Seed dormancy

Some viable seeds may fail to germinate even in the presence of all necessary conditions for germination. This condition is known as seed dormancy. Seed dormancy can be caused by internal factors, such as immature embryo, hardness of seed coat and presence of inhibitors. Hard seed coat restricts water uptake and gaseous exchange. Seed dormancy can also be caused by external factors such as lack of water, air, optimum temperature, PH, and light. Seed dormancy can be overcome by soaking the seed in water to soften the seed coat and remove inhibitors. Mechanical abrasion such as scratching or burning the seed can also weaken the testa. Soaking seeds in alcohol or concentrated acid for certain period of time also helps to overcome seed dormancy. Some seeds break seed dormancy after passing through the gut of specific animal species in which the hard coat is softened and germination inhibitors are removed.