Solanum habrochaites crosses F2 fertilty

Last season I grew four F1 tomato/habro crosses. Their tomato mothers were College Challenger, Jaune Flammée, Matt’s Folly and Pink Berkeley Tie-dye. I collected lots of F2 seeds and this season sowed about 15 of each, so around 60 seeds. Of these I have had only a few germinate, one from Matt’s Folly and several from Pink Berkeley Tie-dye. On closer inspection the vast majority of the F2 seeds seem to be just empty cases. It appears that the F1s have a great deal of trouble producing viable seed. I wonder if anyone else has encountered this.

The F1 phenotypes were very much dominated by the father, Solanum habrochaites: leaf shape, flower structure and overall habit all were those of daddy. I wonder if daddy also imparted his self-incompatibility. There were buzz pollinators about but not in huge numbers and only late in the season so maybe I’m seeing only the natural crosses. Perplexing!

It looks like I’ll have to grow some more F1s and backcross them with tomatoes. This sets the project back a bit. Having only these F2s will not provide much of a genetic base from which to launch a mixed species landrace!

I used Joseph’s promiscuous project to cross with LA2329 on the assumption that it would maybe help to have a bit of recent cross with Solanum habrochaites in the mix. I made the cross twice in 2021 and 2022 so in 2023 I grew out both F1 and F2 seed which I ended up mixing. I put some in to germinate and it hasn’t done great yet but the cells in the flat may have been too moist. However, a few did finally come up so will see. I have quite a lot of seed- so am really actually thinking about trying to direct seed some of it to find out if that will lead to some useful natural selection. I tried to do the same with Big Hill and MMM in 2022 but in 2023 I made the mistake of growing them isolated from Promiscuous x LA2329. I think the F1 hybrids do have the S alleles! I attempted crossing Exserted Orange and Exserted Tiger both with LA2329 on the theory that the existing exsertion might be helpful. The EO x LA2329 cross has germinated great- but I don’t trust that it is a cross for sure. The ET x LA2329 cross is also up. Also I have more of the F1 seed for both though I might save it for next year.