Cold atmospheric plasma treatments have been applied on lenses seeds and shoots to improve their germination and vigor rates. Two approaches have been considered: direct plasma exposure and plasma activation of liquids (tap water, demineralized water and liquid fertilizer). A special focus has been drawn on reactive oxygen species generated in the plasma phase but also in plasma activated media to understand their impact on germination process as well as on plants growth.
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.
Tap water, demineralized water and liquid fertilizer have been activated using an atmospheric pressure plasma jet (APPJ) to investigate their benefits for the germination rate and stem elongation rate of lentils from Puy-en-Velay (France). By plasma-activating tap water, we have obtained germination rates as high as 80% (instead of 30% with tap water). Also, higher stem elongation rates and final stem lengths were obtained using activated tap water compared with commercial fertilizer. We show that these rates of germination and stem growth strongly depend on the combination of two radicals generated in the liquids by the plasma: hydrogen peroxide and nitrate. This synergy appears to be a condition for releasing seed dormancy through the endogenous production of NO radicals.
Reactive oxygen and nitrogen species (ROS and RNS) play important roles in various physiological processes (e.g., phagocytosis) and pathological conditions (e.g., cancer). The primary ROS/RNS, viz., hydrogen peroxide, peroxynitrite ion, nitric oxide, and nitrite ion, can be oxidized at different electrode potentials and therefore detected and quantified by electroanalytical techniques. Nanometer-sized electrochemical probes are especially suitable for measuring ROS/RNS in single cells and cellular organelles. In this article, we survey recent advances in localized measurements of ROS/RNS inside single cells and discuss several methodological issues, including optimization of nanoelectrode geometry, precise positioning of an electrochemical probe inside a cell, and interpretation of electroanalytical data.
We wish to transmit messages to and from a hypersonic vehicle around which a plasma sheath has formed. For long distance transmission, the signal carrying these messages must be necessarily low frequency, typically 2 GHz, to which the plasma sheath is opaque. The idea is to use the plasma properties to make the plasma sheath appear transparent.
A nanometer-sized dielectric particle lying on a dielectric substrate is exposed to the flux of low-energy electrons, ion and electron fluxes from a cold plasma and the fluxes from the combination of these two sources with the help of particle-in-cell simulation to investigate the particle lofting phenomenon. The results are of interest for dust mitigation in the semiconductor industry, the lunar exploration, and the explanation of the dust levitation.
T. Dufour
,S. Zhang
,S. Simon
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(2018)
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"Reactive species involved in higher seeds germination and shoots vigor through direct plasma exposure and plasma-activated liquids"
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Thierry Dufour
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