Dissertation submitted for the degree of Doctor of Philosophy in the field of knowledge 20 “Agricultural Sciences and Food” (speciality 205 “Forestry”). – Uman National University, Uman, 2026.
The dissertation presents a comprehensive study and scientific substantiation of a technology for the vegetative propagation of blue spruce (Picea pungens f. glauca) under the conditions of the Right-Bank Forest-Steppe of Ukraine. The research analyses the biological features of rhizogenesis in stem cuttings under the influence of modern plant growth regulators of different formulations. Optimal conditions for rooting and subsequent growing-on of planting material in open-ground conditions were identified, and practical recommendations for the use of the obtained plants in landscaping were developed.
The results of three-year experimental studies (2023–2025), aimed at determining the effects of auxin type, concentration, and exposure duration on the rooting of stem cuttings of Picea pungens f. glauca, are presented. It was established that the natural rooting capacity of the species is low, with the control treatment averaging 1.3–1.7 rooted cuttings (4.4–5.6%).
The application of indole-3-butyric acid (IBA) was shown to significantly enhance rhizogenesis efficiency. The highest rooting percentage (28.9%) was obtained at a concentration of 150 mg L⁻¹ with a 6-hour exposure, exceeding the control by more than sixfold. At a concentration of 100 mg L⁻¹, the optimal treatment duration was 12 hours, resulting in a rooting rate of 25.6%, whereas prolonging the treatment to 24 hours led to a decline in performance. It was also established that extended exposure at a high concentration (150 mg L⁻¹ for 24 hours) markedly inhibited rooting, reducing it to 5.6%, which indicates a phytotoxic effect.
A similar pattern was observed for naphthaleneacetic acid (NAA): the highest rooting percentage (24.4%) was achieved at a concentration of 150 mg L⁻¹ with a 6-hour soaking period, whereas extending the exposure to 24 hours reduced the value to the control level (4.4%).
In experiments with commercial formulations, the highest rooting rate was obtained with Rhizopon 0.5 %, averaging 34.4%, while the application of Clonex Purple resulted in 37.8%, representing the maximum among all treatments. At the same time, increasing the concentration of the active substance (Rhizopon 1 %, IBA 5000 mg L⁻¹) led to a decline in rooting efficiency to 11–12%.
It was established that a similar trend was also observed for morphogenetic parameters, including the number and length of roots, as well as shoot elongation. The highest values for these traits were recorded following the application of Clonex Purple. Slightly lower, yet still substantially higher than the control, results were obtained with the powdered formulation Rhizopon 0.5 %. Increasing the concentration of auxins (IBA and NAA up to 5000 mg L⁻¹) led to reduced effectiveness compared with lower concentrations; in such cases, the advantage over the control was negligible or absent.
The obtained results confirm a clear dependence of rooting efficiency on auxin concentration and duration of treatment, and substantiate the use of moderate concentrations combined with short exposure periods as the most effective approach for improving the vegetative propagation of Picea pungens f. glauca.
The technological aspects of growing-on rooted cuttings of Picea pungens f. glauca under open-field conditions were outlined. The timing and methods of transplanting were described, along with the preparatory measures required prior to planting.
Approaches to soil preparation are presented, including the application of organic and mineral fertilisers (compost and nitrophoska), which ensure the formation of a favourable nutrient environment for root system development and plant growth.
The principal agronomic practices for plant maintenance during the growing-on period are identified, in particular irrigation regimes, the use of shading nets, and soil mulching. These measures were shown to support optimal water, temperature, and light conditions.
It was established that the integrated application of these practices ensures successful establishment of rooted cuttings, promotes active growth, and facilitates the formation of high-quality planting stock under open-ground conditions.
The features of the use of Picea pungens f. glauca in landscaping of various types of territories and its role in the formation of ornamental plantings were revealed. The directions of the species application in urban green spaces, parks, squares, private areas, as well as near administrative buildings were analyzed.
Landscape design principles governing the use of blue spruce are discussed, including its combination with coniferous and deciduous species, its role in creating colour contrasts and multi-layered plantings, and its function as a dominant, focal, or background element within compositions.
