Comparison of physiological traits and nitrogen and phosphorus removals of nymphaea tetragona and pontederia cordata

Two aquatic plants are hydroponics cultivated in 6 tanks (three parallel tanks for each plant) with same planting density of 20, to investigate physiological traits of plants and main physical and chemical traits of effluents. Nitrogen (N) and phosphorus (P) contents and dimension of plants are measured. Biomass, tillers and roots densities of plants are also measured. Analysis on physiological traits of plants and N and P removals of effluents during the treatment for heavy polluted river water is conducted, another tank without planting for contrast (CK). Results show POD activities of roots, Chla, Chlb and SP contents of leaves between two plants all varied significantly, while CAT activities of roots did not. POD and CAT activities of roots of Nymphaea tetragona exceeds Pontederia cordata by 0.0757 U/(g.min) and 0.084 3 mg/(g.min), while Chla, Chlb and SP contents of leaves of Pontederia cordata exceeded Nymphaea tetragona. by 0.1886 mg/g, 0.0443 mg/g and 24.079 5 mg/g. Roots lengths of Nymphaea tetragona. are longer than Pontederia cordata, while stems and leaves lengths are shorter, and tillers, roots densities, biomass are lower than Pontederia cordata. N and P contents of roots, stems and leaves of Nymphaea tetragona. are lower than Pontederia cordata by decreasing 1.88 g/kg and 0.30 g/kg, 3.07 g/kg and 0.54 g/kg, 4.22 g/kg and 0.59 g/kg. TP and soluble P removals of the tanks are lower than tanks with Pontederia cordata by declining 15.84% and 13.54%, while TN and NH₄⁺-N removals exceeded 13.83% and 15.60%.