Non-thermal plasma holds great potentials as an efficient, economical, and eco-friendly seed pretreatment method for improving the seed germination and seedling growth, but the mechanisms are still unclear. Therefore, a plant model organism Arabidopsis thaliana was used to investigate the physio-biochemical responses of seeds to non-thermal plasma at different treatment times by measuring the plant growth parameters, redox-related parameters, calcium (Ca²⁺) level and physicochemical modification of seed surface. The results showed that short-time plasma treatment (0.5, 1, and 3 min) promoted seed germination and seedling growth, whereas long-time plasma treatment (5 and 10 min) exhibited inhibitory effects. The level of superoxide anion (O₂^•−) and nitric oxide (NO) and the intensity of infrared absorption of the hydroxyl group were significantly higher in short-time plasma treated Arabidopsis seeds, and the level of hydrogen peroxide (H₂O₂) was remarkably increased in long-time plasma treated seeds, indicating that O₂^•−, ·OH, and NO induced by plasma may contribute to breaking seed dormancy and advancing seed germination in Arabidopsis, while plasma-induced H₂O₂ may inhibit the seed germination. The intensity of hydroxyl group and the contents of H₂O₂, malondialdehyde, and Ca²⁺ in Arabidopsis seedlings were obviously increased with the plasma treatment time. Catalase, superoxide dismutase, and peroxidase activities as well as proline level in short-time treated seedlings were apparently higher than in control. The etching effects of plasma on seed surface were dose-dependent, spanning from slight shrinkages to detached epidermis, which also significantly increased the oxidation degree of seed surface. Therefore, the improved activities of antioxidant systems, moderate ·OH, H₂O₂, and Ca²⁺ accumulation and seed surface modification induced by plasma all contribute to the enhanced seedling growth of Arabidopsis after short-time plasma treatment.

Radiation is widespread in nature, including ultraviolet radiation from the sun, cosmic radiation and radiation emitted by natural radionuclides. Over the years, the increasing industrialization of human beings has brought about more radiation, such as enhanced UV-B radiation due to ground ozone decay, and the emission and contamination of nuclear waste due to the increasing nuclear power plants and radioactive material industry. With additional radiation reaching plants, both negative effects including damage to cell membranes, reduction of photosynthetic rate and premature aging and benefits such as growth promotion and stress resistance enhancement have been observed. ROS (Reactive oxygen species) are reactive oxidants in plant cells, including hydrogen peroxide (H₂O₂), superoxide anions (O₂^•−) and hydroxide anion radicals (·OH), which may stimulate the antioxidant system of plants and act as signaling molecules to regulate downstream reactions. A number of studies have observed the change of ROS in plant cells under radiation, and new technology such as RNA-seq has molecularly revealed the regulation of radiative biological effects by ROS. This review summarized recent progress on the role of ROS in plant response to radiations including UV, ion beam and plasma, and may help to reveal the mechanisms of plant responses to radiation.