Relationship between cold plasma treatment-induced changes in radish seed germination and phytohormone balance

This study aimed to estimate the dependence of the effects of radish (Raphanus sativus) seed irradiation with atmospheric cold plasma (CP) on physiological seed condition or dormancy status. Seeds were treated for different durations with a scalable dielectric barrier discharge (DBD) device. The relationship between the effect of CP on germination kinetics with changes in the content of phytohormones in seeds stored for different periods of time after harvesting (1, 5, and 7 months) was estimated. CP treatment efficiently stimulated germination only in freshly harvested (not after-ripened seeds), and these changes correlated with a decrease in abscisic acid (ABA) and an increase in gibberellin (GA) content. CP treatment induced a fast decrease in ABA content and ABA/GA ratio in after-ripened seeds (5 months after harvesting) but did not stimulate germination. Primary evidence of direct ABA modification by the reactive compounds from the gaseous phase of CP was obtained.