The Tropical Fruit Forum

 Poncirus hybrids decoupled from the bitter resins associated with Poncirus may themselves serve as hardy parents in further Citrus breeding efforts.
It may take 2 generations of extreme selections to recapture desirable Winter hardiness. In the early stages of breeding low seediness isn't particularly desirable, as it limits the pool of available seedlings for further selection.
The concept of developing,or discovering unique new flavors and niches for their use is interesting and worthy of pursuit.

Good point, I'll keep these under observation. It's unlikely that these will be super hardy, their likelihood of being edible as an acid fruit should be higher. As usual, that's probably going to be a roll of the dice .

Considering only one selection has fruited at this point it's still very much in the evaluation process. Some selection goals would eventually be reduced seediness, larger fruit size and increased sugars.
Several of the survivors have been propagated and are currently being trailed. The cold hardiness appears to be adequate for zone 6b, but the fruit characteristics of the remaining selections need to be tested.
The 026 selection seedlings appear to be nucellar at this point, perhaps exclusively so.
There have been inquiries from 2 small nurseries to date, but little of the propagation material has been distributed to date.

Only one of the seedlings has fruited at this point, although 2 additional trees have begun to flower for the first time. This particular fruit has acid flavors in addition to hints of Grapefruit taste. There are no grapefruit genetics involved, the faint bitterness likely came from the Poncirus parentage. The fruits are rather seedy, very thin rinded, subsequently will not keep for long periods.
Ripening is early as Poncirus. The tree is completely deciduous and has been acceptably hardy here in zone 6b.

Fruit with seeds removed.


The juice has an orange color.


Diluted to 30% juice/70%  water and sweetened it makes a desirable beverage.

 

My immediate plans are to cross the Conestoga Segentranges with Citrandarins containing Changsha parentage. 852 and progeny such as Bishop.
Additionally, to cross 5 Star Citrumelo with all of the above. 5 Star has survived here, but suffers dieback each Winter.

Poncirus Plus Nucellar seedlings. During the process of repotting Poncirus Plus seedlings today I found at least 3 sets of multiple seedlings from a single seed. This should indicate that some of the seedlings are of Nucellar origin.

There are several that might be. I found the low percentage of trifoliate plants interesting, considering #026 (the pollen donor) is morphologically nearly indistinguishable from straight Poncirus.

I have used a similar set up for the past few years. White overwintering plastic film reduces daytime solar gain. It's very important to prevent excessive heat buildup to prevent the formation of  tender, new growth. A small emergency heat source may save vulnerable trees on the few, out of ordinary cold nights. It's again important to not overdo this emergency heating.
Night time temperatures can be below freezing without harm if the plants are dormant. venting needs will largely be determined by the amount of sunshine. Trees planted directly in the ground will not be as vulnerable as potted trees. Slightly moist soil will retain more heat from day into night, especially during sunny days.
Further tweaks include insulating between the inside and outside soil at the perimeter, using water barrels as heat storage sinks(this can be a disaster if the water freezes).
There are also seasonal white shading sprays that can be applied to rigid plastic and glass surfaces to reduce solar gain.

I would expect Flying Dragon flowers being pollinated by regular Poncirus to have a fewer Flying Dragon seedlings.

I've recently seen suggestions that cold temperatures that aren't lethal may contribute to initiation of phase change. Summer temperatures get rather high, as only the polyfilm ends are removed. As the interior has filled up with growth, ventilation has been reduced. I use cooling misters on the hottest days.
Possibly, both temperature extremes have an effect on maturation, but I don't have any data to support the idea.

Poncirus Plus seedlings, which germinated rather well.

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Kabosu seedlings on the far side. No Poncirus genetics.
Meyer Lemon pollinated by Segentrange 026 pollen seedlings on the near side. These seedlings are quite variable as Meyer Lemon is Zygotic.

Despite 026 appearing very similar to Poncirus, it's seedlings resulting from a Conestoga 026 x Meyer Lemon cross show monofoliate and bifoliate, as well as trifoliate seedlings.

There's not much to lose. I have planted immature Clementine seeds and got good germination. The biggest danger I foresee is susceptibility to decay, especially with the adhering flesh.

A trial could be attempted be sowing a large population of the highest percentage of zygotic Poncirus seed available. Provided the seedling population shows variation in hardiness, the hardiest specimens might attain your goal. If your goal is beyond the genetic capability of the seedlings you plant, success would be unlikely.