Ishchuk G. Biological peculiarities of North American species of Juglans L. genus and the perspectives of their use in the Right-Bank Forest Steppe Zone of Ukraine

The dissertation deals with the research of bio-ecological peculiarities of North American species of Juglans L. genus, in particular, J. nigra L., J. cinerea L., J. rupestris Engelm., J. californica Wats., J. major (Torr.) Heller., J. hindsii Jeps in the conditions of the Right-Bank Forest Steppe Zone of Ukraine. Morphological characteristics of North American species of Juglans L. genus, their system, philogenesis and the history of origin and distribution were presented. The duration of a dormancy period, phonological growth and development rhythms of the species and their dependence on the sum of active and effective temperatures, growth peculiarities, flowering and fruiting, pollen fertility, winter, frost-, drought-, heat resistance, resistance to pests and disease were studied. It has been recorded that North American species of Juglans L. genus are well propagated with seeds, the best ways of interrupting dormancy being the treatment of seeds with concentrated sulphuric acid. The evaluation of advantageous and beneficial introduction of North American species of Juglans L. genus was made; ornamental properties were studied; as a result two physiognomic types of J. rupestris and J. hindsii were identified. Practical recommendations as to the use of North American species of Juglans L. genus in forest culture and building construction were suggested.