Abstract

Salinity first strikes crops via osmotic shock, collapsing the soil-to-leaf water gradient long before toxic ions build up. To disentangle this early phase, we exposed two contrasting Chilean quinoa (Chenopodium quinoa) ecotypes—AZ2 (coastal lowland) and AZ9b (salares desert)—to 0, 150, and 300 mM NaCl for seven days and quantified root hydraulics, leaf gas exchange, and whole-plant water status. Both genotypes initiated osmotic adjustment, as evidenced by higher root-sap osmolality and a decrease in stem water potential (?stem). However, only desert ecotype AZ9b deployed a xerophyte-like hydraulic strategy: root hydraulic conductivity (Lpr) remained constant, stomatal conductance (gs) remained twice that of AZ2 at 150 mM, and ?stem declined just enough to preserve leaf turgor. Even at 300 mM, AZ9b’s Lpr was triple that of AZ2. Microscopic observations confirmed that AZ2 roots underwent cortical collapse and early suberization, whereas AZ9b maintained an intact cortex with minimal barrier formation, keeping radial water flow open. Thus, swift coordination of Lpr, gs, and osmotic adjustment stabilizes ?stem and safeguards the water balance within the first week of salt exposure. Early hydraulic resilience, not late-stage ion exclusion, has emerged as a practical breeding target for enhancing quinoa performance in saline marginal soils. © The Author(s), under exclusive licence to Brazilian Society of Plant Physiology 2025.