Ultrastuctural dimorphism of micropyle determines differential germinability of Sesbania cannabina seeds

Abstract

S. cannabina seeds, obtained from a naturally occurring single population contained both dormant and non-dormant seeds. The water uptake pattern indicated that non-dormant seeds absorbed sufficient water to allow them to germinate whereas dormant seeds failed to germinate due to restricted water entry. Using a scanning electron microscopy testa ultrastructural studies revealed that the closed micropyle and limited opening of the hilar groove restricts water from entering dormant seeds whereas an open type micropyle allows large amounts water uptake and successful germination in non-dormant seeds. So, variability with respect to germinability and testa ultrastructure exists within a single seed lot of S. cannabina. In this case micropyle acts as the determining factor for dimorphism and influences the germinability.