Summary
You have reached the end of module 3. In this module you have studied how seeds develop in the field, and how this development can be influenced by external factors such as temperature, climate, humidity and the passage of time.
Once seeds have entered a genebank, you have discovered how drying at different temperatures can help improve their longevity, and how important it is to make sure delays in processing are kept to a minimum. You have glimpsed some of the experiments that are starting to shed light on the genetic basis of seed longevity.
In the next online learning section, module 4, you will shift your attention to water activity in seeds, and discover what happens inside seeds when they are dried.
Module 3 at a glance:
- The longevity and viability of seeds is affected by environmental conditions while the seeds are developing in the field.
- Seeds continue to lose water after they have achieved mass maturity, and this too can affect their longevity and viability.
- When harvested too early, seeds still have high moisture content, which is associated with unacceptably high rates of decline in viability during storage.
- It is therefore important to harvest as close as possible to the time when natural dispersal occurs, and when seeds have dried naturally on the parent plant in situ.
- Where seeds have not dried in situ, initial drying at high temperature (eg: 30°C) followed by drying according to the Genebank Standards can improve the longevity of seeds.
- Whatever happens to seeds after they enter the genebank and before they are placed in storage can also affect longevity and viability.
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