Blackberry synthetic seeds storage: effects of temperature, time, and sowing substrate

In vitro propagation, is becoming the predominant method for blackberry propagation due to its advantages compared to agamic traditional propagation methods. Synthetic seed technology represents a promising approach to further enhance the productivity of in vitro propagation facilitating the exchange of plant materials among laboratories and contributing to germplasm conservation efforts. This study aimed to establish an optimal protocol for the storage and sowing of synthetic blackberry seeds obtained through the encapsulation of clump bases. The synthetic seeds were sown without storage (Control) and after storage periods of 30, 60, and 120 days at 4 °C and 25 °C in the dark, in three different substrates (agarised, perlite, and potting). After forty-five days from sowing viability, regeneration rate, shoot and root numbers and lengths, as well as fresh and dry weights of the plantlets, were assessed. Results indicated that agarised substrate consistently exhibited favourable outcomes, with sustained regeneration rates and robust plantlet development even after prolonged storage at 4 °C. Synthetic seeds sown in perlite and potting substrates demonstrated enhanced regeneration rates following storage at 4 °C for 60 and 120 days. On the contrary, storage at 25 °C resulted in a notable decline in regeneration rate, highlighting its inadequacy for blackberry synthetic seed conservation purposes. These findings underscore the importance of sowing substrate selection and storage temperature in optimizing the storage and sowing protocols for synthetic blackberry seeds.