干旱区生态环境知识资源中心

Commercialisation of many Australian everlasting daisy (Asteraceae) species is limited by poor germination, due in part to dormancy. This study examined the effect of storage temperatures of 5, 15, 25 and 38 degrees C on seed viability and germinability of Schoenia filifolia subsp. subulifolia, Rhodanthe chlorocephala subsp. rosea and an unnamed species of Craspedia. Short-term storage (< 18 months) at coot temperatures increased seed moisture content, 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 ambient conditions, both viability and germinability declined in cohorts of Schoenia and Rhodanthe. Detailed tests on 8-month-old seeds of Schoenia revealed that dormancy was not due to mechanical barriers, as scarification did not improve germination. However, gibberellic acid (GA(3)) and KNO3 applications overcame the dry-storage requirement to break dormancy in this species. High-temperature, dry storage is an important treatment to break dormancy for planting arid-zone Asteraceae seeds of less than 6 months of age.