Cold Atmospheric Plasma-Enabled SiOx Nanocoatings for Surface Energy Modulation and Enhanced Seed Germination

Modern agricultural systems demand higher and more reliable yields under increasing constraints on land, water, and fertilizer inputs. Rapid and uniform seed germination is therefore critical for improving crop establishment and overall yield performance. Although existing strategies, such as ionizing gas treatments, polymer coatings, and nanoparticle-based seed treatments, can enhance water uptake and early vigor, they often suffer from limited stability, processing complexity, or potential seed damage. Here, we introduce a dry, cold atmospheric plasma (CAP)-assisted deposition platform for the conformal SiOx nanocoating of seeds, enabling a hydrophilic, storage-stable surface modification under ambient conditions. The deposition process was systematically optimized to achieve rapid, uniform coating formation directly on the seed surface. As a model system, corn seeds (Zea mays L.) were coated with SiOx nanofilms under optimized conditions. Wettability analysis revealed a ∼4-fold reduction in the static water contact angle for SiOx-coated seeds relative to pristine controls, compared with a ∼2.9-fold reduction for plasma-treated seeds without precursor introduction. Importantly, the SiOx-induced hydrophilicity exhibited superior stability, showing less than 3° contact angle recovery after 21 days of storage, whereas plasma-treated seeds alone displayed ∼50° recovery within 120 h. This stable and enhanced surface hydrophilicity translated into accelerated germination and improved early seedling vigor, resulting in SiOx-coated seeds exhibiting improved total seedling growth immediately after treatment and maintaining an approximately 38% increase compared with pristine controls after storage, demonstrating consistent storage stability. In comparison, the early-germination and seedling-growth advantages of plasma-treated seeds diminished substantially after storage, indicating that CAP-deposited SiOx provides a more persistent and storage-stable functional modification. Collectively, these results establish CAP-deposited SiOx nanocoatings as a scalable, solvent-free nanotechnology platform for stabilizing seed hydrophilicity, accelerating germination, and promoting early seedling growth under agronomically relevant conditions.