic soil (root ‘a’ in Fig. 4), while concurrently the O2 levels around a neighbouring root drastically diminish (root ‘b’). Interestingly it could be observed that as O2 leakage from the main part of root ‘a’ diminishes with time, leakage from its laterals roots could be observed (Fig. 5). In contrast, O2 release from the neighbouring roots remained virtually unchanged during this ~5.5 day period.Fig. 4

Bottom Line: At onset of darkness, oxia in the rhizosphere was drastically reduced, but subsequently oxia gradually increased, presumably as root and/or soil respiration declined.The study demonstrates a high spatio-temporal heterogeneity in rhizosphere O2 dynamics and difference in ROL between different parts of the rhizosphere.The work documents that spatio-temporal measurements are important to fully understand and account for the highly variable O2 dynamics and associated biogeochemical processes and pathways in the rice rhizosphere.

View Article: PubMed Central - PubMed

Affiliation: Institute of Biology and Nordic Center for Earth Evolution (NordCEE), University of Southern Denmark, 5320 Odense M, Denmark ; Scottish Marine Institute, Scottish Association for Marine Science, Oban, Scotland PA37 1QA UK ; Greenland Climate Research Centre (CO Greenland Institute of National resources), Kivioq 2, Box 570, 3900 Nuuk, Greenland.

ABSTRACT

Background and aims: Radial O2 loss (ROL) strongly affect the O2 availability in the rhizosphere of rice. The ROL create an oxic zone around the roots, protecting the plant from toxic reduced chemical species and regulates the redox chemistry in the soil. This study investigates the spatio-temporal variability in O2 dynamics in the rice rhizosphere.

Method: Applying high-resolution planar optode imaging, we investigated the O2 dynamics of plants grown in water saturated soil, as a function of ambient O2 level, irradiance and plant development, for submerged and emerged plants.

Results: O2 leakage was heterogeneously distributed with zones of intense leakage around roots tips and young developing roots. While the majority of roots exhibited high ROL others remained surrounded by anoxic soil. ROL was affected by ambient O2 levels around the plant, as well as irradiance, indicating a direct influence of photosynthetic activity on ROL. At onset of darkness, oxia in the rhizosphere was drastically reduced, but subsequently oxia gradually increased, presumably as root and/or soil respiration declined.

Conclusion: The study demonstrates a high spatio-temporal heterogeneity in rhizosphere O2 dynamics and difference in ROL between different parts of the rhizosphere. The work documents that spatio-temporal measurements are important to fully understand and account for the highly variable O2 dynamics and associated biogeochemical processes and pathways in the rice rhizosphere.

No MeSH data available.


Related in: MedlinePlus