【作者】 张兵之；

【导师】 吴振斌；

【作者基本信息】 中国科学院研究生院（水生生物研究所） ， 环境科学， 2007， 博士

【摘要】 化感作用是水生植物与藻类竞争的重要手段。化学生态学的观点认为,化感作用仅存在于外来植物与本地物种之间。本论文以水鳖科的外来植物伊乐藻对本地分离的铜绿微囊藻的化感作用为研究对象,同时以苦草对铜绿微囊藻的化感作用为参照,采用在不同规模下共培养和植物种植水培养铜绿微囊藻的方法实验证明了伊乐藻对本地分离的铜绿微囊藻株系(FACHB905)有明显的抑制作用,而苦草则不具有明显的抑藻作用,并成功地从伊乐藻中分离得到几种甾酮类化感物质。对伊乐藻中化感物质分泌的量与其所处生长环境之间的关系作了定性说明,且对如何利用伊乐藻的化感现象应用于富营养化湖泊的治理与生态修复提出了建议。具体结论如下:1.伊乐藻与铜绿微囊藻(FACHB905)的共培养实验表明,伊乐藻对铜绿微囊藻存在明显的抑制作用,对于8 L铜绿微囊藻溶液当起始浓度为105个/mL时,在10天的实验周期内对藻的抑制达到半数致死量时所需的伊乐藻为3g(鲜重);对于400 mL铜绿微囊藻溶液当起始浓度为105个/mL时,在10天的实验周期内对藻的抑制达到半数致死量时所需的伊乐藻为0.2g(鲜重),即伊乐藻对铜绿微囊藻的化感抑制作用在一定范围内可获得良好的重现;2.不同营养和光强下培养的苦草其种植水对铜绿微囊藻的抑制实验表明:苦草与铜绿微囊藻(FACHB905)之间不存在明显的化感作用,这也符合Alastair(2003)关于化感作用仅存在于外来植物与本地物种之间的观点;3.伊乐藻中的化感物质不是以挥发态的形式释放到环境中去的;4.以柱层析、薄层层析、气相色谱质谱联用、液相色谱质谱联用、核磁共振等手段首次从伊乐藻体内成功分离并鉴定出化感物质豆甾-4-烯-3,6-二酮(分子式为C29H46O2、分子量为426)及其同系物(分子式为C29H46O2、分子量为412)和豆甾-4,22-二烯-3-酮,4-甲基-(分子式为C30H49O、分子量为424)。其中豆甾-4-烯-3,6-二酮为伊乐藻中主要的化感物质,在干粉中的含量约为4 ppm,以96孔板法作为活性检测方法时其活性效应在6.5mg/L时达到48%。5.不同环境下培养的伊乐藻其种植水对铜绿微囊藻的抑制情况表明,伊乐藻分泌化感物质的量与其所处的生境有关,当其处于逆境中时,如受到光限制或者营养限制时分泌化感物质的量会增多。因而利用植物化感控制富营养化湖泊中藻类过渡繁殖时,要遵循先降低营养盐水平后利用植物化感的原则,即利用植物化感控藻是一个长期、缓慢的过程。更多还原

【Abstract】 The release of allelochemicals was an important trait developed by macrophytes against planktonic algae. It was believed that allelopathy existed only between foreign plants and native life-forms from the chemical ecological point of view. The allelopathical effects of Eloeda nuttallii (Hydrocharitaceae), which was one of the typical foreign plants, on Mycrocystis aeruginosa (FACHB905),a local isolated species, were studied in this paper. In parallel, researches to identify the allelopathical effects of Vallisneria spiralis on M. aeruginosa were conducted. The experiments were performed in co-existing systems under different scale, together with cultivating M. aeruginosa in the liquor cultured with plants. The results showed that E. nuttallii could effectively inhibit the growth of M. aeruginosa in laboratory, while V. spiralis did not have obvious allelopathical effect on M. aeruginosa. The allelochemicals stigmasta-4, 22-dien-3-one, 4-methyl-, stigmast-4-en-3, 6-dione and its homolog were separated, identified and quantified from E. nuttallii. The relationship between the amount of allelochemicals excreted from E. nuttallii and the right living environment was demonstrated qualitatively. Some comments on how to use the allelopathical effects of E. nuttallii to improve the environment quality were suggested in conclusion. The results were summarized as followed:1. The co-existing test of E. nuttallii and M. aeruginosa (FACHB905) showed that E. nuttallii could effectively inhibit the growth of M. aeruginosa. At the end of the 10-day period, the EC50 was 3.0 g (fresh weight) of E. nuttallii for 8 L M. aeruginosa liquor with the initial concentration of 105 cell / mL. As for 400 mL M. aeruginosa liquor, the EC50 was 0.2 g (fresh weight) of E. nuttallii. The results indicated that the allelopathical effect between E. nuttallii and (FACHB905) was repeatable in a certain range.2. Under different nutrient levels and the luminous intensity, the liquor cultured with V. spiralis have no obvious allelopathical effects on M. aeruginosa. The result was consistent with the opinion of Alastair (2003) who proposed that allelopathy existed only between foreign plants and native life-forms.3. The allelochemicals excreted to the surrounding water from E. nuttallii in non-volatile status.4. Stigmast -4-en-3, 6-dione (molecular formula was C29H46O2, molecular weight was 426), its homolog (MF was C28H42O2, MW was 412) and stigmasta-4, 22-dien-3-one, 4-methyl- (MF was C30H49O, MW was 424) as allelochemicals from E. nuttallii were successfully separated and identified by thin-layer chromatography (TLC), gas chromatography-mass spectrometer (GC-MS), liquid chromatography-mass spectrometer (LC-MS) and nuclear magnetic resonance (NMR) for the first time. Stigmast -4-en-3, 6-dione was the main allelochemical extracted from E. nuttallii. The concentration could reach 4 ppm in dry powder. The inhibition rate was 48% with 96-well plate method.5. Under different environmental conditions, inhibitory effects of the liquor cultured with E. nuttallii on M. aeruginosa indicated that the amount of allelochemicals excreted from E. nuttallii was regulated by the surroundings. Under stress, e.g. restricted light or limited nutrients, the allelochemicals excreted from E. nuttallii would increase in amount. Therefore, it is essential to decrease the eutrophic level first and foremost, then make use of phyto-allelopathy against excess reproduction of algae in eutrophic lakes. It would be a long-term and slow process to control algae by phyto-allelopathy.更多还原