【摘要】 在实验室条件下,比较研究了不同浓度(0.5、1、2、4、8、16mg/L)的氨氮(NH4+-N)对沉水植物黑藻(Hydrilla verticillata)的生理生化影响,测定了黑藻生物量、叶绿素、可溶性糖、蛋白质含量和过氧化物酶(POD)、超氧化物歧化酶(SOD)、谷氨酰氨合成酶(GS)的活性变化。实验结果表明低浓度的氨氮(0.5、1、2mg/L)对轮叶黑藻的生长稍有促进作用,但培养液中氨氮浓度超过4mg/L时,黑藻的相对生长率(R)明显下降,当浓度达到16mg/L时,黑藻在20多天内全部死亡。在低浓度氨氮条件下,黑藻叶绿素和可溶性糖含量随氨氮浓度增加呈上升趋势,当培养液中氨氮浓度超过4mg/L时,叶绿素和可溶性糖含量在第24、32、40天取样时较对照组明显降低。低浓度氨氮处理组(0.5、1、2mg/L)的蛋白质含量先下降后又上升,而对照组的蛋白质含量一直在上升,高浓度氨氮处理组(8、16mg/L)的蛋白质含量则呈明显下降趋势。POD、SOD和GS活性变化趋势基本一致,在高浓度氨氮条件下增加显著,并表现为先上升再下降的格局,在第16天或第24天达到最大值。研究结果提示在富营养化条件下氨氮浓度的升高将影响其生理功能,过高浓度的氨氮对轮叶黑藻是一种逆境胁迫,可抑制其生长甚至导致植物死亡。轮叶黑藻对氨氮浓度变化虽有一定耐性,但耐性会随时间延长而变弱。更多还原

【Abstract】 Physiological effects of NH-4-N concentrations (0.5, 1, 2, 4, 8, 16 mg/L) on Hydrilla verticillata cultured in media were investigated at laboratory conditions. The biomass, chlorophyll contents, soluble sugar contents, protein contents, as well as the activities of superoxide dismutase (SOD), peroxidase (POD) and (GS) of Hydrilla verticillata were analyzed. The results showed that low NH-4-N concentration (0.5, 1, 2 mg/L) could simulate the growth of H. verticillata cultured in media while a NH-4-N concentration of above 4 mg/L would deter the growth of H. verticillata markedly. The plants died within three to four weeks when the concentration of NH-4-N in culture solution reached 16mg/L. The chlorophyll contents and the soluble sugar contents of H. verticillata went up with increase of NH-4-N concentration in low NH-4-N concentration experiments (0.5, 1, 2 mg/L NH-4-N). However, when NH-4-N concentration was above 4 mg/L the contents of chlorophyll and soluble sugar in the 24th d, 32nd d and 40th d sampling decreased noticeably compared to the control experiment. In low NH-4-N concentration (0.5, 1, 2 mg/L) experiments the protein contents of H. verticillata decreased initially and increased later; in control experiments the protein content went up continuously; in high NH-4-N concentration (8, 16 mg/L) experiments the protein content decreased remarkably. Overall, the activities of GS, POD and SOD showed no difference in their changing trends; these enzymatic activities increased noticeably under the condition of high concentration of NH-4-N and showed a pattern of initial increasing and subsequent decreasing with activities peaking in the sixteenth or the twenty-fourth day. The results indicate that the increased NH-4-N concentrations were a stress to H. verticillata under eutrophic condition. The increased NH-4-N concentrations could affect the physiological function of H. verticillata, by restraining its growth, and even resulting in its death. Although H. verticillata could resist the changes in NH-4-N concentrations to some extent, its tolerance gradually weakened with time.更多还原