Work

Rhizosheath formation is positively correlated with retention of water in the rhizosphere and water deficit stress tolerance in pearl millet

Year: 2025

Type: article

Abstract: Plants have evolved adaptive strategies to enhance hydromineral uptake, with rhizosheath formation - the adhesion of soil particle to roots - emerging as a key mechanism for improving water deficit stress tolerance. In pearl millet (Pennisetum glaucum), intraspecific genetic diversity has been observed in rhizosheath formation and root architectural traits, with differences in rhizosheath size correlating with shifts in rhizosphere bacterial community composition and diversity. To investigate the role of rhizosheath in water deficit stress tolerance, we conducted a study using four pairs of closely pearl millet lines contrasting in rhizosheath size. Plants were grown in an arenosol under greenhouse conditions with natural light. After 3 weeks of irrigation, they were subjected to two water stress regimes (partial and severe deficit) for two weeks, alongside a well-watered control. Under water stress, rhizosheath mass was positively correlated with soil moisture, plant biomass, leaf water potential, and several root traits (length, average diameter, root area, root volume; p < 0.001). Under moderate water stress, high-rhizosheath lines (HRL) maintained higher leaf water potential (-2.07 MPa vs. -2.63 MPa) and exhibited less shoot biomass reduction (14% vs. 25%) compared to low-rhizosheath lines (LRL). Under severe stress, HRL showed greater resilience, with a smaller reduction in root biomass than LRL (54% vs. 71%). These results suggest that rhizosheath formation enhances root system development and sustains plant growth under moderate water deficit, likely by improving rhizosphere water retention.

Source: Scientific African

DOI: 10.1016/j.sciaf.2025.e03103