| heal.abstract |
Lithodora zahnii (Heldr. ex Halacsy) I.M. Johnston (Lithospermum zahnii) is a dense dwarf subshrub, with silvery-hairy young shoots, greenish or grayish linear leaves and blue or white flowers. It is a vulnerable endemic species of Greece, found only in certain rocky places, of the south Peloponnese peninsula. It flowers from late March to June. In vitro propagation of L. zahnii was studied as a first step to introduce the species as a bedding plant, a plant for rock gardens, roof gardens, restoration of downgraded landscapes and slope stability. Seeds were germinated on solid half strength MS medium with 2% sucrose, at 10°C, under 16-h photoperiod of 37.5 μmol m-2 sec-1 fluorescent light. Nodal explants from in vitro grown seedlings were cultured on solid MS with 2% sucrose supplemented with 0.2 or 0.5 mg/L BA or zeatin in order to induce shoot production. In all media the percentage of explants yielding shoots was high. The highest number of shoots (average 6.7 shoots per explant) was produced on the medium with 0.2 mg/L zeatin. BA media gave fewer but longer shoots. On the medium with 0.2 mg/L BA an average of 3.7 shoots per explant of 1.6 cm long was taken after two months in culture. At the first subculture high shoot multiplication rate occurred on a medium with 0.2 mg/L IBA from explants excised from microshoots produced on zeatin-media, and on a medium with 0.2 mg/L BA from explants excised from microshoots produced on the same medium. However a significant number of the produced shoots were hyperhydrated. Hyperhydration was eliminated when sucrose or agar concentration was increased, or the IBA or BA concentration was reduced to half. Hyperhydration was also eliminated when the culture vessels were covered with plastic wrap instead of the transparent semi-hard plastic film used routinely; plastic wrap increased the shoot multiplication rate too; IBA-media with plastic wrap cover gave the highest multiplication rate (2.3 to 3.1). Simultaneously, on IBA-media roots were formed; the highest rooting percentage (93%) occurred on a medium with 0.2 mg/L IBA, 20 g/L sucrose, 8 g/L agar and plastic wrap as culture vessel cover. |
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