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采用实验生态学方法研究了不同质量浓度Hg~(2+)和Pb~(2+)胁迫对脆江蓠(Gracilaria chouae)生长及光合生理的影响。实验设置Hg~(2+)质量浓度为0.01 mg/L、0.025 mg/L、0.05 mg/L、0.1 mg/L、0.25 mg/L和0.5 mg/L,Pb~(2+)质量浓度为0.05 mg/L、0.1 mg/L、0.5 mg/L、1 mg/L、2 mg/L和4 mg/L,以未添加重金属的实验组为对照,持续培养7 d,分别测定不同处理藻体的生长速率、光合放氧速率、光合色素含量、叶绿素荧光和光合碳代谢途径中关键酶活等生理生化指标。结果表明,在Hg~(2+)胁迫下,藻体特定生长率(SGR)显著下降(P<0.05),质量浓度达到0.5 mg/L时藻体出现负增长;光合放氧速率降低35.48%~77.59%;叶绿素a、类胡萝卜素含量显著下降(P<0.05),Hg~(2+)质量浓度高于0.1 mg/L时藻体藻蓝蛋白和藻红蛋白含量显著降低(P<0.05);最大光合效率(F_v/F_m)和实际光合效率(Y(Ⅱ))随着Hg~(2+)浓度增加先降低后升高,0.05 mg/L时出现第二个峰值,丙酮酸磷酸双激酶(PPDK)也出现相似趋势。藻体对Pb~(2+)的敏感程度低于Hg~(2+),Pb~(2+)质量浓度为0.5 mg/L时,光合产氧速率显著下降(P<0.05),质量浓度到达1 mg/L时,藻体SGR和叶绿素a、类胡萝卜素出现显著下降(P<0.05),而叶绿素荧光参数和藻蓝蛋白含量则无显著性差异;Pb~(2+)质量浓度达到4 mg/L时1,5-二磷酸核酮糖羧化酶(RuBiSCO)出现显著下降(P<0.05),PPDK酶活性则显著上升(P<0.05)。实验结果证实:重金属Hg~(2+)和Pb~(2+)胁迫对脆江蓠的生长和光合作用都有不利影响,藻体对Hg~(2+)胁迫的敏感度要高于Pb~(2+),Hg~(2+)质量浓度为0.01 mg/L时,藻体出现胁迫,并随着浓度的增加而加剧,Pb~(2+)质量浓度超过1 mg/L时,藻体胁迫明显。
The effects of different concentrations of Hg 2+ and Pb 2+ on the growth and photosynthetic physiology of Gracilaria chouae were studied using experimental ecology. The concentration of Hg 2+ in the experiment was set as 0.01 mg / L, 0.025 mg / L, 0.05 mg / L, 0.1 mg / L, 0.25 mg / L and 0.5 mg / 0.05, 0.05, 0.1, 0.5, 1 mg / L, 2 mg / L and 4 mg / L respectively. The experimental groups without heavy metals were used as control for 7 days. Body growth rate, photosynthetic rate of oxygen release, photosynthetic pigment content, chlorophyll fluorescence and photosynthetic carbon metabolism pathways such as physiological and biochemical indicators. The results showed that under the stress of Hg 2+, the specific growth rate (SGR) of algae was significantly decreased (P <0.05). When the concentration of 0.5 mg / L was added, the algal biomass was negatively increased; the photosynthetic oxygen evolution rate was reduced by 35.48% (P <0.05). When the concentration of Hg 2+ was higher than 0.1 mg / L, the content of phycocyanin and phycoerythrin decreased significantly (P <0.05) ; The maximum photosynthetic efficiency (F_v / F_m) and actual photosynthetic efficiency (Y (Ⅱ)) firstly decreased and then increased with the increase of Hg 2+ concentration, while the second peak appeared at 0.05 mg / L, A similar trend also appears in kinases (PPDKs). The sensitivity of Pb2 + to algae was lower than that of Hg2 +. When Pb2 + concentration was 0.5 mg / L, the photosynthetic oxygen production rate decreased significantly (P <0.05) At 1 mg / L, the SGR, chlorophyll a and carotenoids decreased significantly (P <0.05), while the chlorophyll fluorescence parameters and phycocyanin did not show significant difference. The Pb 2+ concentration reached At 4 mg / L, RuBiSCO decreased significantly (P <0.05) and PPDK activity increased significantly (P <0.05). The results showed that heavy metal Hg 2+ and Pb 2+ stress had adverse effects on the growth and photosynthesis of Nephelium crassipes, and the sensitivity of alga to Hg 2+ stress was higher than that of Pb When the mass concentration of Pb 2+ was above 1 mg / L, the algae appeared stress when the concentration of Hg 2+ was 0.01 mg / L, Algal stress is obvious.