The Tropical Fruit Forum

Thorniness is genetically determined, in experiments in China thornless plants were produced by inbreeding. This FD may also be suitable for producing thornless seedlings through self-pollination.

I think citrus growing is an exciting area and a real passion, but it is still an exotic niche, at least for the time being, as long as there is only halfway edible fruit. That will certainly change abruptly as soon as the first hardy varieties appear.
I think after many years it's easy to understand if other things become more important at some point. Bernhard once said to me that now, with the tree care, there is finally a reliable income, something that was very reassuring. I can well understand that. Bernhardt now maintains a citrus collection (the former Fabian collection) beside the tree care where there are many of his own varieties.
Thank you Usirius for the information about Dr Frey, this is the first time I can read any information about him.

All this preparatory work by these many people brings me once again to the thought that I have been thinking about for a long time
how to deal with the possibility of an edible hardy citrus?
How can this breeding work be secured without a few, big ones, taking the credit and, above all, the financial harvest?
I experience this problem with other fruit varieties and have already had my negative experiences.
There are so many of us and an invaluable amount of preparatory work has been done without which this breakthrough would not be possible. I think it would also make sense to secure this work through open source licences in the interests of open exchange and cooperation? https://www.opensourceseeds.org/en/breeder-information
Would this be helpful?

Well said!

I have wondered the same thing, but the literature mentions a single dominant gene. Presumably there is another mechanism behind it that influences inheritance, your explanation sounds plausible.
Another possibility would be to exclude by chance that only the seedlings that did not inherit the gene became varieties.
I think this is less likely, but it cannot be ruled out.

There is a variety called Tahizu, which is quite similar to Yuzu, but of course not identical. Tahizu is Otahaite x I P or vice versa.
Perhaps it would be helpful to cross a pseudo-yuzu that already contains the Ruby gene...? That would save a generation.
If Ruby is dominant, it will be fairly quick to create a Blood-Yuzu hybrid. It will take longer to restore the Yuzu characteristics by backcrossing...

So an F1 hybrid should also be blood?

Thank you, Boris.

Morton's orange parent is supposedly also 'Ruby.'

According to this source, Ruby is one parent of Morton, (page 7, second column)

https://journals.flvc.org/fshs/article/download/100828/96780

"Reciprocal crosses were made of P. trifoliata and Ruby sweet orange; 54 citrange hybrids were produced. Eleven different citranges—Norton, Morton, Sanford, Willitts, Phelps, Coleman,
Rustic, Savage, Saunders, Cunningham, and Etonia—were grown from seeds of a single fruit of P. trifoliata crossed with pollen from a single flower of Ruby sweet orange (Swingle 1913)."

C35 also has Ruby as a parent, but probably not the same Poncirus variety as it was release only 1987

https://citrusvariety.ucr.edu/crc3912

If Dimicelli is highly nucellar, try using I.P. It might be able to overcome that.

However, Stan McKenzie said he got it from Europe a long time ago.

all that is known for sure is that it is a seedling that came from Bernhard Voss in Germany. I have spoken to Bernhard about it, but he doesn't know where the seeds came from either. It will probably remain a secret forever.

I think it might makes sense to cross Morton with Sanford. Since both varieties share the same parentage, a direct cross could recombine the genes of Poncirus and orange, potentially resulting in favorable new combinations.
With a sufficiently large number of offspring, it might be possible to achieve a desirable mix of traits from both parents.
Sanford is zygotic and thus well-suited as the seed parent, while Morton could serve as the pollen donor.
Crossing with other citrus varieties increases the range of possible trait combinations, raising the probabilities

A recombination of F1 traits through sibling crosses could theoretically steer results more precisely in a desired direction.
But it is theory and everything is worth trying.