Effects of cadmium stress on seed germination and seedling growth of three species of Salvia

To investigate the remediation potential of Salvia for cadmium (Cd) in soil, three species of Salvia were used as experimental materials to compare the effects of different mass concentrations of Cd²⁺ on seed germination and seedling growth of S. przewalskii, S. substolonifera, and S. plebeia. Additionally, membership function and principal component analyses were employed to comprehensively evaluate the tolerance of these Salvia species to the heavy metal Cd. The results demonstrated that, under 5～20 mg·L⁻¹ Cd²⁺ stress, the germination indexes of S. przewalskii and the control group did not significantly differ (P > 0.05). However, under 50 mg·L⁻¹ Cd²⁺ stress, the germination percentage of S. przewalskii significantly decreased to 63.33%. The germination process of S. substolonifera was expedited, and its germination potential significantly increased under 5～20 mg·L⁻¹ Cd²⁺ stress; After the soil Cd²⁺ concentration was increased to 50 mg·L⁻¹, S. substolonifera seeds merely germinated and lost viability. The germination percentage of S. plebeia was 98.33% under 5 mg·L⁻¹ Cd²⁺ stress; it was considerably inhibited and decreased to 65.0% under 10 mg·L⁻¹ Cd²⁺ stress and it did not germinate at all when the Cd²⁺ concentration reached 20 mg·L⁻¹. The order in which the three Salvia species tolerated Cd was S. przewalskii > S. substolonifera > S. plebeia, according to the principal component and membership function analyses. In conclusion, S. przewalskii can be used as a soil remediation plant in areas with heightened levels of Cd contamination due to its better Cd tolerance.