Maturity-Dormancy Relationships in Attached and Detached Seeds of Medicago lupulina L. (Black Medick)

Abstract

Seeds of Medicago lupulina L. (black medick) possess a nondormant phase during their development. The duration of this phase depends on the environment under which the seeds mature and the genotype of the parent plant. Both seeds attached to the parent and those detached before maturity exhibit this behavior. The ecological significance of the nondormant phase is that developing seeds can germinate immediately under favorable conditions, thus establishing large populations rapidly in a suitable habitat. Seeds maturing under less optimal conditions for germination develop an impermeable testa and a strong dormancy, which can last for many years. Morphological and anatomical studies indicate that embryo maturity precedes the development of impermeability in the testa.