Fulltext

Investigation of small-scale processes in the rhizosphere of Lupinus albus using micro push-pull tests

Knecht, K. ; Nowack, B. ; Schroth, M. ; Suter, M. ; Schulin, R.

In: Plant and Soil, 2014, vol. 378, no. 1-2, p. 309-324

Ajouter à la liste personnelle
    Titre
    • Investigation of small-scale processes in the rhizosphere of Lupinus albus using micro push-pull tests
    Auteur
    • Knecht, K.. Institute of Terrestrial Ecosystems, ETH Zurich, 8092, Zurich, Switzerland
    • Nowack, B.. Institute of Terrestrial Ecosystems, ETH Zurich, 8092, Zurich, Switzerland
    • Schroth, M.. Institute of Biogeochemistry and Pollutant Dynamics, ETH Zurich, Zurich, Switzerland
    • Suter, M.. Eawag: Swiss Federal Institute of Aquatic Science and Technology, Dübendorf, Switzerland
    • Schulin, R.. Institute of Terrestrial Ecosystems, ETH Zurich, 8092, Zurich, Switzerland
    Type de document
    • Postprint
    Langue
    • Anglais
    Publié dans
    • Plant and Soil, 2014, vol. 378, no. 1-2, p. 309-324. Springer International Publishing
    Autre version électronique
    Identifiant OAI-PMH
    • oai:doc.rero.ch:326437
    Summary
    Background and Aims: Rhizosphere processes affect the mobility, phytoavailability and toxicity of solutes in soil. To study reactions in the rhizosphere under quasi in situ conditions, we recently developed the "micro push-pull test” (μPPT) method, combining micro-suction cups with the principle of the "push-pull test” method known from groundwater applications. Here we report the application of μPPT to investigate rhizosphere reactions in situ, i.e. degradation of deuterated citrate (citrate-d4) in the rhizosphere of Lupinus albus grown in sand-filled rhizoboxes. Methods: In a μPPT, a solution containing reactive (citrate-d4) and non-reactive solutes (bromide) is injected into a porous medium and shortly thereafter, the pore water solution is re-extracted from the same location. Concentration ("breakthrough”) curves of extracted reactants can be compared to those of the non-reactive solute, allowing the determination of reaction rates. We applied the μPPT in rhizoboxes with Lupinus albus and sampled different types of micro-habitats: bulk soil, rhizosphere of normal roots and rhizosphere of cluster roots of different ages. Results: Breakthrough curves of citrate-d4 varied considerably between tests adjacent to cluster roots and normal roots, and in bulk soil. Degradation of citrate-d4 in bulk soil and adjacent to normal roots was below detection, while we found strong degradation of citrate-d4 adjacent to 4 to 5-days old cluster roots. In situ degradation rate constants for citrate-d4 around cluster roots were found to be in the range from 0.38 to 0.71h−1. Conclusions: We successfully applied the μPPT to the rhizosphere. The μPPT is useful to investigate local processes in microcosms and to monitor processes also over time (e.g., during cluster-root development) due to its non-destructive nature.