水体的营养水平对苦草(Vallisneria atans)生长的影响

Effects of Nutrient Level on Growth of Vallisneria atans in Water

在室外控制条件下,以太湖梅梁湾水体现状营养水平(ρ(TN)为5 mg/L和ρ(TP)为0.2 mg/L)为依据,研究营养盐含量升高对苦草生长的影响.结果表明:①在满足光补偿点及无种间竞争等的条件下,苦草在营养水平为ρ(TN)>10 mg/L和ρ(TP)>0.4 mg/L的水中也能成活.②随着营养盐含量的升高,苦草生物量的增长率逐渐降低,当水中ρ(TN)达到10 mg/L和ρ(TP)达到0.4 mg/L时,苦草的生物量开始减少;营养盐含量升高对苦草叶片特征的影响不明显,而苦草根状茎的生物量却随着营养盐含量的升高而逐渐减少,当水体营养水平达到ρ(TN)为10 mg/L和ρ(TP)为0.4 mg/L时,除叶片长度外,苦草的其他形态指标值均显著下降.③在梅梁湾水体现状营养水平的基础上,当水中磷含量增加1倍时对苦草生长造成的抑制作用大于氮含量增加1倍时;当二者均增加时,对植物生长造成的抑制作用显著增加.

Based on the current nutrient level （ρ（TN） 5 mg/L and ρ（TP） 0.2 mg/L） in Meiliang Bay of Lake Taihu, the effects of nutrients concentration on the growth of Vallisneria atans were studied in controllable outdoor experiment. Results show that： O Vallisneria atans can grow in those water bodies with nutrient level exceeding ρ（TN） 10 mg/L and ρ（TP） 0.4 mg/L, if the light compensation point can be satisfied and without existence of other macrophytes. 0 The growth rate of Vallisneria atans showed a decreasing response to an increase in nutrient concentration, and the Vallisneria atans biomass began to decrease only when the nutrient levels exceeded ρ（TN） 10 mg/L and ρ（TP） 0.4 mg/L; there were few changes in Vallisneria atans leaves, otherwise, rhizome biomass decreased following the increasing of nutrients, and all morphological date, except leaf length, decreased significantly when nutrients concentration exceeded ρ（TN） 10 mg/L and ρ（TP） 0.4 mg/L. （3） Based on the nutrient level in Meiliang Bay of Lake Taihu, doubling the phosphor content, compared to nitrogen, will much more suppress the macrophytes, and the negative effects will significantly increase when doubling both of them.