Juliette Sebastien

UMR ECODIV

PhD student / Oct 2025 to Oct 2028

Role of rhizodeposition in soil organic‑matter dynamics

This research seeks to elucidate how carbon released through rhizodeposition shapes soil‑microbial functioning and organic‑matter turnover. A particular focus is placed on the relationship between root‑derived carbon inputs and the priming effect, whereby microbial activity accelerates the decomposition of native soil organic matter. The project combines controlled‑environment experiments with field studies to capture these processes under diverse conditions. Ultimately, this work aims to advance our understanding of plant–soil interactions in carbon storage and to inform sustainable agricultural practices that enhance soil health and contribute to climate‑change mitigation.

Puu-Tai Yang

CEREGE

Postdoctoral researcher / April 2026 to April 2028

Monitoring the transfer of rhizodeposits into the soil

Plants exude low‑molecular‑weight organic acids into the rhizosphere, shaping the formation and destabilisation of organo‑mineral associations and ultimately controlling soil‑carbon storage. This study seeks to characterise the spatial heterogeneity of soil physicochemical properties near sorghum roots using two‑dimensional imaging approaches. The findings will provide new insights into carbon‑sequestration mechanisms operating at the plant–soil interface.

Franziska Anna Steiner

ENS PSL

Postdoctoral researcher / April 2026 to April 2028

Potential of clay‑mineral amendments to enhance the sequestration of rhizodeposit‑derived carbon under climate‑change conditions

This research aims to evaluate the capacity of reactive clay‑mineral amendments to enhance the stabilisation of root‑derived carbon in sandy Arenosols. The work examines how such amendments promote the formation of persistent mineral‑associated organic matter and influence the carbon budget of soils cultivated with contrasting sorghum genotypes. It also investigates how shifts in the biogeochemical and physical properties of amended soils modulate plant–soil interactions and the fate of rhizodeposits in a changing climate. Through the combined use of isotopic tracing and thermal fractionation of soil‑organic‑matter pools, this project seeks to advance our understanding of mineral‑mediated mechanisms of long‑term carbon sequestration in coarse‑textured soils.

Marcel Nahim Diouf

UMR Eco&Sols

Postdoctoral researcher / July 2025 to July 2027

Phenotyping of sorghum rhizogain

Rhizogain refers to a sheath of soil tightly adhering to the roots, held together by root exudates and fungal or bacterial filaments. In sorghum (Sorghum bicolor)**, it represents a root trait with strong intra‑specific genetic variability. Its phenotyping relies on quantitative measurements such as adherent soil mass (ASM) and the rhizogain biomass/root biomass ratio (RB), assessed at an early vegetative stage (around 5 weeks).

The rhizogain plays a major functional role in the acquisition of water and poorly mobile nutrients (phosphorus, nitrogen), in stabilizing soil around the roots, and in creating a specific microbial habitat that promotes rhizosphere bacterial diversity. Genomic regions (QTLs) controlling this phenotype have been identified, opening perspectives for breeding sorghum varieties adapted to water‑limited conditions in Sahelian environments.