We studied growth enhancement of radish sprouts (Raphanus sativusL.) induced by low pressure O₂radio frequency (RF) discharge plasma irradiation. The average length of radish sprouts cultivated for 7 days after O₂plasma irradiation is 30–60% greater than that without irradiation. O₂plasma irradiation does not affect seed germination. The experimental results reveal that oxygen related radicals strongly enhance growth, whereas ions and photons do not.

Oxygen plasma inside a narrow tube using an AC high-voltage glow discharge at low pressure was produced for the sterilization of the inner surface of a tube. A tube having a length of 500 mm and diameter of 4 mm was sterilized by treatment for 10 min.

We have investigated the effects of plasma irradiation on the growth of dry yeast (Saccharomyces cerevisiae) using a scalable atmospheric-pressure dielectric barrier discharge (DBD) device. NO of 380 ppm, NO₂ of 10 ppm and O₃ of 560 ppm were detected 1 mm below the discharges, which were produced by the DBD plasmas. DBD plasma irradiation of 10 to 100 s enhances the growth of yeast in the lag phase, whereas that of 120 and 150 s suppresses the growth. O₃, NO₂, photons, and heat generated by the plasma irradiation are not responsible for the growth enhancement of the dry yeast. Plasma etching has little effect on the growth of dry yeast cells. NO plays a key role in the growth enhancement of dry yeast cells.