The control of cyanobacterial blooms by plant growth retardants (ancymidol, paclobutrazol, uniconazole)

The seasonal blooming of cyanobacteria in water bodies creates considerable medical and veterinary problems, because certain species are potential sources of toxins, principally neuro- and hepatotoxins. Much effort has been devoted to prevent them blooming. In this study, axenic cultures of Microcystis aeruginosa and Anabaena sp. were cultivated in medium Z supplemented with growth retardants. Cells were counted under a microscope each week for up to 8 weeks of culture. The growth retardants paclobutrazol, ancymidol and uniconazole greatly reduced the number of living cells, the effect already being striking after 24 hours of culture. Plant growth retardants can be effectively used in control of cyanobacterial blooms.