Rhizodeposition of organic C by plants: mechanisms and controls

By C. Nguyen. 2003

882 citations recorded by the source corpus.

During their life, plant roots release organic compounds in their surrounding environment. This process, named rhizodeposition, is of ecological importance because (1) it is a loss of reduced C for the plant, (2) it is an input flux for the organic C pool of the soil and (3) it fuels the soil microflora, which is involved in the great majority of the biological activity of soils such as the nutrient and pollutant cycling or the dynamics of soil borne pathogens, for example. The present review first examines the mechanisms by which major rhizodeposits are released into the soil: production of root cap cells, secretion of mucilage, passive and controlled diffusion of root exudates. In a second part, results from tracer studies (43 articles) are analysed and values of C flux from the plant root into the soil are summarized. In average, 17% of the net C fixed by photosynthesis is lost by roots and recovered as rhizosphere respiration (12%) and soil residues (5%), which corresponds to 50% of the C exported by shoots to belowground. Finally, the paper reviews major factors that modify the partitioning of photoassimilates to the soil: microorganisms, nitrogen, soil texture and atmospheric CO2 concentration.

Subfields: Plant Science, Soil Science

View Paper: https://www.semanticscholar.org/paper/979f5da29597fd05d09eaff20cb345e5cfb78c94

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Plant Science

1. Y. Kuzyakov
2. P. Hinsinger
3. J. Lynch
4. J. Pausch
5. H. Lambers
6. Davey L. Jones
7. E. Blagodatskaya
8. R. Finlay

In Soil Science

1. Y. Kuzyakov
2. E. Blagodatskaya
3. J. Pausch
4. P. Hinsinger
5. Davey L. Jones
6. R. Bardgett
7. C. Nguyen
8. R. Finlay

Citations in the corpus

• Ecology of Denitrifying Prokaryotes in Agricultural Soil (2007, background): “This amount of carbon released by roots into the soil can be up to 20% of photosynthetically fixed carbon during the vegetation period (Hütsch et al., 2002; Nguyen, 2003).”
• Partitioning the components of soil respiration: a research challenge (2006, background): “14C-labelling experiments have shown that an average of 14% of photosynthetically fixed C in perennial plants is lost as root respiration (Nguyen 2003).”
• Photoassimilate allocation and dynamics of hotspots in roots visualized by 14C phosphor imaging (2011, neutral): “The advantages and disadvantages of these labeling approaches were reviewed in several publications (Whipps, 1990; Kuzyakov and Domanski, 2000; Nguyen, 2003; Kuzyakov and Schneckenberger, 2004; Werth and Kuzyakov, 2008).”
• Biological carbon assimilation and dynamics in a flooded rice - Soil system (2012, background): “The extent of this input also determines the extent of accumulation of organic C in soils (Nguyen, 2003; Weintraub et al., 2007), and provides the labile energy for up to 50%of soilmicrobial activity in terrestrial ecosystems (Högberg et al.”
• When Roots Lose Contact (2009, background): “Additionally, gaps at the soil–root interface would hinder the diff usion of exudates into the soil and thus would infl uence the activity of bacteria and fungi, which rely on root exudates and debris as C sources (Lynch and Whipps, 1990; Nguyen, 2003).”
• Nitrogen rhizodeposition of legumes. A review (2011, background): “Quantitative data providing reliable estimation of these pathways are sparse but a recent review concerning carbon rhizodeposition showed that sloughing-off of border cells and secretion of mucilage represent a very small proportion of carbon rhizodeposition (N’guyen, 2003).”
• Rhizoeconomics: Carbon costs of phosphorus acquisition (2005, background): “Root exudates in general represent about half of all belowground carbon allocation, with great variability (Nguyen, 2003).”
• Contribution of exudates, arbuscular mycorrhizal fungi and litter depositions to the rhizosphere priming effect induced by grassland species (2015, background): “The main component of rhizodeposition is root exudates through which 10-100 times more carbon is released than mucilage and sloughed-off border cells (Nguyen, 2009).”
• Interactions between arbuscular mycorrhizal fungi and phosphate-solubilizing fungus (Mortierella sp.) and their effects on Kostelelzkya virginica growth and enzyme activities of rhizosphere and bulk soils at different salinities (2011, background): “The P solubilization occurs in the rhizosphere soil where organic compounds are released by roots or mycorrhizae (Nguyen 2003; Amos and Walters 2006).”
• Are root exudates more important than other sources of rhizodeposits in structuring rhizosphere bacterial communities? (2010, background): “Nguyen (2003) reported that the partitioning of pulselabelled 14C photosynthates to roots, rhizosphere respiration, and soil residues decreased with increasing plant age (28–600 days) by 43%, 28%, and 20%, respectively.”
• Biochemical cycling in the rhizosphere having an impact on global change (2009, neutral): “1998), and less than 5% of the carbon transferred to the rhizosphere through root exudates is incorporated into soil organic matter (Kumar et al. 2006; Nguyen 2003).”
• The dynamics of neutral sugars in the rhizosphere of wheat. An approach by13C pulse-labelling and GC/C/IRMS (2004, background): “These values were in good agreement with the mean value of 0.33 reported in the literature by Nguyen (2003) from more than 60 data sets of pulse labelling of annual plants.”