OVERCOMING POOR GERMINATION IN AUSTRALIAN DAISIES (ASTERACEAE) BY COMBINATIONS OF GIBBERELLIN, SCARIFICATION, LIGHT AND DARK

The cultivation of many Asteraceae native to Australia is currently restricted by poor germination. In this study the effect of scarification, gibberellic acid (GA(3)), and light on the percentage germination of 27 species of native Australian daisies (Asteraceae) was investigated. Three germination treatments were applied; intact achenes moistened with water, scarified achenes moistened with water, and intact achenes moistened with 500 mg 1(-1) GA(3), at two light levels (light and dark). No single treatment resulted in optimum germination for all species. The testa and pericarp were influential in suppressing germination of Leucochrysum stipitatum, Rhodanthe chlorocephala ssp. chlorocephala, Rhodanthe manglesii and Rhodanthe stricta, while an embryo dormancy which could be overcome by GA(3) limited germination of Brachyscome iberidifolia, Chrysocephalum apiculatum, Leucochrysum fitzgibbonii, Leucochrysum molle, Myriocephalus stuartii, Rhodanthe polygalifolia and Rhodanthe moschata. Light stimulated germination of Brachyscome iberidifolia, Chrysocephalum apiculatum, Hyalosperma glutinosum ssp. venustum, Leucochrysum fitzgibbonii, Leucochrysum stipitatum, Rhodanthe humboldtiana, Rhodanthe stricta, and Waitzia acuminata. However, germination of Rhodanthe chlorocephala ssp, chlorocephala was inhibited by light in control treatments. Recommendations for improved seed propagation of each species are summarised.