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| Titel |
Hotsphere illumination |
| VerfasserIn |
Bahar S. Razavi, Duyen Hoang, Shibin Liu, Yakov Kuzyakov |
| Konferenz |
EGU General Assembly 2017
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250148434
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| Publikation (Nr.) |
 EGU/EGU2017-12692.pdf |
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| Zusammenfassung |
| Soils are the most heterogeneous parts of the biosphere, with an extremely high
differentiation of properties and processes at all spatial and temporal scales. Importance of
hotspheres- environment with abundant high microbial activity- i.e.: rhizosphere,
detritusphere, biopores, spermosphere and hyphasphere calls for spatially explicit methods to
illuminate distribution of microbial activities (Kuzyakov and Blagodatskaya, 2015).
Zymography technique has previously been adapted to visualize the spatial dynamics of
enzyme activities in rhizosphere.
Here, we further developed soil zymography to obtain a higher resolution of enzyme
activities by enabling direct contact of substrate-saturated membranes with soil. For the first
time, we aimed at quantitative imaging of enzyme activities in various hotspheres. We
calculated and compared percentage of enzymatic hotspots of four hotspheres:
Spermosphere, rhizosphere, detritusphere and biopores.
Spatial distribution of activities of two enzymes: β-glucosidase and phosphatase were
analyzed in the spermosphere and rhizosphere of maize and lentil. Zymography has been
done 3 days (spermosphere), 14 days (rhizosphere) after sowing. Further, manure was placed
on surface of rhizoboxes to visualize spatio-temporal distribution of the enzyme activities in
detritusphere after 25 days. Biopores were produced by earthworms (Lumbricus terrestris L.)
in transparent boxes for 2 weeks and enzyme distribution were measured by zymography
thereafter.
The developed in situ direct soil zymography visualized the heterogeneity of
enzyme activities along and across the roots. Spatial patterns of enzyme activities as a
function of distance along the root demonstrated plant specific patterns of enzyme
distribution: it was uniform and homogenous along the lentil roots, whereas the
enzyme activities in maize rhizosphere were higher at the apical or proximal root
parts.
For the first time were applied “spatial point pattern analysis” to determine whether the
pattern of hotspot distribution is localized (aggregated) or dispersed.
Under effect of earthworms (in biopores), the hotspots were dispersed in whole soil
profile but the distribution of hotspots in rhizosphere and spermosphere were localized and
mainly associated with root or with manure layer (in detritusphere). Much higher enzyme
activities per mm2 of hotspots were found in rhizosphere (12-5 fold), detritusphere (10-4),
spermosphere (9-4) and biopore (9-1), compared to the bulk soil. Despite the transient nature
of spermosphere, its microbial activities had long-lasting impact. We conclude that plant
induced hotspots with high enzyme activity; while, earthworms spread out enzyme activities
in the whole soil profile. Concluding, direct zymography enabled to illuminate the
contribution pattern of hotspheres to emerging soil properties and ecosystem processes. |
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