Biological mechanisms of a novel hydro-electro hybrid priming recovers potential vigor of onion seeds

Onion (Allium cepa) seeds gradually lose vigor during storage, even under optimal conditions. Some of the loss in vigor is reversible and can be recovered by priming. Electrostatic field priming can instantly increase seed vigor and accelerate germination, though the effects are short-lived. Hydro-priming is most widely used as it does not use chemicals and is a clean process, but requires a long priming time and precise seed moisture control. Here, we investigated the potential of combined hydro-electrostatic hybrid priming on the recovery of vigor in onion seeds. Hydro-electrostatic hybrid priming lead to improved seed vigor recovery. Circular dichroism spectroscopy and electron paramagnetic resonance revealed exposure to an electrostatic field enhanced SOD activity in seeds by changing the secondary structure of the enzyme and led to more efficient free radical scavenging; scanning and transmission microscopy revealed these effects promoted more complete and rapid healing of embryo cell organelles and plasma membranes during the incubation stage of hydro-priming. Hydro-electrostatic hybrid priming has the advantages of greater recovery of potential vigor and a shorter processing time than single hydro-priming, leads to longer lasting effects than single electro-priming, and does not require any chemicals.