The in vitro shoot regeneration of Ehretia asperula Zol. and Mor.

Xa den young branches in the orchard were sterilized and used as explants for shoot initiation and growth experiments. The shoot induction was carried out with BA (benzyl adenine) or TDZ (thidiazuron). New shoots sprouted after one week of culture and the highest shoots (2.02 cm) were on MS medium (Murashige and Skoog medium) with BA 0.6 mg/L after 3 weeks. Furthermore, the number of leaves per shoot was also higher than other treatments (8.31 leaves per shoot). In vitro shoots were used in other experiments to investigate the effects of explants, biotin concentrations, minerals, type and concentration of cytokinins on the formation and elongation of shoots and clusters. When 5 mg/L biotin was added to MS medium, shoots grew better. The MS medium appeared to be most suitable for the initiation and elongating of shoots, followed by WPM (woody plant medium) and SH medium (Schenk and Hildebrandt medium), while B5 medium (Gamborg B5 medium) was the least effective. The spouting from three-week-old explants was earlier than others (4 and 5 weeks of age), which in turn affected on the shoot elongating. BA 1.5 mg/L was suitable to induce shoot clusters (3.91 shoots per explant) after 4 weeks.