Effects of exogenous calcium (Ca) on tolerance of Allium cepa var. agrogarum L. to cadmium (Cd) stress

Cadmium (Cd) pollution is one of the most extensive and harmful environmental problems worldwide. Calcium (Ca) is an essential macroelement that plays a crucial role in regulating plant growth and development. Allium cepa is well known and commonly used in many laboratories primarily due to its many advantages, such as low cost, short test time, ease of storage and handling, large number of roots, and large cells with excellent chromosome conditions. In the present study, this plant was chosen as the experimental material to investigate whether the application of exogenous Ca can enhance the tolerance of A. cepa var. agrogarum L. to Cd stress. Therefore, supplementing exogenous Ca with an optimal concentration can effectively relieve the phytotoxicity of Cd stress to A. cepa var. agrogarum L. by decreasing excessive Cd accumulation, maintaining high levels of photosynthesis characteristics, and maintaining the balance of water content, photosynthetic pigments, and nutrient elements, among others.