Effects Of Nitrate Enrichment In Water On The Growth Of Elodea Nuttallii

Nitrogen is one of the most important elements for the growth of submerged plant. Nitrate can influence the growth of Elodea nuttallii. The experiment of nitrate enrichment in water column on the growth of Elodea nuttallii, including tiller number, branch, height, weight, et al., were conducted. Total nitrogen in the water column were prepared using KNO3 in 2.0,5.0,10.0 mg·L-1 concentrations. Results showed that the wet weight of Elodea at the end of the experiment increased significantly; with the increase of nitrate in the overlying water, the relative growth rates (RGR) of Elodea decreased, that was 17.39±3.45 mg·g·d-1,15.25±1.51 mg·g-1·d-1 and 13.78±0.56 mg-g·d-1 in the three nitrogen concentrations accordingly; the concentrations of nitrate were also decreased the tiller number of Elodea, the tiller number of each plant was 3.34 individuals,2.86 individuals and 2.47 individuals in the three nitrogen concentrations accordingly. The heights of all the Elodea did not increase significantly (p<0.05) during the experiment. Nitrate enrichment increased the total nitrogen concentration in the tissues of Elodea. The biomass of phytoplankton and periphyton in the system did not change significantly in the experiment, which indicated that phytoplankton and periphyton may not significantly affect the growth of Elodea nuttallii.