摘要:
为探究陆生植物对水华蓝藻的化感作用，本文采用不同浓度的蟛蜞菊(Wedelia chinensis)水提液对卵孢金孢藻(Chrysosporum ovalisporum)进行了为期6 d的室内培养试验，结果发现：蟛蜞菊水提液对卵孢金孢藻的化感作用总体上呈“低促高抑”；当蟛蜞菊水提液浓度大于6 g·L-1时，将显著降低卵孢金孢藻光合作用有效量子效率(YⅡ)、最大量子产量(Fv/Fm)、叶绿素a(Chl-a)含量和藻细胞生物量(P<0.01)；当浓度大于8 g·L-1时，单位藻细胞内的超氧化物歧化酶(SOD)、谷胱甘肽-S-转移酶(GST)活性显著高于对照组(P<0.05)，表明蓝藻细胞受到较强的胁迫作用；透射电镜观察结果表明：高浓度蟛蜞菊水提液会破坏细胞膜，导致藻细胞内的类囊体、羧基体、气囊等超微结构受损，并最终导致藻细胞溶解、藻丝断裂和死亡。此外，本文利用Logisitic模型研究了蟛蜞菊水提液对卵孢金孢藻的半效应浓度(EC50)，其24 h、48 h、72 h和144 h的EC50分别为：3.78 g·L-1、4.47 g·L-1、4.72 g·L-1和6.55 g·L-1。本研究为中国湖泊蓝藻水华的防治增添了基础数据和新的技术思路。
Abstract:
In order to explore the allelopathic effects of terrestrial plants on cyanobacterial species that cause algal bloom, Chrysosporum ovalisporum was exposed to different concentrations of Wedelia chinensis water extracts during a 6-day incubation. The results showed that low concentration extracts of W. chinensis significantly improved the growth of C. ovalisporum, while the high concentrations extracts showed significantly negative effect on C. ovalisporum. The values of potential maximal photochemical efficiency of PSⅡ (Fv/Fm), effective photochemical quantum yield of PSⅡ (YⅡ) and chlorophyll-a (Chl-a) were significantly reduced by the extracts when its concentrations were greater than 6 g·L-1 (P<0.01). Compared with the control group, the superoxide dismutase (SOD) and gutathione-S-transferase (GST) activity of C. ovalisporum in high concentration W. chinensis extracts treatment group (8 g·L-1) increased significantly (P<0.05), which indicated that C. ovalisporum survive extreme environmental stress. Transmission electron microscope (TEM) pictures showed that ultra-structures of C. ovalisporum cells, such as thylakoid, carboxyl, gas vesicles and cell membranes were destroyed by the extracts of W. chinensis, consequently, resulting in the dissolution, fracture of C. ovalisporum filaments. In addition, the median effect concentration (EC50) of W. chinensis water extracts in 24 h, 48 h, 72 h and 144 h were 3.78 g·L-1, 4.47 g·L-1, 4.72 g·L-1 and 6.55 g·L-1, respectively, estimated by using Logisitic growth model. Our study contributes to the existing knowledge and data of freshwater cyanobacterial bloom, and provides insights for its control and freshwater system restoration infected by cyanobacterial bloom.
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