Germination and growth responses of milk thistle (Silybum marianum) to seed priming with selenium and nano-selenium under salinity conditions

Salt stress is a significant factor that impacts on seed germination, establishment, and growth of plants. This study investigated the impact of selenium and nano-selenium seed priming on the germination and growth characteristics of milk thistle under salinity conditions. Consequently, two experiments were arranged separately as a completely randomized factorial design with three replications. In the 1st and 2nd experiment, seeds of milk thistle were subjected to seven priming levels (control (no priming), 5, 10, and 15 mg/L selenium, and 5, 10, and 15 mg/L nano-selenium) and four salinity stress levels (0, 20, 40, and 60 mM NaCl) in laboratory and greenhouse setting, respectively. Salinity and priming treatments showed significantly affected all germination characteristics. Significant effects were detected in GR, MGT, RL, SFW, SDW, and SVI concerning the interaction between salinity and priming. The highest GR, SL, SFW, SDW, and SVI, along with the lowest MGT were recorded at 15 mg/L of nano-selenium across all salinity levels in comparison to non-priming treatments. Salinity and priming treatments significantly affected all plant attributes in pot studies, with the exception of Chl b. The interaction between salinity and priming significantly affected PH, RL, RDW, SDW, RWC, and antioxidant activity characteristics. In both non-salinity and salinity conditions, the 15 mg/L nano-selenium exhibited the most pronounced growth characteristics across all features. Overall, 15 mg/L nano-selenium treatments markedly improved germination and growth characteristics of milk thistle under salinity stress conditions.