Germination
|
|
In a botanical sense, germination is the process of emergence of growth from a resting stage. We typically think of the sprouting of a seedling from a seed of a flowering plant or gymnosperm. However, the growth of a hypha from a fungal spore is also germination. In a more general sense, germination can imply anything expanding into greater being from a small existence or germ.
Seed germination
The seed of a higher plant is a small package produced in a flower or cone containing an embryo and stored food reserves. Under favorable conditions, the seed begins to germinate, and the embryonic tissues resume growth, developing towards a seedling. The part of the plant that emerges from the seed first is termed a radicle. In some definitions, the appearance of the radicle marks the end of germination and the beginning of establishment, a period that ends when the seedling has exhausted the food reserves stored in the seed. These are critical phases in the life of a plant. The mortality between dispersal of seeds and completion of establishment can be so high, that many species survive only by producing huge numbers of seeds.
Some seeds require particular conditions to germinate, such as the heat of a fire (e.g., many Australian native plants), or soaking in a body of water for a long period of time.
Stratification of seeds
Seeds must be mature and environmental factors must be favorable before germination can take place. When a mature seed is placed under favorable conditions and fails to germinate, it is said to be dormant. The length of time plant seeds remain dormant can be reduced or eliminated by a simple seed treatment called stratification. Seeds should be planted promptly after stratification. If the seed is allowed to dry out, dormancy may be triggered again and your efforts will be wasted.
External links
- The Seed Site (http://theseedsite.co.uk/): collecting, storing, sowing, germinating, and exchanging seeds, with pictures of seeds, seedpods and seedlings.
- Sowing Seeds (http://theseedsite.co.uk/seedsowing.html) A survey of seed sowing techniques.
- Seed Germination: Theory and Practice, Norman C. Deno, 139 Lenor Dr., State College PA 16801, USA. An extensive study of the germination rates of a huge variety of seeds under different experimental conditions, including temperature variation and chemical environment.
- How to Germinate Seed (http://www.evergreengardenworks.com/seed.htm) A bonsai propagator's views.