Dormancy

• Most seeds do not grow or germinate immediately after they are formed. They go through a resting period called dormancy. Seeds often remain dormant until the following spring, when conditions are more suitable for germination.
• Dormancy is brought about in a number of ways:
  1. Growth inhibitors (e.g., abscisic acid) may be present in the outer part of the seed. These may be broken down by water, cold, or decay.
  2. Impermeable testa: The testa (seed coat) may block water or oxygen from entering the seed. The testa eventually decays and breaks down, allowing water and oxygen to enter the seed and germination to occur.
  3. Tough testa: A testa that is too tough may physically prevent the embryo from emerging.
  4. Lack of growth regulators: Seeds may lack the required growth regulators to stimulate germination. These regulators can be triggered by environmental factors such as increased light or higher temperatures in spring.

Advantages of Dormancy

1. Protects the seedling from harsh winter conditions.
2. Provides time for seed dispersal to new locations.
3. Allows a long growing season for seedlings after germination.
4. Staggered dormancy means seeds remain in the soil over time, increasing the species' chances of survival.

Breaking Seed Dormancy

• Dormancy means that seeds remain viable (i.e., capable of growing into new plants) for long periods of time, often over a year.
• This allows seeds to be stored and sold in packets for agriculture and gardening.
• Before planting, it may be necessary to treat the seeds in order to break their dormancy.
• This may involve: 5. Soaking the seeds in water: softens the testa, allowing water to enter the seed and activate enzymes. 6. Placing seeds in a cold place overnight: placing seeds in a cold environment overnight mimics winter conditions. Seeds are then moved to a warm location to simulate spring, encouraging germination. Tricks' seeds into thinking it's winter. 7. Scraping their surface to break the tough testa: scraping or scratching the testa (e.g., with sandpaper) weakens the tough seed coat, allowing water and oxygen to enter.