In vitro propagation, also known as micropropagation, has become the most widely employed method for blackberry propagation, as it overcomes the limitations of the traditional asexual propagation methods (mainly layering and cutting). In this context, synthetic seed technology represents a strategy to enhance the productivity of in vitro propagation and facilitates the exchange of plant materials between laboratories, contributing to germplasm conservation. This study aimed to identify the most suitable vegetative propagule for the encapsulation of blackberry. To this end, uninodal microcuttings (nodes) and the base of clumps were used to produce synthetic seeds for the cultivars Thornfree and Chester. Forty-five days after sowing, viability (percentage of green propagules without browning or necrosis), regeneration (percentage of propagules that sprouted and rooted simultaneously), number of shoots produced, shoot length, number of roots produced, root length, and the fresh and dry weights of the plantlets were measured. The results demonstrated that both considered propagules allowed us to obtain satisfactory regeneration rates. However, plantlets originating from the encapsulated clump's base had more shoots and roots, resulting in greater fresh and dry weights than the plantlets derived from encapsulated nodes. Therefore, for achieving more robust plantlets and enhancing overall procedural efficiency, we recommend using the base of clumps as a propagule for blackberry encapsulation.
Keywords: alginate beads; micropropagation; small fruit; synseeds; vegetative propagules.