Oct. 27, Seed Dormancy and Seed Banks

Seed dormancy means that seed is in a state of suspended growth and development. This is a reduction in the metabolic rate. This gives resistance to adverse environmental conditions.

The conditions that must be present to break dormancy differs by species. Some species germinate as soon as the environment is suitable for growth. Other species need something else such as; An intial drying period, exposure to a long period of cold, scarification of the seed coat, or intense heat.

There are possible selective advantages to these cues to break dormancy. The cue for long periods  of cold are advantagious for species because of long winters.

Different species of plants produce seeds that require different cues to grow. A seed bank is produced by the different speices’ seeds waiting for these cues. A seed bank is a collection of dormant seeds in the soil. Seed banks allow dispersal in time as well as space.

There is a broad inverse correlation between the lifespan of adult plant and longevity in the seed bank. Annual plants will tend to have seeds that last for a long time . The storage effect is a model that shows the environment varies over time, and different species respond to the environment each year. An environment good for one species may not be good for another species. As long as the species has atleast one tough life storage stage that can get you from one good year to another good year this prevents the population from crashing. Populations stores up the good years to make it through the bad ones.

Long lived seeds do not need long live matured plants, but long lived matured plants do not need long lived seeds.

 

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