Encapsulation of vitro-derived propagules of blackberry in calcium alginate

Interest in blackberry cultivation is progressively increasing together with the demand for nursery materials of high quality. The traditional agamic propagation methods for blackberry are layer, rooting of hardwood cuttings, softwood cuttings, taking of suckers, and the use of roots for root cuttings. However, the need for a large area for planting, and high labour demand, are among the main limitations related to the abovementioned propagation methods. In this context, the in vitro propagation (micropropagation) of blackberries allows to overcome the abovementioned limitations and nowadays is the most widespread propagation method. In particular, the possibility of increasing productivity of in vitro propagation can be achieved through encapsulation technology for the production of synthetic seeds. However, while for different plant species the use of synthetic seeds has an applicative potentiality, in blackberry, the researcher has only recently begun to formulate hypotheses on procedures for the production and use of encapsulated propagules. The present experiment was conducted on the Thornfree blackberry cultivar to study the encapsulation process to i) identify the type of propagules (single node and clump’s base) to be encapsulated and ii) the treatments to enhance the rooting process (immersion of the propagules in an Inductive Liquid Solution containing IBA before or after encapsulation and increase IBA concentration in the artificial endosperm). The results show that the clump’s base is the most suitable propagule for encapsulation since it allows to obtain more and longer shoots and a higher number of roots. Consequently, the plantlets derived from encapsulated clump bases have a higher fresh and dry weight compared to those derived from encapsulated nodes. Furthermore, it has been found that the conversion of the base of the clumps was strongly influenced by the presence of growth regulators. Indeed, at low IBA concentration (0.1 mg l-1 ), the conversion rate was rather high (around 94%), while increasing IBA concentration up to 3 mg l-1 and even more at 5 mg l-1 , the conversion rate decreased significantly. Indeed, the immersion in a liquid encapsulating solution with high IBA concentration before or after encapsulation decreased the number of shoots produced and had negative effects on the development of the root system. Further studies could evaluate other factors, such as the effect of temperature and storage time of the capsules, as well as the type of seeding substrate