EVALUATING MUTATION BREEDING METHODS TO FAST-TRACK THE DOMESTICATION OF TWO AUSTRALIAN NATIVE CALANDRINIA SPECIES FOR ORNAMENTAL HORTICULTURE

There are about 50 Calandrinia (Portulacaeae) species native to Australia. These annual or perennial herbaceous succulents occur mainly in semi-arid regions. They tend to have attractive flowers. We are conducting plant improvement research on two Australian Calandrinia species with anticipated potential as ornamental flowering pot plants. Calandrinia sp. nov. (not yet fully classified) has large flowers (ca. 7 cm diam.) featuring concentric coloured ring patterns of bright violet, red, orange, and yellow in each flower. Calandrinia balonensis selections have smaller (ca. 4 cm diam.) pink/purple and sometimes white flowers. Being succulents, both species have relatively low water requirements. They are floriferous throughout the year. Neither species is currently available in the ornamentals industry. To enhance variation in our parent germplasm, the mutation breeding techniques of induced polyploidy by in vitro colchicine treatment of seedlings, and gamma irradiation of vegetative cuttings are being applied. These tools have demonstrated potential to quickly introduce desired horticultural traits, such as compactness, multiple branching, novel flower form, and brighter flower colours.