不同暴露方式下水生植物化感物质抑藻效应的比较研究

Comparative Study on Antialgal Effects of Allelochemicals from Aquatic Plants under Different Exposure Protocols

为研究水生植物释放的化感物质在生态水平上的有效作用模式,选择水生植物释放的壬酸、N-苯基-1-萘胺和咖啡酸等不同类型化感物质,比较高剂量单次暴露与低剂量多次暴露对铜绿微囊藻(Microcystis aeruginosa)生长的影响,探讨化感物质不同投加频次、剂量和光暗条件等对多次暴露抑藻效果的影响。结果显示,3种化感物质以2 h为间隔、分5次、每次添加0.5 mg·L-1的方式暴露时均表现出比以总剂量2.5 mg·L-1单次暴露更强的抑藻效果,在实验的第7天壬酸、N-苯基-1-萘胺和咖啡酸的抑藻率是单次暴露组的1.8、1.1和1.6倍。以1 h间隔、10次暴露的壬酸和N-苯基-1-萘胺,抑制率随着单次添加量的减少而降低,但在单次暴露剂量低至0.1 mg·L-1时两种物质仍能显著抑制铜绿微囊藻的生长,第7天N-苯基-1-萘胺的平均生长抑制率仍可以达到50.25%。壬酸和N-苯基-1-萘胺在铜绿微囊藻生长的黑暗阶段多次暴露比在光照阶段的抑藻效果好,第3天的平均抑制率分别是是光照阶段的2.2和1.3倍。上述结果表明,水生植物释放的化感物质可以通过低剂量多次暴露实现比高剂量单次暴露更强的抑藻效果。因此,加强对化感物质多次暴露方式下抑藻作用的研究将推动自然环境中水生植物化感作用生态机制的进一步揭示,有利于指导水生植物化感作用的理论研究和实践应用。

To explore the effective pathway of how the allelochemicals released by aquatic plants work at ecological levels, three typical allelochemicals including nonanoic acid, N-phenyL^-1-naphthylamine and caffeic acid, from different chemical classes, were selected to compare their inhibition effects at high-dose single exposure and low-dose repeated exposure on the growth of Microcystis aeruginosa. The influences of exposure frequency, dose and light conditions on the repeated exposure effect were examined. Stronger inhibition on cyanobacterial growth was observed in the low-dose （0.5 mg·L^-1） repeated exposure （five times at 2 h interval） group than that in the high-dose （2.5 mg·L^-1） single exposure group. The inhibition ratio of nonanoic acid, N-phenyL^-1-naphthylamine and caffeic acid in the former group was 1.8, 1.1 and 1.6 times that of the latter group on the 7^th day. When nonanoic acid and N-phenyL^-1-naphthylamine were repeatedly exposed 10 times at 1h interval, the cyanobacterial growth inhibition ratio decreased with the reduction of single dose. However, the growth ofM.aeruginosa was significantly inhibited by the two allelochemicals when the single dose was as low as 0.1 mg·L^-1, with an inhibition ratio up to 50.25% by N-phenyL^-1-naphthylamine on the 7^th day. The inhibition effects of nonanoic acid and N-phenyL^-1-naphthylamine when repeatedly added under dark phase were stronger than that under light phase, the cyanobacterial growth inhibition ratio of the former group was 2.2 and 1.3 times that of the latter group on the 3^rd day. All above results indicated that the allelochemicals released by aquatic plants could exert more effective inhibition on the growth ofM.aeruginosa by low-dose repeated exposure than high-dose single exposure. Hence, further study on the antialgal effects of plant allelochemicals through repeated exposure would be helpful for revealing allelopathy mechanism of aquatic plants in natural environments, and guiding their theoretical research and practical application.