Thanks and yes I'm familiar with the word cryogenic; even since way before I read any Arthur C. Clarke
. I note the need for drying before freezing. I'm not sure how well I can accomplish that but post-freeze germination testing would tell. An interesting experiment for my 'lab' (kitchen). And my little greenhouse is a pretty effective place to dry without burning.
I regularly keep all my seeds in the fridge, as dry as I can, and they stay viable longer than 'normal'; although I try to use them within their 'official' life span. But in this case I'm saving parsnip seed which does not 'germinate after many years'. Neither do onions, assorted alliums (allia!) and doubtless some others (corn? I don't grow that so haven't paid attention.)
One parsnip head gives a TON (not literally) of seed! I don't really need to save it indefinitely but I hate to throw most of it away and repeat the overwintering of the mighty plant & root if I want to keep saving seed.
I harvested the seed today - dried 'on the vine' and I'm already testing it.