One of the F1 hybrids that I managed to grow in the basement overwinter was [Jagodka X Loose/Open]. Don't know who the daddy was, other than it had an open flower structure. I managed to get 13 F2 plants ready by early summer. Today I scored the plants, and selected the ones I want to save for seed. Daddy was a red-fruited determinate plant with a somewhat longer growing season than Jagodka. All of the flowers of the F2 had industrialized flowers.
F2: Jagodka X Loose/Open
Among the F2 of [Hillbilly X Jagodka] I found some indeterminate plants with internode-distancess about 1/3 the length of some of the other plants. What that did, was make them compact plants that almost resemble determinates. I collected the first blushing fruits from the patch today. I'm letting them finish ripening in the shed.
I made my final (until I change my mind) determination today about what plants to save a lot of seeds from in the [DX52-12 X Jagodka] F2 clade. I tasted fruit from every plant. Bleck!!! More details about that in a post in a few days. I ended up eliminating some plants based on bad taste. I eliminated a lot based on small fruits. I eliminated some based on lack of vigor or productivity.