The influence of growth regulators on dahlia propagation in tissue culture and acclimatization of plants in ex vitro conditions

The aim of the work was to evaluate the influence of cytokinins on in vitro propagated dahlia and their consequent effect on acclimatization. Plant material consisted of shoot tips and nodes. Among the three cytokinins, benzyladenine, kinetin and 2-isopentenyl-adenine, only BA effectively stimulated the shoot multiplication from axiliary buds. The highest multiplication rate was obtained from nodes in the presence of 0.25– 0.5 mg·dm–3 BA. Higher concentrations shortened the internodes and decreased the leaf blades and growth of callus. 1 mg·dm–3 of KIN and 2iP positively influenced the shoot growth and size of leaves. Gibberellic acid (GA3) used with BA increased the number of auxillary shoots. The best quality shoots and the highest multiplication rate were obtained when 2 mg·dm–3 BA was used with 5 mg·dm–3 GA3. Cytokinins affected the rooting and acclimatization ex vitro. Dahlia shoots multiplicated in the presence of 1 mg·dm–3 KIN or 2iP rooted faster in the soil and 100% survived in field, while those from 1 mg·dm–3 BA media rooted slowly, had shorter shoots and only 60% of them survived. Plants bloomed after 11–12 weeks in the field. Dahlia plants that had been multiplicated in the presence of KIN had larger diameter and fresh weight in the field. BA and 2iP positively influenced the flower diameter, length of flower stalk and a number of the first-order shoots.