Changes in seed germination, hormone content and explant growth induced by pre-sowing cold plasma treatment

Abstract

The aims of study were to evaluate effects of atmospheric cold plasma (CP) irradiation on dynamics of radish (Raphanus sativus) seed germination, to estimate the content of main phytohormones involved in the control of germination, and to compare the development of plant explants derived from control and treated seeds. Freshly harvested radish seeds were treated for different durations (1, 3, 5, 7 and 10 min) with a scalable dielectric barrier discharge CP device. Germination tests in vitro were performed and at the same time methanol extracts of dry seed homogenates were prepared for phytohormone analysis by HPLC. The indices of germination kinetics were determined using Richards plots. The effects on callus and adventitious root formation was assessed by culturing seed-derived R. sativus explants on the nutrient media. CP treatment significantly increased Vi (%) - final germination percentage in all experimental groups of treated seeds and decreased Me (days) - the median germination time, indicating that CP treatments stimulate germination. ABA content was strongly reduced (this change strongly correlated with stimulation of germination), and GA7 content was increased in in all groups of CP-treated seeds. Approximately, three-fold increases in the frequency of adventitious rooting in comparison to control were observed on dissected radish leaf segments developed from 1 min and 10 min CP treated seeds.[...]