Growth, Heavy Metal Accumulation, and Translocation in Chamomile (Matricaria recutita L.) and Safflower (Carthamus tinctorius L.) Under Severe Cd and Pb Contamination in an Alkaline Soil

Severe cadmium (Cd) and lead (Pb) contamination can compromise the productive and safe use of agricultural and degraded soils, yet plant tolerance, metal partitioning, and removal efficiency under alkaline soil conditions remain insufficiently resolved. This study aimed to evaluate growth responses, Cd and Pb accumulation, root-to-shoot translocation, and phytoremediation traits in chamomile (Matricaria recutita L.) and safflower (Carthamus tinctorius L.) under severe Cd and Pb contamination in an alkaline soil. A 4-month greenhouse experiment used 120 independent 5-L pots containing alkaline soil amended with 0, 50, or 100 mg Cd kg−1 and 0, 1500, or 3000 mg Pb kg−1. Chamomile accumulated 138.6 mg Cd kg−1 DW in shoots at Cd50, with a Bioconcentration Factor (BCF) value of 3.04 and a Translocation Factor (TF) of 1.56, whereas 100 mg Cd kg−1 caused severe biomass suppression and reduced translocation. Safflower showed significant growth stimulation at Pb1500, with shoot dry and fresh weight increasing by 17% and 44%, respectively, while Pb remained predominantly belowground (TF < 1); growth was strongly inhibited at Pb3000. Aboveground removal remained low, representing approximately 0.18% of the measured post-harvest soil Cd pool for chamomile at Cd50 and 0.008% of the soil Pb pool for safflower at Pb1500. Chamomile therefore warrants repeated-harvest evaluation for Cd phytoextraction, whereas safflower warrants long-term assessment for Pb phytostabilization-oriented management. Field and multi-season studies are needed to verify remediation efficiency, metal mobility, and safe biomass management.