Micropropagation of blackberry genotypes.
The purpose of this study was to develop an efficient in vitro multiplication system for blackberry (Rubus fruticosus L.). A successful in vitro culture technique would provide an alternative method, which can potentially multiply selected blackberry genotypes more rapidly than traditional nursery systems. Two genotypes, 'Čačanska bestrna' and blackberry selection No. 7, were sterilised using 0.15% mercuric chloride as sterilization solution. The use of mercuric chloride had a direct beneficial effect to overcome the contamination from all starting plant material. Four types of modified MS medium containing 1, 2 or 4 mg L-1 6-benzylaminopurine (BAP) or combination of 1 mg L-1 BAP, 0.1 mg L-1 indole-3-butyric acid (IBA) and 0.1 mg L-1 gibberellic acid GA3 were tested in multiplication stage. Generally, the highest proliferation rate was obtained for cultivar 'Čačanska bestrna' that produced 6.3 shoots (longer than 10 mm) on a medium containing 4 mg L-1 BAP. All in vitro shoots started spontaneous rooting on multiplication media after depletion of cytokinines after 1 month of cultivation. High survival (more than 95%) was obtained after acclimatization. The plants established after a period of in vitro culture showed no visible morphological differences compared with conventionally propagated plants. In conclusion, R. fruticosus can be efficiently propagated using a modified MS medium.