Micropropagation of mountain ash (Sorbus spp.) specimens of the National dendrological park “Sofiyivka” collection

Abstract

Aims. Analysis of technologies existing, their improvement, and development of new technologies of the genus Sorbus L. plants micropropagation. Methods. The shoot tips (ranging from 1.0 to 1.5 cm in length with apical meristems) were cut from three- to five-year-old plants of six species of Sorbus (S. aucuparia L., S. domestica L., S. ×hybrida L., S. rosea McAll., S. sambucifolia (Cham. et Schlecht.) M.Roem., and S. torminalis (L.) Crantz.) and of three cultivars of S. aucuparia (S. aucuparia ‘Nevezhens'ka’, S. aucuparia 'Edulis', and S. aucuparia 'Kubova') and they were used as explants for micropropagation. The plant materials decontamination, introduction, and proliferation were carried out according to commonly used protocols with appropriate adjustments, beginning with the balance of auxins and cytokines in modified media for optimizing morphogenesis and acclimatization techniques of plant-regenerants and growing them to commercial qualities. Results. The viability and quality characteristics of Sorbus explants, as well as of plant-regenerants growing out of them, were on average higher on basic of Murashige and Skuga nutrient media modified according to our developed protocols. The plant-regenerants adaptation to non-sterile ex vitro conditions, which was carried out in peat discs in special chambers with artificial light regulation at a 16-hour photoperiod and light intensities of 1–3 kilolux, and temperature of 22–24 °C, and air humidity of 80–90% was successful. The adapted peat disks plants took root better on a substrate made of forest soil, sand, perlite, and mountain moss peat in the ratio: of 50:20:20:10. The survival rate of regenerating container plants transferred to the open soil of the nursery in the second decade of May under two-day shading and subsequent constant drip irrigation reached about 100%. Conclusions. Our improved micropropagation technology, adaptation, and growing microclones can be used for mass propagation and preservation of Sorbus spp. in ex situ conditions.