Effects of long-duration non-thermal plasma treatment on quinoa seeds: surface chemistry, mesoscale morphology and germination under optimal and saline conditions

This study examined the effects of prolonged exposure to dielectric barrier discharge plasma at atmospheric pressure and saline stress on quinoa seeds ( Chenopodium quinoa cv. Titicaca). Reactive species (O 3 , N 2 O, and CO 2 ) were monitored in real time, and changes in the surface chemistry, mesoscale morphology, germination rate, and fresh biomass were analyzed. During extended plasma treatment, it is probable that an equilibrium will be established between the concentration of reactive species in the plasma and the functional groups present on the seed surface. The plasma treatment changed the seed surface and increased the oxygen-to-carbon ratio without causing structural damage. The germination assay showed that 20 min exposure of seeds to plasma did not negatively affect the process. Plasma had a slight impact on fresh biomass, whereas 300 mM NaCl stress significantly reduced the biomass. Plasma can be both a treatment and a stressor, and excessive oxidative stress from prolonged plasma exposure can reduce germination and biomass. • Long plasma treatment changes quinoa seed surface chemistry without damage. • Reactive species balance achieved in plasma. • Germination is unaffected by plasma, while salt stress limits growth. • Minor plasma effect vs. major saline stress impact. • Dual role of plasma in seed treatment.