模拟水体硝态氮对黄菖蒲生长及其氮吸收的影响

为了对挺水植物在水环境与水生态修复中的应用提供参考依据,选取黄菖蒲(Iris pseudacorus L.)为对象,通过模拟水培实验,对比研究了6种水体硝态氮质量浓度(10.68、23.88、42.22、63.33、82.92、97.13 mg·L~(-1))下,黄菖蒲地上和地下生物量、根冠比、叶绿素含量、氮累计吸收量以及对硝态氮去除效果的差异,以期明确模拟水体硝态氮质量浓度对黄菖蒲生长及其氮吸收能力的影响.结果显示,首先,不同硝态氮质量浓度对黄菖蒲地上部分(茎叶)生长的影响大于地下部分(根);当硝态氮质量浓度为10.68 mg·L~(-1)时,黄菖蒲的根冠比增加;当硝态氮质量浓度为42.22~97.13 mg·L~(-1)时,黄菖蒲的根冠比减少.其次,黄菖蒲适宜生长的硝态氮质量浓度为23.88~63.33 mg·L~(-1);硝态氮质量浓度低于10.68 mg·L-1或高于82.92mg·L-1时,均会对黄菖蒲的叶绿素合成产生抑制作用.再次,黄菖蒲对氮的累积量随硝态氮质量浓度增加而增加,且地下部分对氮的累积能力优于地上部分;6种浓度下,单株黄菖蒲的氮累计吸收量为10.56~75.43 mg,其地下部分依次为地上部分的7.2、2.3、2.5、2.1、1.6以及1.5倍.此外,黄菖蒲对氮的利用效率与硝态氮质量浓度之间成显著的幂函数关系,且地上部分的氮利用效率高于地下部分.最后,黄菖蒲对硝态氮的去除率随硝态氮质量浓度增加而增加,6种浓度下黄菖蒲对硝态氮的去除率介于94.9%和99.3%之间,且水体中硝态氮质量浓度随时间延续呈指数函数降低.结果表明,黄菖蒲对硝态氮有很好的去除效果,但黄菖蒲的生长及其对氮的吸收与去除效率受水体硝态氮质量浓度影响显著,且地上部分较地下部分更为敏感.

Effects of Nitrate in Water on the Growth of Iris pseudacorus L. and Its Adsorption Capacity of Nitrogen in a Simulated Experiment

In order to provide references for the application of emergent plants in the remediation and restoration of aquatic ecosystems, a hydroponic experiment was conducted for Iris pseudacorus L. with different nitrate mass concentrations (i. e., 10.68, 23.88, 42.22, 63.33, 82.92, 97.13 mg·L^-1). The effects of nitrate mass concentration in water on the growth and nitrogen absorption capacity of I. pseudacorus were evaluated by the aboveground biomass, belowground biomass, root-shoot ratio, chlorophyll content, nitrogen uptake, and nitrate removal efficiency of the plants. The following results were obtained from the experiment. 1 The effects of nitrate mass concentration on the aboveground (stems and leaves) growth of the I. pseudacorus were greater than that on the belowground (roots) growth. Compared with the values before the experiment, the root-shoot ratio of the I. pseudacorus increased in the treatment with 10.68 mg·L^-1 of nitrate mass concentration; while the root-shoot ratio decreased in the treatments with 42.22-97.13 mg·L^-1 of nitrate mass concentration. 2 The I. pseudacorus grew better with nitrate mass concentration ranging from 23.88 mg·L^-1 to 63.33 mg·L^-1; and the chlorophyll biosynthesis of the plants was inhibited in the treatments with 10.68, 82.92, and 97.13 mg·L^-1 of nitrate mass concentration. 3 The total nitrogen accumulation of the I. pseudacorus was in range of 10.56-75.43 mg in the experiment, which increased with the increase of nitrate mass concentration; and the accumulation of nitrogen in the belowground parts was 7.2, 2.3, 2.5, 2.1, 1.6, and 1.5 times of that in the aboveground parts, respectively. 4 The nitrogen utilization efficiency of the aboveground parts was higher than that of the belowground parts. 5 The removal rates of nitrate by I. pseudacorus were 94.9%-99.3%, which increased with increasing nitrate mass concentration. The nitrate mass concentration in water decreased with time in exponential function. In conclusion, I. pseudacorus has promising performance in the removal of nitrate in water, but its growth, nitrogen adsorption, and nitrate removal rate were significantly affected by the nitrate mass concentration. Moreover, the response of growth and nitrogen adsorption in aboveground of I. pseudacorus to nitrate mass concentration was more sensitive than that in belowground.