Regulating Effect of Sodium Selenite Addition on Seed Germination and Growth of Pepper (Capsicum Annuum L.) Under Mixed Salt Stress

Purpose Mixed salt stress significantly inhibits pepper germination and seedling growth, but it is unclear whether the negative effect can be mitigated by selenium (Se) addition. Methods Four pepper varieties with large differences in salt tolerance were used as materials in this study. Based on the significant stress of mixed salts, the concentration of sodium selenite was set to 0, 5, 10, 20, 40, 80, and 120 mu mol L- 1, respectively. Various parameters related to seed germination, seedling growth and development, as well as internal physiological indicators were measured, and the alleviating effects of sodium selenite on salt stress was comprehensively evaluated by fuzzy membership function method. Results The results showed that with the increase of sodium selenite concentration, the germination rate, relative salt damage mitigation rate, root fresh weight, fresh weight above ground, root length, hypocotyl length, and seedling activity index all showed an initial increase followed by a decrease, while the contents of superoxide anion radical (O-2(-)), malondialdehyde (MDA), proline (Pro) and the activities of catalase (CAT), peroxidase (POD) and superoxide dismutase (SOD) decreased first and then increased. On the whole, the total weighted values of membership function values of each index of the four varieties increased first and then decreased with the increase of sodium selenite concentration. The addition of appropriate concentration of exogenous sodium selenite (10-20 mu mol L- 1) significantly improved seed germination of pepper, meanwhile, it alleviated the effect of salt stress and promoted root and above ground growth by significantly reducing the content of O-2(-) and MDA. Conclusions The appropriate concentration of exogenous Se could promote the growth and development of pepper seedlings and ensure the cultivation of strong seedlings by promoting the early and rapid germination of seeds and reducing the degree of stress.