How does the presence of endosperm affect seed size and germination?

Abstract

Endospermic seeds may germinate more successfully than non-endospermic seeds. The quantity of reserves of endosperm is directly related to seed size; large seeds may present higher percentages of germination than small seeds. We investigate whether the capacity for germination differs between seeds with and without endosperm in two species of Brassicaceae (Lepidium virgnicum and Brassica rapa) and two species of Fabaceae (Crotalaria pumila and Medicago sativa). We also investigate whether seed size within each seed type influences percentage of germination. Seeds were collected from populations of these species, weighed and classified as large or small seeds. Large and small seeds of species of both families, with both endospermic and non-endospermic seeds, were germinated under controlled conditions. Endospermic seeds of Brassicaceae presented a higher percentage of germination than the non-endospermic seeds. Non-endospermic seeds of Fabaceae germinated more than the endospermic seeds of the same family. Regardless of the presence of endosperm, large seeds presented a higher percentage of germination than small seeds. However, it is not possible to generalize that seeds with endosperm will be of greater size and thus present higher percentages of germination, since the species of Fabaceae do not fit this pattern. It is inferred that the endosperm acts as a storage tissue in Brassicaceae, while in Fabaceae it may function more as a protective barrier for the embryo, but this requires further investigation.

Keywords

• Brassicaceae
• cotyledons
• dicotyledons
• embryo
• Fabaceae