Abstract
The article presents the results of optimizing micropropagation and ex vitro adaptation conditions for blackberry plantlets of the Rubus L. cultivars Natchez and Heaven Can Wait. During the micropropagation stage, the most effective shoot multiplication was achieved on MS medium supplemented with 0.5 mg/L BAP and 0.1 mg/L GA3, resulting in the formation of 5.3–5.8 shoots per explant with an average height of 5.27–5.43 cm. For ex vitro rooting and adaptation, the best results were obtained using a peat and perlite substrate (3:1) moistened with a 0.01% solution of succinic acid. After 8 weeks, the Natchez cultivar showed a shoot length of 8.47 cm, and Heaven Can Wait reached 7.10 cm. Both cultivars developed more than 11.42 roots on average, with root lengths ranging from 10.35 to 11.52 cm. The use of growth stimulants (humic acid, nanosilicon, and succinic acid) significantly improved rooting efficiency, with the succinic acid treatment achieving the highest results – rooting and adaptation rates of 87% to 97%. These findings confirm the effectiveness of growth stimulators in enhancing the propagation and adaptation of blackberry plantlets under ex vitro conditions.