Multiple shoot regeneration of kenaf (Hibiscus cannabinus L.) from a shoot apex culture system

In this research, a medium was developed that would stimulate multiple shoot initiation from shoot apex explants of Hibiscus cannabinus L. (kenaf). Adventitious shoot formation on a shoot induction media supplemented with combinations of 2,4-dichlorophenoxyacetic acid (2,4-D) (0, 0.5, 2.3 μmol·l^-1) and thidiazuron (N-phenyl-N'-1,2,3-thiadiazol-5-ylurea; TDZ) (0, 1, 5, 20 μmol·l^-1) was evaluated. Multiple shoot induction medium with 1 μmol·TDZ l^-1 resulted in the highest number of regenerated shoots per explant for all three kenaf cultivars tested (Tainung 1, Tainung 2, and Everglades 71). The 2,4-D did not enhance multiple shoot formation. Additionally, kenaf cultivars 7N and SF459 also produced multiple shoots on the induction medium with 1 μmol·TDZ l^-1. Multiple shoot clumps formed after 2 weeks in culture without callus formation. Shoots elongated and rooted within 2 weeks after subculture on a plant growth regulator-free medium. A histological study demonstrated the de novo regeneration of shoots from the shoot apex.