Agronomijas v stis - Latvijas Lauksaimniecības universitāte

Ondrušková et al., 2003; Petri and Burgos, 2005; Gajdošová et al., 2006; Gajdošová et al., 2007).However, the results show that the different cultivars within the same species can differ in theirrequirements for the optimal growth regulator concentrations therefore it is important to get exactinformation on culture conditions for different cultivars.In this paper micropropagation by axillary branching and adventitious shoot regeneration isdescribed in a wide range of Vaccinium corymbosum L. and Vaccinium vitis-idaea L. cultivars.Material and methodsAs an initial plant material for axillary shoot formation stem cuttings with dormant buds werecollected from the selected cultivars of mature plants during February and the beginning of March:Vaccinium corymbosum L. - cvs. ´Berkeley’, ´Bluecrop´, ´Blueray´, ´Duke´, ´Brigitta´ andVaccinium vitis-idaea L. - cvs. ´Red Pearl´ and ´Koralle´. Nodal segments with buds were washedunder running water for 1 h and sterilised 2 min in 70 % ethanol, 6 min in a 0.1 % solution ofmercuric chloride with 3 drops of Tween, followed by washing 3x15 min in sterile distilled water.For shoot regeneration dormant apical and axillary buds were used, from which the upper scaleswere removed after sterilisation. Anderson’s Rhododendron medium - AN (Anderson, 1980) with30 g l -1 sucrose, 8 g l -1 Phyto agar, pH adjusted to 4.8 – 5.0 and supplemented with differentcytokinin concentrations was used for cultivation. Cultures were maintained in the growth chamberat 23 ± 2 o C under 16/8 light and dark photoperiod and a light intensity of 50 µmol m -2 s -1 providedby white fluorescent lamps. In V. corymbosum cvs. 0.5 and 2.0 mg l -1 zeatin and in V. vitis-idaea L.cvs. 0.25 – 2.0 mg l -1 zeatin and 2.5 - 20.0 mg.l -1 2-iP, were tested for axillary shoot regeneration.The influence of cytokinins, zeatin and 2-iP, on shoot regeneration ability was evaluated after 5weeks. Data evaluation was performed using Statgraphic PLUS 5 for Windows.For adventitious shoot regeneration leaves from the in vitro plants of V. corymbosum L. - cvs.´Berkeley´, ´Bluecrop´ and ´Brigitta´ with cut margins were cultivated horizontally with adaxialsurface on an AN medium with 30 g l -1 sucrose, 8 g l -1 Phyto agar, pH adjusted to 4.8-5.0,supplemented with 0.5 mg l -1 zeatin and 2.2 mg l -1 TDZ. Their regeneration ability based on shootproliferation was evaluated in three subcultures, during a five week period. In V. vitis-idaea L. -cvs. ´Red Pearl´ and ´Koralle´ as primary explants stem cuttings and leaves from in vitro plantswere used for adventitious shoot induction. For each experiment 30 explants were cultivated (5explants/culture dish x 6 culture dishes). AN medium with zeatin in concentrations 2.2 and 4.4mg.l -1 or thidiazuron in concentrations 1.1 mg l -1 , 2.2 mg l -1 and 3.3 mg l -1 was used the forinduction of adventitious organogenesis. After 5 weeks of cultivation the explants were transferredinto an AN medium with 0.5 mg.l -1 zeatin for shoot multiplication. The percentages of explantsregenerating shoots or inducing callus and the number of regenerated shoots per explant after 3subcultures were recorded. The long-term shoot proliferation was performed on an AN mediumwith 0.5 mg l -1 zeatin. For the microshoot rooting an AN medium supplemented with 0.8 mg l -1IBA and 0.8 g l -1 charcoal was tested.Results and DiscussionThe results of the experiments on shoot regeneration from dormant apical and axillary buds in V.corymbosum L. showed that shoot regeneration ability is highly dependent on cultivar andcytokinin concentrations. Zeatin in a concentration of 2 mg l -1 was proved to be more effective forshoot regeneration in comparison with 0.5 mg l -1 zeatin (Figure 1).The statistically significant differences in the number of shoots per explant were obtained on amedium with 2 mg l -1 zeatin in tested cultivars with the highest regeneration ability in cvs.‘Brigitta’ and ‘Blueray’.76