Abstract: Calcium, an essential element for plants, plays a crucial role in root development, stem and leaf growth, and cell wall synthesis. To investigate the effects of Ca in alleviating Cd-induced seed germination delay and oxidative damage of seedlings, we examined the effects of Ca addition on seed germination, growth parameters, activities of antioxidant enzymes, degree of membrane damage and contents of photosynthetic pigments, and osmoregulation substances in the presence of 250 μmol·L^-1 Cd, with the energy plant Miscanthus sacchariflorus as a research object. Results showed that 250 μmol·L^-1 CdCl₂ exposure increased ROS content and aggravated cellular oxidative damage, resulting in a significant decrease in germination indicators and a significant inhibition of seedling growth. In contrast, addition of Ca increased germination rate, germination potential, germination index, and vitality index of M. sacchariflorus seeds by 1.22, 1.33, 1.32, and 1.96 times as compared to the seeds treated by Cd alone by increasing the activity of lipase and protease. Cd-induced oxidative damage was weakened and the reduction of root growth, fresh weight and photosynthetic pigment contents was mitigated by decreasing Cd uptake, increasing free proline content, and stabilizing membrane integrity, thereby attenuating the activities of SOD, POD, and CAT. The mitigation effects of Ca on the phytotoxicity of Cd were increased initially, and decreased with increasing Ca concentrations. 5 mmol·L^-1 CaCl₂ had the strongest effect in alleviating the phytotoxicity of Cd in M. sacchariflorus. Our results provide scientific evidence in the phytoremediation of Cd-polluted soil by exogenous Ca.

Key words: energy plant, Ca, Cd stress, seed germination characteristics, soil remediation