Author Topic: Recreating the grapefruit - C. maxima X Morton, troyer, poncirus, kumquat, Moro,  (Read 999 times)

Lauta_hibrid

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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

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

Till

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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

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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?
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.
« Last Edit: December 09, 2024, 12:38:29 AM by SoCal2warm »

SoCal2warm

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Yes, a good idea. I have pollinated my Chandler with Morton (and other Poncirus hybrids). ... Let's hope that seeds are in it.
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.
« Last Edit: December 09, 2024, 01:08:41 AM by SoCal2warm »

Till

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Thank you, SoCal2warm, for the background information. It will be difficult indeed to recreate a grapefruit. But perhaps something very similar is possible. I mean some citrumelos have a taste very close to pure grapefruit. Dunstan and Batumi Citrumelos come very close to it. Would they be sweet you had something like a grapefruit.

From where do you have that Chandler is triploid? I have never found that written, neither on an official homepage of UCR, nor in articles of the breeder, nor in private conversation. I fear that you have confused Chandler with some other Siamese Sweet crosses. I also doubt that Chandler is seedless because of triploidity. The reason will just be that it is self-incompartible to its own pollen as are all pumelos.

My Chandler was surprisingly seedless when cross-pollinated with Poncirus and other Citrus. I only got one seedy fruit after I had pollinated with African Shadock x Poncirus. I thought that Chandler accepted the pollen of A. x P. better than other pollen because it is half pumelo. This interpretation contradicts, however, the experience of others like Alan who were more successfull in producing Chandler hybrids.
And now I think I got it: My Chandler blooms abundantly but only the very last flower of a flower umbel produces a fruit no matter how it was pollinated. So all of my many pollinated flowers fell off except the very few flowers that opened at the end of flower period and that I did not pollinate any more. So this year, I used a trick: I cut off all flowers except the pollinated ones, namely only one from every umbel. And see what happened: These flowers formed the fruits. Now that is not proof that Chandler willingly accepts non-pumelo pollen. But I am optimistic that the nice fruits that now hang on the tree indeed contain seeds.
What speaks, by the way, against the theory that Chandler is triploid is that it abundantly produces pollen. Triploid plants are usually pollen sterile.

Ilya11

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Chandler pomelo has a triploid set of chromosomes (that's what makes it "seedless").
Entirely false. Chandler is diploid and give many seeds when cross pollinated with compatible pollen.



Image from https://citrusvariety.ucr.edu/crc3244
« Last Edit: December 09, 2024, 03:32:13 AM by Ilya11 »
Best regards,
                       Ilya

Lauta_hibrid

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Thank you, SoCal2warm, for the background information. It will be difficult indeed to recreate a grapefruit. But perhaps something very similar is possible. I mean some citrumelos have a taste very close to pure grapefruit. Dunstan and Batumi Citrumelos come very close to it. Would they be sweet you had something like a grapefruit.

From where do you have that Chandler is triploid? I have never found that written, neither on an official homepage of UCR, nor in articles of the breeder, nor in private conversation. I fear that you have confused Chandler with some other Siamese Sweet crosses. I also doubt that Chandler is seedless because of triploidity. The reason will just be that it is self-incompartible to its own pollen as are all pumelos.

My Chandler was surprisingly seedless when cross-pollinated with Poncirus and other Citrus. I only got one seedy fruit after I had pollinated with African Shadock x Poncirus. I thought that Chandler accepted the pollen of A. x P. better than other pollen because it is half pumelo. This interpretation contradicts, however, the experience of others like Alan who were more successfull in producing Chandler hybrids.
And now I think I got it: My Chandler blooms abundantly but only the very last flower of a flower umbel produces a fruit no matter how it was pollinated. So all of my many pollinated flowers fell off except the very few flowers that opened at the end of flower period and that I did not pollinate any more. So this year, I used a trick: I cut off all flowers except the pollinated ones, namely only one from every umbel. And see what happened: These flowers formed the fruits. Now that is not proof that Chandler willingly accepts non-pumelo pollen. But I am optimistic that the nice fruits that now hang on the tree indeed contain seeds.
What speaks, by the way, against the theory that Chandler is triploid is that it abundantly produces pollen. Triploid plants are usually pollen sterile.

I quote your post just to mention that after a video that talks about the metabolism of plants I mention "... the leaf makes photosynthesis, that generates sugars that travel to the bud, which is at the base of the leaf, and that stimulates it to form flowers instead of branches and leaves... that is why when a ring is made the sugar increases, since. or it can travel to feed. the root, and stimulates flowering. when there are many flowers the hormones suddenly drop (the hormones are stimulated by sugar) and so the plant throws them away. that is why my technique that I use from that moment on I call it "removing competition", meaning that I remove the flowers and buds that want to form outside of those that pollinate... it is a lot of work but I have managed to get all the fruit to be pollinated by me alone...

Lauta_hibrid

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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?
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.

About making a "new grapefruit" it's just a way of saying... since there is the "New Zealand grapefruit" which is not a grapefruit, but produces a fruit so similar that it is called that, there is also the "Paraná grapefruit" which is a variety described in Argentina but came from Asia. It is almost the same but very juicy and sweeter and less bitter than the line of grapefruits that came from the Barabados (the "real" varieties). That's why I call it that. If the grapefruit becomes quite resistant, imagine if you change something in the origin we would make something new inspired by the original. Anyway, thank you very much for that contribution, surely at some point I took everything you explained there to speak well founded hehe. For now I show you my first seedlings of Pummelo x poncirus flor grande and pummelo x troyer. And the variety of pummelo that I used does not have a name, it has many seeds (26 seeds).  And I think we all deduce the triploidy because Chandler belongs to the same breeding plan as Oroblanco, which is defined as the result of crossing 4n x 2n.
Pummelo x troyer



Pummelo x Poncirus:




Till

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Nice  :)

There were serveral crosses made with Siamese Sweet. Not all were triploid. Chandler and Valentine, for instance, not.

Curiousgardener23

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Till, I think that breeding the low acid genes into hardy citrus is a really cool thing to do and hope that you have good results. This was actually the reason why I asked if the African Shadock x Poncirus was low acid because I was hoping the African Shadock was a lower acid pomelo. I found a paper from 2009 looking at nucellar embryony (apomixis)
in Citrus maxima × Poncirus trifoliata and it seemed that the researchers crossed Chandler (mother) and “Rubidoux” and “Webber Fawcett” (pollen). Then looked at the nucellar embryony rates in the population. The title was "AFLP markers closely linked to a major gene essential for nucellar embryony (apomixis) in Citrus maxima × Poncirus trifoliate". It seems to me it would have been really valuable if the researchers had tasted the hybrids to identify low acid populations that had low nucellar embryony that could have been released for breeding of low acid cold hardy citrus (likely not an objective of the research though so probably didn't/wouldn't happen).

Lauta_hibrid

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To add something interesting, I made a cross that I never saw the result of, I think I have the largest amount of kumquat hybrids that exist hehe. and I still need more. it is Kumquat Nagami x C. maxima. it is the smallest citrus (well, kumquat hindssi it would be, but it is not edible, although in the future I will cross it too 😁). the idea was to create a giant kumquat, or something with edible skin... we will see what happens. the strange thing is that the leaf morphology (it is the only thing we can analyze for now), the kumquat has leaves with short and articulated petioles, but hindssi and meiwa usually throw out leaves without articulated. Nagami also does it sometimes... so my question is what would happen in this genetic fight? well, it seems that both messages collide, since leaves without articulated, articulated and some with half articulated and wings and half without articulated appeared.  I thought that the message of dividing the leaf into 2, foot and blade, and the extension of the first part like wings, would be something that occurs separately, but it seems that the message is mixed up and what on one side are well-separated wings on the other is part of the blade... I don't know what you think, it surprised me.





The latter is the leaf of a young C. maxima plant.


Till

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These leave forms are interesting. Let's see what dominates at the end. It may be that the plant finally decides to prefer a certain leaf form. I had a seedling of Limequat Tavares, father plant supposedly Yuzu, that had long petioles weakly winged. The Yuzu influence was quite clear. But after about 20cm it decided to produce non-winged leaves. The opposite happens with C. ichangensis leaves. Sometimes they are first not winged and later they are.

Regarding low acidity: Yes, I think that is something we should try. Siamese Sweet and it hybrids are the varities that have been scientificly proven heredity patters. Sucrena may also be interesting but has different genetics. For those that are interested: See https://citrusgrowersv2.proboards.com/thread/728/inheritance-low-acidity. We discussed the inheritance of acidless varieties there.

Aside from the inheritance of strictly acidless varieties it may also be helpful to take notice of acidity levels in hybrids between normal sweet varieties and Poncirus or C. ichangensis. When I began with citrus breeding I was told by the literature that all such crosses were sour. But my present impression is that high acidity levels are often not inherited in a strictly dominant fashion. Morton is quite sweet, Swingle 5 Star is sour but not extremly so. Similar another citrumelo of mine. The same can be said of PT #7 and HRS899 Q/O. Keraji mandarine should be further checked. Its offspring Staraji is sweet. Perhaps that is not just good luck but result of very special genes of Keraji mandarine. We need more hybrids to check that.

 

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