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Nonthermal plasma has been explored as a green technology for improving seed wettability and crop productivity. In this investigation, we demonstrate scalable dielectric barrier discharge (DBD) plasma treatment of rice seeds at atmospheric pressure to elucidate the effect of plasma on seed hydration, hygroscopicity, and moisture content. These properties are associated with seedling quality, nutrition, and shelf-life storage. The floating approach was utilized to evaluate seed wettability for a large-scale seed lot because treated seeds become superhydrophilic and sink immediately into water, whereas nontreated seeds float on the surface. We proved that a hydrophilic surface is necessary to improve water absorption, but the extent of physical etching and chemical functionalization had the greatest impact. After 5 hours of imbibition, the seeds that were treated with plasma for 10 min absorbed ~20% more water than the nontreated seeds. After plasma treatment, seed vigor increased dramatically, as evidenced by the radicle emergence times of ~64 hours for treated and ~69 hours for nontreated seeds. Furthermore, the treated seeds yielded seedlings that were ~10% longer compared to the nontreated seeds on day 14 of germination, even after an artificial aging process. During treatment, the moisture content of the seed was linearly reduced due to an ionic wind with a velocity of ~4.7 m/s, which was generated using a localized nonuniform electric field that was applied around the seed’s surface. DBD plasma can modify seed coatings at the nanoscale level but not the availability of its primary nutrition and hygroscopicity. Although the treated seed absorbed moisture four times faster than the nontreated seed during the first 24 hours of storage in a ~99% RH environment, there was no difference in moisture content subsequently. Thus, plasma treatment combines the advantages of efficient imbibition and vigor enhancement, and is beneficial for long-term seed preservation.

We demonstrate atmospheric corona plasma can modify rice (Oryza sativa L.) seed surface wettability and eliminate attached microorganisms at ambient temperatures, which can enhance germination and extend shelf life. High electric field strength up to 10 5 V/cm at the electrode tips is the critical factor for generating corona discharge plasma and, consequently, providing reactive oxygen and nitrogen species (RONS) via electron-induced impact ionization. We show that the reactive species and ions are primarily responsible for enhanced seed surface wettability via water imbibition (WI) and apparent contact angle (ACA) measurement. A scanning electron microscope was employed to confirm that the cold corona plasma treatment can decontaminate seedborne pathogenic fungi. Sterilized seeds with better surface wettability are more likely to germinate and yield higher quality seedlings. In addition, we demonstrate the potential use of the corona plasma process for seed storage extension and quality retention through accelerated aging germination and decreased moisture content. Germination of treated seed after passing accelerated aging process is approximately 90%, similar to that of unaged and untreated seeds.

The application of atmospheric non-thermal plasmas and nanomaterials for seed technology is relatively new compared to their use in industrial and agricultural sectors. This study aimed to investigate the potential of plasma-activated water (PAW) priming, silver-nanopriming and green silver-nanopriming for seed performance enhancement in maize. The experiment was carried out using two lots of maize seeds with a one-year difference in age. Seed treatment procedures were priming with PAW formular 1 (PAW1), with silver nanoparticles (AgNPs) using PAW formular 1 (PAW1SNP), with green-AgNPs using PAW formular 1 (PAW1GSNP), with PAW formular 2 (PAW2), with AgNPs using PAW formular 2 (PAW2SNP), with green-AgNPs using PAW formular 2 (PAW2GSNP) and hydropriming with deionised water; untreated seeds were used as the control. Results showed that the best protocol for enhancing seed vigour and germination performance of maize was PAW2. Priming with PAWs, PAW1 or PAW2, has the potential to enhance the physiological quality of maize seeds, particularly new seeds. The limitations of PAW1SNP, PAW1GSNP, PAW2SNP and PAW2GSNP in seed enhancement and storability after priming treatments are discussed.