典型微囊藻毒素对白菜种子发芽的生态毒性

以白菜种子为实验对象,研究了微囊藻毒素（MC-LR和MC-RR）和铜绿微囊藻提取液对白菜种子发芽率、根伸长、芽伸长和生物量的影响,探讨其对白菜种子发芽的生态毒性。结果表明,在实验浓度范围内,MC-LR和MC-RR毒性与白菜种子发芽的发芽率、根伸长抑制率、芽伸长抑制率和生物量抑制率之间存在显著的剂量-效应关系,毒性敏感高低指标为根伸长〉芽伸长〉生物量〉发芽率,MC-LR的毒性大于MC-RR,其根伸长50%抑制率浓度值（IC50）分别为3.32mg·L^-1和12.68mg·L^-1。铜绿微囊藻提取液对白菜种子发芽的生态毒性远高于MC-LR和MC-RR纯品水溶液,是否由于藻液中多种微囊藻毒素共存时产生了毒性协同作用或藻液中其他毒性污染物的存在而引起的,其机理有待进一步研究。

Ecotoxicity of Microcystins to Seed Germination of Chinese Cabbage

The eco-toxicological effects of microcystins（MC-LR and MC-RR）and the extract of Microcystis aeruginosa on the seed germination of Chinese cabbage were investigated.The influence of microcystins on the seed germination rate,inhibition rate of root elongation,shoot elongation and biomass were studied.Results showed that there existed significant dose-effect correlations between the inhibition rate of root elongation（or shoot elongation,or biomass）and concentrations of the tested two microcystins.The IC 50 of MC-LR and MC-RR based on root were 3.32 mg·L^-1 and 12.68 mg·L^-1 respectively,much less than the IC 50 values based on shoot and biomass,which indicated that the root elongation was the most sensitive physiological indicator to the two microcystins,followed by the shoot elongation,biomass and seed germination rate.MC-LR was more toxic than MC-RR.The eco-toxicity of cyanobacteria bloom to seed germination was much higher than the purified microcystins,which was probably the synergy effect of various microcystins or the possible presence of other potentially toxic compounds in the extract of Microcystis aeruginosa.The exact mechanism needs further study.