Comparative analysis of phytoremediation capabilities of Salvinia molesta under single and combined heavy metal stress (Cr, Ni, Cd): growth, biochemical responses, and metal accumulation.

This research study uses Salvinia molesta to assess its ability to remediate contaminated environments which show single and combined heavy metal contamination from chromium (Cr), nickel (Ni) and cadmium (Cd). The study aimed to evaluate how different metal exposure conditions affected the plants' ability to absorb metals and their growth and biochemical changes. Plants were grown in hydroponic systems using Hoagland's nutrient solution, which included different chromium, nickel and cadmium concentrations that were tested both separately and through binary combinations of chromium + nickel, nickel + cadmium and chromium + cadmium for a period of 60 days. Higher metal concentrations resulted in substantial growth and biomass reduction, which reached its highest level during testing of two metal substances together. The research found that plants accumulated proline while their antioxidant activity showed greater levels of DPPH, metal chelation, reducing power, CAT and SOD. The study found that chlorophyll, protein and carbohydrate levels decreased when metal concentrations increased. Plants absorbed metals in proportion to the metal concentration, with Cr and Ni being absorbed more than Cd. The combination of two metals brought about both positive and negative effects which impacted how plants took up minerals and showed their physiological functions. They were grown in a hydroponic basket and watered with Hoagland's nutrient solution infused with heavy metal salt test solutions. Metal analysis was quantified using an inductively coupled plasma mass spectrometer, while related biochemical parameters were analysed using standard spectrophotometric methods (chlorophyll content, proline accumulation, phenol, flavonoid levels, and antioxidant activity). Statistical analysis was conducted to provide further information on the significant variations between different treatments with respect to the effects of the interactions between metals and their impact on plant physiology. The biochemical study revealed a substantial increase in activity of the antioxidant enzymes under metal stress during defence against oxidative damage. Growth parameters were significantly affected by metal impacts, with a 79% reduction in the highest impacted parameter.