Physiological responses of Leersia hexandra Swart to Cu and Ni Co-contamination: Implications for phytoremediation

Abstract

This study investigates the physiological responses, co-enrichment mechanisms, and rhizospheric environment characteristics of L. hexandra in soils polluted with copper (Cu) and nickel (Ni). The growth of L. hexandra was significantly inhibited (p < 0.05) under combined Cu and Ni stress, particularly at higher Cu concentrations (150 mg·kg⁻¹), leading to stunted growth, yellowing, and wilting. The accumulation of heavy metals was predominantly observed in the roots, with Cu showing a higher accumulation than Ni. Furthermore, heavy metal stress altered the rhizospheric microbial community, reducing the relative abundance of Firmicutes while increasing that of Proteobacteria, Patescibacteria, and Bacteroidota. The secretion of organic acids, particularly malic acid, increased under heavy metal stress, indicating an adaptive mechanism of L. hexandra. These findings enhance our understanding of the adaptation mechanisms of plants to heavy metal co-contamination and provide insights into the development of effective phytoremediation strategies. Future research will focus on field trials and advanced molecular analyses to further unravel the mechanisms of heavy metal tolerance in L. hexandra, enhancing its application in phytoremediation strategies.