Assessment of frost and drought resistance in species and cultivars of the genus Ligustrum L. for nursery stock production

The relevance of this study is driven by the need to improve the assessment of plants’ adaptive potential for urban landscaping, particularly in Kyiv, where factors such as water deficiency and temperature fluctuations are critical in selecting species capable of withstanding environmental stress while maintaining ornamental value. This study aimed to investigate the frost and drought resistance of species and cultivars of the genus Ligustrum L., enabling an evaluation of their adaptive capacity for use in urban environments. Physiological methods were employed to assess indicators such as water retention capacity, water deficit, water content, heat resistance, and frost resistance. The findings indicated that Ligustrum vulgare L. and its cultivars exhibit high frost resistance, as evidenced by minimal tissue damage at -25°C, averaging 7.0-13.9 points. Other species demonstrated minor tissue damage at -20°C (on average, less than 2 points), suggesting that this temperature is not critical for them. At -25°C, the overall damage score increased significantly. In particular, Ligustrum ovalifolium Hassk. and its cultivars exhibited scores ranging from 14.2 to 24.8, while Ligustrum japonicum Green Century and Ligustrum ibota Musli recorded scores of 30.7 and 26.3, respectively. These values approach critical thresholds; however, during the growing season, cells and tissues demonstrated the ability to recover. Ligustrum vulgare L., Ligustrum ovalifolium Hassk., and certain cultivars displayed considerable drought resistance, as indicated by relatively minor fluctuations in leaf moisture content. The results also highlight the stable water‑regulating function of these species, along with high heat resistance, particularly at 50°C. Notably, an increase in temperature to 60°C proved critical for all species, leading to partial browning or complete necrosis of leaf blades. The assessment of these parameters facilitates the selection of initial material for the production of resilient nursery stock suited to urban environmental conditions