Comparative Assessment of Lead and Copper Toxicity on Growth Dynamics of Spinacia oleracea L.

Abstract

Soil contamination with heavy metals is a serious environmental problem that negatively affects plant growth, crop productivity, and food safety. This study was conducted to evaluate the growth and stress responses of Spinacia oleracea L. under lead and copper stress conditions. Plants were treated with different concentrations of lead and copper salts at 0, 100, 200, and 300 ppm under controlled conditions. Several growth parameters were measured, including plant height, root and shoot length, number and size of leaves, fresh and dry biomass, and inflorescence development. The results showed that copper exhibited a concentration dependent effect on plant growth. At lower concentrations, copper slightly enhanced growth parameters, likely due to its essential role as a micronutrient involved in enzymatic activities and metabolic processes. However, higher concentrations led to growth inhibition. In contrast, lead exposure caused a significant and consistent reduction in all measured growth parameters, indicating strong phytotoxic effects. Lead toxicity likely interfered with physiological processes such as photosynthesis, nutrient uptake, and water balance, resulting in reduced biomass and overall plant vigor. Statistical analysis confirmed that these effects were significant compared to control treatments. The findings highlight that while copper may support plant growth at optimal levels, lead poses a severe risk even at relatively low concentrations. This study emphasizes the importance of monitoring and managing heavy metal contamination in agricultural soils. Future research should focus on understanding the physiological, biochemical, and molecular mechanisms underlying heavy metal stress tolerance and developing effective strategies to mitigate their adverse effects in crop plants.