1. Maturity of embryo: The seeds of some plants, when shed will contain immature embryo. Such seeds germinate only after maturation of embryo.
2. Viability: Usually seeds remain viable or living only for a particular period. Viability of seeds range from a few days
(eg: Oxalis) to more than hundred years. Maximum viability (1000 years) has been recorded in lotus seeds. Seeds germinate only within the period of viability.
3. Dormancy: Seeds of many plants are dormant at the time of shedding.
