Effects of DBD Direct Air Plasma and Gliding Arc Indirect Plasma Activated Mist on Germination, and Physiological Parameters of Rice Seed

Rice seeds ( Oryza sativ a L.) have been treated with cold atmospheric plasma in air both directly in a dielectric barrier discharge and indirectly by gliding arc discharge with plasma activated mist. Comparisons of impacts of the two methods on rice seeds germination and physiological parameters are presented. Plasma has been found to increase seeds hydrophilization and water uptake through decrease of liquid contact angle and increase of total surface free energy of seed’s coat. Germination of treated seeds and their seedling growth parameters are enhanced by plasma application. After 20 min of seeds direct and indirect exposures respectively, germination potential increases by 36.73 and 50.4%, germination rate by 26.0 and 30.0%, and germination index by 25.92 and 36.53%. Also, total shoot length increases by 42.2 and 48.5%, and total root length by 15.93 and 22.42%. Plasma enhances physiological changes by increasing nonenzymatic antioxidants substances which in turn increase the tolerance against abiotic stresses. After 20 min for direct and indirect exposures respectively, free proline increases by 30.0 and 40.0%, total soluble carbohydrates by 49.7 and 54.6%. Also, cellular reactive oxygen species (ROS) increase by 52.0 and 60.0%, and malondialdehyde (MDA) decreases by 68.0 and 88.0%. Indirect exposure of rice seeds by plasma activated mist shows enhanced effects on germination and physiological parameters compared to direct one and could be more practical when applied to large scale seeds plasma treatment.