Write short notes on seed dormancy.

Dormancy: The failure of a seed to germinate due to unfavourable internal conditions, even though external conditions like temperature, moisture are suitable is called dormancy.
* The dormancy of seed may be caused by hard seed coat. Eg : Fabaceae.
* Dormancy caused by hard seed coats can be broken by scarification.
* Seeds of plants like tomato contain chemical compounds, which inhibit their germination.
* Seed germination may be inhibited if embryo fails to reach morphological maturity.
Eg : Ranunculus.