Shoot proliferation ability of selected cultivars of Rubus spp. as influenced by genotype and cytokinin concentration

The aim of this work was to develop protocols for micropropagation of selected Rubus cultivars – ‘Tulameen’ and ‘Black Jewel’ (Rubus idaeus L.), ‘Black Satin’ (Rubus fruticosus L.) and ‘Tayberry’ (Rubus fruticosus x Rubus idaeus). Nodal segments carrying dormant buds were used for in vitro culture establishment. For shoot initiation, MS medium containing 8 g*L-1 phytoagar, 30 g*L-1 sucrose, 1 mg*L-1 6-benzylaminopurine (BAP), 0.2 mg*L-1 indole-3-butyric acid (IBA) and 150 mg*L-1 cefotaxime was used. The shoot proliferation ability of each cultivar was evaluated by multiplication coefficient (number of shoots formed per explant) during 4 subcultures. Statistical analyses confirmed the significantly higher shoot multiplication ability in cvs. ‘Black Satin’ and ‘Tulameen’ in comparison with cvs. ‘Tayberry’ and ‘Black Jewel’, as well as significant differences in shoot proliferation between subcultures (1st and 2nd versus 3rd and 4th). Testing of influence of different BAP concentrations on shoot formation showed that BAP 1-2 mg*L-1 is the best for shoot proliferation with the higher multiplication rate obtained in cv. ‘Black Satin’ in comparison with ‘Black Jewel’. Statistical evaluation showed that genotype and BAP concentration significantly influenced the ability of shoot proliferation in Rubus cultivars.