Final answer:
The primary function of the seed coat is to offer desiccation resistance, protecting the embryo by preventing it from drying out and enabling dormancy for extended periods.
Step-by-step explanation:
The seed coat's most important function is to provide desiccation resistance for the seed, thereby ensuring the protection of the embryo within. During the plant's reproductive process, the seed coat develops from the integuments of the ovule, creating a rigid, protective layer. This is critical for the seed to maintain dormancy, which can last for varying periods depending on the environmental conditions, thus dispersing the progeny through time. Additionally, the seed coat aids in providing physical protection against mechanical damage.