不同浓度铵态氮对镉胁迫轮叶黑藻生长及抗氧化酶系统的影响

Effects of different concentration ammonium-N on Hydrilla verticillata antioxidant enzymes under Cd stress

用含有不同浓度NH4+-N(0、0.5、2.0和4.0mg.L-1)和10mg.L-1Cd的1/10Hoagland营养液培养沉水植物轮叶黑藻,研究了氨态氮对Cd胁迫下轮叶黑藻的生长及抗氧化酶系统的影响,探讨富营养化污染水体沉水植物退化机理.结果表明,10mg.L-1Cd对轮叶黑藻能产生明显的胁迫作用,叶绿素合成量明显降低;超氧化物岐化酶(SOD)与过氧化物酶(POD)活性呈先升高后下降的趋势.NH4+-N能加速Cd对植物的胁迫作用,单因子Cd作用3h时SOD明显升高,而Cd和NH4+-N共同作用0.5hSOD就明显升高.Cd与NH4+-N共同作用时,相对于叶绿素和蛋白质,抗氧化酶是早期敏感指标,并且SOD比POD更敏感.本试验条件下,NH4+-N与Cd共同作用2d后,对轮叶黑藻的胁迫作用主要取决于Cd,NH4+-N的作用几乎可以忽略.

In this paper, submersed plant Hydrilla verticillata was cultivated in a 1/10 Hoagland culture medium added with different concentration NH4 ^＋ -N （0, 0.5, 2. 0, 4. 0 mg · L^-1 ） and 10 mg · L^-1 cadmium to study the effects of NH4 ^＋ -N on H. verticillata growth and its antioxidant enzyme system under Cd stress, and approach the degradation mechanism of submersed macrophyte in eutrophic and polluted water bodies. The results showed that under 10 mg · L^-1 Cd stress, the chlorophyll content of H. verticillata decreased obviously, and SOD and POD activities increased first but declined then. NH4 ^＋ -N accelerated the stress effect of Cd. Under 0. 5 h joint stress of Cd and NH4 ^＋ -N, SOD activity increased significantly, while such an increase needed 3 hours under single Cd stress. Relative to chlorophyll and protein, antioxidant enzyme system was an early sensitive index, and SOD was more sensitive than POD. After two days exposure to Cd plus NH4 ^＋ -N, H. verticillata was mainly stressed by Cd, and NH4 ^＋ -N stress could be neglected.