Abstract: In order to make better use of the submerged macrophyte to treat tailwater from wastewater treatment plant, Myriophyllum spicatum was exposed in tailwater to investigate its physiochemical responses to different concentrations of ammonia for 10 days. The results showed that a low concentration (<3.5 mg·L^-1) of ammonia could facilitate the growth of submerged macrophyte. When the ammonia concentration was more than 3.5 mg·L^-1, declined chlorophyll a and soluble protein contents as well as significantly increased proline content of M. spicatum were observed after 5 d exposure. Additionally, SOD activity of the plant significantly increased, indicating the appearance of oxidative stress, and the prolonged exposure (10 d) impaired the growth of M. spicatum exposed to high ammonia concentration (>3.5 mg·L^-1). The ammonia tolerance threshold of M. spicatum in the tailwater was 3.5 mg·L^-1 as determined in this study. Thus, remarkable attentions should be paid to ammonia concentration when submerged macrophytes were used to purify the tailwater in artificial wetland.

Key words: soybean, heavy material cadmium, transcriptome