Ines Vršek

In vitro propagation of Inula verbascifolia (Willd.) Hausskn. subsp. verbascifolia

Abstract A clonal propagation method has been developed for Inula verbascifolia (Willd.) Hausskn. subsp. verbascifolia, a species of horticultural as well as potential medicinal interest. Shoots originating from aseptically germinated seeds were used for culture initiation. The highest multiplication rate of 6.5 shoots per explant was achieved in an 8-week culture period on Murashige and Skoog medium supplemented with 2.2 μM 6-benzylaminopurine and 2.9 μM gibberellic acid. During the first three subcultures of the multiplication phase, two-thirds of explants spontaneously rooted on all tested media. Rooting of excised shoots on MS medium supplemented with 3 μM IAA or 3 μM IBA was 100%. Aside from the fact that all the explants were rooted on this root-inducing media, explants developed a surprisingly high mean number of shoots, 4.6 and 2.9 after 4 weeks, on medium supplemented with IAA or IBA, respectively. Rooted plantlets were transferred to potting soil and acclimatized to outdoor conditions.

Intra- and interpopulation variability and taxonomic status of Berberis croatica Horvat

Abstract Morphological and anatomical traits of Berberis croatica Horvat that would facilitate its separation from the two related taxa, B. aetnensis C. Presl and B. vulgaris L., and their ITS (Internal Transcribed Spacers of nuclear ribosomal DNA) relationships were analyzed. Results show that B. croatica differs from the two related taxa in the following characteristics: plant height, blade width, petiole length, internode length, number of stomata on adaxial and abaxial leaf side, total number of stomata per leaf as well as length of the guard cells and of the stomatal pore on the abaxial epidermis. The analysis of molecular variance (AMOVA) show that 24% of the total variance of investigated morpho-anatomical traits was attributable to variability among species. Phenotypic differentiation of species and populations was evident in all of the investigated taxa. Southern populations of B. croatica grouped with the populations of B. aetnensis with whom they proved to be highly similar. ITS sequence analysis did not separate B. aetnensis, B. croatica and B. vulgaris. The nature of distinctive morpho-anatomical traits combined with the lack of ITS differences suggests an intraspecies taxonomic rank for B. croatica.

Influence of the photoperiod, daminozide application and fertilization on New England aster

The species Aster novae-angliae L., New England aster, is a short day perennial, flowering from the end of August to the end of October. It is branched out and reaches a height to 1.2 m. New England aster is grown in gardens and for cutting production. It has a flowering pot plant potential, but many of its cultivars are too tall to be grown in pots. Regulation of the day length may affect its flowering period while the application of growth retardants may regulate the shoot length and branching, as well as induce flowering in this Aster species. Growth regulators are applied in floriculture to reduce the vegetative growth of plants and to improve their aesthetic value by inducing shorter internodes (Gibson and Whipker, 2003 ; Marosz and Matysiak, 2005 ; Pinto et al. 2005 ; Pobudkiewicz and Treder, 2006). Balanced nutrition is an important tool in cultivation of agricultural plants as well as for flowering pot plants and it has to be adjusted to the plant requirements during particular development stages for which only orientational values are available for the majority of ornamental plants (Macz et al. 2001 ; Kant et al. 2005 ; Berzsenyi and Dang, 2006 ; Sharma and Sharma, 2006 ; ). The objectives of this work are to define the possibility of growing Aster novae-angliae L., ‘ September Ruby’ , as a flowering pot plant in the late summer period, determine the effect of day length and the cultivar’ s response to one time application of growth retardant, as well as topdressing with liquid mineral fertilizer on its growth and flowering.