Seed Dormancy of Nodding Beggarticks (Bidens cernua L.)

Abstract

For prompt germination, the achenes of the nodding beggarticks (Bidens cernua L.) required 6 to 12 weeks of afterripening at 2 C and exposure to light. Without cold afterripening, a slow but complete germination was obtained after 2 weeks when the achene and seed inside, or the seed excised from the achene, were clipped at the distal end and germinated in light at 24 C. The embryo behaved like a clipped seed. Complete germination within 7 days, in light or dark, of the clipped seed was obtained by treating with gibberellic acid (GA) or N-6-benzyladenine (BA). The barriers to germination in the non-after-ripened seed appear to be first in the achene, the coverings of the seed itself and in a metabolic factor.