A simple and effective method for the micropropagation and in vitro induction of polyploidy and the effect on floral characteristics of the South African iris, Crocosmia aurea

South Africa is home to approximately 10% of the world's flora, many of which are endemic to the country. A large number of South African genera have been improved for horticultural use and many of these are economically important as cut flowers or ornamentals on international markets. The genus Crocosmia, an attractive member of the family Iridaceae, has potential both as an ornamental plant and for cut flower production, although market potential of the species may be increased by improving the size of the flowers and inflorescence. Polyploidy has been used as a tool in the improvement of ornamental plants and has led to the development of several improved ornamental species. This study established a micropropagation protocol for Crocosmia aurea, using seed as the source material. Tetraploidy was induced by treating seeds with colchicine. These seeds were subsequently germinated and multiplied in vitro using the established protocol. The resulting tetraploid plantlets were successfully hardened-off and used to study the effect of the induced tetraploidy on the plant characteristics. The tetraploid (4n) plants were found to have longer, wider leaves as well as longer inflorescence stems and fewer, but larger, flowers than their diploid (2n) counterparts. These polyploid selections have potential in the ornamental/floriculture trade.