DIFFERENT GENOTYPES OF PTILOTUS EXALTATUS AND THEIR SUITABILITY FOR CULTIVATION

German horticulture has previously evaluated the genus Ptilotus (originating from Australia) for ornamental use. However, due to poor seed quality and low germination rates, the commercial cultivation of P. exaltatus proved to be difficult in the past. Furthermore, results of research e.g., for in vitro propagation cannot be applied to all genotypes due to the large diversity between the individual genotypes. Also, detailed comparison in order to verify genotypes suitable for cultivation is missing. The aim of this research project was to provide an overview of several genotypes of P. exaltatus to determine the most suitable genotype for cultivation. The research focused in particular on in vitro propagation, root formation and greenhouse acclimatization. Various concentrations of BAP and IBA were tested to define an optimal medium of culture for propagation and root formation, respectively, but also to evaluate their later influence in the greenhouse. During acclimatization, a standard substrate mixed up with perlite (ratio: 2 parts substrate:1 part perlite) was used, proving cultivation was possible using standard methods of production. IBA was used to initiate root formation, but also influenced plant diameter and leaf quantity in vivo, even at the beginning of acclimatization. During the later greenhouse cultivation this effect was compensated for. IBA influenced dichotomy positively. A culture medium treated with 1 mg/L IBA in vitro could reduplicate dichotomy in vivo. These results depended on outer conditions. Although P. exaltatus can probably be cultivated year-round in its natural habitat Australia, the cultivation under central European conditions is effective from April until September only. Furthermore, chances of survival and growth rates of rootless young plants were tested. Although a culture medium containing the phytohormone BAP resulted in the best propagating levels (highest rate: 18), plants produced were short and “sensitive” under greenhouse conditions. In conclusion, the three genotypes of Ptilotus investigated grew well using standard growing practices and submitting them to typical greenhouse conditions. Phytohormone IBA improved dichotomy distinctively. Furthermore, a genotype could be determined which produces the best results in plant growth. Further study of producing cloned ‘mother plants’ in vitro is highly recommended.