Influence of the Plasma-Activated Water Process Time on Germination, Growth, and Secondary Metabolite Accumulation in Radish Sprouts (Raphanus sativus L.)

This study investigated the effects of plasma-activated water (PAW) on the germination, growth, and accumulation of secondary metabolites in radish sprouts (Raphanus sativus L.).PAW was generated via corona discharge and applied to seeds for 0 (control), 10, 20, and 30 minutes.As the PAW treatment time increased, significant increases were observed in the cumulative germination, final germination percentage, germination energy, and germination speed.The 30-minute treatment led to the most notable improvements in the germination parameters.However, shoot and root lengths significantly decreased, and the shoot water content was reduced, likely due to osmotic stress induced by elevated electrical conductivity (EC) and hydrogen peroxide (H 2 O 2 ) levels.Despite growth suppression, the 30-minute treatment significantly increased the content and concentration of various glucosinolates (progoitrin, sinigrin, gluconapin, neoglucobrassicin, and 4-methoxyglucobrassicin) and phenolic acids (chlorogenic acid, benzoic acid, epicatechin, and trans-cinnamic acid).These results suggest that the PAW treatment, when applied at an optimal duration, can enhance both seed germination and the accumulation of bioactive compounds in radish sprouts through redox-related signaling pathways.