This study was conducted in 2023-2024 to clarify the origin and introduction of purple-leaved hazel, and to examine the morphological and physiological characteristics of the best genotypes developed by the authors. Morphometric analysis of nuts, quantitative and qualitative composition of pigments in leaves in dynamics, and observation of the influence of abiotic and biotic environmental factors were carried out. It was found that there were mutants in Corylus with red/purple colouration of the pellicle of kernels and/or leaves. They have been found repeatedly in different places in Europe, belonging to the species Corylus avellana and/or Corylus maxima. Taxonomists consider these taxa to be distinct; however, molecular studies suggest that Corylus maxima should be synonymised with Corylus avellana. The best selections of purple-leaved hazel are characterised by high-quality nuts weighing 2.5-3.2 g with a kernel percentage of 48.0-51.7. The content of chlorophyll a, chlorophyll b, carotenoids, and anthocyanins in purple-leaved selections ‘Profesorskyi’, ‘Aspirantskyi’, and ‘Akademichnyi’ was generally higher than in green-leaved varieties, although this difference was not statistically significant in most cases, except for anthocyanins. The high anthocyanin content in the leaves (up to 0.69 mg/g in May) and in the fruit involucres gave these genotypes exceptional decorative effect during the first half of the growing season and beyond. These genotypes had high winter hardiness and drought resistance and are well adapted to local soil and climatic conditions. Among the biotic environmental factors, the nut weevil Curculio nucum (damaging the nuts), and the powdery fungus Phyllactinia guttata (affecting the leaves) had a negative impact. The fungus Erysiphe corylacearum, new to Ukraine, was also found on the leaves. These findings support the wider introduction of purple-leaved hazel, as the best genotypes are highly ornamental and also produce nut. The obtained data will be useful for forest restoration, landscaping and amateur gardening
Mezhenskyj et al. (Fri,) studied this question.