高铵条件下绿狐尾藻的生理与氮磷吸收特征

为了探讨水生植物绿狐尾藻(Myriophyllum aquaticum)在生态湿地系统对高铵态氮(NH_4~+-N)的耐受及氮(N)、磷(P)吸收能力,试验设置3个高NH_4~+水平(70、210、420 mg·L~(-1))的营养液,对绿狐尾藻培养21 d,研究高浓度NH_4~+对绿狐尾藻生理及N、P吸收特征的影响.结果表明,70 mg·L~(-1)高NH_4~+处理,绿狐尾藻生长健壮,培养21 d后,茎高和生物量分别达到40.56 cm和17.82 g·穴-1;与70 mg·L~(-1)高NH_4~+对照相比,210 mg·L~(-1)高NH_4~+处理下,绿狐尾藻丙二醛含量显著增加,但叶绿素和可溶性糖含量仍较高,说明其受到一定NH_4~+的胁迫,但不影响其正常生长,茎和生物量的生长速率与对照无显著差异.当NH_4~+水平达到420 mg·L~(-1)时,丙二醛含量增加了2倍,茎高和生物量生长速率仅为对照的27.4%和17.9%,植物受到严重胁迫,生长受阻甚至死亡.3种高NH_4~+处理下,绿狐尾藻总N和总P含量的变化范围为30.7~53.4 mg·g~(-1)和3.8~7.7mg·g~(-1),表现出对N、P超高的吸收能力.鉴于绿狐尾藻在高浓度NH_4~+-N中的高耐受性,及很强的N、P吸收能力,绿狐尾藻可作为高铵/氨废水生物处理中理想的湿地生物,将具有良好的应用前景.

Physiological Characteristics and Nitrogen and Phosphorus Uptake of Myriophyllum aquaticum Under High Ammonium Conditions

Ammonium nitrogen (NH₄⁺-N) at high concentrations is toxic to plants. In order to explore the NH₄⁺-N tolerance of Myriophyllum aquaticum (M. aquaticum) and its ability of nitrogen (N) and phosphorus (P) uptake, this study used a nutrient solution with three NH₄⁺-N levels (70, 210, 420 mg·L^-1) to incubate M. aquaticum for 21 d. The characteristics of plant physiology and N and P uptake of M. aquaticum were measured. At NH₄⁺-N of 70 mg·L^-1, M. aquaticum grew healthily, and shoot height and biomass linearly increased with the increase incubation time. Relative shoot height and biomass of M. aquaticum were 40.56 cm and 17.82 g·hole^-1 on day 21, respectively. Compared to the control with 70 mg·L^-1 ammonium, malondialdehyde (MDA) content of M. aquaticum was significantly increased; chlorophyll and soluble sugar contents were also high at NH₄⁺-N of 210 mg·L^-1. M. aquaticum suffered from the NH₄⁺-N stress. However, the stress of 210 mg·L^-1 NH₄⁺-N did not affect its normal growth and there was no significant difference in the relative growth rate of the shoot height and biomass compared with the control. At NH₄⁺-N of 420 mg·L^-1, MDA contents of M. aquaticum doubled and the shoot height and biomass growth rate were only 27.4% and 17.9% of those for 70 mg·L^-1 NH₄⁺-N, indicating that M. aquaticum was subjected to serious stress that caused unhealthy growth or even death. At three NH₄⁺-N levels, the ranges of N and P content of M. aquaticum were 30.7-53.4 mg·g^-1 and 3.8-7.7 mg·g^-1, respectively, which indicated that M. aquaticum had a high uptake capacity of N and P. M. aquaticum is an ideal wetland plant that has a good application prospect for constructed wetlands in biological treatment of high-ammonia wastewater.