Optimizing soil water content under elevated temperature and CO2 enhances oilseed rape (Brassica napus) remediation of cadmium-contaminated soils.

Phytoremediation strategies for contaminated sites must consider the complex impacts of environmental changes on plant growth and heavy metal uptake. This study investigated the effects of soil water content (SWC: optimal, reduced and elevated), elevated temperature (25 °C vs. 21 °C), and elevated both temperature and CO2 concentration (25 °C, 800 ppm CO2vs. 21 °C, 400 ppm CO2) on energy crop oilseed rape (Brassica napus L.) efficiency to remediate Cd contaminated soil (1-50 mg kg-1). B. napus showed good tolerance to low and moderate Cd contamination, effectively removing Cd while offering potential for bioenergy production. Elevated temperature, alone or combined with CO2, stimulated plant growth, which partially alleviated Cd toxicity and reduced Cd accumulation in plant tissues. However, the effect depended on soil water content (SWC) and Cd concentrations in the soil. The highest Cd removal efficiency, requiring the fewest plant harvesting cycles under ambient temperature and CO2 conditions, was observed at optimal SWC. Increased temperature alone and combined with elevated CO2 boosted Cd remediation by B. napus and the highest Cd removal rate (up to 211 %) was observed at low and moderate soil Cd contamination (1-10 mg kg-1) under elevated temperature coupled with elevated SWC. Optimizing SWC, temperature, and CO2 is crucial for enhancing phytoremediation by influencing plant growth, metal uptake, and translocation. This research highlights the potential of optimizing SWC under elevated temperature and CO2 conditions to enhance B. napus's efficiency in remediating cadmium-contaminated soils, contributing to sustainable environmental management.