Polyploidy breeding in vitro: experiences with ornamentals

Chromosome doubling is a frequently used strategy in breeding programmes. In ornamentals now mostly in vitro protocols are used for polyploidisation, as good micropropagation protocols have already been established for many plant species. Tissue culture protocols offer a broader pallet of methods that can be evaluated for polyploidisation as compared with the in vivo applications of antimotitotic agents. Here we give an overview on in vitro polyploidisation methods with practical examples on herbaceous and woody ornamental species: Helleborus, Ranunculus, Spathiphyllum, Buddleja and Rhododendron.