The dormant state is inherent to the seeds of the overwhelming majority of wild-growing plants, as well as many
cultivated plants. The ability of seeds to maintain viability for a long time without proceeding to germination is one of the
most important adaptive properties of plants. It allows them to outlive the unfavorable periods of the year; therefore, a stock
of seeds is created in the soil, which is an important condition for the preservation of species.
The seeds differ in the depth of dormancy and in the methods of taking out from it. On the basis of this the classification
system of types of dormancy developed by M. G. Nikolaeva and recently slightly modified by J. M. Baskin и C. C. Baskin has
been built. Five classes of dormancy were identified: physiological (PD), morphological (MD), morphophysiological (MPD),
physical (PY) and combined (PY + PD). Physiological dormancy, in its turn, is divided into deep, intermediate and shallow.