Plasma induced long-term growth enhancement of Raphanus sativus L. using combinatorial atmospheric air dielectric barrier discharge plasmas

• Plant growth enhancement due to plasma has been analyzed in combinatorial way.
• Dielectric barrier discharge plasma in air was irradiated to seeds of radish sprout.
• There is little direct correlation between reactive species and growth enhancement.
• Growth enhancement is sustained for 7 days by 180 s plasma irradiation.

Combinatorial analysis has been carried out to investigate the long-term effects of plasma irradiation of radish seeds on the subsequent sprout growth (Raphanus sativus L.) using atmospheric dielectric barrier discharge plasmas in air. The average seedling length was maximized with 180 s of plasma irradiation when the seed was 5 mm from the electrode edge and 3 mm below the electrode. With these parameters the average seedling length was 250% longer than that not irradiated after three days of cultivation. Observation of the seeds using an infrared (IR) camera and scanning electron microscopy revealed that the temperature rise and etching of the seeds during the plasma irradiation have little effect on growth enhancement. The interaction between radicals and seeds for a duration of 180 s leads to the growth enhancement of radish sprouts for 7 days.