Seed dormancy is maintained by abscisic acid (ABA), a plant hormone that blocks germination until environmental conditions are favorable. Gibberellins (GA) antagonize ABA — once GA levels rise relative to ABA, the seed commits to germination and radicle elongation begins.
This hormone balance is regulated at the gene expression level. The key genes:
Reactive oxygen species (ROS) and reactive nitrogen species (RNS) — whether generated by plasma discharge, electric field exposure, or natural stress — interact with the ABA/GA axis by:
The net result is a molecular switch from dormancy maintenance to active germination. This is the same pathway activated by stratification (cold treatment), scarification (seed coat damage), or after-ripening — natural dormancy-breaking processes that all involve controlled ROS production.
Relevance to plasma agriculture: Plasma-activated water (PAW) delivers a cocktail of ROS/RNS (H₂O₂, O₃, NO₂⁻, NO₃⁻, peroxynitrite) directly to the seed surface. These species diffuse into the seed coat and interact with the ABA/GA regulatory machinery, effectively mimicking — and accelerating — natural dormancy release. This explains why PAW is especially effective on aged seeds: their dormancy is biologically locked, and exogenous ROS/RNS provide the chemical trigger their depleted endogenous signaling can no longer generate efficiently.
Note: The ABA/GA mechanism is proposed in the Xiao et al. 2024 PAW study based on existing plant biology literature; gene expression in PAW-treated seeds was not directly measured in that experiment.