Research Article

Plant and Soil

, Volume 166, Issue 1, pp 55-62

First online:

A critical review of labelling techniques used to quantify rhizosphere carbon-flow

  • Andrew A. MehargAffiliated withInstitute of Terrestrial Ecology

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Abstract

The rhizosphere is a major sink for photo-assimilated carbon and quantifying inputs into this sink is one of the main goals of rhizosphere biology as organic carbon lost from plant roots supports a higher microbial population in the rhizosphere compared to bulk soil. Two fundamentally different14CO2 labelling strategies have been developed to estimate carbon fluxes through the rhizosphere — continuous feeding of shoots with labelled carbon dioxide and pulse-chase experiments. The biological interpretation that can be placed on the results of labelling experiments is greatly biased by the technique used. It is the purpose of this paper to assess the advantages, disadvantages and the biological interpretation of both continuous and pulse labelling and to consider how to partition carbon fluxes within the rhizosphere.

Key words

carbon-flow carbon cycling continuous labelling pulse labelling rhizosphere roots soil microbial biomass