BREAKING OF DORMANCY IN THE SEEDS OF ASTRAGALUS-MONGHOLICUS BUNGE (LEGUMINOSAE)

The cause of seed dormancy observed in Astragalus mongholicus Bunge an d its breaking method were studied. It was clear that seeds of this pl ant have dormancy caused by an impermeability that developed with prog ressive dryness of legumes and seeds. The hard-seededness started with in 9 days after being harvested from the plants grown in the field. Th is impermeability of the seeds was easily broken by freezing treatment with water at -22 degrees C in a deep freezer, followed by thawing. T he germination percentage increased rapidly with longer freezing. From these findings, we concluded that freezing treatment with water at -2 2 degrees C for more than 30 days followed by thawing is useful for br eaking impermeability of the seeds of A. mongholicus. This simple meth od will be applicable to cultivation in the field.