Handroanthus heptaphyllus as bioindicator of chromium-contaminated environments

Heavy metals are among the main pollutants contributing to environmental degradation. Among these met-als, we can highlight chromium (Cr) as an extremely toxic element. Thus, it is necessary to identify plant spe-cies capable of resisting this contamination type to reestablish the ecological conditions of the affected environment. Therefore, the aim of this study was to investigate the possibility of using Handroanthus hepta-phyllus in areas contaminated with Cr, based on morpho-physiological and biochemical variables. Seedlings of H. heptaphyllus were grown at five Cr concentrations: 0, 50, 100,150 and 200 mg L-1. Each sampling unit consisted of a pot with five plants. Photosynthetic and morphological variables of the shoot and root system, photosynthetic pigment, lipid peroxidation (MDA), hydrogen peroxide content, as well as guaiacol peroxi-dase (POD) and superoxide dismutase (SOD) enzyme activity were evaluated. Chromium concentrations neg-atively affected variables such as shoot and root dry weight, as well as root volume and diameter. In addition, reductions in photosynthetic rate, stomatal conductance, and transpiration rate were observed. Overall, moderate Cr levels promoted increased SOD and POD activity. The production of reactive oxygen species (ROS) may have contributed to the decrease in dry biomass, due to the negative correlation between H2O2 concentration and dry biomass production at different Cr concentrations. Thus, Cr concentrations were harmful to H. heptaphyllus seedling growth, and thus a sensitive behavior of the species was observed. These results confirm that H. heptaphyllus seedlings can be used as bio-indicator of chromium-contaminated areas. (c) 2023 SAAB. Published by Elsevier B.V. All rights reserved.

Automated summary

This study aimed to investigate the potential use of Handroanthus heptaphyllus in chromium-contaminated areas. The results showed that chromium concentrations negatively affected plant growth and physiological variables, but moderate levels of chromium promoted increased SOD and POD activity. Therefore, H. heptaphyllus seedlings can be used as a bio-indicator of chromium-contaminated areas.