The purpose of the researches is to improve the blackberry assortment on the basis of studying morphological peculiarities of the new cultivars and their adaptivity in the soil and climatical conditions of the Ukraine’s Western Lisosteppe for the further strain investigation and introduction into the breeding programmes. The study of the individual peculiarities of the shoots growth, the establishment terms of the beginning of the rest period and effect climatic conditions to the plants growth will allow to assess the adaptive potential of introduced cultivars to certain soil and climatic conditions.

The experiments were conducted in the Western Lisosteppe on the basis of the Institute of Horticulture NAAS of Ukraine (Kyiv) during 2015–2016. The object were 25 blackberry cultivars, namely Adriene, Apache, Asterina, Black Butte, Black Diamond, Black Magic, Black Pearl, Brzezina, Čačanska Вestrna, Chester, Chief Joseph, Heaven Can Wait, Jumbo, Karaka Black, Kiowa, Loch Tay, Natches, Navaho, Orkan, Ouachita, Reuben, Tornfree, Triple Crown, Nasoloda and Sadove chudo. The plants had been planted according to the methods of the collectional strain investigation in the autum of 2014. The planting plan was 3.00x1.25 m. The agrotechnical measures were carried out in conformity with the accepted technology of the small fruit crops cultivation.

Researching the dynamic of blackberry shoots growth of the current year began after their appearing above the soil. After increasing the number and length of young shoots, the records were marked, and then their length was measured once a decade. Measurements were made until the two decades did not observe the presence of growth.

The morphological structure of the bushes each cultivars of the studied was determined at the beginning of the study. Blackberry cultivars are divided by their growth habit into three types, namely: with trailing shoots, semi-erect shoots and erect shoots.

As a result it was determined that cultivars with trailing shoots have a rather long period of the most intensive growth, which lasts in middle August; semi-erect cultivars intensively increase the length of the shoots in early August, and erect cultivars – late July. The beginning of the period of intensive growth of the trailing cultivars was observed in May till early June; erect – middle May; semi-erect cultivars – late May. In general, the period of shoots growth trailing and semi-erect cultivars continued until the early October and limited to a daily average temperature below 10 °C. Erect cultivars finish the shoots growth 10-15 days earlier. Plants of the studied varieties of blackberries come in the winter almost without leaves fall. Based on our own research, it was found that cultivars with trailing shoots underwenr more damage from low temperatures in the winter, as compared to the cultivars with more erect shoots.

Key words: blackberry, shoot, cultivar, intensive growth, average temperature, leaves fall.