总氮浓度对3种沉水植物生长的影响

在1/40 Hoagland营养液的基础上,采用NH4NO3为氮源,设定了2、4、8、16 mg·L-1 4个不同总氮浓度的培养液,以洗净的长江河沙为栽培基质,分别对3种我国湖泊中常见的沉水植物马来眼子菜(Potamogetonmalaianus)、苦草(Vallisneria natans)和黑藻(Hydrilla verticillata)进行了为期45d的水培试验,研究了水体中不同总氮浓度对3种沉水植物分枝数、根长、株高、鲜重等生长指标的影响,以期为富营养化水体中沉水植被的恢复与先锋物种的选择提供科学依据.结果表明,试验结束时不同处理的马来眼子菜的各项生长指标均显著增加,苦草没有产生新的分枝,黑藻的根长没有显著的增加;不同处理的3种沉水植物的鲜重在试验结束时均有显著增加,其增加的顺序表现为马来眼子菜＞苦草＞黑藻的趋势;植物株高和鲜重的净积累随处理浓度的升高而显著增加,根系的净伸长则随处理浓度的升高而显著降低.由于马来眼子菜所有的生长指标均表现出比苦草和黑藻有显著的生长优势,因此,在符合本试验条件的水体沉水植被的恢复过程中可以作为先锋植物.

Responses of three submersed macrophytes to total nitrogen supply

In order to study the responses of submersed macrophytes to different total nitrogen (TN) supplies and provide scientific recommendations for pioneer species to be used in the restoration of an eutrophic lake, three common submersed macrophytes (Hydrilla verticillata, Vallisneria natans and Potamogeton malaianus) distributed in the lakes of China were cultivated for 45 days in 1/40 strength Hoagland nutrient solution at different TN concentrations (added as NH4NO3). TN concentrations tested were 2, 4, 8 and 16 mg·L-1. The results showed that all the plants grew well over the whole range of TN supplied. Tiller number and shoot height were positively correlated to TN concentrations, while root length was negatively correlated. P. malaianus had the largest tiller number, shoot height and root length. In general, the biomass increased with increasing TN concentration, and the order of biomass increase was P. malaianus> V. natans > H. verticillata. Therefore, P. malaianus is an ideal pioneer species in the restoration of eutrophic lakes.