The science of seed storage
The following animation tells the story of a genebank manager’s efforts to ensure the seeds she sends out are viable. Breeders have an obvious need for seeds that will germinate, but seed viability is just as important for any user of genetic resources, whether they are a researcher in a university, a regional crop improvement network, an NGO, a community genebank or a farmer.
The animation reminds you of some of the processes genebanks use to conserve seeds, and introduces some of the scientific principles underlying them. You are probably already familiar with the processes, but perhaps not so familiar with some of the science. As you watch the animation, think about the biological processes that a genebank is relying on when they carry out these everyday routines.
Transcript: Video 2: Overview of genebank operations
The seeds of hope.
Conserved in the 1990’s, the traits of these seeds could solve some of today’s problems.
But the seeds have been in storage for a very long time.
Alessia, the genebank manager wants to share a sample with breeders.
But if the seeds are to be useful for breeding, Alessia knows she must ensure they are viable.
And that means applying the latest seed science.
Because these seeds have been ageing, even under the dry and cold conditions in the active store ...
The science of seed quality begins in the field.
As flowers develop into seeds, a lot of biochemical changes are going on.
Understanding the science of how seeds develop can help you improve your seeds’ chances of survival in the genebank:
How genes control the way the seeds develop …
The differences environmental conditions can make …
How to work out the best time to harvest …
In this course, you’ll learn about scientific discoveries that throw light on these important issues.
And can make improvements to seed quality management.
Once the seeds are checked into the genebank, time is of the essence.
The ageing process has already begun.
Alessia’s team must move quickly, to ensure the seeds are sorted before they lose viability.
In this course, you’ll use simple calculations to help keep your seeds in tip-top condition.
What can science tell us about managing seed quality in the drying room?
Should we dry seeds of some species at higher temperature for the first few days?
How can we make the most of movements of water into and out of the seeds?
And how does the amount of water within a seed affect which chemical reactions can go on inside that seed?
These are important issues, because water is crucial to the seeds’ viability.
Once they go into storage, these seeds will be kept in a state of suspended animation.
It’s amazing to think that inside these sealed bags are living things that must grow again, perhaps in many years’ time.
What’s keeping them alive?
Low temperatures and low moisture content put the brakes on ageing.
Giving the seeds the best chances of survival in the cold, dry store.
But once they come out of storage, the seeds will need higher temperatures and higher moisture content, to germinate.
Alessia knows the breeders she sends her seeds to, will depend on those seeds being able to grow.
So how can she check that her seeds have the potential to germinate?
And do so in sufficient number to be useful to breeders?
Viability testing gives her vital information about how well they are likely to grow.
As you work through this course, you’ll discover some underlying patterns in seed viability, and predictions you can make.
So you’ll be able to work out when you need to replenish your base stock, or the seeds you have available to send out to breeders.
But not all seeds germinate that easily.
Some wild species have a natural block that prevents germination.
It’s called dormancy.
In the wild, dormancy helps.
It ensures seeds do not grow in the wrong place or at the wrong time.
Like in a giraffe’s stomach!
Dormancy can help wild seeds to spread far from the parent plant.
But it’s not what you want in a genebank.
So how can you overcome this natural block to germination?
Again, understanding the science can help.
You’ll discover useful dormancy-breaking techniques.
So you can be sure your seeds will germinate when you want them to!
Alessia knows that the seeds in her genebank are only as useful as their genes.
It’s not enough to be able to regenerate the seeds.
What Alessia needs is for all new generations to continue to contain the same beneficial genes as the original ones.
This is called genetic integrity.
In future years, Alessia will compare every new generation of seeds to an original sample.
To ensure genes for beneficial traits do not get lost.
So with a bit of science, and a lot of record-keeping …
Alessia can be sure she is sharing exactly the same germplasm that originally arrived at the genebank many years ago.
The germplasm that breeders need.
When the time comes for you to distribute your own seeds, the science of seed quality management can give you peace of mind.
So when you send out seeds to breeders, you too can be sure your seeds are of the best quality.
This animation gives you an overview of the key processes in seed storage, and the biological processes they rely upon. Use the note-writing box below to write down what has struck you most about those biological processes, and why this science matters.
When you are ready, press 'reveal' to see our comments.
Discussion
The animation shows how seed quality management protects seeds through a number of processes, based on the underlying biology of the seed. At the drying phase, movement of water out of the seed is key. In the storage phase, whether this is over the short, medium or long term, seed longevity comes into play. When you carry out viability testing to see how well seeds germinate, you may need to consider natural mechanisms such as dormancy. And when replenishing your inventory (regeneration), you are considering seed development.
Genetic integrity: a key aim