A comparative study on the growth and nitrogen and phosphorus uptake characteristics of 15 wetland species

Abstract

The biomass, root morphology and nutrient uptake capacities of 15 species of local wetland plants were investigated in hydroponic culture. The wetland plants were exposed to 38.5 mg·L−1 of NH-N, 132.8 mg·L−1 of NO-N and 10 mg·L−1 of dissolved inorganic P for 28 days. Mean total biomass of the 15 species ranged from 1.2 to 21.6 g plant−1, with above/below ground ratios (AG:BG) in the range 1.7–5.5. Mean NH-N, NO-N uptake rates ranged from 3.7 to 14.3 mg N·day−1 (accounting for 8.0–49.4% of the NH-N supply) and 17.8 to 59.4 mg N·day−1 (17.8–59.6% of the NO-N supply). Mean P uptake rate ranged from 1.71 to 4.61 mg P·day−1 (24.1–61.5% of the P supply). The N and P concentrations in plant tissues ranged from 28.2 to 606.1 mg N·plant−1 and 4.1 to 53.1 mg P·plant−1, with AG:BG ratio in the range 1.7–7.0 and 1.6–4.6, respectively. The accumulation of N and P in plant tissues was both significantly correlated with plant biomass and root surface area. Among the different species, Canna generalis, Typha latifolia, Thalia dealbata and Lythrum salicaria had greater above- and below-ground biomass, larger root surface area, and greater nutrient uptake and storage rates than the other plants. Our results suggest (or indicate) that the selection of plant species suitable for constructed wetlands can be based on plant biomass and root surface area.