Effects of cold plasma treatment on soybean (Glycine max L. Merr cv. Zhongdou 40) seed germination and seedling growth were studied. Seeds were pre-treated with 0, 60, 80, 100 and 120 W of cold plasma for 15 s. Results showed that plasma treatments had positive effects on seed germination and seedling growth, and treatment of 80 W had the highest stimulatory effect. Germination and vigor indices significantly increased by 14.66% and 63.33%, respectively. Seed's water uptake improved by 14.03%, and apparent contact angle decreased by 26.19%. Characteristics of seedling growth, including shoot length, shoot dry weight, root length and root dry weight, significantly increased by 13.77%, 21.95%, 21.42% and 27.51%, respectively, compared with control. The seed reserve utilization, including weight of the mobilized seed reserve, seed reserve depletion percentage and seed reserve utilization efficiency significantly improved by cold plasma treatment. In addition, soluble sugar and protein contents were 16.51% and 25.08% higher than those of the control. Compared to a 21.95% increase in shoot weight, the root weight increased by 27.51% after treatment, indicating that plasma treatment had a greater stimulatory effect on plant roots. These results indicated that cold plasma treatment might promote the growth even yield of soybean.

Effects of cold plasma treatment on seed germination, seedling growth, antioxidant enzymes, lipid peroxidation levels and osmotic-adjustment products of oilseed rape under drought stress were investigated in a drought-sensitive (Zhongshuang 7) and drought-tolerant cultivar (Zhongshuang 11). Results showed that, under drought stress, cold plasma treatment significantly improved the germination rate by 6.25% in Zhongshuang 7 and 4.44% in Zhongshuang 11. Seedling growth characteristics, including shoot and root dry weights, shoot and root lengths and lateral root number, significantly increased after cold plasma treatment. The apparent contact angle was reduced by 30.38% in Zhongshuang 7 and 16.91% in Zhongshuang 11. Cold plasma treatment markedly raised superoxide dismutase and catalase activities by 17.71% and 16.52% in Zhongshuang 7 and by 13.00% and 13.21% in Zhongshuang 11. Moreover, cold plasma treatment significantly increased the soluble sugar and protein contents, but reduced the malondialdehyde content in seedlings. Our results suggested that cold plasma treatment improved oilseed rape drought tolerance by improving antioxidant enzyme activities, increasing osmotic-adjustment products and reducing lipid peroxidation, especially in the drought-sensitive cultivar (Zhongshuang 7). Thus, cold plasma treatment can be used in an ameliorative way to improve germination and protect oilseed rape seedlings against damage caused by drought stress.

This study investigated the effect of cold plasma seed treatment on tomato bacterial wilt, caused by Ralstonia solanacearum (R. solanacearum), and the regulation of resistance mechanisms. The effect of cold plasma of 80W on seed germination, plant growth, nutrient uptake, disease severity, hydrogen peroxide (H₂O₂) concentration and activities of peroxidase (POD; EC 1.11.1.7), polyphenol oxidase (PPO; EC 1.10.3.2) and phenylalanine ammonia lyase (PAL; EC 4.3.1.5) were examined in tomato plants. Plasma treatment increased tomato resistance to R. solanacearum with an efficacy of 25.0%. Plasma treatment significantly increased both germination and plant growth in comparison with the control treatment, and plasma-treated plants absorbed more calcium and boron than the controls. In addition, H₂O₂ levels in treated plants rose faster and reached a higher peak, at 2.579 µM gFW⁻¹, 140% greater than that of the control. Activities of POD (421.3 U gFW⁻¹), PPO (508.8 U gFW⁻¹) and PAL (707.3 U gFW⁻¹) were also greater in the treated plants than in the controls (103.0 U gFW⁻¹, 166.0 U gFW⁻¹ and 309.4 U gFW⁻¹, respectively). These results suggest that plasma treatment affects the regulation of plant growth, H₂O₂ concentration, and POD, PPO and PAL activity in tomato, resulting in an improved resistance to R. solanacearum. Consequently, cold plasma seed treatment has the potential to control tomato bacterial wilt caused by R. solanacearum.