Seed dormancy is generally an undesirable characteristic
in agricultural crops, where rapid germination and growth
are required. However, some degree of dormancy is advantageous,
at least during seed development. This is particularly
true for cereal crops because it prevents germination of
grains while still on the ear of the parent plant (preharvest
sprouting), a phenomenon that results in major losses to the
agricultural industry. Extensive domestication and breeding
of crop species have ostensibly removed most dormancy
mechanisms present in the seeds of their wild ancestors, although
under adverse environmental conditions, dormancy
may reappear. By contrast, weed seeds frequently mature
with inherent dormancy mechanisms that allow some
seeds to persist in the soil for many years before completing
germination.