The seed coat's most important function is to provide protection for the

Sporophyte embryo. 

Seed coat are one of the three parts of the seed of plants. The endosperm, embryo and seed coat. The number one function of seed coat is for protection against the environment. A seed need protection from water, heat,. This can all affect the chance of being a mature animal. This can also provide insuation during sub freezing temperatures. It also protects the endosperm which is the primary source of food of the developing embryo.