Abstract

Surface-applied chia (Salvia hispanica) seed mucilage forms a thin, biodegradable “biomulch” whose crop-scale effects remain undocumented. We applied 0, 0.10, or 0.25 % (w/w) mucilage to maize (Zea mays L.) grown in coarse quartz sand and withheld irrigation for seven days. The 0.25 % film-maintained soil water content 6–8 percent points (pp) higher and reduced cumulative evapotranspiration by 39 %, keeping midday stem and root water potentials 0.4 MPa less negative and leaf relative water content ?86 % (controls 72 %). The root sections showed minimal cortical collapse and delayed exodermal suberization, corroborating hydraulic protection. Nevertheless, chlorophyll and carotenoids fell by 12–18 %, suggesting that improved hydration came at the cost of restricted CO2 diffusion and mild oxidative stress under low humidity. Thus, chia mucilage combines strong soil drying suppression with a conservative photosynthetic response. The method offers a rapid, low-input option for episodic drought, pending field validation of film persistence, infiltration behavior, and cost–benefit across soils. © 2025 Elsevier B.V.