Comparative Study on Nitrogen and Phosphorus Removal Efficiency and Rhizosphere Microbial Mechanisms of Six Wetland Plants in Eutrophic Water

To address the limited understanding of interspecific differences in eutrophic-water remediation, six representative wetland plants—Myriophyllum spicatum, Oenanthe javanica, Zizania latifolia, Ipomoea aquatica, Iris pseudacorus, and Typha orientalis—were evaluated in a unified hydroponic system. The removal efficiencies of total nitrogen (TN), total phosphorus (TP), and ammonium nitrogen (NH4+-N) were compared together with plant biomass accumulation and root-associated and fepiphytic microbial community characteristics. The results showed marked interspecific differences in growth and pollutant removal, with the M. spicatum treatment exhibiting the highest overall purification performance, achieving removal rates of 83.3% for NH4+-N, 87.3% for TN, and 78.6% for TP after 42 days. Community-composition analysis suggested that the superior purification performance of M. spicatum was associated with a greater relative abundance of Proteobacteria and putative nitrogen- and phosphorus-cycling bacterial groups. By integrating a plant-free control with a side-by-side comparison of six wetland plants under identical hydroponic conditions, this study establishes a comparative framework linking nutrient removal to plant growth and microbial community assembly. Overall, M. spicatum was identified as the most promising species, providing new insight for wetland-plant selection and eutrophic-water remediation.