Abstract
Lead toxicity is a serious problem affecting plant structure and water regime. This study investigated the anatomical and physiological responses of Vicia faba L. to lead (Pb) stress, focusing on plant growth in lead-contaminated substrates at concentrations of 0, 500, and 1000 ppm over a 30-day period. Anatomical parameters including the number of vascular bundles (VB), distance between bundles (dVB) (µm), metaxylem diameter (Mxd) (µm), and thickness of the outer wall of epidermal cells (tWEC) (µm) were measured alongside physiological parameters such as RWC, stomatal conductance, and osmotic potential. Lead accumulation in tissues with certain growth parameters were also measured. The findings showed significant sensitivity of metaxylem diameter to Pb stress, especially at 1000 ppm, indicating changes in hydraulic conductivity. Lead stress also increased the thickness of epidermal cell walls at 1000 ppm, showing adaptive structural changes due to lead toxicity. While RWC had minor variations, osmotic potential decreased notably at 1000 ppm Pb, indicating disruptions in water regulation. Stomatal conductance was also affected by Pb stress, highlighting physiological alterations. The study also found significant lead accumulation in plant tissues, indicating the plant's ability to absorb and retain lead under stress. These results contribute to our understanding of the complex responses of Vicia faba L. to lead stress, including a decrease in plant growth, and emphasize the intricate mechanisms involved in plant-metal interactions and their implications for plant health and environmental sustainability