Hi GMCPaul,
Lets approach this from a little different angle. Remember the fire triangle? Fuel, heat, and oxygen are required to start and sustain a fire. Fungal diseases in ginseng are similar in that they need the host plant (in this case the seed), the pathogen and moisture. One of the biggest issues in stratifying seed is keeping it disease free. Just like removing oxygen from a fire, if you remove excess moisture you reduce the chance of fungal disease greatly.
The commercial growers I know of always stratify their seed above ground. This helps to prevent rust which has been associated with temperatures getting too cold. After depulping, they treat the seed with a fungicide and mix it with pre-sifted sand, and place the seed/sand mix into plastic totes in a large cooler. The temperatures are cool, but not freezing. As the weather turns cold, the seed doesn't get so cold as to induce rust. In the spring, the totes are taken out into an open air building to warm naturally. It stays there until it is time to plant in August. When it is time to plant, the sand is washed off the seed with water (this is the only water the sand will see in the cycle). Most of the seed at this point will float. However, the moisture retained in the sand during stratification is sufficient to keep the seed completely viable.
After separating seed from sand, the seed is put into large tubs of water and allowed to soak/hydrate over night. The next day, the seed is stirred well and the remaining floaters are skimmed off. The seed is then spread out to dry again. After a few days, they normally bleach the seed. Some growers rinse the bleach off, others don't. They see this as an additional deterrent to disease organisms. Again, the seed is left to surface dry so it will flow through automated seeders.
The seed I have this year is testing viability in the high 90%s, but about 20% of it will float when it gets to me. Cracking a few of those seeds will reveal that most of those floaters are still good seed. Don't forget, the grower floats the seed also right out of the boxes. So any seed that goes beyond that point, sank at some point.
I did an unwitting experiment a couple years ago with a few ounces of seed that I'd forgotten about after planting and left in a plastic tub behind the seat of my pickup. We were having weather in the 80s when I realized that seed was still there. On a lark I went ahead and soaked it thinking I could use it as material for testing seeder designs. To my surprise, nearly all the seed sank and about half of it was grinning within a day's time. I planted it, and it remained viable (even grinning) in that bed all summer. That fall i moved and scooped up the top couple inches of soil from that bed with some of those seeds in it. I spread that soil and seed over a tilled bed around some ferns and mulched it with straw. Some of those seeds germinated last spring -not a high percentage, but enough to show that the seed can withstand much dryer conditions than we had previously thought even though in this case an additional dormancy period was experienced.
So, when you say
\"Seems to me if you were using seeds that's been stratified and lost so much moisture that they float that these seeds could be far closer to the end of there viability since they've lost so much moisture they float they may not retain enough to remain viable until time to sprout\"
, you are simply mistaken. I understand your logic...as I shared it until I learned better. Now, if seed is allowed to dry out too much, viability will indeed be affected. But seed can be dry enough to float and still be completely viable and in fact show very high germination rates.