Cross-breeding chilis (on purpose!)

That's an interesting but complicated chart, gringo. I think it's probably not very useful to us ordinary gardeners and experimenters. I'll try and answer your question as simply as I can.

Chillies and sweet peppers, when left to their own devices, are mainly self-pollinating, but they are sometimes cross-pollinated by insects. So if the chilli you nibbled and liked was grown from non-hybrid seed, there's quite a good chance that replanting its own seeds will result in offspring with similar fruit. But if it happened to be a fruit from a cross-pollinated flower, they might turn out very different from their parent. It could be interesting to grow out seeds from those hybrid offspring, and after growing out and selecting for a few generations you might have a new stable variety. But if you wanted to maintain the original pure variety, you would reject them as off-type.

If you wanted to deliberately cross two varieties and leave it less to chance, then you would need to isolate the parent plants or flowers, by distance or barrier, and remove the anthers from a female parent flower before they shed their own pollen. Then hand pollinate it with pollen from the desired male parent variety. That way all the seeds should produce F1 hybrid offspring to start your breeding experiment with. It's fiddly but not complicated.

But if that nibbled chilli was from a commercial variety, it could already be an F1 hybrid. Lots of peppers and chillies are hybrids nowadays. That means the seeds in it will produce F2 hybrid plants which could be very variable, depending on how different the two original crossed parents were. Some look very different and others less so. The differences could be in less visible characteristics like disease resistance or earliness.

So starting with an F1 variety could eliminate the first step of hand pollinating, if you want to experiment with breeding your own new variety. Some amateur breeders have also worked at de-hybridising their favourite F1 varieties to produce a similar non-hybrid variety, by growing out the seeds and selecting offspring similar to the desired type in each generation.

But, getting back to Chileman's chart, it's about crossing different Capsicum species, not varieties. It shows that this can be done in some cases, but the highest fertility (HF) is obtained when both parent varieties are from the same species (except for a few obscure and very closely related species). So I'd recommend you stick to crossing the same species too, unless you want to start with something more difficult and less likely to succeed.

I'm not sure how those chart results were obtained, but if it was from breeding experiments by plant scientists, they have laboratory techniques for increasing the success of inter-species hybrids that us ordinary gardeners don't have.

Some of the species on that chart are also obscure and rare in our part of the world. Our most common species is C. annuum, which includes a wide variety of chillies and sweet peppers. Others that used to be rare but are becoming more readily available nowadays are C. baccatum, C. chinense, C. frutescens and C. pubescens. I've had good success with growing C. baccatum varieties, and it could be interesting to try crossing some of them.

Oh, that turned out to be a long complicated reply. My shorter answer is, plants grown from the seeds of some random chilli that you don't know the origin of might produced similar chillies or they might be very different. If they are different there was probably cross-breeding at some stage, but it's unlikely to be an inter-species cross. It's most probable that the cross was between two varieties of the same species. You could try it if you like experiments and surprises. The result will probably be edible, but you might be surprised by the level of heat if the cross was with a sweet or much hotter variety. If you want to do your own deliberate cross, it's best to choose parents that are different varieties of the same species. You'll need to isolate the parent plants or bag the flowers, and remove the anthers from the female parent flower before they start to shed pollen, and then carefully hand pollinate with pollen from the plant you want to be the male parent. You could just grow two different varieties close together outdoors, and hope bees will cross pollinate some of the flowers. But you won't know which of the seeds, if any, result from crossing until you grow them and see the fruits.

Great info - thanks Zelenina!

You're welcome! I hope it was all understandable. Feel free to ask more questions.

The other thing is that, once you have crossed your chillies, you will need to grow (and isolate) a large number of the seeds into plants to make sure you have plants to select the best traits from. And then also grow them for a number of years if you want to have a stable. open-pollinated new variety. I think it is 7 generations, which with lights and heat you could compress into about 4.5-5 years BUT in that period you'd have to have enough space to grow those chillies and keep them from crossing from others.

For me, it's that last bit that stops me. I don't have much room. Or patience. That said I will be trying to stabilise a bean that has come about as either a rogue or cross with Pea Bean Inca.

I crossed a Numex Twilight with a Red Cayenne. It wasn't particularly scientific, and I didn't bother with hand pollination. Just gave the Cayenne a gentle tap and shake while holding it above the Twilight, at the stage when both plants were in flower.

I've grown a small number of F1s and a few F2s, with a lot more variations appearing in the F2s, as would be expected. None of the plants so far have had the best characteristics of both parents. And the best plants didn't produce the best tasting pods, so it's been an interesting experiment rather than a great success.