The study was conducted to evaluate the adaptive capacity of microplants of Arctic bramble (Rubus arcticus L.) under ex vitro conditions and to analyze cultivar-specific characteristics during their subsequent in vivo adaptation under the environmental conditions of Moscow. The objects of the study were plants of nine R. arcticus cultivars (Anna, Beata, Linda, Sofia, Astra, Aura, Elpee, Pima, and Galina). For ex vitro adaptation, high-moor peat and peat mixed with river sand (3 : 1), vermiculite (3 : 1), perlite (3 : 1), and zeolite (3 : 1) were used as substrates. The highest ex vitro survival rate of microplants (78–92%) was observed for a high-moor peat and zeolite mix (3 : 1); it exceeded the levels obtained for other treatments by 5–36%. In 2022, adapted microplants were transplanted into open ground at the R.I. Schroeder Arboretum (Moscow); their growth and development were assessed during 2022–2024. The planting trenches were 80 cm wide and 50 cm deep and were filled with an Agrobalt-V high-moor peat (pHKCl 2.5–3.0). The planting scheme was 0.3 × 0.8 m. All experiments were conducted in three replicates, with ten plants per replicate. The in vivo survival rate of microplants at the year of transplantation was 100%, and their overwintering survival in years 2 and 3 of cultivation was also 100%. In years 2 and 3 of open-ground cultivation of the studied cultivars, the plant height ranged from 8.9 to 12.8 cm. The 2- and 3-year-old plants formed four to five and five to seven shoots, respectively. Flowering of R. arcticus plants lasted 18–21 days, and fruit-ripening period made 11–15 days. The maximum average fruit weight (1.42–1.50 g) was observed for the cultivar Galina.
Makarov et al. (Sun,) studied this question.