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| Titel |
Does the rhizosphere hydrophobicity limit root water uptake? |
| VerfasserIn |
Mohsen Zare, Mutez Ahmed, Eva Kroener, Andrea Carminati |
| Konferenz |
EGU General Assembly 2015
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250104718
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| Publikation (Nr.) |
 EGU/EGU2015-4150.pdf |
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| Zusammenfassung |
| The ability of plants to extract water from the soil is influenced by the hydraulic conductivity
of roots and their rhizosphere. Recent experiments showed that the rhizosphere turned
hydrophobic after drying and it remained dry after rewetting [1]. Our objective was to
investigate whether rhizosphere hydrophobicity is a limit to root water uptake after
drying.
To quantify the effect of rhizosphere hydrophobicity on root water uptake, we used
neutron radiography to trace the transport of deuterated water (D2O) in the roots of lupines
experiencing a severe, local soil drying. The plants were grown in aluminum containers
(30x30x1 cm) filled with sandy soil. The soil was partitioned into nine compartments using
three horizontal and three vertical layers of coarse sand (thickness of 1cm) as capillary
barrier. When the plants were 28 days old, we let one of the upper lateral compartments
dry to a water content of 2-4%, while keeping the other compartments to a water
content of 20%. Then we injected 10 ml of D2O in the dry compartment and 10 ml in
the symmetric location. The radiographs showed that root water uptake in the soil
region that was let dry and then irrigated was 4-8 times smaller than in the wet soil
region[2].
In a parallel experiment, we used neutron radiography to monitor the rehydration of
lupine roots that were irrigated after a severe drying experiment. Based on root swelling and
additional data on the xylem pressure, we calculated the hydraulic conductivity of the
root-rhizosphere continuum. We found that the hydraulic conductivity of the root-rhizosphere
continuum was initially 5.75x10-14 m s-1and it increased to 4.26x10-12 m s-1after four
hours.
Both experiments show that rhizosphere hydrophobicity after drying is associated with a
reduction in root water uptake and a big decrease in hydraulic conductivity of the soil-root
system.
[1] Carminati et al (2010) Plant and Soil. Vol. 332: 163-176.
[2] Zarebanadkouki and Carmianti (2013) Journal of Plant Nutrition and Soil Science.
Vol. 177: 227-236. |
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