  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 1850 min (31h)
to 1500 min (26 h), hence representing a time saving of at least 5 hours. We
show that the admixture of nitrogen to helium can further increase this time
saving up to 8 hours. 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{\deg} to 25{\deg}) as well as increased water absorption (water uptakes
measured 8 hours 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 ageing 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 (SP-DBD) supplied with a He-N2 gas
mixture can be considered as a relevant dry atmospheric priming plasma (DAPP)
in the same way as those used in routine by seed companies.
