Investigating the Effect of Different Working Gases Plasma (Air, Nitrogen, and Argon) on Barley Germination

Abstract This research explores how varying the working gas in a plasma system affects reactive oxygen and nitrogen species (RONS) concentrations and their subsequent impact on seed germination, vegetative and root growth rates, and germination percentages. A non-thermal plasma system with air, nitrogen, and argon gases was employed, activated by a 10kV high-voltage DC device with a 30W power output. Optical emission spectroscopy (OES) was utilized to identify the primary active species generated from different gas feeds. The system operated at a flow rate of 2.5 liters per minute for each gas. Barley seeds were immersed in this activated water. A total of 144 seeds were divided into four groups: three groups soaked in plasma-activated distilled water and one control group soaked in non-activated distilled water. After a 24-hour soaking period, the seeds were planted in four germination plates and kept in a room with normal humidity and temperature, being watered every six hours. Over six days, the seeds were monitored for radical length, plumule length and germination percentage. Results showed clear differences between plasma-activated groups and the control group. The plasma treatment led to increases in germination rate, root length, and vegetative length, with air plasma showing the highest effect (germination: 100%, root length: 4.59 cm, vegetative part: 13.24 cm). This study concludes that plasma-activated water significantly affects the germination process and that plant growth responses vary with different gases used for activation, likely due to changes in RONS concentrations.