倪氏拟多甲藻叶绿素荧光活性对环境因子的响应

采用叶绿素荧光分析技术探讨了温度、pH、光强对水华优势种倪氏拟多甲藻光合活性的影响。结果表明, 倪氏拟多甲藻光系统Ⅱ的量子产量Y(Ⅱ)和最大光化学效率(Fv/Fm)随温度(7.5-20.0℃)升高而显著增加(P0.05), 在低温下电子传递速率未受阻, 细胞在7.5-20.0℃内均有高光合活性; 10.0 ℃下的光合活性随pH增大先升高后降低, 峰值出现在pH 7.3时, 光合活性顺序为: 弱碱性 中性 酸性; 快速叶绿素荧光动力学曲线分析显示pH 7.3下的光合活性为典型OJIP曲线, 其他pH下PSⅡ反应中心、电子受体库受损, 显示该藻适应较窄的pH范围, pH7.0-8.0内是其适宜的条件; 快速光响应曲线显示其半饱和光强Ek为385.52 mol photons/(m2s), 表明其具有高光饱和点, 耐受高光强。研究表明藻细胞光合活性对温度和光强变化有较强适应性, 对pH的变化敏感, 弱碱性条件是其光合作用的适宜条件; 低温时细胞通过环式电子链提高光化学效率, 降低高光强可能带来的光损伤; 弱酸性(pH 5.0)会同时损伤其光系统Ⅰ和光系统Ⅱ, 造成其光化学效率的显著下降;倪氏拟多甲藻在低温和高光强下的独特光合特性使其在春季淡水水体中占据竞争优势, 是其形成水华的内在原因。

THE EFFECTS OF TEMPERATURE,pH AND LIGHT INTENSITY ON CHLOROPHYLL FLUORESCENCE OF PERIDINIOPSIS NIEI,A WATER BLOOM FORMING SPECIES

In this study, we aimed to characterize the photosynthetic activities of Peridiniopsis niei. We applied chlorophyll fluorescence analysis to evaluate the photosynthetic activities at different temperatures, light intensities and pH values. The results showed that both the actual photosynthetic efficiency of photosystem II (Y (II))] and the maximum quantum yield (Fv/Fm) were significantly raised (P0.05) along with the increase in the temperature (7.5-20). The electron transport rate was not interdicted at low temperatures. High photosynthetic activities of the cells were maintained at the temperature 7.5 to 20. At 10 the photosynthetic activities first increased and then decreased along with the increase in the pH value, and the activities reached the maximum at pH 7.3. The order of activities was Alkalescency Neutral Acidity. The rapid chlorophyll fluorescence kinetics curve showed that the reactive center of PSII and the electron acceptor bank were damaged at different pH values except for pH 7.3. These suggested that Peridiniopsis niei might adapt to only a small range of pH values, which could be pH7.0-8.0. The half saturated light intensity (Ek) was 385.5mol photons/(m2s), indicating that Peridiniopsis niei had high tolerance to strong light. Our study suggested that 1) Peridiniopsis niei may tolerate low temperature and high light intensity 800 mol photons/(m2s)], 2) alkalescency could be suitable for the photosynthetic activities, 3) acidity may reduce the photochemical efficiency through the damage of photosystem I and II, 4) the high rate of cyclic electron transport may underlie the high photochemical efficiency and counter the damage caused by the high light. The high tolerance to low temperature and intense light enabled Peridiniopsis niei to be the dominant species, which could be the simplest explanation of Peridiniopsis bloom.