Heavy metal tolerance and accumulation in the species ( var. and L.): A pot experiment.

This study delves into the heavy metal tolerance and accumulation capabilities of var. () and L. () in a pot experiment, specifically focusing on cadmium (Cd), chromium (Cr) and lead (Pb). Agricultural topsoils were spiked with varying concentrations of these heavy metals (0 mg/kg, 75 mg/kg, 150 mg/kg, 225 mg/kg and 300 mg/kg) for each element. The experiment involved cultivating 15 pots each of and over 60 days. Results indicated that both species experienced delayed germination, with exhibiting a significant drop in germination percentage to 53 % at the highest concentration (300 mg/kg), while showed a tendency for an increased germination percentage of up to 80 % at elevated metal concentrations; however, these differences were not statistically significant. Both and demonstrated a stable decline in growth rate from 0.05 cm/day to 0.04 cm/day with increasing heavy metal concentrations, and the he reduction in relative growth rate was significant at the highest concentration compared to the control. The stress tolerance index revealed a significant decrease in plant heights for , in contrast to the stable performance of , showcasing the tolerance of to toxic conditions. Despite insignificant differences in fresh biomass due to metal treatments, consistently yielded higher biomass, yet it had a lower edible index due to its higher root biomass. Leaf areas increased significantly in both species at higher soil treatments, while root lengths remained unchanged, suggesting their resilience to elevated heavy metal concentrations. Analysis of plant tissues (leaves, stems and roots) using ICP-OES revealed that accumulated the highest Cd concentration (864 mg/kg), whereas accumulated the highest Pb concentration (953 mg/kg) in root parts. Both species significantly accumulated Cr in roots, demonstrating a sequestration mechanism. These findings suggest that both species, particularly, possess strong tolerance and accumulation capabilities for non-essential heavy metals, making them potential hyperaccumulators for green remediation techniques in toxic soil environments. Understanding the molecular mechanisms driving these responses and validating phytoremediation potential in real-world scenarios is essential for developing sustainable soil management practices.