Seed treatment with cold plasma and electromagnetic field induces changes in red clover root growth dynamics, flavonoid exudation, and activates nodulation

The effects of presowing treatment of red clover seeds with cold plasma (5 and 7 min) and electromagnetic field (10 and 15 min) on plant agronomic performance were studied. Seed treatments stimulated germination and this effect correlated with changes in the balance of seed phytohormones: a decreased amount of abscisic acid and an increased gibberellin/abscisic acid ratio. Experiments performed in rhizoboxes revealed that seed treatments stimulated root growth and root nodulation. Stressor and dose‐specific changes in the amounts of flavonoids important for communication with nitrogen‐fixing strains of rhizobacteria were detected in the root exudates. The results suggest that besides changes in plant's internal processes, the response of plants to seed treatment involves beneficial modulation of plant communication with microorganisms. Stimulation of germination induced by red clover seed treatment with cold plasma and electromagnetic field correlated with a decreased amount of abscisic acid and an increased gibberellin/abscisic acid ratio. Experiments in rhizoboxes revealed stimulated root growth, increased the number of root nodules, and changes in the amounts of flavonoids important for communication with nitrogen‐fixing rhizobacteria in the root exudates.