Seed Dormancy - Plant Growth Substances

Seed dormancy is critically important for the survival of plants. Factors involved in seed dormancy are:

A. Environmental Factors

1. Light requirement for germination-positive or negative
2. High or low temperatures
3. Absence of water

B. Internal Factors

1. Seed coat-prevention of gas exchange
2. Seed coat-mechanical effects
3. Embryo immaturity
4. Low ethylene concentration
5. Presence of inhibitors
6. Absence of growth promoters.

C. Timing Mechanism

1. After-ripening
2. Disappearance of inhibitors
3. Synthesis of growth promoters