Characteristics of growth, nutrient uptake, purification effect of Ipomoea aquatica, Lolium multiflorum, and Sorghum sudanense grown under different nitrogen levels Original Research Article

This study aims to identify the growth, nutrient uptake, and purification efficiency of Ipomoea aquatica, Lolium multiflorum, and Sorghum sudanense under different nitrogen levels. In comparison with NH4+ or NO3− as the sole N source, the relative growth rate (RGR) and biomass of three species culture in the NH4NO3 solution increased significantly (p < 0.05); the maximum uptake capacity (Vmax) of NH4+ was higher than that of NO3− whereas the Km were slightly lower than that of NO3− of three species; the addition of NO3− to the NH4+ solutions stimulated the NH4+ uptake, whereas, the addition of NH4+ to the NO3− solutions suppressed NO3− uptake of three species; L. multiflorum at the studied supply rates of nitrogen exhibited a higher uptake capacity and a lower affinity for ammonium, conforming with adaptation to a high NH4+ nutrient levels. However, the S. sudanense has a competitive advantage over the other two species at high NO3− nutrient levels; the NH4+ and NO3− purification efficiency had obvious changes when High-nitrogen and Low-nitrogen wastewater were treated by three species. These findings would help select a suitable species to remove contamination and improve water quality in constructed wetland treatment systems.