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1
Cold Hardy Citrus / Japanese kunenbo
« on: April 26, 2018, 09:24:52 PM »
Kunenbo ( 九年母 ) translates from Japanese as "nine year mother" or "ninth century mother". The latter would make sense if the fruit had been imported from China and/or first gained prominence in Japan in the Ninth Century, and then later became the "mother" of several other important varieties. Four hundred years ago kunenbo used to be one of the most popular citrus fruit varieties in Japan, but it was later surpassed by unshiu mikan (Satsuma) , which actually came about from a hybrid between kishu and kunenbo. Satsuma probably inherits its cold hardiness and aroma from kunenbo. (Kishu is an excellent tasting mandarin as well and has loose skin that easily comes right off) Satsuma has a lot fewer seeds than kunenbo.





As you can see from the pictures, kunenbo (at least this particular variety of it) looks like a delicious fruit, the inside almost looks kind of tangelo or orange-like, and the fruits are definitely on the big side for a mandarin.

As far as flavor goes, one Japanese blog had this to say: "It seems to have a thick portion of skin and it has a scent of turpentine oil on the rind, but I do not particularly care about the scent of the oil, but on the contrary the mandarin fragrance and the fruit's taste of sour and sweetness is refreshing and what I thought it might be good for scenting it. Although there is taste and sweetness, there is also a moderate sour taste, which is very juicy and delicious."
https://hkankou.exblog.jp/14589984/

2
I recently found an interesting DNA study done in Japan that could help provide more insight into the very far back origins of several cold-hardy Japanese citrus varieties.

Some things to bear in mind, this genetic marker analysis is not exactly indicative of precise ancestry percentages. It is only looking at certain markers, so this is only going to give us a very rough idea of the probable ancestry.


Apparently citron (C. medica) is nearly identical to Ichang papeda (C. ichangensis) in the DNA marker analysis, such that the study did not bother to differentiate them.
This means that wherever you see "C. medica" in the ancestry of these cold-hardy Japanese citrus varieties it is actually C. ichangensis.

The following percentages are not exact, they are rough estimates I copied from a visual graph:

C. ichangensis: 91.5% C. medica, 8% C. maxima, 0.5% reticula
Ichang lemon: 60% C. medica, 40% C. maxima
Yuzu: 99% C. medica, 1% C. reticula
Hyuganatsu: 26% C. reticula, 40% C. medica, 34% C. maxima
Kunenbo: 30% C. reticula, 65% C. medica, 5% C. maxima
Kunenbo (II) : 35% C. maxima, 65% C. reticula
Sudachi: 33% C. reticula, 67% C. medica
Kabuchi 33% C. reticula, 51% C. medica, 19% C. maxima
Kabosu: 34% C. reticula, 58% C. medica, 8% C. maxima
Kinkoji: 36% C. reticula, 0.5% C. medica, 63.5% C. maxima
Shiikuwassha 44% C. reticula, 56% C. medica
Keraji: 50% C. reticula, 16% C. maxima, 34% C. medica
Natsudaidai 52% C. reticula, 0.5% C. medica, 47.5% C. maxima
Satsuma: 25% C. maxima, 75% C. reticula
Hirado Buntan: 100% C. maxima


Hybrid Origins of Citrus Varieties Inferred from DNA Marker Analysis of Nuclear and Organelle Genomes,
Shimizu T, Kitajima A.
https://www.ncbi.nlm.nih.gov/pubmed/27902727


Some thoughts.

Yuzu is believed to share about half-and-half ancestry from C. reticula and C. ichangensis (or possibly even an earlier papeda species forerunner of C. ichangensis), so the fact that C. reticula barely showed up in the genetic analysis is a clear example of how imprecise the ancestry results of such an analysis are.
Yuzu probably wasn't just a simple cross of C. ichangensis with C. reticula; there probably had to be a few generations sexual propagation for the C. reticula gene markers to get bred out.

Apparently there are two very different forms of kunenbo, one with C. ichangensis ancestry, the other without. It looks like Kinkoji doesn't have any recent C. ichangensis ancestors, so it probably didn't descend from the kunenbo type in the study that showed C. ichangensis ancestry. The same is probably true of Satsuma as well.

Natsudaidai apparently doesn't have any close connection to Yuzu.
(Nansho-daidai I believe is Tiwanica lemon)

The overall ancestry composition in the graph is consistent with the theory that Hyuganatsu resulted from buntan getting pollinated by yuzu. However, if you look at the flow chart, the study inferred that Tachibana-B was one of the parents of Hyuganatsu. The graph shows Tachibana-B to be about 31% C. reticula, 69% "C. medica" (remember represents C. ichangensis here), so it may be that buntan (C. maxima) was pollinated by Tachibana-B, rather than yuzu. Although with that high a percentage of C. ichangensis I suspect Tachibana-B originated from a yuzu cross.

And the study does confirm the leading theory that Ichang lemon is a hybrid between C. ichangensis and C. maxima (though still doesn't prove whether it was a simple cross).

Keraji displays a surprisingly high percentage of C. ichangensis. It was my understanding that keraji originated, over a progression, from a triple backcross of Kunenbo with Shiikuwasha (C. depressa). It's possible that the C. ichangensis genes were positively selected for over time, since those genes conferred cold hardiness.

This isn't from this study but is just some things I've been able to put together from other studies, that may help you make some more sense of those varieties in that list:

Shiikuwasha x kunenbo = kabuchi; kabuchi x kunenbo = kikaimikan; kikaimikan x kunenbo = keraji
kishu x kunenbo = Satsuma; buntan x kunenbo = kinkoji ( kinkoji = Bloomsweet)
kabosu and sudachi are almost certainly hybrids from yuzu


Another DNA marker analysis done in China did not seem to show a connection between Changsha mandarin and C. ichangensis, which is interesting because the fruits/seeds of Changsha mandarin appear very morphologically similar to clementine-yuzu hybrid. The analysis did suggest Changsha mandarin might have just a little C. maxima ancestry though (maybe 15%)
Genomics of the origin and evolution of Citrus, Guohong Albert Wu, Javier Terol

Of course it's also possible the gene markers could have been completely bred out over numerous suceeding generations, since Changsha mandarin originated from growing in the wild.


A note about availability of these varieties in the U.S.
Most of these varieties on this list are fairly available to those in the U.S. The main exceptions are Kunenbo and Hyuganatsu.
Kabosu can be harder to find. Shikuwasa and Keraji seem to be fairly prevelent in Georgia and North Carolina, but I don't believe they can be found in the rest of the country. (Shikuwasa is sometimes written shikwasa, different spellings) C. ichangensis used to be more popular, but currently I don't think it is available from any mail order nurseries. It can still be found in Europe. Bloomsweet was introduced into the U.S. from Texas, so can be found in that part of the country.

Hyuganatsu isn't too difficult to get in Japan, it is sometimes sold as a seasonal specialty fruit. (I don't know whether it actually displays any exceptional cold hardiness traits) Kunenbo used to be the popular fruit in Japan hundreds of years ago before it was replaced by what is today called Satsuma. It's not widely available any longer but can still be found in some botanical and historical collections.
The UCR collection in California supposedly has one but apparently from the descriptions the type they have is not the delicious tasting one that exists in Japan, and in any case it's not available to the public.

Hirado Buntan isn't really that cold hardy but is more cold tolerant than other pomelos.



3
I'm going to be trying to hybridize pear with quince to get some new varieties that will be good for out of hand eating.

I have Karp's Sweet and Passe Crassane in zone 10, and
Kuganskaya, Crimea (Krimskaya), and Comice in zone 8


I did a lot of research and tried to select the quince cultivars that would be the most edible. Kuganskaya supposedly has slightly better flavor and is slightly less fibrous than Aromatnaya, though the fruit size is smaller and it is not as disease resistant, nor productive, nor do the fruits have as much aroma. Crimea is very productive, and supposedly has more flavor than Aromatnaya, though the eating quality may not be quite to the same level. I think all three are in the same subclass of quinces though (i.e. Russian) so the differences may be pretty small when compared to regular quinces.

I selected Comice because, well of course it has exceptional flavor that few other pear varieties compare to, but second because it is one of the few pear varieties considered compatible on quince rootstock, so I thought there might be better compatibility. Passe Crassane is a rarer French varietal pear that seems to be pretty obscure outside of Europe, and is notable for being believed to be a rare pear-quince hybrid.

There's a reason for both those that are growing in zone 10. I've read a report that Karp's Sweet in particular needs a lot of heat to produce the best eating quality, and Passe Crassane variety can be extremely susceptible to disease if not grown in a dry climate.


Further information for those of you who don't know anything about quince:

Why try to hybridize them? Well, if you've ever encountered a quince fruit at a market, they have an amazing aroma and fragrance. It almost smells like an intense heirloom apple mixed with pear, mixed with something else that could best be described as a green unripe mango smell, with hints of violet. Some people believe the aroma is a little like lemons and oranges, somewhat citrus-like (which might be a little stretch). It's the type of aroma and flavor that you want to keep eating. Except you can't, the fruits are astringent. Imagine the most amazing flavor but you are eating sawdust, or maybe chewing on a dry sponge. Some varieties are better for out of hand eating than others, but all of them have some level of tannins that cause astrigency. I wouldn't say it's much worse than an astringent persimmon though. In addition the texture of quince fruit is pretty dense (probably caused by pectin content). Some people compare it to eating a block of wood, albeit a deliciously flavored block of wood (maybe balsa wood?). It's the type of fruit you'll either love of hate. I can only eat about half of one before the astringency starts becoming too much, though at the same time there's a part of me that feels compelled to eat more. So obviously, there's the possibility that hybridization may be able to remove this astringency, or be able to capture the aroma and flavor in the form of a completely edible pear.

In the old days quinces were used in pies and jams because of their naturally high pectin content. It only takes a little to act as a thickener. (In case you were wondering why people ever grew quinces)
Quince can also be good in desserts. Once cooked, the flavor and texture are completely transformed, develops a deep flavor almost like cough medicine, and the astringency almost completely disappears. Because of the tannins being exposed to air it turns pink after cooking too. 1/4 quince to 3/4 apple can add a lot of flavor. Some people even used to hang a quince fruit in a closet or doorway to perfume the surrounding space.


Normally, trying to hybridize pear with quince is not easy. Most of the hybrid seedlings will die or be severely stunted, so there are compatibility problems. But the rare seedling is able to grow to produce fruits. The hybrids also seem to be very susceptible to disease, possibly I would hypothesize because the ones that show the least incompatibility have weaker immune response. Technically quince and pear aren't even in the same genus.

Luther Burbank was one of the early pioneers in plant hybrization and at one point made an attempt to crossbreed quince with pear, and obtained a few hybrid seedling plants, but after grafting some of cuttings onto an apple tree for a few years he was unable to obtain any fruit. (Luther Burbank: Methods and Discoveries 4: 138-140, (1914))

Another bit of related trivia here, the quince variety 'Van Deman' was selected by Luther Burbank from among 700 different crosses he had made between 'Orange' and 'Portugal'. He was trying to obtain the best qualities from both parents. Well let's see, I believe I have eaten a Van Deman quince before when it was at the very peak of ripeness. It was decently palatable (eaten raw I mean, and of course that's probably very subjective), although probably nothing special compared to the Russian cultivars.

4
Cold Hardy Citrus / citrus grown from seed shows more cold hardiness
« on: March 24, 2018, 09:11:54 PM »
I've observed that citrus grown from seed seems to do better, showing apparently more cold hardiness and being able to survive compared to the grafted plant that died.
I've observed this with lemons and kumquats, and there's also the white grapefruit growing at the Chelsea Physic garden in London up against a protected corner which was originally raised from seed before being planted outside after many years.

This is an interesting observation because the vast majority of the time, when people attempt to plant citrus outside to see if it can survive where they're at, the citrus came from a nursery and is on grafted rootstock.

These observations are coming from zone 8, in the Pacific Northwest. I have no doubt these plants would do much better on Flying Dragon rootstock in colder climates. But here they seem to grow more vigorous and be less susceptible to losing leaves on their own roots. I've also had a few plants on Flying Dragon or citrange that had most of their stems turn brown and die back whereas the seed-grown ones were more resilient. My Satsuma mandarin on unknown rootstock (it's dwarf though) also has not done as well as another Satsuma grown from seed, despite the seedling starting out smaller.

5
Citrus Buy, Sell, & Trade / Mandarinquat seeds
« on: February 15, 2018, 01:31:04 AM »
Mandarinquat is a fairly cold hardy citrus that can survive down to 14 F, it's more hardy than Calamondin but less hardy than kumquat
mandarinquat = mandarin x kumquat
skin is moderately edible, not as good as kumquat
interior is more edible and more flesh than kumquat

3 seeds, 4 dollars (seeds will go out, might send you the bill later)

limited time, probably ending in next few days

6
mangosteen and lychee, temperature kept at a constant 77-79°


the one in the very front is a citron

7
They had Valencia oranges and Page mandarins at the store today.



I also already have started seedlings from both.
I think a cross between the two would make an extremely good tasting orange.

8
Citrus Buy, Sell, & Trade / yuzu seeds available - ending Dec 26
« on: December 22, 2017, 03:18:31 PM »
Yuzu seeds available, free shipping, will send you 2 seeds. Only available for the next 4 days.

Yuzu is a cold-hardy sour citrus, and the rind is very fragrant. (Not very good for eating though, but the zest is used to flavor things)

Can also send some limequat seeds if you want (Mexican lime x kumquat)

For best germination results, peel off the outer coating of the seed and wrap it in a moist (not too wet though) paper towel and place in a sealed plastic bag, leave in a warm place and wait 2-4 weeks. Then plant sprout in moist potting soil in a plastic cup. Cover the top with plastic wrap to hold in moisture, but punch 2 or 3 tiny holes in the top. Keep in a warm place with an overhead lamp.

Yuzu is hardy to 10 °F, and there are even a few specimens growing outside in Seattle (if the tree was planted after it already reached decent size).

Sorry, won't send to Europe or Florida.

leave a post below and then send a PM with address

9
Cold Hardy Citrus / keraji mandarin
« on: December 20, 2017, 07:35:50 PM »
Keraji is a cold hardy Japanese mandarin with yellow-orange skin. The taste is like lemonade and the fruits are small and a bit seedy. Supposedly keraji can handle down to 12 °F.

One tree was growing outside unprotected and fruiting in Virginia Beach.

Apparently it was a fairly popular tree in the Southeast among those growing cold hardy citrus, but I can't seem to find any nurseries carrying it now.

A nursery owner in Georgia was kind enough to send me seeds


During my research I came across something interesting in a Japanese genetic analysis paper. Seems like keraji shares in common a parent with satsuma mandarin, a type of Japanese tangor called kunenbo which must be confering a degree of exceptional cold hardiness (it's a parent of bloomsweet as well). The analysis actually indicated keraji was probably a backcross of kunenbo with another sour-type citrus known as kubachi (today rather obscure, but the pictures I was able to find look similar to kabosu or sudachi).

I just read another research paper DNA analysis that says keraji appears to be a cross between kunenbo (seed parent) and kikai-mikan. I found a picture of kikai-mikan and not surprisingly the fruit looks a lot like a cross between both the pictures of kubachi and kunenbo I saw. So it looks like keraji may indeed be a backcross with kunenbo—that is (kubachi x kunenbo) x kunenbo.

For any of you who may be interested, here's the picture of kikaimikan (喜界みかん) I was able to find:


And here's here's a Japanese site showing pictures and description of Kunenbo:
http://www.michinosima.com/kaimono/kunenbo.html

The name Kunenbo translates as "nine year mother". The fruits appear pretty similar to a Kara mandarin. (One of Kara's parents is Satsuma, and Satsuma is a Kunenbo cross with Kishu. Kara is also pretty cold hardy and grows in frosty areas of Japan. Maybe that's giving too much information here)

I suspect there might be different cultivars of keraji as well, with slightly different qualities when it comes to edibility/flavor, if these plants have been propagated at some point from seed. The seeds seemed pretty big like they would be really easy to grow, so that may be likely.

Well that's pretty funny, I start a thread about keraji and show you pictures of its entire lineage of obscure parents but don't show you a picture of keraji itself. Well, there are plenty of pictures of keraji mandarin on the internet so you don't need me to post that there.













10
Cold Hardy Citrus / Growing rare cold-hardy hybrid
« on: December 19, 2017, 08:17:23 PM »
I'd like to post a quick picture of 3 of a very rare variety of cold-hardy citrus I have. It's a CiTemple 'edible' cross with Ichang papeda, that was then crossed with Minneola tangelo. (Well actually, to be more exact, it's a seedling grown from one of the fruits)



So far the 3 plants haven't fruited yet, and I still reserve a little bit of skepticism that the plants are as claimed, just because the existence of this sort of hybrid is incredibly unusual. I'll fruit them out and report on the fruit quality and cold-hardiness later. There's potential here that this could be the "holy grail" of cold-hardy citrus.

I have two inside a grow tent (to make sure they put on growth over the Winter) and one outside in the greenhouse. So far this cold-hardy hybrid doesn't really have an official name.

(CiTemple is a specific cultivar of citrange, in case anyone reading here was not aware)

11
Citrus General Discussion / Satsuma mandarins may be related to Yuzu
« on: December 07, 2017, 04:17:49 AM »
This is just a hunch but something I've suspected is that Satsuma mandarins may in fact have ancestry from Yuzu.
There are a couple of things that causes me to think this.

Satsuma mandarins are more yellow in hue than the deep orange of other mandarin fruits.

Satsuma shows significantly more cold hardiness than other mandarins.
The only other mandarin types known to be cold hardier than Satsuma are Keraji and Changsha. Keraji is also fairly yellowish in color, and I suspect has heritage from Nansho Daidai (also I believe descended from Yuzu). Changsha is very reddish orange in color and originates from a drier more interior part of China (and as far as I know it was never brought over to Japan) so I believe Changsha is probably separate and does not have anything to do with the origins of Satsuma. Both these two mandarins are not anywhere near the same level of edibility and deliciousness as Satsuma, and the fruit of both are smaller in size as well.

Although the flavor of Satsuma does not have as much tang as other mandarin varieties, there is something in the aroma of Satsuma that is very aromatic and deep, it reminds me of Yuzu. Other mandarin varieties do not really have this quality.

Under the Japanese system, Satsuma-type mandarins are classified in a completely separate family from the other mandarins, though they are all considered to be mikan.
The Satsuma-type mandarin originally came from China, though it later became far more popular in Japan than China.

Just to clear up a little bit of language naming ambiguity, originally "yuzu" was the Chinese name for sour citrus in particular pomelo, but the Japanese took this word and applied it to the citrus now most commonly known as Yuzu (C. junos). The Chinese refered to this citrus as xiang feng (translates as "fragrant orange").
Some of you might note the similarity here to the name "Shangjuan" (fragrant ball). Shangjuan and Xiang yuan are just alternative romanized spellings of the same Chinese word. Among the cold-hardy growing citrus community in America and Europe, Shangjuan has typically refered to the citrus also known as Ichang Lemon (not quite the same citrus as Ichang papeda). However, in China Xiang yuan more commonly refers to the Chinese citron. The Ichang Lemon and Yuzu (C. junos) still exist in China but are very rare, and most Chinese in these regions don't have any knowledge of them. In contrast, Yuzu is well established in traditional Japanese cuisine, and after declining in popularity for a while, has even made a modern comeback in flavored food and beverage products. Most of these citrus were brought over to Japan during the Tang Dynasty (late 7th Century). (The pomelo reached Japan later, from Taiwan, probably since they were only found in the Southernmost parts of China, and weren't as cold hardy as the more mandarin-type fruits)

12
Cold Hardy Citrus / Citrumelos in England
« on: December 05, 2017, 06:41:46 PM »
This is a small tree growing at the back of a house in the Wollaton area of Nottingham.


The owner planted it about 29 years ago, and having obtained the plant from a nursery in Lincolnshire. When contacted, the now retired owner of the nursery stated he had received cold-hardy citrus seeds from the USA and was told they came from a citrumelo, the particular variety being 'Dunstan'.

This tree does have trifoliate leaves and the fruits were observed to be bigger than those of Poncirus. It's possible this tree may be a hybrid of Dunstan citrumelo with something else.


The grower of this tree believed at first that the plant was from seeds of Troyer Citrange. However, 13 years before this picture was taken he had also been sent Swingle citrumelo seeds, so he now believes that is what this is, since the fruits look a lot more like Citrumelo than Citrange. The tree is in the county of Buckinghamshire, and regularly experiences frosts from late September to early May, and in more recent years experienced minimum temperatures down to -12 °C (10.4 F).


The tree is more like a rounded shrub about 2m (6ft) tall and wide. It is growing close to a rhododendron, and the fruits developed quite low down and hidden by the rhododendron leaves. The owner never noticed flowers or developing fruit until December when, to his great surprise, he noticed eight fully formed yellow fruits growing at the very bottom of the tree.


Unfortunately the taste was completely awful, even worse than poncirus.
The fruit shows a very thick pith. This does sometimes happen when growing citrus in cool climates. Seeds appeared to be poorly formed.

The next specimen is not a citrumelo at all but is believed to be a grapefruit, growing outside in London!
A seedling was sown in 1948 and kept in a pot until 1990, when the original owner died. It is now growing in the Chelsea Physic Garden, and has fruited regularly since 1998. It's in the corner of a sheltered walled garden.





It's worth noting that being located in the center of a large city probably has an effect on the localized climate, and the garden is located next to the Thames river.


credit: all pictures and above information come from http://www.homecitrusgrowers.co.uk/

13
Some of you may be aware that Oroblanco and Melogold grapefruits are triploid, meaning they have 3 sets of chromosomes rather than the normal 2.
So a natural question that arises is what would happen if you tried to breed a triploid citrus with something else? What would you get.
Although Oroblanco is normally considered seedless, I found several fully formed large seeds inside one the fruits I just bought. I'm assuming all/most of these seeds are nucellar (clones of the parent) but it got me thinking.

I've been doing a lot of research, and wanted to present to you what I've found so far, in an attempt to answer the question. I'm no expert in this area.

Basically, when a triploid like Oroblanco pollinates another citrus variety (generally a monoembryonic variety) it induces the formation of seed. These seeds will be haploid, having only a single set of chromosomes from the female fruit parent. Most of the gametes produced from a triploid will have unevenly split chromosomes during meiosis, but a smaller portion will also be diploid and haploid. That means that pollen from a triploid parent could contribute either one or two sets of chromosomes. Assuming that the female parent is diploid, this will result in the seed either having 2 or 3 sets of chromosomes. So you could get a normal zygotic seedling, or you could get another triploid. The triploids will have a lower probability of having fully formed seeds, so the majority will not survive. (Embryo rescue techiques are usually employed to be able to grow these underdeveloped seeds, but in a small number of cases the seeds will be well formed enough to be able to germinate on their own)

It is also possible for a triploid parent to produce an unreduced gamete but this comparatively much more rare, so in that case the gamete would be able to contribute 3 sets of chromosomes.

Haploid citrus plants are normally feeble and slower growing, generally sterile, and right now I cannot find any references to a haploid citrus plant ever having produced fruit. But for breeding purposes, they can be reconstituted back to normal diploids by treating the growth on bud shoots with colchicine, and then later taking a graft from that offshoot.

This still leaves so many questions but it's a start to understanding.

Quote
Triploid plants can and do go through meiosis (cite). Of course, their fertility is lowered with most gametes being aneuploids (uneven number of chromosomes), however, triploid plants also produce small numbers of euploids (1x, 2x, 3x)(Fig 1 of the above cited source).

This should make you wonder why we don't often observe seeds in triploid fruit since they can make viable gametes (1x, 2x, 3x). This seems to be purely driven by the number of female gametes (ovules) produced vs. the number of male gametes (pollen grains) produced. Plants produce many more pollen grains than ovules making it much more likely that a euploid pollen grain will be produced. Contrasted by the small number of ovules produce making it very unlikely that a euploid ovule will be produced.

The fertility of triploid plants is the foundation for one of the most used mechanisms for polyploid formation called the triploid bridge. The triploid plant produces 1x, 2x, and 3x gametes that combine with the 1x gametes produced by a diploid plant to form 2x, 3x, and 4x offspring
 

I could well be wrong about most of the seeds in Oroblanco being nucellar. That would be interesting.

14
Take a look at this origins of citrus diagram from National Geographic:

http://www.nationalgeographic.com/magazine/2017/02/explore-food-citrus-genetics/

And it doesn't even show all the original citrus varieties! I have quite a few varieties that have ancestry from citrus species not shown on that diagram (C. trifoliate, C. ichangensis, C. taiwanica, etc).

There's so much diversity in the citrus family, and the amazing thing is it's possible to hybridize them together.

15
Finally, a raspberry that can survive in Southern California


Bababerry raspberry is suspected to actually be a hybrid between regular raspberry and the wild California Smoothleaf raspberry. Normally raspberries don't grow too well in the hot dry climate of Southern California (although blackberries do just fine). It's in a spot that gets shaded in the afternoon.

Behind the raspberry you can see a 'Karp's Sweet' quince tree and a Mauritius lychee tree in the background.

16
Citrus General Discussion / just repotting some of my plants
« on: July 11, 2017, 08:14:36 PM »
Here you can see an Ichang lemon, Bloomsweet grapefruit, and two mangosteen plants in the back.


I can guarantee you those little mangosteen plants won't be sitting outside for long, it's pretty hot dry and sunny, and two days ago it got down to 54°F in the early morning.

17
Citrus General Discussion / Thread for Citrus Breeders
« on: June 27, 2017, 04:31:21 PM »
Is anyone here attempting to breed new varieties of citrus?
Share your breeding attempts or accomplishments here. Maybe we can exchange seeds.

18
Citrus General Discussion / breeding - what can I do with citron
« on: June 26, 2017, 11:53:55 PM »
Does anyone have any ideas on what I could do with Etrog citron in terms of breeding?
I have flying dragon poncirus trifoliate and some changsha mandarin seeds. I'm interested in breeding a cold hardy lemon—a true lemon in the sense that it will have citron in its ancestry.

maybe (citron x poncirus) x changsha ?


Common lemons, in case anyone didn't know, are hybrids between citron and sour orange (basically)

19
Here's a bit of information that will be very useful to anyone trying to breed new varieties of citrus and wants them to be seedless.

Crossing a tetraploid citrus with a regular diploid citrus will result in a triploid citrus. Triploids are generally sterile and seedless. This is a strategy that has been used in many cases to breed seedless citrus varieties (although there are other strategies).

It turns out that most regular citrus varieties—the ones that are polyembryonic producing clonally from seed—will convert to tetraploids at least once in a while. That is, if you grow 300 seeds, at least one of them will likely turn out to be tetraploid, even though it is otherwise a clone of its diploid parent. Tetraploids are often slightly bigger and slightly deeper in color than their corresponding diploid parent.

Some citrus varieties are more likely to convert to tetraploids than others. For example, out of 78 seeds grown from a Duncan grapefruit, 5 turned out to be tetraploids.
'Mapo' tangelo (7 out of 73) and 'Tardivo di Ciaculli' mandarin (2 out of 38) also had high rates of tetraploid seed. For Minneola Tangelo, 3 tetraploids were observed out of 166 seeds.
Something else notable, it appeared that plants producing fruit in colder conditions in marginal climatic areas had an increased likelihood of producing tetraploid seed.

Troyer citrange had very high rates of polyploidy, as high as 10-20 percent of the seedlings. (Carrizo was almost as high too)

Now, you most likely may not be able to know the chromosome count of any individual seedling, but if you grow enough of them, there should be some seedless plants two generations down the line. Assuming you try to prevent self-pollination. A much more convenient strategy is to rely on the blossoms of the tetraploid plants to pollinate other citrus varieties which are known not to be polyembryonic, usually mandarin but also pomelo.

If it's not polyembryonic, that means all the seeds that form inside the fruit are zygotic, formed by sexual recombination. If the variety also happens to be self-incompatible, it will require two different parents for fertilization, seed formation, and most likely fruit formation too. Unless the variety is parthenocarpic, meaning it will be capable of producing fruits without any fertilization, which many citrus varieties are. Yes, the terminology can get a little complicated and there are many aspects to breeding and growing different types of citrus varieties in orchards.

20
Cold Hardy Citrus / citrus varieties in order of cold-hardiness
« on: June 16, 2017, 04:32:14 PM »
This is a list of different citrus in order of how much cold they can handle:

kumquat > mandarin > orange > grapefruit > pomelo

I might write:

orange > lemon > lime

I don't want to put them with grapefruit because there are different grapefruit varieties spanning the range from being as cold-hardy as orange to being as cold-sensitive as lime. Although kieffer limes are about as cold-hardy as orange (probably since they are believed to have some papeda in their ancestry).

Minneola tangelos are probably somewhere between mandarin and orange. Clementines and tangerines span the range between mandarin and orange.

Not only are pomelos the most vulnerable to cold, they also need a lot of heat to ripen. Despite being a pomelo-grapefruit hybrid, Oroblanco is probably one of the cold-hardier grapefruits, being close to orange in cold-hardiness. (Due to its comparatively smaller fruit size and sweetness it is also as easy to ripen as common grapefruits)


Among the extremely cold-hardy citrus varieties:

trifoliate > Ichang papeda > Thomasville citrangequat > common trifoliate hybrids (citrange) > yuzu > taiwanica lemon

There is in general a trade-off between cold-hardiness and edibility.



21
I have a theory about the lineage origins of Ichang papeda, Yuzu, and Ichang lemon, which are all probably related.

I believe there was probably an original cold-hardy papeda species, similar in morphology to Ichang papeda, that has now been lost. This original cold-hardy papeda species naturally hybridized with sour mandarin and grew wild in the mountainous interior region of China. This resulting citrus is what the Japanese would later call Yuzu, after the fruit was brought to Japan during the Tang dynasty. Usually producing seed that were clones of the parent, there probably were several interbreeding events that mixed up the genes, making them more uniform and stable, so that Yuzu became like a species.

I believe that Yuzu (it might not be the same cultivar type we know today) may have hybridized again with its original ancestor papeda species resulting in the Ichang papeda.

I believe it likely that Ichang papeda crossed again with Yuzu resulting in the Ichang lemon. Or possibly a primitive Ichang lemon. This Ichang lemon was then identified by humans and selectively bred for bigger size and more pulp.

 I do not want to speculate too much but one thing I think might be possible, the original lemon could have been crossed with an orange, and then the new lemon, which closely resembled the original, was selected as the more desirable one and repeatedly propagated from seed (possibly until its genes became stable).

It is very unlikely a pomelo would have been available in this colder mountainous region of China, so if there are any pomelo genes in Ichang lemon they most likely would have had to come through some sort of orange or orange-mandarin (these type of Citrus unshiu × Citrus sinensis fruits were very common and China and Japan and could be more cold hardy than orange).

However, if Ichang papeda were crossed with yuzu, and then crossed with orange, one would presumably expect the color of the resulting Ichang lemon to be much more orange than it is. There are other hybridization possibilities of course, but I do not think any of them to be too likely. Maybe if the mandarin genes in the original lemon got suppressed from several sexual events (while it was growing in the wild) it could then have been enough papeda-like to later cross with another mandarin-dominant variety without taking on an orange coloration. Or the orange could have been backcrossed into the lemon over two generations. If the resulting Ichang lemon was superior to the previous, the old variety may have simply been discarded, no longer grown by the people living in that area.

Why do I believe this? There was a genetic study done in Japan that showed a very strong connection in Ichang papeda to having a yuzu ancestor (although the presumption was not conclusive).

So the lineage diagram, according to my theory, would basically look like this:

...........papeda ancestor    sour mandarin
.....................l_____________l
................................l
papeda ancestor......yuzu
..........l____________l
.....................l
...........Ichang papeda.......yuzu
.....................l___________l
...............................l
................primitive Ichang lemon
...............................l
......................Ichang lemon

22
I found a source selling an unusual citrus variety. They say it was from a seed from a fruit they got at a South Carolina citrus expo, and they were told the fruit was from a cross between Minneola tangelo (itself a Duncan grapefruit x mandarin hybrid) and Ichang papeda, which was then crossed again with a Tangor (a cross between tangerine and sweet orange).

They have no idea how cold-hardy this thing is, but think it should be hardy to zone 8 (presumably, based only on the fact it is an Ichang papeda hybrid).

I don't know if it was carefully bred from each cross (with only the best offspring selected from several seedlings) or whether they were just simple crosses, in which case one has no idea if the final offspring retained any of the original cold-hardy papeda genes. And then that the final plant was grown from a seed from this fruit? Really sounds like it could be luck of the draw with the genes, even if one could be certain it actually did come from Ichang papeda, two (or three) generations back.

Does anyone know anything about this variety or does it seem familiar to anything else you have ever read about?

Do you think it's worthwhile to buy it?
(Sorry, I'm going to have to keep the source secret for now because I want it to sell out to someone else)


23
These are two rare (and very expensive) Thai durian varieties.

ก้านยาว gâan yaao "long stem"
and
ชะนี chá-nee , main meaning "gibbon" but side meaning "prostitute"



http://christianpfc.blogspot.com/2016/12/durian-and-pomelo-varieties.html

And while we're on the topic, take a look at these Vietnamese "milk melons" (actually gourds)



http://karenmystory.blogspot.com/2015/05/all-picture-of-asian-fruit-that-look.html



24
Has anyone here ever been successful sprouting citrus seeds that they ordered through the mail?

Am I just being stupid? Are there any chances these things can germinate? I see loads of citrus seeds being sold in online market places. Are the sellers and buyers just ignorant, or do most people actually get their seeds to sprout??

I read somewhere citrus seeds may not be viable unless you get them directly from the fruit.

25
Citrus General Discussion / whole new subcategories of citrus
« on: June 12, 2017, 10:01:11 PM »
Like a color palette, from just a handful of original citrus species has resulted all sorts of new families, each with their own unique character.

Repeatedly backcrossing a pomelo with mandarin resulted in the common Orange. And the flavor is not quite the same as either of its original ancestors. All that selective inbreeding eliminated nuances in flavor and resulted in high levels of Valencene.
Cross an Orange again with a tangerine (mandarin) and you get a Tangor.

When a Pomelo that had been brought to Jamaica inadvertently hybridized with Orange and the resulting offspring, which had small sour fruits that grew in clusters like grapes, began spreading in the wild, that was the start of the lineage that today is known as grapefruit. And grapefruit, while similar to pomelo in many respects, also has its own unique flavor differences. It developed very high levels of the pungent sweet compound thioterpineol, the most characteristic component of grapefruit aroma.

Cross a grapefruit with a mandarin and you get a Tangelo (which really does taste like a cross between mandarin and pomelo).
Cross a tangelo with a pomelo again and you get a Tangelolo.
These are all just varying combinations on a spectrum between mandarin and pomelo, yet each family is unique and has its own taste.
Cocktail Grapefruit was a hybrid between grapefruit and mandarin, but is still considered a grapefruit.
And what if you cross a grapefruit with a pomelo? Oro Blanco is conveniently easy to categorize as a grapefruit because its pomelo parent happened to be Siamese Sweet, which did not have much flavor of its own to contribute. So Oro Blanco mostly takes on the grapefruit flavor of its Duncan parent.

There are so many potential combinations. What other new families could be possible?

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