With roughly a quarter of plant species facing extinction worldwide, scientists are working quickly to store many seeds for use in the future. Seedbanking is an area of science that provides an ‘insurance policy’ against a total loss of plants. As you now know, seeds are the most important part of the plant!
The Australian PlantBank is the award-winning home of plant conservation research, germplasm collection and storage in NSW, located at the Australian Botanic Garden Mount Annan. Our seed and tissue culture collections provide an insurance policy against extinction of native plants in the wild, including many edible bush foods.
Watch the short video below for a tour of the PlantBank facility with John Siemon, former Curator Manager at the Australian Botanic Garden, Mount Annan.
Scientists know that seed collections are the most compact and cost-effective method of storing a wide range of plants. So how do they do it? First, PlantBank scientists test seed collections to make sure they will be able to grow into healthy plants one day. To do this, they focus on three things: seed fill, viability and germination.
Testing Seed fill - is the seed full?
When seed collections come into PlantBank, seed fill (the internal part of the seed) is checked first, to see which seeds have an intact endosperm and embryo (see image below). This can be done by cutting the seeds in half with a scalpel and examining them under a dissecting microscope. This is called a 'cut test'. In some species, seed fill can be determined by floatation: a filled seed will sink while an empty seed will float. Also, scientists listen for the sound the seeds make when dropped onto a hard surface – empty seeds and filled seeds sound different.
Testing Viability - is the seed alive?
Whenever we make seed collections we try to ensure that seeds are viable and mature (ripe). If the seed is filled, scientists then need to find out whether the seed is alive (viable). This can be difficult, as living and dead seeds look exactly the same! The simplest test of viability is the germination test, as seeds that germinate are definitely alive. Viability is very important because if seeds are not viable, they will not germinate.
Testing Germination - is the seed ripe?
Germination refers to whether or not a seed can germinate or ‘sprout’. This happens when the embryo shoot inside the seed breaks through the seed coat and grows up towards the light. The number of seeds in a collection that pass the viability test doesn’t necessarily equal the number of seeds that can germinate, the difference being that some seeds are immature, or dormant (which means they are ‘asleep’).
Read more about our testing procedures and what a seed’s colour can tell us by clicking here. Also watch the videos for more footage of the PlantBank.