How hardy is N1TriVoss?

Do not have experience yet , mine is for the first winter in the open field, but it is supposed to withstand -18C.

According to its breeder, Bernhard Voss, it is hardy to -12°C. But Bernhard seems to have given conservative data for frost hardiness because a year or so ago he gave all his plats 2-3 (minus) degrees more. It is also difficult to estimate for me whether he gives the degrees that his plats can at least withstand or whether he states what they can at most withstand. I ask myself this question because Bernhard Voss lives in an area where the winter is usually relatively mild and the plants might be bred just in the last years. His frost test on the homepage is over 10 years old.
But see his homepage yourselfs: http://www.agrumi-voss.de/index.htm You will find his emailadress under "Preise/Zubehör". Or you can contact him via this forum.

For what its worth I have several cross breeds which I have hope for... Perhaps like many a man before me , I have thoughts of something better than will actually come to "fruition" .

I have a Pomello x trifoliate, it has flowered in the past but fruit never matured - the trifoliate leaves are huge especially the centre one which is about 12cm or 4" in length - it is in a pot and plan to be planted this spring. I also have Dunstan & Swingle citrumello's - neither have fruited yet, but hopeful one of them will be more than a decoration.

The Swingle i tasted at the seed spitting contest at the 2009 Citrus Expo in Lake City SC didn't taste nearly as bad ad I was led to believe it would be...

For what its worth...............

Greg

Yes, Greg, we should try more combinations. And it sounds interesting what you have. We people from the cooler regions need not compete with the best citrus sold on the market. So I see no point in the categorical judgement of some that any Poncirus hybrid is not worth growing.
To come back to my sugar orange idea: What if somebody of us crosses a sugar orange with Ichangiensis? It could be expected to be hardy up to -12°C and might be sweet due to the sugar orange. I hope for more cold hardiness. Therefore my favorite is Poncirus. But such a cross could be very nice also.
I found, by the way, a huge blood sugar orange on ebay that I will buy. It will allow me my experiment and will bring me closer to my dream of a blood citrange.

I thought crossing the mildest, best flavoured citranges like Rusk with each other might eventually lead to good results. But citranges seem to have already lost a lot of hardiness, by the time they've been crossed they'll barely be hardier than satsumas or mandarins I think so it sort of defeats the purpose.

That is also my theory. And I have done the first cross this year. Well tasting Sanford Curafora (F2) with Poncirus. I hope I get zygotic seeds. I think we must come over 50% of Poncirus genes. I'll see what I can breed out of Poncirus X F2 Citranges / Citrandarins. I expect that they taste awful. But my hope is that the children of F3 crosses do well in all respects.

Till, I just found this,

from http://www.ars-grin.gov/npgs/pi_books/scans/29/pi029_048.pdf

Saunders Citrange:

"Fruits small, orange yellow, with unusually thick skin. Pulp vesicles rather
large, adhering compactly, making the interior of the fruit seem hard and dry as compared to the other citranges. What juice there is, is sharply acid
entirely free from the bitter taste so prominent in some of the citranges"

What would happen if it was crossed with a sibling, a Phelps or Sanford citrange, which do produce zygotic seedlings.

http://fshs8813.wpengine.com/proceedings-o/1962-vol-75/5-13%20%28COOPER%29.pdf

Unfortunately I know of no source for these plants.

Never have seen this citrange available in nurseries. Probably lost long time ago.
It is also described here by W.T.Swingle as having no bitter taste.

I don't think you go the right way, I mean back-crossing with PT and looking for good fruits. This takes many years between two generations with very very few chance to succeed.
Simpler would be to back-cross the cold-hardy F1 with good citrus and screening for cold-hardiness. It would take one or two years in field to screen the cold-hardy hybrids, depending on where you do the field test.
No need to wait for fruits...
MHO.

I also think that crossing F1 citranges/citrumelos back to poncirus is not the best way to produce hardy edible stuff; it can produce only decorative hybrids, something like fragrant poncirus.

All poncirus hardiness genes are present in F1 crosses, but in heterozygous state, that is in only one copy. Crossing two F1 hybrids to each other will produce some plants with two copies of each hardiness gene. The same is true for the good taste genes coming from orange ancestor.

The main problem is just combinatorial, because only few plants will possess two copies of all hardiness genes as well as good taste genes. It necessitates the screening of F2 populations of the order of ten of thousands, may be even more.

It was not done before mainly because of the rarity of zygotyc F1 parents and to the less extent the lack of financial resources.

Crossing F1 citranges to oranges will never give plants with winter hardiness of poncirus, but could give plants with edible fruits with levels of citrange hardiness. Cold hardiness gene alleles from poncirus will always be present in one copy.

If they still have them and can ship out of FL let us know...that's one I wouldn't mind adding to my collection.
Thanks