Good question, Glen! For the ECHO seed banks, we use the 10% bleach soak when we do germination testing in a sterile lab situation for petri and paper towel tests. This cuts down on mold that might grow in the petri dish or wet paper towel. These tests quickly gives us a better idea of how many seeds are alive without having to plant them in soil.
Mold isn’t usually an issue when seeds are planted in soil where there is balance of good and bad fungi so we don’t use the bleach soak when we do soil germination tests. Using bleach doesn’t inhibit germination but it isn’t necessary for germinating seeds in soil. Please keep in mind that germination testing is usually required for any company or organization that sells seeds. The test needs to be accurate and the purpose is to let customers know how many seeds in that packet are viable.
If it was my own personal seeds, I would just stick them in a wet paper towel without bleaching them and see how many germinate after a few days so that I know how many to seeds I should plant in the field. Some people pre-germinate their seeds and then plant them, but a simple germination test uses a small sample of seeds and is mainly used to know the viability of a seed lot in preparation for planting.
In case you are curious, we use petri and paper towel tests for seeds that will germinate within a week or so because it cuts down on the cost of using soil for tests. We use soil tests for seeds that need a little longer to germinate (some seeds can take 2 months before they sprout!) or that don’t germinate well outside of the soil. If you have any other questions or thoughts, feel free to post them!