Quantitative importance of various rhizodeposition processes: lessons from a mechanistic functional-structural root model
Résumé
Rhizodeposits, defined here as any organic materials released by living roots, can represent
up to 15% of net amount of carbon (C) photosynthesized by a plant (Pausch and Kuzyakov,
2018). Rhizodeposits have been shown to play an important role in plant growth through
various mechanisms (e.g. by favoring water uptake through mucilage secretion, or nutrient
uptake through the exudation of soluble compounds), and to represent a major contributor to
the formation of stable soil organic matter - and thus to the mitigation of climate change
through soil C sequestration. Decomposing rhizodeposition into its elementary processes (e.g.
exudation, mucilage secretion, cells sloughing) is required for a better understanding of the
response of rhizodeposition to various environmental constraints and of its associated-
benefits. While many works have attempted to quantify the exudation of soluble organic
compounds at the scale of a plant or the net rhizodeposition of C in soils, very few studies
have been able to estimate the amount of mucilage or sloughed cells released by a whole root
system over time. Consequently, while it has been claimed that the amount of soluble organic
C is much higher than the amount of C released as mucilage or sloughed cells by roots
(Nguyen, 2003; Rees et al. 2005), the relative importance of distinct rhizodeposition processes
in plant’s and soil’s C balance remains largely unknown. While the comparison of mucilage
secretion and citrate exudation within a FSPM has been recently attempted (Landl et al. 2021),
no model has been developed so far for simulating such rhizodeposition processes as part of
plant’s C management. The present work aimed to give a better assessment of the
contribution of distinct rhizodeposition processes to the total amount of organic C released by
roots, for different plant species, growth stages and environments
Domaines
Sciences du Vivant [q-bio]Origine | Fichiers produits par l'(les) auteur(s) |
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