Sustainable improvement of seeds vigor using dry atmospheric plasma priming: Evidence through coating wettability, water uptake, and plasma reactive chemistry

Lentil seeds have been packed in a dielectric barrier device and exposed for several minutes to a cold atmospheric plasma generated in helium with/without a reactive gas (nitrogen or oxygen). While no impact is evidenced on germination rates (caping nearly at 100% with/without plasma exposure), seeds' vigor is clearly improved with a median germination time decreasing from 1850min (31h) to 1500min (26h), hence representing a time saving of at least 5h. We show that the admixture of nitrogen to helium can further increase this time saving up to 8h. Contrarily, we demonstrate that the addition of molecular oxygen to the helium discharge does not promote seeds' vigor. Whatever the plasma chemistry utilized, these biological effects are accompanied with strong hydrophilization of the seed coating (with a decrease in contact angles from 118 degrees to 25 degrees) as well as increased water absorption (water uptakes measured 8h after imbibition are close to 50% for plasma-treated seeds instead of 37% for seeds from the control group). A follow-up of the seeds over a 45-days aging period shows the sustainability of the plasma-triggered biological effects: whatever the plasma treatment, seeds' vigor remains stable and much higher than for seeds unexposed to plasma. For these reasons, the seed-packed dielectric barrier device supplied with a He-N-2 gas mixture can be considered as a relevant dry atmospheric priming plasma in the same way as those used in routine by seed companies.

Automated summary

Cold atmospheric plasma generated in helium has been shown to improve the vigor of lentil seeds, reducing germination time significantly. The addition of nitrogen to the helium gas mixture further increases this time saving, while the addition of molecular oxygen does not have a positive impact. The plasma treatment also results in increased hydrophilicity of the seed coating and enhanced water absorption, leading to sustained biological effects and higher vigor in the seeds over time.