无机氮化合物及pH值对紫背浮萍生长的影响

以紫背浮萍为对象,研究了氨氮、硝酸氮浓度和pH值等对其生长的影响.结果表明,低pH值对紫背浮萍的生长具有抑制作用,紫背浮萍耐受的pH值低限在6左右.高的pH值本身对紫背浮萍生长没有显著影响,但以氨为氮源时,pH值大于7会加剧非离子态氨的解离,从而对紫背浮萍的生长具有明显的抑制作用.紫背浮萍的生长随非离子态氨浓度增加受抑制程度逐渐增加,非离子态氨浓度大于2mg/L时,基本上不能生长.紫背浮萍可以利用硝酸根离子作为氮源,在研究的浓度范围(20～40mg N/L)内硝酸氮对紫背浮萍的生长没有影响.氨氮和硝酸氮浓度的增加可使紫背浮萍鲜叶片的叶绿素含量增加,在相同氮浓度下,氨氮中生长的紫背浮萍的过氧化物酶活性高于硝酸氮中的活性.

Studies on the effect of inorganic nitrogen compounds and pH on the growth of Spriodela polyrrhiza

The effect of the concentrations of ammonia nitrogen and nitrate nitrogen as well as pH value on the growth of Spriodela polyrrhiza was studied. Low pH value had inhibition on the growth of Spriodela polyrrhiza; the low limit of pH value tolerated by Spriodela polyrrhiza was about 6. High pH value itself did not affect markedly the growth of Spriodela polyrrhiza; but under the condition of ammonia as nitrogen source, it could aggravate the disintegration of un-ionised form ammonia in pH value above 7; so that it could inhibite the growth of Spriodela polyrrhiza markedly. The inhibiting degree of growth of Spriodela polyrrhiza increased gradually with the increase of concentration of un-ionised form ammonia; and the growth was impossible basically as the concentration greater than 2mg/L. Nitrate could be utilized as nitrogen source; with its concentration in the concentration range of studies (20~40mg N/L), it would not affect the growth of Spriodela polyrrhiza. The increases of ammonia nitrogen and nitrate nitrogen concentrations could increase the chloropyll content of the fresh leaves of Spriodela polyrrhiza; and under same nitrogen concentration, the peroxidase activity of Spriodela polyrrhiza grown in ammonia nitrogen was higher than that grown in nitrate nitrogen.