Variation in frost resistance of ten poplar clones tested in eastern Ukraine

Assessing frost tolerance of hybrid poplar clones in the temperate zone is a key factor to select genotypes used for plantation forestry to intensify wood production and to strengthen forests’ adaptability to extreme weather conditions. This study aimed to evaluate frost resistance of ten poplar clones, aged 7 years, in eastern part of Ukraine. We analyzed frost resistance by comparing the average tissue damage indices of control plants with those exposed to frost temperatures of –25 °C and –30 °C. Cluster analysis further classified the clones into four distinct groups based on their frost resistance potential. Clones, which have been cultivated or intercrossed in Ukraine since the 1960s, are more resistant to frost due to the acclimatization of their parental individuals. Clones ‘Gulliver’ (P. deltoides), ‘Lvivska’ (P. × euramericana cv. ‘Regenerata’ × P. trichocarpa), and ‘Nocturne’ (P. trichocarpa × P. lasiocarpa) are characterized by the highest frost resistance in eastern Ukraine. Clones ‘Strilopodibna’ (P. × euramericana × P. nigra cv. ‘Italica’), ‘Perspektyvna’ (P. × euroamericana cv. ‘Regenerata’ × P. lasiocarpa), ‘Dorskamp’ (P. × euroamericana cv. ‘Dorskamp’), and ‘Ghoy’ (P. × euroamericana cv. ‘Ghoy’) were the most damaged by frost. The OLS regression model explained 64% of the variability in tissue damage, with clone and freezing temperature being the most influential factors (R² = 0.640, Fstat = 17.49, p < 0.0001). In conclusion, our study demonstrated the importance of testing cultivars under local climatic conditions before using them on a commercial scale.