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Author Topic: breeding cold hardy pomelo  (Read 1049 times)

SoCal2warm

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breeding cold hardy pomelo
« on: June 12, 2017, 08:26:46 PM »
I'm going to embark on an attempt to breed a cold-hardy pomelo that can grow in zone 8 and that is eating quality (or very close to it).

.......................Red............................................Red
...yuzu........Thai pomelo.....Ichang Lemon.........Thai pomelo.......Bloomsweet
.....l__________l_____________l_______________l....................(Kinkoji)
.............l.....................l........................l........................................l
.............l____________l........................l_______________________l
.......................l........................................................l
.......................l________________________________l
...............................................l
..................................."Fragrant Wind" pomelo


The breeding will take 3 generations. The goal of zone 8 would mean it would have substantially more cold-hardiness than most cold-hardy citrus varieties, but not as much as the extremely cold-hardy citrus species (Poncirus and its hybrids). Basically this pomelo should be about as hardy as kumquat.

For the sake of reducing time, the next generation of seeds will have to be grown before the traits of its parents can be fully examined. This will entail growing a very large number of seedlings.

All the origin varieties have a very high degree of edibility, considering the level of their cold tolerance. Hopefully this results in a highly optimal ratio of edibility to cold-hardiness.







Millet

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Re: breeding cold hardy pomelo
« Reply #1 on: June 12, 2017, 09:02:03 PM »
Good luck with your trials.  Hope your not to old at this time.

SoCal2warm

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Re: breeding cold hardy pomelo
« Reply #2 on: June 17, 2017, 12:59:12 AM »
This will be used to germinate the seeds



The electric heat mat is needed because these will be growing in zone 8a (it was 55-60°F outside two days ago, so much for things warming up in June).

I want to start off with a pomelo cultivar that's more interesting than the standard 'Chandler' (it almost seems to be the only pomelo variety available anywhere in America, not that much interest in different pomelo cultivars I guess).

fyliu

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Re: breeding cold hardy pomelo
« Reply #3 on: June 17, 2017, 01:41:25 AM »
Sounds good.

How cold tolerant are most of the pummelos at present time? Zone 8a as in Vancouver or 8b like Seattle? I'm just looking at a map of the zones to get an idea of roughly what you're trying to achieve. West coast is kind of weird where elevation and proximity to water has a major effect on the zone. Sacramento is 9b and so is Bakersfield. Barstow is on the edge of 8a and 8b. Very confusing to me. You seem to know what you're doing. Good luck.

http://planthardiness.ars.usda.gov/PHZMWeb/

SoCal2warm

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Re: breeding cold hardy pomelo
« Reply #4 on: June 17, 2017, 02:43:26 AM »
How cold tolerant are most of the pummelos at present time?
Not cold tolerant at all. Pomelos are the most cold vulnerable out of all the citrus, more cold vulnerable than orange and more cold vulnerable than grapefruit. That's probably one reason you don't see pomelo very often in the U.S. 

It's not really surprising. View oranges and grapefruits as being on a continuum between mandarins and pomelo. Mandarins are the more cold hardy of the two, so in general the more mandarin it has in its ancestry, the more cold hardy the citrus type will be.

That's part of what makes this challenging. It would be quite an accomplishment to have a pomelo variety that could grow in zone 9 (let alone even thinking about it surviving in zone 8 ). And I am talking specifically about pomelo, not grapefruit, because although the two are very similar there is a fundamental difference in flavor between these two groups. Grapefruits have more of a pungent, slightly putrid smell, and carry a small degree of tangy orange flavor. The aroma of pomelo is a little bit more floral and clean, and subtle with nuances, and usually have less bitterness than grapefruit.

Chandler is probably somewhat more cold hardy than other pomelos, but it's still a little more vulnerable to cold than the average grapefruit. What I mean specifically, most Thai pomelo varieties could be grown in zone 10 but they wouldn't grow that well.

People in the U.S. just don't know that much about pomelos. They are a big thing in Southeast Asia. And they were traditionally grown in Japan, although now grapefruits are much more prevalent in Japan than native pomelo varieties because of cheaper grapefruit imports from the U.S. and fruit being very expensive to grow in Japan because of the limited land and high cost of living and labor costs. Another problem is the language barrier. In Vietnamese the word used for grapefruits is the same as for pomelo, so this leads to much confusion. When Vietnamese talk in English they most often think the fruit they ate in Vietnam is called grapefruit in America, and Vietnamese are the main Southeast Asian group that has immigrated to America. Pomelos are also popular New Year festival fruits in the Canton province of China, where they are usually translated into English as "Chinese grapefruit". The early introduction of grapefruits into the American market place sort of superseded the awareness of pomelo, and so it has become the grapefruit that stuck and became the popular one. There are some interesting old stories from the 1930s about Americans encountering grapefruit for the first time and not knowing what to do with them. One housewife, when given a grapefruit, tried boiling it for two hours in water thinking it was like a cabbage.

So basically the existence of grapefruit has displaced pomelo from gaining popularity in the U.S., even though the two are not exactly the same. And all the exports of American grown grapefruit to other countries are displacing the sales and awareness of pomelo even there. Grapefruit is more practical for the U.S. citrus industry to grow than pomelo, because grapefruits have been bred to be more cold hardy than when they first appeared in Jamaica.

Another issue, most of the Asian pomelo varieties would require a lot of heat to fully ripen and, as hot as Southern California is, all the area within zone 10 is in proximity to the coast and still does not get quite enough heat throughout the year to become sweet enough. This has no doubt hindered the introduction of pomelo into California and explains why there is such little variety. All three of the pomelo varieties (2 of them actually being grapefruit-pomelo hybrids) commercially available in the state resulted from hybrids of 'Siamese Sweet', a very sweet but mostly flavorless pomelo variety, and were bred by the University of California research station in Riverside. Pomelos ripen well around Miami (Florida) though, and probably would in Brownsville (Texas) too, I would imagine.

>> One correction to add: I have heard of Chandler pomelos being grown in zone 9b but these are places that have a lot of heat (Texas, Florida)
« Last Edit: June 17, 2017, 01:37:41 PM by SoCal2warm »

countryboy1981

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Re: breeding cold hardy pomelo
« Reply #5 on: June 17, 2017, 11:52:23 AM »
Doesnt bloomsweet grapefruit have a high percentage of pomelo in its dna?

SoCal2warm

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Re: breeding cold hardy pomelo
« Reply #6 on: June 17, 2017, 01:11:31 PM »
Doesnt bloomsweet grapefruit have a high percentage of pomelo in its dna?
The origins of Bloomsweet are not exactly known, but it is almost certainly not a "real" grapefruit. (It is believed to have originated from Japan, with no relation to the original grapefruit lineage that grew in the wild in Jamaica) Bloomsweet could probably be more accurately classified as a pomelo hybrid, although it is grapefruit-like. There was a genetic study in Japan that indicated one of the direct parents was a variety known to be a orange-mandarin cross, so I think it likely Bloomsweet has less than 50 percent pomelo in its heritage. (This isn't that unusual, a cocktail grapefruit is less than 50% pomelo too) I personally believe Bloomsweet probably derived its cold hardiness from a yuzu ancestor, although it may have been bred for cold hardiness over several generations too, so there may be other genes at play.

It is something of a small mystery, which makes this variety all the more interesting to use for breeding.
« Last Edit: June 17, 2017, 01:36:08 PM by SoCal2warm »

SoCal2warm

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Re: breeding cold hardy pomelo
« Reply #7 on: June 21, 2017, 08:42:36 PM »







SoCal2warm

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Re: breeding cold hardy pomelo
« Reply #8 on: June 22, 2017, 12:54:28 AM »
Another difference between grapefruit and pomelo, in most grapefruit varieties virtually all the seeds are formed asexually and are clones of the parent, whereas seeds in pomelo (most varieties) only form from sexual reproduction. This could make the breeding of pomelo substantially simpler than grapefruit.

fyliu

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Re: breeding cold hardy pomelo
« Reply #9 on: June 22, 2017, 12:55:26 AM »
Great information. I had no idea pummelos are that cold sensitive. Must be that my climate is very suitable for them that I don't know this about them. They seem to be the strongest fruit trees in the property.

SoCal2warm

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Re: breeding cold hardy pomelo
« Reply #10 on: June 22, 2017, 02:32:06 AM »
They seem to be the strongest fruit trees in the property.
It might have to do with the rootstock. Grapefruits are often grafted onto shaddock rootstock, and when Chandler is grafted onto shaddock, you're basically grafting pomelo onto pomelo, so it's going to be much more compatible and the tree is going to grow more vigorously. In any case, pomelos can get to be quite big trees. When grown own-root, they can get to be up to 50 feet high under optimal conditions, and about just as wide. Grapefruit can get up to 45 feet high. Well you can see why rootstock is used.

The primary reason however rootstock is used is to induce a degree of incompatibility to cause the tree to be more pernicious and start beginning fruit production earlier in its lifespan (so the tree's juvenile energy won't be diverted to growth).

SoCal2warm

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Re: breeding cold hardy pomelo
« Reply #11 on: June 22, 2017, 04:13:32 PM »
Yuzu seeds and Thai Red pomelo



Who knows if the seeds are still viable

SoCal2warm

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Re: breeding cold hardy pomelo
« Reply #12 on: August 19, 2017, 01:56:20 PM »
Here's a Yuzu tree in California



found it after scourering several local nurseries in the area

SoCal2warm

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Re: breeding cold hardy pomelo
« Reply #13 on: August 19, 2017, 04:23:21 PM »
Just wanted to add: it's not really true that pomelos are always that cold vulnerable. Limes are probably more cold vulnerable than pomelo trees. Pomelo might fall somewhere close to lemon. To some degree it depends on the cultivar variety. Pomelos usually come from tropical countries like Thailand, Malaysia, Vietnam (particularly the southern half), although there is a variety in Thailand that grows in a slightly more mountainous area in zone 9b and is known to be just a little more cold hardy. Then there are the "Chinese grapefruits" which I personally suspect might actually not have 100 percent pomelo ancestry, but who knows... They are grown in Southern China. The winters there can be cold, if not freezing, going all the way into Spring, cold and wet. (Though after that it's hot and humid, great growing conditions) It is zone 10, but the early Spring is far colder and wetter than what those in zone 10 California experience. Each climate zone has its own subtleties I suppose.

The pomelos towards the more cold hardy end of the spectrum probably have as much cold tolerance as the average orange, if I had to guess, while there's certainly many pomelos in Thailand that wouldn't be happy with anything lower than zone 10. (necessary heat for ripening is a different matter)

I suspect most pomelos in Thailand and Malaysia would be happier in zone 11 than they would in zone 10. Or to be a little more exact, happier in 10b bordering on the edge of 11a than they would be growing right on border between 10b and 10a. Chandler is probably just a tiny bit more cold hardy than the average pomelo variety in Asia (but I could be wrong about this).

Going back to the Chinese grapefruits really quick, they are probably all or mostly pomelo, and are classified under Citrus maxima. I'm just thinking there might be somewhere like 10 percent C. reticula in there, since they are sweeter and do have a thinner rind than other pomelos. "Chinese grapefruit" really isn't the best terminology, that's just the common English translation, from a time Americans were much more familiar with grapefruit than having any idea what a pomelo was. In Asia though they're both considered the same thing ( "Chinese grapefruit" and pomelo I mean), they don't think of the different varieties as a fundamentally different fruit. Maybe I should have best avoided using the word "grapefruit" altogether to avoid confusion and just called it Chinese-type pomelo. (by using the word grapefruit I was just trying to emphasize that it might not be completely C. maxima)
« Last Edit: August 19, 2017, 04:59:39 PM by SoCal2warm »

Millet

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Re: breeding cold hardy pomelo
« Reply #14 on: August 19, 2017, 10:27:10 PM »
Wonder what the cold hardiness of a Valentine pummelo is compared to other pummelo varieties.  I ask this because Valentine is not a true pummelo, it is a hybrid of pummelo and a blood orange.

SoCal2warm

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Re: breeding cold hardy pomelo
« Reply #15 on: August 22, 2017, 12:20:17 PM »
Wonder what the cold hardiness of a Valentine pummelo is compared to other pummelo varieties.  I ask this because Valentine is not a true pummelo, it is a hybrid of pummelo and a blood orange.
I don't think blood oranges are very cold hardy. I've also noticed that hybrids between different citrus species often show slightly less cold tolerance than their parents (and may be slightly less resilient in general). I think it's a mild form of what is known as outbreeding depression.

Ilya11

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Re: breeding cold hardy pomelo
« Reply #16 on: August 22, 2017, 01:17:08 PM »
Millet,
Valentine parentage  is more complex,
it is ‘Siamese Sweet’ pummelo x ( ‘Ruby’ blood orange x 'Dancy' mandarin) that can be compared to PummeloxClementine
Best regards,
                       Ilya

Millet

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Re: breeding cold hardy pomelo
« Reply #17 on: August 22, 2017, 04:42:22 PM »
Thanks Ilya, I appreciate it.

SoCal2warm

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Re: breeding cold hardy pomelo
« Reply #18 on: September 30, 2017, 05:54:01 PM »



Here you can see some of the hybrid citrus seeds being incubated. It's only the first generation.

Citradia

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Re: breeding cold hardy pomelo
« Reply #19 on: September 30, 2017, 10:22:08 PM »
I saw pummelo trees for sale at a nursery in Tallahassee, FL a few years ago and Ben Salley, a citrus grower ("Simply Citrus") in Columbia,SC had a pummelo growing under a magnolia tree when I visited his nursery a few years ago. At one of the Southeastern Citrus Forum meetings I attended, a lady mentioned a pummelo that she grew on St Helena Island in SC. These areas either are or are very close to zone 8 climates.

 

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