Citrus > Cold Hardy Citrus

Recreating the grapefruit - C. maxima X Morton, troyer, poncirus, kumquat, Moro,

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Lauta_hibrid:
Grapefruit comes from the hybridization of C. maxima with an orange, but my question was what would happen if one of the parents was changed? So I proceeded to combine it with several species. Part of this is to create a more cold-resistant version, that’s why I used a large-flowered poncirus, but I also proceeded to mix it with something that has orange genes but is more resistant, that’s why I already have the hybrid x citrange troyer seedlings and this year the fruit of Máxima x citrange Morton (for me the hybrid most similar to an orange) is already fattening. I have 2 fruits forming and we will see later if I get enough seeds. This year I sent a friend seeds of the hybrids with troyer and poncirus and they arrived safely to the US, so he can try them in very cold conditions, maybe for the Máxima x Morton I can send some too.

a_Vivaldi:
What variety of pomelo are you using? Hirado Bundan is said to be the hardiest if that one is available on your region.

Till:
Yes, a good idea. I have pollinated my Chandler with Morton (and other Poncirus hybrids). It got a big fruit. Let's hope that seeds are in it.

The only definite hybrids with Chandler that I have so far are Chandler x (African Shadock x Poncirus), Poncirus x Chandler (only one) and C. ichangensis x Chandler. This year I got a cup of C. ichangensis x Chandler seeds, too.

I use Chandler because it has the genes for low acididy from Siamese Sweet. The coming year, I want to use Valentine as motherplant also. Valentine could also be a good starting point to create orangelike hybrids. Think about Valentine x Citrumelo, Valentine x Citrange, Valentine x Citrandarin, or maybe just Valentine x Poncirus (better tasting). A grapefruitslike hybrid could be Valentine x C. ichangensis. Siamese Sweet can reduce the acids to about the half of the level of the sourer parent. In case of Siamese Sweet this happens to all hybrids. In case of Siamese Sweet hybrids like Chandler or Valentine, 50% of the hybrids get the gene and will have reduced acids.

SoCal2warm:

--- Quote from: Lauta_hibrid on November 25, 2024, 03:04:40 PM ---Grapefruit comes from the hybridization of C. maxima with an orange, but my question was what would happen if one of the parents was changed?

--- End quote ---
Grapefruit is a specific cross that has a specific origin.

There are several traditional Japanese varieties where C. maxima was introduced into mandarin (C. reticulata) breeding. (Think for example about the slightly sour more aromatic flavor of Satsuma mandarins)

The result will be a little bit different from the typical grapefruit flavor.

These fruits will be, in many ways, analogous to grapefruit, but they will not truly be real grapefruits. They will be similar but they will not have quite the exact same type of flavor.
This can be difficult to describe.

I can get into the chemical components of the aroma, if you want. One of the most important aroma compounds in both pomelo and grapefruit is nootkatone. It occurs only at very low levels but it's very potent at those low levels. It smells a little in the direction of mouth-puckering rhubarb but also a bit of a cleaner green and woody dimension. 

But in grapefruit, in addition there is 1-p-Menthene-8-thiol (also called "Grapefruit mercaptan"), which smells kind of distinctively like "grapefruit" but in a completely different way. It was a subtly sweet aroma that is slightly pungent (slightly mild smell, in a way, yet "potent" in feeling at the same time). And strangely, if you compare it to the smell of coffee there is some subtle underlying similarity in the feel. It brings to mind more of a "pink grapefruit" feel. This almost feels more like edible grapefruit candy than natural grapefruit.

The distinctive aroma of orange (and especially Valencia variety of orange) comes from a substance called valencene, which is actually related to nootkatone, but doesn't have the oxygen atom that nootkatone has. They do kind of share some similarity in overall underlying feel but are also very different. Valencene does not have the rich mouth-puckering slightly "dirty" rhubarb feel that nootkatone has.

I think another important compound you'll find in many of the more aromatic mandarins is sinensal. It has a "bright" and "juicy" feeling, but also some "orange-citrus" tonalities like D-limonene does. Again, it's very reminiscent of "orange" but in more of a different way from valencene.

This is only a basic overview only touching the surface. Of course the full story is much more complicated.


When you cross a pomelo with a mandarin, you're going to get something that's a little bit similar to tangelo in flavor. But of course it will be more sour yellow and aromatic because it will have a higher percentage of C. maxima ancestry than a tangelo does. So maybe somewhere between a tangelo and a "grapefruit" sort of feel, but not with all of the distinctive aroma of a real grapefruit.

Keep in mind your offspring will likely be tasty but will contain a huge number of seeds. 

The C. maxima x C. reticulata hybrids tend to have a little more hardiness than regular sweet oranges, so should grow well (or at least acceptably) in climate zone 9b.

SoCal2warm:

--- Quote from: Till on December 08, 2024, 11:19:03 AM ---Yes, a good idea. I have pollinated my Chandler with Morton (and other Poncirus hybrids). ... Let's hope that seeds are in it.

--- End quote ---
Chandler pomelo has a triploid set of chromosomes (that's what makes it "seedless"). That means when crossed with another variety, there is the chance for the offspring to also be triploid (and even a very small chance it could be tetraploid, which could then be useful for a subsequent round of breeding).

The good news is that pure pomelos produce only zygotic seed (resulting from sexual recombination), rather than high levels of nucellar seed (genetic clones of the fruit parent).

Seeds should form in the fruits. If they do not, it means the fruit was not properly pollinated. 

(Some varieties of pomelo, such as Hirado Buntan, do not produce many fruits if the flowers are not pollinated by another variety. (Maybe slightly more than half of pomelo varieties require pollination for fruit set. But Chandler pomelo does not require pollination to produce fruit (parthenocarpy). And it is very difficult to find any pomelo varieties in the U.S. that are not the Chandler variety)


I found this:

"A pummelo that has been cross-pollinated by another pummelo is apt to have numerous seeds, but if cross-pollinated with any sweet or mandarin orange, will not be seedy."
https://ocfruit.com/Pummelo.php

I'm not sure if it is true, or why it would be true. Perhaps oranges just produce much lower pollen levels.

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