F2 citrange winter hardiness trial

[kumin]

The Conestoga River is a mile from my location. It's the name I chose for the group of survivors of a cold hardiness test undertaken in 2018/2019. The test involved 20,000 C-35 seedlings of which only 3,000 showed genetic diversity. A few dozen of these seedlings survived a low temperature of -12°F. The survivors were further propagated and are presently undergoing additional trialing. One has fruited at this point and 2 additional plants have produced a few flowers.

[bussone]

The Conestoga River is a mile from my location. It's the name I chose for the group of survivors of a cold hardiness test undertaken in 2018/2019. The test involved 20,000 C-35 seedlings of which only 3,000 showed genetic diversity. A few dozen of these seedlings survived a low temperature of -12°F. The survivors were further propagated and are presently undergoing additional trialing. One has fruited at this point and 2 additional plants have produced a few flowers.

These are the ruby blood orange / poncirus crosses you tortured a few years back?

What are the fruits like? It’s hard to find much on the fruit of rootstock hybrids.

[kumin]

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.

 

[Zitrusgaertner]

........... survived a low temperature of -12°F. The survivors .......

-12° is -24,44°C that's lower than some Poncirus trees would survive. Are you really sure?

[kumin]

 Fahrenheit -11.8° and Celsius -24,5° photos. There were also -6°F readings in the same week.
Poncirus did show a bit of injury on late season growth.

[drymifolia]

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.

I'd grow that! Are you planning to eventually sell cuttings or seeds of any of your survivors, or still just using them for further breeding? And are the seeds from that one polyembryonic/nucellar?

[kumin]

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 trialed. 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.

[kumin]

 Meyer Lemon x Conestoga 026 seedling. This plant hasn't developed leaf petioles to this point. Perhaps they'll appear in later foliage.

[hardyvermont]

Leaves are thick and serrate, maybe tetraploid?

[kumin]

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 .

[David Kipps]

"A few dozen of these seedlings survived a low temperature of -12°F."  How much visual diversity did you observe among these?  Did they lean heavily toward looking as though they inherited an unfair share of trifoliata?  Did you get any mono-foliate? No/short thorns? Odd colors? Etc.?

[kumin]

There is considerable variation among the trees. The very hardiest phenotypically favor Poncirus. There are 2 trees that are phenotypically more citrus like. These 2 are less hardy. Most are heavily thorned, but one or 2 are less thorny. The 2 less hardy trees are mostly monofoliate.

[kumin]

A rather quick inspection of a number of selections planted outdoors and which remained outside over the past Winter, have shown the following order of hardiness following a sustained low temperature of 2 degrees during high winds:

1. Poncirus   Only damaged on late season growth.

2. Poncirus Plus    Also only damaged on late growth.

3. Conestoga 011 Segentrange    A little damage on late growth, similar to Poncirus late growth. Tetraploid

4 Conestoga 010 Segentrange   Survival very close to that of Poncirus and is breaking buds, flowering

5. Conestoga 006 Segentrange  To this point is indistinguishable from 010, is also flowering.

6. Conestoga 026 Segentrange Also appears similar to 010 and 006, fruited last year. Is marginally less hardy than the Selections listed above.

7. Conestoga 001 Segentrange Semi-evergreen, the first flush of leaves in the Spring are distorted, may relate to the absence of true Winter bud scales. No bark cracks seen.

8. Conestoga 067 Segentrange The second most Citrus-like in appearance survived with injury.

9. Bishop Citrandarin heavily damaged, but likely to survive.

10. 1279 Citrandarin heavily damaged, may not survive.

11. 058 Segentrange Very Citrus-like in habit, vigorous, hardiness is not exceptional, damage at 15 degrees in tunnel.

[kumin]

Bishop seedlings displaying monofoliate leaves. There may be 2 trifoliate zygotic seedlings for each monofoliate seedling. Very likely there's also a percentage of Nucellar seedlings present.

[kumin]

Zygotic Meyer Lemon x 026 Conestoga seedlings showing variation in leaf form s.

[kumin]

Bishop Citrandarin has survived the Winter in better condition than I expected. It certainly has the potential to survive 0°F.

[kumin]

Several Conestoga selections blooming and several are fruiting for the first time. I'm discovering the first year flowers on a seedling tree are often predominantly staminate flowers. Last Spring 006 and 010 flowered, but failed to set fruit, as many of the flowers lacked styles. This being the second year, many of the flowers are perfect.



006 fruitlets

006 fruitlets



010 fruitlets

010 fruitlets

Many of these flowers are pollinated by either Myer lemon, or Bishop Citrandarin pollen.
I'm discovering that 010 and 006 are nearly identical in cold hardiness. 011 is very hardy, but likely equal to 006 and 010 rather than superior to them.

[kumin]

5* Citrumelo flowers just started to bloom. I've pollinated a number of these with Conestoga 010 pollen. Hopefully some of the seedlings will be hardier than 5*.

[Walt]

Good luck!  Sounds like a good cross.

[kumin]

Reddish tint on newly emerging leaves on Meyer lemon X Conestoga 026 crosses. Only a few show this trait, likely inherited from Meyer.

[kumin]

There's a good chance this Poncirus Plus seedling is Tetraploid. Deep green, broad, short aspect and thick leaves are all indications of tetraploidy. Notched leaf margins are an additional indication.

[mikkel]

It might be an good idea to collect and breedalso with tetraploids. One day it might be helpful in creating triploid seedless hardy varieties.
I have some tetraploid Citrumelos and maybe sinensis x ichangensis. Who knows what it might be good for.

[BorisR]

Hello, kumin. I have several trifoliata seedlings that I consider to be tetraploids. Among other signs, they have double spines. I think this can be used as an additional sign of tetraploidy in trifoliata. Have you seen anything like this in your tetraploids?

[kumin]

A search on this forum for: 011 twin thorns should give you an older post addressing the issue
  Yes, the plant that has been confirmed to be Tetraploid has had frequent twin spines. The name assigned to this selection is Conestoga 011.

[kumin]

 Variable Bishop Citrandarin seedlings.