Recent studies have shown that nanomaterials, including carbon nanotubes, are associated with a wide range of effects on living organisms, from stimulation to toxic effects. Plants are an important object of such research, which is associated with the potential use of carbon nanomaterials in agriculture and environmental protection. At the same time, the specific mechanisms of formation of plant resistance to the effects of carbon nanotubes remain not fully understood, especially in woody plants. Therefore, we studied the effect of aqueous colloids of multi-walled carbon nanotubes (MWCNTs) with an outer diameter of 10–30 nm and a length of about 2 μm at a concentration of 1, 10, 50, and 100 mg/L on morphometric parameters and the level of expression of stress resistance genes in Betula pubescens Ehrh. and B. pendula Roth. plants in greenhouse conditions. The results showed an increase in the length and diameter of the shoot in the studied plants. The dry biomass of the leaf increased by 30%, the stem by 42%, and the root by 49% when using MWCNTs at a concentration of 10 mg/L. The expression of the stress resistance genes DREB2 and PR-10 significantly increased under the influence of 1 mg/L MWCNTs on plants of both species. At the same time, the use of 100 mg/L nanoparticles led to a decrease in the studied parameters in Betula pendula, which may be associated with the negative effect of MWCNTs in high concentrations. The revealed positive effects of low concentrations of MWCNTs on morphometric parameters and stimulation of stress resistance genes by nanotubes open up prospects for their use in woody plant biotechnology.

Impregnation is a common method of protecting wood from external influences. This study proposes the use of spent engine oil as an impregnating composition for modifying birch wood to make it resistant to biological degradation and water. The indicators of water resistance and dimensional stability of wood such as wetting contact angle, thermogravimetric analysis, Fourier transform infrared spectroscopy (FTIR), and biodegradation tests have been determined. It has been found that treatment with spent engine oil significantly increases the dimensional stability (56.8% and 45.7% in tangential and radial directions) and water-resistant indicators of wood. Thermogravimetric analysis has showed that the curves for the impregnated specimens were different from the control group and had two sharp peaks at 302 and 357 °C. However, FTIR indicated that no clear chemical reactions occur between spent engine oil and wood. A study on wood resistance to biological degradation has showed a significant increase in resistance against brown rot (Poria placenta fungi) in the treated specimens, in contrast to the control group. Thus, impregnation of wood with spent engine oil makes it possible to increase wood resistance to water and biological degradation.

This study examined the bioproductivity of two poplar genotypes propagated by single-tree stem cuttings. The experiment compared variants using cuttings of different lengths (10–22 cm) and containers with volumes from 1 to 3 L. It was found that the best growth performance of seedlings in height according to the traditional container technology (70.6 ± 5.5–111.5 ± 5.0 cm) was observed in the intersectional hybrid of poplar ‘E.s.-38’ (genotype 1). The predominance of the genotype factor over the technology of rooting cuttings was established. The fast-growing genotype 1, E.s.-38, had higher productivity and plant height indices, suggesting it as a variety that can allow for the growth of standard planting material in containers in one season. For genotype 1, the length of cuttings was 10–14 cm when the container volume was increased to 3 L, which could increase the number of cuttings from one mother plant by 2–3 times. The revealed correlations between the height of the seedling and the diameter of the increment, as well as the analysis of the proportions of plant organs, showed that biological features of the rooting of stem cuttings depended on the genotype of poplars. The natural type G2 was characterized by the prevalence of root system growth over the growth of other organs; in the case of short cuttings, the proportion of leaves increased in plants to enhance photosynthesis and ensure rhizogenesis.

The article deals with the bioproductivity of 2 poplar genotypes propagated by single-tree stem cuttings. The experiment compared variants using cuttings of different lengths (10-22 cm) and containers with volumes from 1 to 3 litres. The experiment also considered the variant grown using the Pot-in-pot technology. It was found that the best growth performance of seedlings in height according to the traditional container technology (70.6±5.5-111.5±5.0 cm) was observed in the intersectional hybrid of poplar ‘E.s.-38’ (genotype 1). Annual seedlings of black poplar (genotype 2) were inferior in this index (53.7±4.8-68.1±7.8 cm). PiP technology in case of both genotypes showed good results of height gain (genotype 1 - 165±10.3 cm, genotype 2 - 73.3±8.6 cm). The predominance of the factor ‘Genotype’ over the technology of rooting cuttings (selection of the length of the initial material and the volume of the growing container) was established. In terms of total biomass, G1 (54.4 g) on average exceeds G2 (9.9 g) (natural species) (by 5.5 times), which is determined by a reliable difference in height (by 1.74 times), in diameter by 1.7 times. For both genotypes, depending on the cultivation variant, we can distinguish productivity groups based on the total dry weight of plants: high-productive groups: for G1 - 3L18cm; 3L14cm; 2L22cm; PiP, for G2 - PiP; 3L22cm; 3L18cm, low-productive groups: for G1 - 2L10cm; 1L10cm; 1L14cm, for G2 - 3L14cm; 3L10cm; 2L14cm; 2L10cm; 1L14cm; 1L10cm. The fast-growing genotype 1 ʻE.s.-38ʼ has high productivity and plant height indices, which allows it to be recommended as a variety allowing to grow standard planting material in containers in one season. For genotype 1, the length of cuttings can be 10-14 cm when the container volume is increased to 3 litres, which will increase the number of cuttings from one mother plant by 2-3 times. For genotype 1, the use of containers with a volume of 2 or more litres will produce planting material with a height of more than 100 cm and a diameter of 8-10 mm. Planting material of hard-to-cut poplar species and varieties should be grown in containers with the volume of at least 2 litres. The optimum length of cuttings is 22 cm. Application of Pot-in-pot technology will increase the height of containerised seedlings of fast-growing poplar genotypes by 47 %, diameter by 60 %, and in case of hard-to-propagate genotypes it will increase the height by 20 %, diameter by 20.3 %, which agrees with the data of researches obtained in nurseries of different countries.

Wood natural structure can be considered as a suitable matrix for modifying with nanoparticles of various chemical nature. The research aims at obtaining a woodbased nanocomposite by modifying wood with compositions of waste vegetable oil and zinc oxide nanoparticles and studying the properties of this nanocomposite. Silver birch (Betula pendula) wood samples were chosen as study objects. Refined sunflower oil left after cooking was the oil base of the developed impregnating compositions; nanosized zinc oxide powder was the filler and modifier. The sol-gel method providing a narrow range of particle size distribution was used for synthesis of zinc oxide nanoparticles from Zn(NO3)2·6H2O as starting material. Aqueous ammonia solution was used as a precipitant. The synthesized zinc oxide nanoparticles contained no impurities, were mostly spherical and had the size less than 20 nm. The size of zinc oxide agglomerates was no more than 100 nm, allowing them to easily penetrate into the wood material cavities. A stable suspension of synthesized zinc oxide nanopowder in used sunflower oil was prepared and applied for wood modification by hot-and-cold bath treatment. It was found that the use of nanoscale zinc oxide accelerates the drying process of vegetable oil coating, increases the strength of such a coating and its resistance to external influences. The use of developed compositions improves the hydrophobic properties of wood, its moisture and water resistance, as well as reduces swelling in the tangential and radial directions. We have chosen the optimal dosage of nanosized zinc oxide (0.1 %) in compositions based on waste vegetable oil for protective treatment of birch wood. Impregnating compositions on the base of waste vegetable oil are environmentally safe and their use allows recycling food industry wastes.