Seed germination and seedling physiological characteristics of Celosia argentea under cadmium stress

Celosia argentea is an annual herb belonging to the family Amaranthaceae. It is a cadmium (Cd) hyperaccumulator, with high ornamental value and strong stress resistance. It is an important plant candidate for the remediation of Cd-contaminated soils. To reveal the adaptive characteristics and physiological mechanisms of C. argentea under Cd stress, the effects of different Cd concentrations (0, 50, 100, 200, and 500 μmol·L⁻¹) on seed germination, seedling growth, and physiological characteristics were studied. The results showed that Cd had little effect on seed germination rate and germination potential, but decreased the germination index, vigor index, and biomass. Celosia argentea grew well under Cd stress. With an increase in Cd concentration, the contents of chlorophyll a, chlorophyll b, and carotenoids decreased. With an increase in cadmium concentration, the activities of superoxide dismutase, peroxidase, and catalase, and the content of free proline first increased and then decreased, while the contents of soluble sugar, soluble protein, and malondialdehyde gradually increased. The results suggest that C. argentea exhibits strong cadmium tolerance and can alleviate the toxic effects of cadmium by improving the activity of antioxidant enzymes and regulating the content of osmoregulatory substances in the body.