Effect of lead toxicity on seed germination in wild plant species of Southern Kazakhstan

This study evaluates the potential of four wild plant species (Centaurea pseudosquarrosa, Plantago lanceolata, Lamium purpureum, and Poa annua) for phytoremediation of lead-contaminated soils in Southern Kazakhstan, specifically assessing their germination vigor and tolerance to varying lead concentrations. Soil samples were collected from lead-contaminated areas in Southern Kazakhstan's industrial and mining regions. Seeds of the four selected wild plant species were cultivated in laboratory conditions on soils containing different lead (Pb) concentrations ranging from 0.01% to 10%. Germination rates and early growth parameters were systematically measured to determine toxicity thresholds and species-specific responses. Seed germination of Centaurea pseudosquarrosa and Plantago lanceolata decreased significantly with increasing lead concentrations, with a lethal dose determined at 7.0% Pb salt concentration. However, these two perennial species exhibited remarkable resilience during early growth stages compared to the annual species Poa annua and Lamium purpureum. Significant variations in plant responses were observed across all treatments, indicating species-specific tolerance mechanisms to lead toxicity. The study demonstrates differential lead tolerance among the four wild plant species, with perennial species showing greater potential for survival in lead-contaminated environments than annual species. The established toxicity thresholds provide baseline parameters for understanding plant responses to heavy metal stress, particularly in the context of Southern Kazakhstan's contaminated industrial landscapes. These findings serve as a scientific reference for developing phytoremediation strategies specific to lead-contaminated soils in industrial regions. The identified resilient species, particularly Centaurea pseudosquarrosa and Plantago lanceolata, could be candidates for further investigation in field-based phytoremediation applications, offering environmentally sustainable and cost-effective solutions for soil remediation in mining-affected areas of Kazakhstan.