Investigation of Anatolian sweetgum trees (Liquidambar orientalis Miller) propagation properties under in vitro conditions

Anatolian sweetgum (Liquidambar orientalis Miller) is a relict endemic species of Turkey. The balsam ?liquid storax? produced by wounding the bark is used in perfume and cosmetic industry. Since the beginning of 20th century the trees has been disappearing due to lower balsam prices and biotic interferences, which is regarded as vulnerable tree species in Europe. The aim of this study was to determine in vitro conditions required for clonal propagation of this species. First, four basal media (LO, MS, SH, and WPM) fortified with different plant growth regulators (2.5 mg/L BAP + 0.1 mg/L NAA or 0.1 mg/L TDZ + 0.01 mg/L 2,4-D) were tested for adventitious shoot induction using hypocotyls obtained from two weeks old seedlings. Afterwards the affects of the explant age (2, 3, and 4 weeks old), dark incubation (control, 1 week and 2 weeks dark), and explant position along the seedling hypocotyl on shoot induction were investigated. SH basal medium with 2.5 mg/L BAP and 0.1 mg/L NAA was found best for shoot induction. ANOVA results of the data showed significant differences for the main effects ?explant age? and ?dark incubation?. No significant interaction were found among the main effects. Explants taken from 3 weeks old seedlings or incubated in dark for 2 weeks produced an average of 19.33 and 20.52 shoots per explant, respectively. Although ANOVA results of the rooting frequencies were not significant, shoots obtained from 3 weeks old explants and incubated under light continuously reached higher rooting frequencies. Average of 77% of shoots formed roots without using any plant growth regulators. This rooting percentage could be further increased by testing different auxins, such as IBA.