8 Danish Scientific Journal No77, 2023 BIOLOGICAL SCIENCES SYNERGISTIC EFFECT OF SYNTHETIC PLANT GROWTH REGULATORS AND MICROFERTILIZERS ON THE GROWTH OF CANOLA (BRASSICA NAPUS L.) Tsygankova V., Andreev A., Andrusevich Ya., Kopich V., Pilyo S., Klyuchko S., Brovarets V. Department for Chemistry of Bioactive Nitrogen-Containing Heterocyclic Compounds, V.P. Kukhar Insti- tute of Bioorganic Chemistry and Petrochemistry, National Academy of Sciences of Ukraine https://doi.org/10.5281/zenodo.10053315 Abstract Synergistic effect of new plant growth regulators Ivin, Methyur, Kamethur and microfertilizers Rostok Extra and Radix Tim forte plus on the growth of shoots and roots of winter canola (Brassica napus L.) cultivar Sherpa was studied. Auxin IAA served as a standard for studying plant growth regulating activity. The highest rates of growth of shoots and roots of canola plants were obtained when the seeds were treated with plant growth regulators Methyur and Kamethur, or microfertilizers Rostock extra and Radix Tim forte plus, or a complex of plant growth regulators with microfertilizers: Ivin+Rostok extra, Ivin+Radix Tim forte plus, Methyur+Rostok extra, Methyur+Radix Tim forte plus, Kamethur+Rostok extra, Kamethur+Radix Tim forte plus. The plant growth reg- ulating activity of Ivin Methyur, Kamethur and microfertilizers Rostok Extra and Radix Tim forte plus was similar or higher than that of auxin IAA. It was concluded that the synergistic effect of plant growth regulators Ivin, Methyur, Kamethur and microfertilizers Rostok Extra and Radix Tim forte plus on improving the growth of shoots and roots of canola plants is due to their auxin-like effect on the activation of processes of elongation, division and differentiation of plant cells, formation and growth of plant tissues and organs, as well as improvement of meta- bolic processes in plant cells. Keywords: Brassica napus L., IAA, Ivin, Methyur, Kamethur, Rostok Extra, Radix Tim forte plus. Introduction. Improving the growth and increas- ing the yield of an important oil and biofuel crop - can- ola (Brassica napus L.) while reducing the use of envi- ronmentally toxic pesticides is an urgent task of modern agriculture [1]. In recent years, considerable attention has been paid to the development of new environmen- tally friendly plant growth regulators based on syn- thetic low molecular weight heterocyclic compounds, pyridine and pyrimidine derivatives [1 - 4]. The new plant growth regulators based on synthetic compounds, derivatives of N-oxide-2,6-dimethylpyridine (Ivin), 6- methyl-2-mercapto-4-hydroxypyrimidine sodium and potassium salts (Methyur and Kamethur), were devel- oped at the V.P. Kukhar Institute of Bioorganic Chem- istry and Petrochemistry, of the NAS of Ukraine. Our previous studies have shown that the use of these plant growth regulators based on synthetic compounds, pyri- dine and pyrimidine derivatives, separately or in a com- plex with microfertilizers, improves the growth of grains, legumes and industrial crops, increases their productivity and their adaptive properties to stress fac- tors of abiotic and biotic nature [5 - 9]. Thanks to the use of plant growth regulators based on synthetic com- pounds, pyridine and pyrimidine derivatives and their complex with microfertilizers, it will be possible to re- duce the use of environmentally toxic pesticides for plant protection and improve the ecological condition of the entire agricultural system. Based on the data from our previous studies, the purpose of this work is to study the regulatory effect of plant growth regulators Ivin, Methyur, Kamethur, used separately or in a com- bination with Rostock Extra and Radix Tim Forte Plus fertilizers, on the growth of shoots and roots of winter canola (Brassica napus L.) cv. Sherpa. Materials and methods. The regulatory effect of synthetic plant growth regulators Ivin (N-oxide-2,6-di- methylpyridine), Methyur (sodium salt of 6-methyl-2- mercapto-4-hydroxypyrimidine) and Kamethur (potas- sium salt of 6-methyl-2-mercapto-4-hydroxypyrimi- dine), which were used separately or in a complex with microfertilizers Rostok Extra and Radix Tim forte plus on the growth of shoots and roots of winter canola (Brassica napus L.) cv. Sherpa has been studied. The compositions of the microfertilizers Rostok Extra pro- duced by the LLc “Ukrainian Agrarian Resource” com- pany and Radix Tim forte plus produced by the “For- crop” Company (Spain) and recommendations for their practical use are presented in our previously published work [7]. Plant growth regulators Ivin, Methyur and Kamethur were synthesized in the Department for Chemistry of Bioactive Nitrogen-Containing Heterocy- clic Compounds, V.P. Kukhar Institute of Bioorganic Chemistry and Petrochemistry of the National Acad- emy of Sciences of Ukraine. The plant growth regulat- ing activity of the Ivin, Methyur and Kamethur, micro- fertilizers Rostok Extra and Radix Tim forte plus, which were used separately or in a complex, was com- pared with the activity of auxin IAA (1H-Indol-3- yl)acetic acid) manufactured by Sigma-Aldrich, USA (Fig. 1).