Direct Volume DBD Plasma Treatment of Barley Seeds (Hordeum vulgare): Impact of Surface Functionalization on Germination and Root Development

Abstract

Cold atmospheric plasma (CAP) is an emerging, chemical-free technology with significant potential to enhance crop performance. This study investigates the impact of direct plasma treatment on barley (Hordeum vulgare) seeds using an amplitude-modulated AC dielectric barrier discharge (DBD) in dry synthetic air. By impinging plasma microfilaments directly onto the seed surface, we enabled precise dose estimation and optimization. Plasma microfilaments were generated by amplitude-modulated AC dielectric barrier discharge in dry synthetic air, and the treatment time ranged from 10 seconds to 5 minutes. After treatment, the barley seed surface was analyzed for morphological and chemical changes, as well as for imbibition and germination rates. X-ray photoelectron spectroscopy (XPS) and sessile drop methods revealed a distinct chemical transition from a hydrophobic state, dominated by C-C/C-H bonds, to a polar, oxygen-enriched hydrophilic surface. While these surface modifications accelerated water imbibition, this physical enhancement did not translate into a statistically significant increase in germination speed. This non-monotonic relationship suggests that while Volume DBD effectively tailors seed surface chemistry for improved hydration, the biological triggers for germination may require further optimization of plasma-induced signaling. These findings provide a fundamental framework for developing sustainable dry-priming protocols that minimize water and chemical use in the industrial malting and agricultural sectors.