Causes of seed dormancy in seeds ?

1. Physical dormancy: Some seeds have hard seed coats that prevent water and oxygen from entering the seed, inhibiting germination. This type of dormancy can be overcome by scarification, which involves breaking or weakening the seed coat.

2. Physiological dormancy: This type of dormancy is caused by internal factors within the seed that prevent germination. For example, some seeds require a period of cold temperatures (stratification) or exposure to light (photodormancy) before they can germinate.

3. Chemical dormancy: Some seeds contain chemical inhibitors that prevent germination until certain conditions are met. For example, some seeds require exposure to fire or smoke to break down these inhibitors and allow germination to occur.

4. Morphological dormancy: This type of dormancy is caused by underdeveloped embryos within the seed. The embryo must mature and develop fully before germination can occur.

5. Environmental factors: External factors such as temperature, light, and moisture levels can also affect seed dormancy. Seeds may remain dormant until conditions are favorable for germination.

6. Genetic factors: Some plant species have evolved mechanisms to delay germination until conditions are optimal for seedling survival and growth. This genetic dormancy ensures that seeds germinate at the right time and in the right environment.