Importance of hypocotyl hairs in germination of Artemisia seeds.

Abstract

The nature and function of hairs that occur on the lower portion of the hypocotyl of juvenile Artemisia seedlings was investigated. Our purpose was to determine if these hairs served an important function in seedling establishment of these species, which are often difficult to establish by direct seeding. The hypocotyl hairs occurred in a number of Artemisia species. The hairs form a dense ring around the bottom of the hypocotyl and the radicle emerges through the ring. Apparently, the function of the hairs is to attach the juvenile seedling to the surface of the germination substrate, which may aid in the penetration of the radicle into the substrate. Scanning electron microscope images of the hypocotyl hairs revealed the occurrence of mucilage which may aid in attaching the hairs to the substrate. In most studies, the seedling and breaking the contact of the hypocotyl hairs to the substrate reduced seedling survival and increased the number of surviving seedlings with abnormal geotropism.