Changes in Chromosome Complement and Germination of Lettuce ( Lactuca sativa L.) Exposed to Heavy Metal Stress

Heavy metals are defined by their high atomic mass. When essential to organisms, metal presence improves plant development; if nonessential, metal presence is toxic. This study aimed to evaluate the biological effects of heavy metals (copper, lead, nickel, aluminum, and cadmium) on Lactuca sativa germination, growth, cytogenotoxicity, and physiology. Seeds of L. sativa were placed in Petri dishes with solutions at concentrations of 50, 100, 250, and 500 μM copper, lead, nickel, aluminum, and cadmium at four replicates of 30 seeds each. Germination percentage, speed index, radicle length, and biomass (fresh and dry) were evaluated. Additionally, lipid peroxidation, proline content, and mitotic index, as chromosome abnormalities, were observed. The studied metals were phytotoxic to Lactuca sativa , reducing morphological parameters. Lettuce physiology was affected by the increase in lipid peroxidation and proline content. The metals were cytotoxic and genotoxic, reducing the mitotic index, and chromosome abnormalities were observed.