Cadmium affects the growth, antioxidant capacity, chlorophyll content, and homeostasis of essential elements in soybean plants

Soybean (Glycine max L.), as an oil and protein crop, has attracted interest for its potential in the reclamation/restoration of barren and contaminated habitats due to its ability to tolerate adverse environments. To investigate the effects of the growth (biomass and plant height), chlorophyll content, antioxidative capacity (peroxidase and superoxide dismutase activities), and homeostasis of essential elements in soybean plants induced by cadmium (Cd), a pot experiment was performed. Soybean seeds were cultivated in six different levels of Cd-contaminated soil (0, 0.25, 0.50, 1.00, 2.50, 5.00, and 10.00 mg kg−1) for 27 days at 60 % humidity and 25–35 °C in a greenhouse with natural light. Soybean seedling growth was stimulated and inhibited at low (≤1.00 mg kg−1) and high (≥2.50 mg kg−1) Cd concentrations, respectively. Essential metal elements (Mg, Fe, and Zn) and chlorophyll contents of leaves were increased and decreased at low and high Cd concentrations, respectively. Exposure to high Cd concentrations interfered with the homeostasis of essential elements in soybean plants. High Cd concentrations reduced antioxidant capacity and chlorophyll content, which inhibited soybean growth. The Cd accumulation level (>100 mg kg−1) in soybean plant organs was unsafe for producing soybean products. However, soybean seedlings appear to tolerate moderate Cd contamination.