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This work purpose was to find the impact of Pistia stratiotes L., 1753 - a new species on the territory of Ukraine, on the vitality of other free-floating hydrophytes so-called pleuston- Salvinia natans (L.) All., 1785, S. laevigatum (Humb. and Bonpl. ex Willd.) Heine, 1968, to determine the degree of stability and competitiveness of these species for resources in natural ecosystems relatively to the undesirable species. To find out the influence of P. stratiotes on other free-floating on the water surface plant species which compete for elements of nutrition among each other, we have investigated changes in the content of photosynthetic pigments in S. laevigatum and S. natans, which were exhibited with P. stratiotes for 14 days. Besides changes in water indices, oxygen content, mineralization and pH, were measured.

Aim. To study the adaptive reactions of common wheat (Triticum aestivum L.) and emmer (T. dicoccum Schrank ex Schübl.) seedlings using the parameters of oxidative homeostasis under polyethylene glycol (PEG)-induced osmotic stress and metal (Fe, Cu, Mn, Zn) mixture nanoparticles treatment. Methods. Biochemical assays: spectrophotometric measurements of the activity of antioxidant enzymes (SOD, CAT), the content of proline and products of lipid peroxidation; mathematical statistics. Results. The state of oxidative homeostasis of common wheat (cv. Favorytka, cv. Trypilska) and emmer (cv. Holikovska) seedlings under PEG-induced osmotic stress conditions was investigated and analyzed. The development of lipid peroxidation processes under stress conditions was observed only in the cv. Trypilska seedlings. It was established that proline content in common wheat seedlings of both cultivars under stress had signifi cant (10 : 1) predominance in roots, while in roots and shoots of emmer seedlings proline content increased equally. SOD activity in the leaves of the studied cultivars under stress conditions was not changed. At the same time, an increase of SOD activity by 30 % under osmotic stress was shown in the roots of common wheat of cv. Favorytka, while it decreased by 25 % in the roots of cv. Trypilska. It was established that CAT activity in the roots of both cultivars of common wheat decreased by 25 and 38 %, respectively, whereas in emmer of cv. Holikovska this parameter increased by 35 % under osmotic stress. Presowing treatment using a colloidal solution of a mixture of biogenic metal nanoparticles contributed to the induction of SOD activity in the roots of cv. Favorytka, CAT activity in the leaves of cv. Trypilska, and CAT activity in the roots and leaves of cv. Holikovska compared to non-treated plants. It should be noted that the treatment of plants with metal nanoparticles promoted the restoration of CAT activity in the roots under osmotic stress conditions to the level of the control plants in both wheat varieties. Conclusions. It was established that osmotic stress provoked the development of oxidative processes and inhibition of the activities of antioxidant enzymes, in particular, SOD and CAT, in the seedling roots of common wheat cultivars. It was shown that emmer wheat seedlings of cv. Holikovska can maintain redox homeostasis and avoid oxidative damage under osmotic stress conditions. It was found that the seedlings of common wheat and emmer demonstrated different strategies of osmotic regulation under osmotic stress, which is confi rmed, in particular, at the level of proline accumulation. It was shown that the application of colloidal solutions of metal nanoparticles induced an antioxidant protection system and reduced the oxidative processes, which are inevitable effects of drought. The obtained results indicate that common wheat cultivars are more susceptible to drought compared to emmer wheat of cv. Holikovska.

Aim. The aim of the investigation was to study the effect of hydrogen peroxide on the activity of antioxidant enzymes, pigments’ content and productivity of winter wheat in order to determine the biochemical mechanisms of induced winter wheat plant resistance during ontogenesis in the fi eld. Methods. The study of physiological and biochemical parameters were carried out on winter wheat varieties of the wooded steppe (Poliska 90) and steppe (Skala) ecotypes at the tillering and fl owering phases. The experimental plants were foliar treated with hydrogen peroxide (Н 2 О 2 ) in concentration of 1∙10 –1 M twice, with a 3-day-interval, while the control ones – with distilled water. Spraying of plants was performed at spring (tillering phase). Lipid peroxidation (LPO) was determined as the formation of a peroxidation end product — malondialdehyde, which content was determined as the extinction of its condensation product with thiobarbituric acid. The activity of superoxide dismutase (SOD) was determined by a method based on the ability of SOD to inhibit nitroblue tetrazolium recovery by superoxide radicals in the light in the presence of ribofl avin and methionine. The activity of catalase was calculated using the extinction coeffi cient of − 39.4 mM –1 cm –1 . Results. It was established that after 24 h of hydrogen peroxide treatment the processes of lipid peroxidation were intensifi ed and antioxidant enzymes’ activity was decreased in two varieties. In the next phase of ontogenesis (fl owering) antioxidant enzymes’ activity increased in both varieties: Poliska 90 and Skala, which suppressed the LPO growth. Conclusion. Treatment of plants with hydrogen peroxide promoted the formation of non-specifi c plant resistance and increased grain productivity of winter wheat varieties investigated.

Вивчено сигнальну дію 6-бензиламінопурину (БаП) на клітини листкового мезофілу пшениці в умовах гіпертермії. Встановлено, що БаП за дії гіпертермії регулює вміст фотосинтетичних пігментів, пероксиду водню, активність антиоксидантних ензимів-супероксиддисмутази, аскорбатпероксидази, каталази. Продемонстрована адитивна дія БаП та гіпертермії на активацію антиоксидантних систем клітин. БаП регулює відновні процеси в клітинах листкового мезофілу пшениці в умовах високотемпературного стресу. к л ю ч о в і с л о в а: 6-бензиламінопурин, гіпертермія, антиоксидантні ензими, хлоропласти, пігменти, пероксид водню, конфокальна мікроскопія, пшениця.