Frøskallet

Frøskallet, also known as the "seed skin" or "seed coat," is a protective covering that surrounds the embryo of a seed. It plays a crucial role in the germination process and the survival of the seed. The seed coat is typically composed of two layers: the testa and the tegmen. The testa is the outermost layer, which provides physical protection against mechanical damage and pathogens. The tegmen, located beneath the testa, is a waxy layer that helps to regulate water absorption and prevents the seed from drying out.

The structure and composition of the seed coat can vary significantly among different plant species. In some plants, the seed coat is hard and woody, providing robust protection for the embryo. In others, it is thin and delicate, allowing for easier water penetration but offering less protection. The seed coat also contains various compounds that can influence germination, such as inhibitors that prevent premature germination and stimulants that promote it.

During germination, the seed coat must be broken down to allow the embryo to emerge and begin growing. This process is facilitated by enzymes produced by the embryo itself, which degrade the seed coat's protective layers. The timing and extent of seed coat degradation are critical for successful germination and the establishment of the new plant.

The seed coat's role in seed biology is multifaceted, serving as a barrier against environmental stressors, a regulator of water and nutrient uptake, and a determinant of germination timing. Understanding the structure and function of the seed coat is essential for advancing our knowledge of plant reproduction, seed biology, and agricultural practices.