Phytomanagement capabilities of safflower (Carthamus tinctorius) after morphological examination and cultivation in multi metal-contaminated soil from former mines in Lavrio, Greece.

This study highlights the potential of safflower (Carthamus tinctorius) to achieve robust growth and biodiesel production under extreme heavy metal contamination. A 90-day pot experiment was conducted under greenhouse conditions using multi metal-contaminated soil sourced from former metal mines in Lavrio, Greece, a globally renowned site for its metal extraction history. Treatments included a non-contaminated control, a 1:2 mix of non-contaminated and contaminated soil, a 2:1 mix of the same soils, and a treatment with contaminated soil only. The concentrations of heavy metals in the soil were as high as: Ag (0.44–41.2 mg kg⁻¹), As (7.46–10,886 mg kg⁻¹), Cd (0.56–301.7 mg kg⁻¹), Cu (9.47–1,352 mg kg⁻¹), Zn (62.2–56,834 mg kg⁻¹), Pb (46.1–41,731 mg kg⁻¹), and Sb (0.99–322.33 mg kg⁻¹). Remarkably, safflower did not exhibit significant reductions in biomass or growth across treatments, as evidenced by growth indices such as absolute growth rate and growth ratio. The plant also accumulated significant amounts of metals, surpassing hyperaccumulation thresholds for Zn, Cd, and Pb. Light microscopy examination revealed no notable changes in root morphology or cell structure. Furthermore, negligible amounts of metals were detected in the derived seed oil. These findings demonstrate that safflower is a highly promising candidate for cultivation in heavy metal-contaminated soils, producing substantial biomass under harsh conditions and delivering a safe, biodiesel-compatible end product.