Low- and High-temperature Storage Effects on Viability and Germinability of Seeds of Three Australian Asteraceae

Abstract

Commercialisation of many Australian everlasting daisy (Asteraceae) species islimited by poor germination, due in part to dormancy. This study examined theeffect of storage temperatures of 5, 15, 25 and 38°C on seed viability andgerminability of Schoenia filifolia subsp.subulifolia, Rhodanthe chlorocephala subsp.rosea and an unnamed species ofCraspedia. Short-term storage (< 18 months) at cooltemperatures increased seed moisture content, reduced viability and did notpromote germination. However, storage at high temperatures decreased seedmoisture content, maintained viability and improved germination. In tests oflong-term (> 24 months) storage in ambient conditions, both viability andgerminability declined in cohorts of Schoenia andRhodanthe. Detailed tests on 8-month-old seeds ofSchoenia revealed that dormancy was not due tomechanical barriers, as scarification did not improve germination. However,gibberellic acid (GA₃) and KNO₃applications overcame the dry-storage requirement to break dormancy in thisspecies. High-temperature, dry storage is an important treatment to breakdormancy for planting arid-zone Asteraceae seeds of less than 6 months of age.