Ecological Systems and Devices Annotation << Back INFLUENCE OF PLANT GROWTH REGULATORS ON THE PROCESSES OF HYDROECOSYSTEMS SELF-CLEANING O.V. Savelev, S.M. Chesnokova, T.A. Trifonova The results of the study of the effect of the drugs "Zircon" and "Epin-extra" – synthetic plant growth regulators (PGR) on the processes of self-purification of hydroecosystems by methods of biotesting and laboratory modeling are presented. As test organisms, Daphnia magna Straus branchial filter crustaceans and a cell culture of the green algae Chlorella vulgaris Beij were used. The effect of PGR on the processes of ammonium nitrogen nitrifi cation was studied by laboratory modeling. The work used PGR solutions in the concentration range of 10–9–10–5 mg/dm3, obtained by sequentially diluting the starting preparations in standing tap water. It was found that the studied drugs in the entire range of these concentrations are toxic to daphnia. The effects of their exposure depended on the nature of the active substance, the duration of cultivation and concentration. The drug "Epinextra" (the active substance is epibrassinolide) turned out to be more toxic for crustaceans, and "Zircon" (the active substance is a mixture of hydroxycinnamic acids) was less dangerous. The studied drugs are capable of accumulating daphnia in organisms. The ability to accumulate in the drug "Epin-extra" is most pronounced. The effect of the drugs "Zircon" and "Epin-extra" on the cell culture of Chlorella vulgaris Beij. it depended on their concentration. The studied drugs inhibited the activity of nitrifying bacteria at all concentrations studied. The accumulation of these RRPs in hydroecosystems can cause a change in the structure of hydrobiocenoses and a violation of self-purification processes. Keywords: plant growth regulators, biotesting, Daphnia magna, Chlorella vulgaris, laboratory modeling, nitrifi cation. DOI: 10.25791/esip.5.2023.1371 Pp. 39-46.