I’m so excited! Y’all know how introgressing cold hardiness genes from Poncirus trifoliata, the trifoliate orange, into tastier citrus species is difficult, because the F1 hybrids are essentially mules? They can make seeds, but the seedlings are clones of the mother plant, so they’re dead ends for breeding purposes. So, we have all these citrange (trifoliate orange x tasty orange) and citrumelo (trifoliate orange x pomelo) F1 hybrids that are pretty cold hardy, that make fruit that can be used to make tasty things if sufficiently diluted and sweetened, but we don’t have any varieties that combine the extreme cold hardiness of the trifoliate orange with the extreme tastiness of various true citrus varieties, since we can’t reshuffle the genes in F2 hybrids.
Apparently there’s an exception to the rule that hybrids between trifoliate and tasty citrus are always dead ends. Citrandarins, trifoliate x mandarin hybrids, produce diverse seedlings, not clones of the mother plant! Why haven’t plant breeders been exploring the possibilities in the F2 generation? That F2 generation could have all sorts of interesting things in it, from trees as cold-sensitive as a mandarin, with fruits that taste as bad as trifoliate oranges, to trees as cold-hardy as trifoliate oranges, with fruits as delicious as mandarins.
Here are a couple of seedlings from seeds from the same citrandarin fruit. Look in the upper right corner. There’s a seedling with trifoliate leaves like a trifoliate orange. The seedling right next to it has entire leaves with winged petioles like a mandarin. Who knows what other differences these siblings have? I don’t actually know if these are full or half siblings, since the flower that produced this fruit could have been self-pollinated and/or pollinated by who-knows-what, but the point is, the seedlings are diverse, so they have the potential to be great.
I think everyone who has room, who lives in a zone that trifoliate orange is hardy in (and they’re hardy to -10 F, -23 C, USDA zone 6a), should be growing citrandarin seedlings in case one of them is as hardy as its hardier grandparent, but has tastier fruits. And everyone who can grow citrandarins (which are hardy to 0 F, -17 C, USDA zone 7a) should be growing them, both because the fruits are beautiful and the juice can be used like lemon juice, and to produce seeds that might produce a better combination of traits in the next generation.
There is a Mandarinquat
It’s fairly hardy
Haven’t been able to find any at the Store though.
Like a sweeter Kumquat.
I don’t know too much about citrus breeding but there are a ton of exceptions from the sterile-F1-offspring-rule. I have a Thomasville citrangequat for example. There are a bunch of second generation citranges (Segentranges) and further crosses with pomelo, mandarin, kumquat, etc. and a lot of people are growing more. Also a lot of interesting crosses with ichang papeda for cold hardiness.
And even sterile cultivars can have their uses in plant breeding like in somatic fusion
Crossing trifoliate for cold hardy edible citrus has been going on for more than 100 years. No success so far. Cold hardiness goes away much faster than edibility comes. Look at the crosses Swingle did 100+ years ago for example.
BTW IMHO indio mandarinquat which I have eaten is much more sour than a lemon.
Agreed. The mandarinquats that I tried were about as sour as a Meyer lemon, though with a more mandarin flavor. I wasn’t a fan.
Hope your citrandarin seedlings are doing well? I think this is actually really exciting, since it will likely be a question of pure quantity to find F2-hybrids with desirable features. Where did you get your fertile citrandarin plant from? Is it a well-known clone?