Physical and chemical difference of seed coat between hard and soft seeds of Licorice (Glycyrrhiza Uralensis Fisch)

In this paper, the physical and chemical differences of seed coat between hard and soft seeds from the same Licorice lot were identified. Electron microscopy-based examination revealed that the cracks on hard seeds coat were much less obvious (shallower and narrower) than those of soft seeds, and that hilar fissure from hard seeds was considerably narrower. Endosperm of hard seeds was markedly thicker than that of soft seeds. Finally, X-ray fluorescence spectrometry revealed significant enrichment for 12 out of the 14 tested mineral elements in hard seed coat. It could be concluded that these above features of hard seeds would increase their resistance to physical impact and protect against cracks in seed coat surface, thus contributing to the impermeability of hard seeds.