INTRODUCTION TRIALS OF CULTIVARS OF THE GENUS JUNIPERUS L. IN TECHNOGENIC CONDITIONS OF THE NORTH UKRAINIAN STEPPE AND PROSPECTS OF THEIR URBAN LANDSCAPING USES

Abstract

A comprehensive introduction research of 41 varieties of seven species of the genus Juniperus L. was conducted in Pokrovsk, Donetsk region. In the course of the study, some morphological and decorative features of these cultivars were analyzed. According to needle coloring, we identified 14 cultivars (34% of the total sample) with green needles, 15 ones (37%) are blue in color, 10 ones (24%) are golden-yellow and variegated; 2 ones (5%) are silver-gray. According to the shape of the crown, 15 cultivars (39%) are shrubs; 18 ones (44%) are trailing; 5 ones (12%) are pyramidal; in two cultivars (2% each) crowns are spherical (ball-shaped) and drooping. According to the growth rate, moderately growing plants (17 varieties) dominate in our sample, namely Juniperus squamata ‘Blue Carpet’ and cultivars of J. chinensis; 15 cultivars are characterized by fast growth rates: these are all varieties of J. sabina without exception; 9 cultivars are slow-growing: J. squamata ‘Blue Star’, J. horizontalis ‘Andorra compacta variegata’, J. horizontalis ‘Limeglow’ and others. In terms of vegetation, all cultivars correspond to the vegetation terms of the research area and timely complete shoot and needle growth by cold season beginning. Our study has shown the relationship between annual shoot growth and meteorological data. The correlation between shoot growth and rainfall ranges from 0,24 in J. squamata ‘Hunnetorp’ to 0,70 in J. horizontalis ‘Wiltonii’; and the dependence between shoot growth and air temperature varies from 0,21 in J. squamata ‘Hunnetorp’ to 0,85 in J. squamata ‘Blue Carpet’. The study has shown that 38 cultivars (92%) are not damaged by frost, winter hardiness is evaluated as I point (Juniperus chinensis ‘Stricta Variegata’, J. sabina ‘Arcadia’, J. virginiana ‘Burkii’, etc.); the annual shoot tips are frost-bitten in 3 cultivars (8%), their winter hardiness being assessed as II points (J. horizontalis ‘Limeglow’, J.×media ‘Gold star’, J. ×media ‘Mathot’). Thirty-two cultivars are characterized by high drought resistance (I point): J. chinensis ‘Spartan’, J. sabina ‘Arcadia’, J. virginiana ‘Burkii’, etc.; needles wither and less than 5 % of annual apex shoots dry up in 9 cultivars during the drought (II points): namely J. horizontalis ‘Limeglow’, J. horizontalis ‘Andorra compact variegata’, J. ×media ‘Gold star’, J. sabina ‘Rockery Gem’ J. horizontalis ‘Limeglow’, J. horizontalis ‘Andorra compact variegata’, J. ×media ‘Gold star’, J. sabina ‘Rockery Gem’, etc. The study has shown good prospects for landscaping of these cultivars in urban environments of the north of Ukrainian steppe. According to our research findings, 98% of cultivars are among the highly promising and deserving, namely J. chinensis ‘Spartan’, J. sabina ‘Blue donaube’, J. virginiana ‘Grey Owl’, J. media ‘Mordigan gold’, J. scopulorum ‘Blue heaven’ , J. horizontalis ‘Golden carpet’ and others.