Effect of Plant Growth Regulators on Different Explants and Explant Size of Yellow Everlasting (Helichrysum pallasii Sprengel Ledeb.) Under in Vitro Conditions

In this study, different explants (leaf, stem and root) and explant size (0.5, 1, 1.5 and 2 cm) of yellow everlasting, Helichrysum pallasii (Sprengel) Ledeb., cultured under in vitro conditions including kinetin, 2,4-D, TDZ and zeatin concentrations. Concentrations of 0.5 mg l⁻¹ kinetin + 0.5 mg l⁻¹ 2,4-Dichlorophenoxyacetic acid (2,4-D) and 1mg l⁻¹ kinetin (KIN) + 1 mg l⁻¹ 2,4-D were used for callus induction. Concentrations of 1 mg l⁻¹ thidiazuron (TDZ) and 1 mg l⁻¹ thidiazuron (TDZ) + 0.1 mg l⁻¹ zeatin (ZEA) were used for inducing shoot regeneration. MS medium without any plant grow regulators was preferred as control group. Rooting medium was preferred 1 mg l⁻¹ NAA. In callus regeneration, highest regeneration rates were found as respectively 86.6%, 53.3% and 35.5% from root, stem and leaf explants with 1 cm explant length while the lowest rate (4.4%) found in control group from leaf explant with 2 cm explant length. It was obtained from the medium containing the highest shoot regeneration and from root (24.6%), stem (20.6%) and leaf (16%) explants with an explant length of 1 cm. Similarly, rooting rate from leaf, root and stem explants were found as respectively 43.8%, 32.3% and 21.9% with the 1 cm explant length obtained from 1 mg l⁻¹ TDZ + 0.1 mg l⁻¹ ZEA medium. In conclusion, 1 cm of explant length produced the highest regeneration rate in all source of explants. Also, 1 mg l⁻¹ TDZ combined with 0.1 mg l⁻¹ ZEA were more effective than 1 mg l⁻¹ TDZ treatment alone in shoot regeneration.