Exploring the Optimal Encapsulation Matrix for Artificial Seed Production to Enhance the Ornamental Exploitation of Stachys byzantina K. Koch

The present study aimed to determine the optional alginate and CaCl2 concentrations in the encapsulation formulation to produce alginate beads of Stachys byzantina, thereby offering a potential alternative method for its propagation. Stem explants were derived from in vitro cultures grown on Murashige and Skoog (MS) medium supplemented with 10 μM benzyladenine (BA) and were evaluated for their germination and regeneration potential after a short-term storage period (1, 2, and 3 months). Three different sodium alginate concentrations (2%, 2.5% and 3%) were used for the preparation of alginate beads. For the hardening of the alginate beads, calcium chloride dihydrate (CaCl2·2H2O) at four concentrations (50, 100, 200 and 400 mM) was employed for 35 min. The combination of 100 mM calcium chloride with sodium alginate at concentrations of 2.0%, 2.5%, or 3.0% resulted in high germination rates, ranging from 73.33% to 76.60%. However, germination rates declined with increased storage duration. Among the formulations, 2.5% sodium alginate consistently supported higher germination over time, with rates of 53.33% and 36.66% observed after 2 and 3 months of storage, respectively. The decline in germination rate was followed by an increase in bead hardness over time. The optimal encapsulation matrix composition was identified as 2.5% sodium alginate with 100 mM CaCl2, which yielded the highest regeneration rate of explants after 1, 2 and 3 months of cold storage at 4 °C.