EN
The effect of two different iron chelates and iron concentration on multiplication, shoot growth, chlorophyll content and rooting of Carlina onopordifolia were studied in in vitro culture. FeEDTA presented in MS basal medium was replaced by FeEDDHA, which was applied in three concentrations: 93.5, 187.0 and 280.5 mg dm⁻³ (5.6 mg dm⁻³, 11.2 and 16.8 mg dm⁻³ Fe ions, respectively). Changing chelate or iron concentration in the medium had no effect on axillary shoot number proliferation, but growth of shoots was significantly inhibited by a two- and three-fold increase in concentration of FeEDDHA in the medium. Supplementation of the medium with FeEDDHA as Fe source significantly increased the level of chlorophyll in the leaves. After treatment of shoots with IBA for 5 s and growing them on the MS medium supplemented with FeEDTA, the number of roots per shoot was significantly higher than on medium containing FeEDDHA. Increasing the concentration of Fe ions in the medium after a short pulse (5 s) of IBA had no effect on shoot rooting. After 30 s of 1-g dm⁻³ IBA treatment, growth of roots on medium with FeEDDHA was stimulated. The survival rate was relatively low and did not depend on the type and concentration of iron chelate in the rooting medium.