Structural Characteristics of Shells in a Fibrous Cultivar of Cannabis sativa L

Abstract

ABSTRACT Most commercial products of dehulled hemp seeds frequently include dark green remnants of shells. The entire removal of shell particles including seed coats and pericarp pieces can improve the quality of hempseed-based products. In this study, the structural characteristics of fruit walls (pericarp) and seed coats of Cannabis sativa were examined using scanning electron microscopy. The pericarp was comprised of three distinct zones, exo-, meso-, and endocarp. The exocarp and the mesocarp were tightly fused to form a thick layer. The endocarp was characterized by its sclerenchymatous columnar cells, which contained greatly thickened and multi-porous cell walls. On the other hand, the seed coats were comprised of two leathery coats, the outer and inner coats. The outer seed coat was a conspicuous layer with a reticular-shaped structure like a net. However, the three-layered inner seed coat was composed of two thin layers (inner seed coat 2, inner seed coat 3) and a large rectangular cell layer (inner seed coat1) at the lower position. This work provides a better understanding of the structural characteristics of hemp shells. It will lead to the improvement of dehulling machinery of hempseed and help ensure stringent quality control of hempseed-based products.