OVERCOMING SEED DORMANCY IN EX-SITU PLANT GERMPLASM CONSERVATION PROGRAMS - AN EXAMPLE IN THE ENDEMIC ARGYRANTHEMUM (ASTERACEAE, ANTHEMIDEAE) SPECIES FROM THE CANARY-ISLANDS
Germplasm of 21 diverse Argyranthemum taxa was collected from contrasting ecological zones in the Canary Islands. Seed dormancy was considerable in the majority of taxa. Extensive investigations, based on a germination test procedure algorithm for Asteraceae, with achenes from ray and disc florets of five contrasting taxa identified a procedure to promote full (greater-than-or-equal-to 85%) germination of the seeds from both ray and disc florets of all five taxa; viz, excision of the seeds from the achenes, followed by testing at 15-degrees-C with 2.6 x 10(-3) M GA3 co-applied. Subsequent tests showed that this regime was effective in promoting full germination in seeds from both ray and disc florets of the remaining 16 taxa. The results are discussed in the context of ex situ plant germplasm conservation.