Biological and ecological features of western thuja and the role of the sum of effective temperatures in the development and growth of its cultivars

Abstract

The indicator of the sum of effective temperatures reveals the essence of ontogenetic processes that occur during the development and growth of western thuja and its cultivars introduced into the landscaping of Lviv. The characteristic features of the influence of generative and vegetative processes are highlighted, dusting is distinguished, periods and sums of effective temperatures are determined. The beginning and duration of pollination gave grounds to group the cultivars into three groups: the first group (late April ‒ early May: ‘Aureоspicata’, ‘Brabant’, ‘Columna’ ‘Douglasii Pyramidalis’, ‘Globosa’, ‘Fastigiata’, ‘Filiformis’ ‘Malonyana’, ‘Pendula’, ’Pyramidalis’; the second group (end of the first decade of May): ‘Smaragd’, ‘Spiralis’; the third group (late second decade of May - early June): ‘Holmstrup’, ‘Variegata’ ‘Wareana’. The results of the study of generative and vegetative development of western thuja cultivars formed the basis for assessing the success of acclimatisation and introduction of plants into the landscaping of Lviv.