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Germination
Why seed germination?
Why seed germination?
In some ways, a plant seed is like a tiny time capsule: in 2012, scientists managed to germinate some seeds that were over 30,000 years old (Yashina et al., 2012)! Not only were they able to successfully grow plants, but the plants themselves also successfully produced another generation of viable seeds!
These observations raise a simple question: How did these seeds know when to germinate? As with other organisms, seeds must be able to sense different conditions in the environment, integrate that information, and respond. To answer this question, we must dive in deep to conduct experiments to assess how the germination process works.
The flipside of germination in plants is a condition known as dormancy, which is a period of arrested plant growth. Dormancy is crucial for survival for many plants that inhabit environments where there are conditions or periods of time that don't favor growth, such as during the winter or during dry periods. A seed can be considered to be dormant if it refuses to germinate in spite of what seem like perfectly favorable conditions for growth. This suggests that there may be some endogenous or internal factors that are acting to prevent germination.
To give one example of where and when this could be important, think of what happens to environmental temperatures and day length in the spring and fall. There are points where day lengths and temperatures are very similar during each season, but a plant's fate may be very different if it relies just on these two pieces information and germinates in the fall instead of the spring.
A Question to Consider Before you Begin:
A Question to Consider Before you Begin:
What environmental cues do you think plants might use to help decide that it is time to germinate? Try to come up with a list, and also take a minute to elaborate on how you think each specific cue might be detected by a seed and then translated into a decision to germinate.
References
References
Yashina S, Gubin S, Maksimovich S, Yashina A, Gakhova E, Gilichinsky D (2012) Regeneration of whole fertile plants from 30,000-y-old fruit tissue buried in Siberian permafrost. Proceedings of the National Academy of Sciences 109: 4008–4013
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