The Impact of Lead-contaminated Soil on Eruca sativa Plants

Abstract

Heavy metal contamination is a major environmental concern due to its detrimental effects on soil and water quality as well as human health. This study aimed to evaluate the effects of lead (Pb²⁺) contamination on seed germination, morphological growth, and physiological characteristics of Eruca sativa and to assess its tolerance to Pb²⁺ stress. The experiment was conducted in a private field at the Biology Department, Koya University, Erbil, Kurdistan Region of Iraq, beginning on October 26, 2025. Three Pb²⁺ concentrations (0, 25, and 50 mgkg⁻¹), applied as PbCl₂, were used to treat the soil. The results showed that the soil pollutants with Pb²⁺ significantly reduced seed germination and adversely affected several vegetative growth parameters, including plant height, stem diameter, leaf area and root length compared with the control treatment. In contrast, Pb²⁺ application had no significant effect on the number of leaves, fresh mass of shoot, fresh and dry mass of root, as well as the contents of chlorophyll a, chlorophyll b, and total carotenoids. Lead exposure also significantly altered specific stomatal characteristics, including the stomatal density and width of the abaxial surface and the stomatal width of the adaxial surface. Furthermore, increasing the Pb²⁺ concentration to 50 mgkg⁻¹ reduced the shoot metal tolerance index, indicating decreased tolerance to Pb²⁺ stress. These findings demonstrate that Pb²⁺ contamination negatively affects the germination and growth of E. sativa, while some physiological traits remain relatively unaffected, suggesting differential sensitivity among plant characteristics under Pb²⁺ stress.