Physical dormancy and soil seed bank dynamics in seeds of Melilotus albus (Fabaceae)

Abstract

Information on seed germination and the soil seed bank of a species is important because it contributes to a better understanding of plant reproductive strategies. Melilotus albus (Fabaceae) is considered valuable for honey production and is frequently cultivated as livestock forage. However, it is difficult to germinate M. albus seeds. The primary goal of the present study was to determine the environmental requirements for breaking seed dormancy and the dynamics of soil seed bank. The results indicate that seeds of M. albus have a water impermeable seed coat which can be penetrated by scarification or alternating wet heat and ice water cycles; however, wet heat or dry heat alone were ineffective. After receiving 30 cycles of alternating wet heat and ice water treatments, cracks formed in the lens of seeds. Under natural precipitation and temperature, > 60% of the seedlings emerged in spring. A persistent soil seed bank formed and most seeds were found in the 0–2 cm soil layer. Our findings indicate that seeds of M. albus have physical dormancy; persistence of the seed bank might spread risks associated with a specific seed cohort over multiple years.