Effect of LF-microwave hybrid plasma treatment on radish seed germination and sprout growth

Abstract

Abstract The atmospheric pressure non-thermal plasma generated by low-frequency (LF)-microwave hybrid discharge has been employed to investigate the effects of plasma treatment on the germination and growth of radish (Raphanus sativus L.) sprout seeds. The plasma generated with admixture discharge gas of Ar-O2 was adopted for the irradiation of seeds. Scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX) analyses were performed to elucidate the physical and chemical state changes of seed surfaces after plasma treatment. The reactive species produced in the plasma were investigated using optical emission spectroscopy (OES) and chemical indicator (CI). The results demonstrate that higher reactive oxygen species were generated from the LF-microwave hybrid plasma compared to conventional LF plasma jet. Moreover, the higher germination percentage and shorter germination time were obtained with the LF-microwave hybrid plasma compared to LF plasma jet and control group. It is considered that reactive species produced in the LF-microwave hybrid plasma are related to the germination time of the radish sprout seed.