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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.

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Aim. To isolate, identify, and evaluate in vitro the predacious ability of nematophagous fungi strains, to determine their eligibility for mass production under submerged cultivation; to select the most efficient isolates of predacious nematopha- gous fungi as promising producers of the biopreparation to control plant-parasitic nematodes. Methods. Microbiological, microscopical, cultural-morphological, statistical. Results. The screening to determine the presence of predacious nema- tophagous fungi in different soils from different regions has been conducted for the first time in Ukraine. Out of 75 soil samples, isolated in Kyiv, Chernihiv, Dnipropetrovsk, Volyn and Odesa regions, 88 isolates of predacious nematophagous fungi were obtained which belong to 11 genera by their cultural-morphological characteristics: Arthrobotrys oligospo- ra – 39 isolates, A. musiformis – 25, A. conoides – 11, Drechslerella dactyloides – 3, A. artrobotryoides –2, A. superba – 2, A. megalospora – 2, A. sphaeroides –1, A. flagrans – 1, A. amerospora – 1, A. thaumasia – 1. High nematophagous activity in vitro (90–100 % trapping) regarding free-living nematodes (Rhabditis spp). was demonstrated by 4 isolates of A. oligospora, 18 isolates of A. musiformis, 5 isolates of A. conoides, 3 isolates of D. dactyloides, and one isolate of A. megalospora. Among the 47 most active isolates, 4 isolates of predacious fungi formed chlamydospores under submerged cultivation on two types of liquid media – wort medium and corn-molasses medium: A. musiformis-711, A. musiformis-911, A. conoides-90, D. dactyloides-19. It was found that isolate A. musiformis-911 and A. conoides-90 could form conidia in the submerged culture. Further experiments in determining the character of development for two latter isolates in different types of media under submerged cultivation established that the largest number of chlamydo- spores and conidia were formed by the isolates of A. conoides 90 and A. musiformis 911 on potato dextrose medium, 7.6·105 and 6.5·105 spores/ml respectively. In the wort medium, the productivity of spore formation for the isolate of A. conoides 90 was 35 times lower, amounting to 2.2·104 spores/ml, and in peptone-glucose medium – 90 times lower (8.5·103 spores/ml). The isolate of A. musiformis 911 in the wort medium produced 325 times fewer spores (2.0× ×103 spores/ml) than in potato-dextrose medium, while no chlamydospores and conidia were formed in the peptone- glucose medium. More detailed study of the ratio between isolates-producers and different sources of nutrition as the basis for the optimization of liquid media is required. Conclusions. According to the results of determining nematoph- agous activity regarding free-living nematodes, isolated from different soils in Ukraine and evaluating the character of development under submerged cultivation, two isolates of predacious fungi were selected – Arthrobotrys conoides-90 and A. musiformis-911, which are promising producers of a biological preparation eventually to be used in the biocon- trol of plant-parasitic nematodes. Conidia formation of the two isolates in liquid culture under mass production condi- tions was observed for the first time and could also contribute to their suitability for mass production and biocontrol.