Precision plasma priming of cereals in low-input systems: From biologically effective dose to field establishment

Introduction: Rapid and uniform seedling establishment is essential for maintaining plant density, resource-use efficiency, and stable cereal production in low-input systems. Drought, salinity, low temperature, seed ageing, reduced vigour, and seed- and soil-borne pathogens widen the gap between laboratory germination and field establishment. Cold atmospheric plasma can modify seed-surface properties, microbial load, and redox, hormonal, metabolic, and ionic responses. However, cereal studies remain heterogeneous because treatment time, voltage, or nominal power are often treated as equivalents of biological dose, while genotype, seed-lot status, and post-sowing environment are insufficiently considered. This review proposes a genotype × plasma dose × seed status × environment framework linking physical dose, chemical exposure, biologically effective dose, seed mechanisms, and field establishment.



Materials and Methods: A concept-driven critical narrative review was conducted using peer-reviewed English-language studies published up to 1 June 2026. Scopus, Web of Science, PubMed, Google Scholar, and Crossref were searched using terms related to cold plasma, plasma priming, plasma-activated water, cereal seeds, germination, seedling establishment, RONS, and plasma dose. Studies directly addressing seed treatment or agronomic outcomes were prioritized; irrelevant, duplicate, or biologically uninterpretable reports were excluded. Evidence from wheat, rice, maize, barley, oats, millets, and tef was evaluated across discharge architecture, seed-lot traits, mechanistic responses, and agronomic outcomes. Studies were assessed for experimental scale, characterization quality, dose–response design, control adequacy, and transferability to soil and field conditions.

Results: Device settings alone do not define the dose received by seeds. Dielectric barrier discharge is promising for scalable direct treatment, but seed contacts can generate heterogeneous fields and microdischarges. Atmospheric-pressure jets provide greater spatial control but are sensitive to nozzle distance, gas flow, and ambient-air mixing, while other discharge and plasma–liquid systems create distinct exposure windows. Seed moisture, geometry, coat composition, and vigour further influence discharge behaviour and tissue sensitivity. Within the hormetic window, controlled surface oxidation may improve wettability and water-uptake kinetics. Reactive oxygen and nitrogen species may act directly or stimulate endogenous redox signalling associated with ABA–GA balance, reserve mobilization, antioxidant defence, osmolytes, and ionic fluxes. These responses may accelerate germination, strengthen root growth, reduce microbial load, and improve stress tolerance, whereas excessive exposure is associated with lipid peroxidation, electrolyte leakage, membrane and DNA damage, and reduced viability. Evidence is comparatively stronger for surface modification, water uptake, early root growth, drought-related responses, and fungal control in wheat; cold tolerance and plasma-activated water in rice; reserve mobilization and surface elemental redistribution in barley; and hybrid- and season-dependent field responses in maize. Positive effects on germination and early growth are frequent under controlled conditions, but persistence in soil and translation into stable field performance remain limited. Major constraints include inadequate energy normalization, insufficient measurement of reactive species and seed temperature, use of high-vigour seed lots, lack of multi-environment trials, and poor reporting of initial seed status.

Conclusion: Cereal plasma priming should move from fixed time- and voltage-based treatments toward a diagnostic, response-driven, and controllable system. Minimum reporting should include source geometry, electrical characteristics, gas and humidity, specific energy, seed temperature, chemical indicators of reactive species, and seed genotype, moisture, and vigour, together with biological measures of germination speed and uniformity, root growth, electrolyte leakage, redox status, and microbial reduction. Dose–response experiments, high-throughput phenotyping, Bayesian or machine-learning models, cross-lot validation, and multi-environment testing are required to define context-specific optimal windows. Closed-loop control may reduce undertreatment and oxidative injury. Practical value will be established only when laboratory benefits translate into uniform field establishment, seedling health, and stable crop performance, while scalability, cost, and energy use are benchmarked against conventional priming and disinfection methods.