Low- and high-temperature storage effects on viability and germinability of seeds of three Australian Asteraceae

Commercialisation of many Australian everlasting daisy (Asteraceae) species is limited by poor germination, due in part to dormancy. This study examin ed the effect of storage temperatures of 5, 15, 25 and 38 degrees C on seed viability and germinability of Schoenia filifolia subsp. subulifolia, Rhod anthe chlorocephala subsp. rosea and an unnamed species of Craspedia. Short -term storage (< 18 months) at coot temperatures increased seed moisture co ntent, reduced viability and did not promote germination. However, storage at high temperatures decreased seed moisture content, maintained viability and improved germination. In tests of long-term (> 24 months) storage in am bient conditions, both viability and germinability declined in cohorts of S choenia and Rhodanthe. Detailed tests on 8-month-old seeds of Schoenia reve aled that dormancy was not due to mechanical barriers, as scarification did not improve germination. However, gibberellic acid (GA(3)) and KNO3 applic ations overcame the dry-storage requirement to break dormancy in this speci es. High-temperature, dry storage is an important treatment to break dorman cy for planting arid-zone Asteraceae seeds of less than 6 months of age.