两种营养状态下pH对轮叶黑藻(Hydrilla verticillata)生长和抗氧化酶活性的影响

Effects of pH on the growth of Hydrilla verticillata and its antioxidative enzyme activities under two nutritional conditions

富营养化湖泊夏季藻类生长旺盛、光合作用强烈,湖水pH值普遍升高,因此相关生态因子变化对沉水植物生长影响的研究成为沉水植物组建和水生态恢复的基础。采用实验室模拟方法,研究了中营养(TN0.60mg·L-1;TP0.04mg·L-1)和富营养(TN4.20mg·L-1;TP0.28mg·L-1)两种状态下不同pH(7,8,9,10)对轮叶黑藻(Hydrilla verticillata)生长、叶绿素含量、抗氧化酶和MDA含量的影响。研究发现,培养21d后,pH10时两种营养状态黑藻生长均受到明显抑制,富营养状态下抑制程度更加显著;pH7和pH8时富营养状态增加植物叶绿素含量,pH10时富营养状态叶绿素含量低于中营养状态。超氧化物岐化酶(SOD)和过氧化物酶(POD)在富营养状态下pH8时活性大幅上升,pH9时出现下降,而中营养状态下在pH9时活性才有所升高;过氧化氢酶(CAT)在两种营养状态下,pH9时活性均显著上升,pH10时在富营养状态下受到明显抑制;富营养状态下在pH7～9时,植物丙二醛(MDA)含量随着pH升高显著上升,并且均显著高于中营养状态,在pH9时与中营养状态差异达到最大。研究表明,pH对轮叶黑藻的影响与营养状态相关,当pH大于9时,两种营养状态下轮叶黑藻均受到一定胁迫,富营养状态下作用更加显著。

Bloom and strong photosynthesis of algae in eutrophic lake has increased the pH of lake water in summer. Accordingly, the research of the effect of changed ecological factors on the growth of submerged plant became the basis for the reestablishment of submerged vegetation and water ecological restoration. The effects of different pH （7, 8, 9 and 1 0） on the growth, chlorophyll con- tents, antioxidative enzymes and malondiadhyde （MDA） contents ofHydrilla verticillata under mesotrophic （TN 0.60 mg·L^-1 and TP 0.04 mg·L^-1） and eutrophic （TN 4.20 mg·L^-1 and TP 0.28 mg·L^-1） conditions were studied by the method of laboratory simulation. The results showed that plant growth was obviously inhibited at pHI 0 after 21 days＇ culture, particularly under eutrophic condition. Chlorophyll contents of Hydrilla verticillata increased under eutrophic condition at pH 7 and pH 8, while the chlorophyll contents under eutrophic condition were lower than that under mesotrophic condition at pH1 0. POD and SOD activities significantly increased at pH 8 and were inhibited at pH 9 under eutrophic condition, while the activities of two enzymes didn＇t increase until pH 9 under mesotrophic condition. CAT activitiy significantly increased at pH 9 under both nutritional conditions but inhibited at pH 1 0 under eutrophic condition. MDA contents increased linearly between pH 7 and 9 under eutrophic condition. The content of MDA was significantly higher under eutrophic condition than that under mesotrophic condition between pH 7 and 9, and the difference reached the maximum at pH 9. The research showed that the influence of pH on Hydrilla verticillata was relevant to the nutritional conditions. Hydrilla verticillata was stressed above pH 9 under both nutritional conditions and the stress was even greater under eutrophic condition.