Small datapoint on seed saving
A few years ago a woman for whom I had done a favor gave be a squash as a token of gratitude. I liked it's flavor so I saved seeds from that one specimen and have been growing it since. I have identified it as belonging to the species Cucurbita mixta, a.k.a., Cucurbita argyrosperma. It is a Winter squash of the Cushaw type with a rather hard skin. Fully mature ones require the use of a meat clever and hammer to split open. It keeps well and flavor is good. Since I was running low on the original saved seeds I saved and dried some more this Fall. After drying under air conditioned indoor conditions for a month or so I checked germination on a sample of 10 and got 0/10 = 0%. Next I further dried with the aid of desiccant for several weeks until indicated RH in the bag was below 20%. Again checked germination and got 0/10 = 0%. Next I stored the seeds with desiccant in the freezer for about a week then thawed and rested at room temperature for a few days. Again checked germination and this time got 9/10 = 90%. In retrospect I should have set aside some of the desiccant dried seeds to not be frozen as I cannot say whether the change from 0 to 90% is from the storage frozen or simply the passage of added time. Notably this species is believed to have originated in central Mexico in areas possibly not subject to freezing temperatures.
While not really relevant to the subject of this post, I will attach a photo of the squash under discussion just because I can.