Module 4: Water activity in seeds
Introduction
Welcome to the fourth module of this online course. In previous modules, you learned how seeds naturally lose water while maturing on the parent plant, and that this drying has an impact on seeds’ longevity in storage. In this module, we will take a deep dive into the mechanisms for this.
Genebanks invest a lot of effort in controlling the amounts of water in seeds. Why go to this trouble? In this module you will learn what happens inside seeds as water enters and leaves, and why movements of water can have so much impact on seed longevity and viability.
Variables such as temperature, gaseous environment and moisture history can also affect movements of water in and out of seeds, and either promote or damage the seeds’ ability to germinate once they come out of storage. You can save time and money by monitoring the amount of water in seeds carefully.
By the end of this module, you will be in a good position to apply what you have learned to your own work. We will give you the opportunity to read about the science of this in more depth in our ‘Useful publications’ section.
By the end of this module, you should be able to:
- Describe what changes take place inside a seed when water enters and leaves it.
- Give examples of different drying strategies that can help maintain viability during storage.
- Explain the effect of different combinations of temperature, humidity and moisture history on seeds.
- Calculate the amount of water in a sample of seeds.
- Describe new techniques for measuring water activity and equilibrium relative humidity.
- Explain how genebanks can improve their practice based on research evidence.
- Evaluate the procedures in your own genebank’s workflow.