What is seed dormancy ? Explain the methods of breaking dormancy.

Explanation

The condition of a seed when it fails to germinate even in suitable environmental condition is called seed dormancy. Two types of dormancy: Imposed dormancy and innate dormancy.
Methods of breaking dormancy:
1. Scarification: Mechanical and chemical treatments like cutting or chipping of hard tough seed coat and use of organic solvents to remove waxy or fatty compounds are called as scarfication.
2. Impaction: In some seeds water and oxygen are unable to penetrate micropyle due to blockage by cork cells. These seeds are shaken vigorously to remove the plug which is called Impaction.
3. Stratification: Seeds of rosaceous plants (Apple, plum, peach and Cherry) will not germinate until they have been exposed to well aerated, moist condition under low temperature `(0^(@)C to 10^(@)C)` for weeks to months. Such treatment is called stratification.
4. Alternating temperatures: Germination of some seeds is strongly promoted by alternating daily temperatures. An alternation of low and high temperature imporves the germination of seeds.
5. Light: The dormancy fo photoblastic seeds can be broken by exposing them to red light.