Tolerance of <i>Cordia americana</i> plants exposed to excess copper

Abstract

Copper (Cu) is an essential micronutrient for plants; however, it contaminates air, water, and soil in high concentrations. Phytoremediation is an alternative to using plants that are tolerant to excess metals in the soil. The study aimed to assess the tolerance of Cordia americana species to excess Cu using morphological, physiological, and biochemical variables. The plants were grown in a greenhouse under five Cu concentrations (0 (complete nutrient solution), 15, 30, 45, and 60 μM) in the nutrient solution. Twenty trays (16 liters each) were used, with five plants per tray. The morphological variables of the shoot and root system, photosynthetic variables, chlorophyll a fluorescence, photosynthetic pigments, antioxidant enzyme activity, hydrogen peroxide content, and Cu content accumulated in the tissues were evaluated. Root morphology, photosynthetic variables, chlorophyll a fluorescence, and photosynthetic pigments were not negatively affected by adding Cu to the cultivation system. Biochemical analyses demonstrated that the species used defense techniques against excess Cu, accumulating the metal in its root system and preserving the shoot for photosynthesis. The growth in shoots and roots and biomass production were not affected by increasing Cu concentrations. Therefore, the Cordia americana species has the potential to be used in areas contaminated with Cu.