Seed germination

Posted on Nov 9 2011 at 12:36:01 AM in House & Garden

Seed germination

When germinating seed it is helpful hi remember that a seed is made up of three parts:

—an outer protective coat

—a food supply under the seed coat (the endosperm) —an embryo of a young plant

The protective coat prevents sprouting until ideal growing conditions exist. Bringing seeds out of dormancy involves manipulating conditions to hasten germination. Even with ideal conditions, some seeds are still very difficult to germinate.

There are several factors that affect germination. Water (moisture), light (or dark), oxygen and heat play a part in triggering germination. In addition to environmental factors, seed most be viable.

Water is essential in the first phase of germination. Water penetrates the seed coat and causes the endosperm to swell. The seed coat, softened by water, splits open as the endosperm swells. The water dissolves nutrients in the endosperm making them available to the embryo and growth begins.

The growing medium most be constantly moist, but not wet. Any dry period may cause death of the sprouting embryo. Light can stimulate or inhibit a seed's germination. This determines whether the seed should be sown on the surface of the growing medium or below the surface. Check the seed packet or catalog for light requirements.

Oxygen is required by the embryo to begin growing. The seed must respire to break down the food stored in the seed. This is one reason for using a light, well-aerated growing medium for starting seeds.

Every seed has an optimum temperature range for germination. Many seeds have a fairly wide temperature range for germination, but some are limited to a narrow range. The temperature range is usually given on the seed packet or in the catalog.

The temperatures required by many seeds are higher than those in most homes. The desired constant temperature can be achieved through heating cables placed under germination containers. Setting fiats or pots on radiators, the furnace or on the refrigerator will provide bottom heat. However, these locations may be too hot and cause the soil to dry too quickly.

Once germination occurs, a different, usually lower, temperature may be required for optimal growth of the seedlings.

Seed scaehcelion

The coat of certain seed is extremely tough and must be penetrated by special means. Particularly hard seed may be scarified. Scarification involves breaking, scratching or softening the and coat to allow moisture penetration.

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Created: Nov 9 2011 at 12:36:01 AM
Updated: Nov 9 2011 at 12:36:01 AM
Category: House & Garden
Language: English