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

Abstract

Abstract Seeds of rice (Oryza sativa L.) have been treated with cold atmospheric plasma in air both directly in a dielectric barrier discharge and indirectly by gliding arc discharge through plasma activated mist. Comparisons of impacts of the two methods on germination and physiological parameters of rice seeds are presented. Plasma has been found to increase seeds hydrophilization and water uptake through decrease of liquid contact angles on seed’s coat and increase of total surface free energy. FTIR measurements on seed’s coat show increase of OH, lipids, and carbohydrates for indirect plasma exposure more than direct one as compared to untreated samples. Germination and seedling growth parameters investigations also indicate superiority of indirect over direct plasma exposure. During indirect operation despite the lowering of water uptake, the germination is enhanced due to higher nitrate and nitrite values formed in water mist. Plasma also enhances production of substances contributing to osmotic protection of plants against abiotic conditions such as Proline and soluble sugar. A positive correlation was found between proline and ROS in direct and indirect plasma exposure. The accumulated proline in the plants can adapt with the stress of lack of water because of the low content in lipid peroxidation level giving negative correlation. Indirect exposure of rice seeds by plasma activated mist shows enhanced effects on germination and physiological changes of increasing antioxidants substances which in turn increase the tolerance against abiotic stress. Indirect plasma application through water mist may be more practical on large seed numbers than direct one.