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Topics - SoCal2warm

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Cold Hardy Citrus / Graft chimeras and hardy citrus
« on: January 16, 2019, 10:57:18 AM »
How much do we know about graft chimeras and hardy citrus?

Graft chimeras are a sort of hybrid, but not a genetic one, between two different species that resulted through grafting, typically from growth offshoot coming out of a graft union area and then separately propagated. The graft chimera is comprised of a mixture of cells between the two citrus types.

There are different types of graft chimeras. The most homogeneous ones, and the ones of most interest are periclinal chimeras, which typically involve a single layer of cells distributed throughout the growth of the plant.

I'm also experimenting with joining together different seedlings together at the earliest stage of their development, so that the seedling sprout consists of a mix of cells from two sources. (This takes some very fine precision and a good eye)

How much hardiness can a cold hardy variety confer to another normal citrus variety when they are part of a chimera together?
Could this be a viable strategy for developing new cold hardy citrus?

From what I've seen, many obscure citrus varieties that are believed to have originated as a graft chimera have not actually been confirmed as being so, so it's not truly known with certainty.
The only way to be sure is if there's obvious phenotypical differences in different parts of the tree, or on different parts of the fruit, but in that case its not a very homogenous chimera, and not a periclinal type of one, which would be expected to give the best hardiness because the cells are more evenly distributed throughout the plant.

Say for instance we had a Satsuma graft chimera together with a Satsuma-trifoliate (citrandarin) hybrid.
The Satsuma-trifoliate hybrid within the chimera system could be a triploid with only one of its three sets of chromosomes coming from trifoliate.*
That could potentially make the resulting chimera nearly indistinguishable from normal Satsuma.

* (This could come about through hybridizing a tetraploid Satsuma with a normal diploid trifoliate, or the pollen may have been unreduced coming from the Satsuma, or the female parent being used could have been a "seedless" triploid, and so any rare seeds that did manage to form would be much more likely to have originated from an unreduced female gamete, since triploid cells that undergo meiosis have a fairly high chance of turning out aneuploid and won't develop. Also, you have to have a non-nucellar citrus variety for the triploid to turn out seedless, otherwise the seeds are still going to form from nucellar tissue even though the zygote failed to develop.)

Prague Citsuma is believed to be a graft hybrid, but it has not yet been positively confirmed with certainty. (A few basic tests were done but were inconclusive)

Cold Hardy Citrus / More unusual/obscure cold hardy citrus hybrids
« on: January 13, 2019, 12:28:17 AM »
Let's talk about some of the more unusual and obscure complex hybrids.

Dimicelli - I'm not exactly sure where this one comes from but it's believed to either be a citrandarin or, more likely I've read, someone remembered it being a Clementine cross with CiTemple.

"The common tangerine is the hardiest of the dessert citrus, and was a possible source of genetic material.  The first attempt was Clementine x P. trifoliata, and these survived, at least in Franklin at 0°F (-17.8°C)and in Houstion at 5°F (-15°C)to fruit following the freeze of 1989.  They seem to be hardy to five degree above zero.  Several siblings, 'Dimicelli', 'Backyard' and 'Hardy Fruitful 90 have received the dignity of names."
The Hardy Citrus of Texas, reported by C.T. Kennedy from the notes of John R. Brown, M.D., article in Fruit Gardener, page 14

CiTemple is a Temple orange x poncirus cross, Temple orange actually being a tangor that has zygotic seeds and thus a suitable choice for female parent in hybridization efforts. I've read some references to "CiTemple edible" which was considered particularly good tasting variety for a citrange.

Ventura Lemandarin- This is believed to be a cross between Tiwanica lemon and either Keraji or Satsuma mandarin.
Ventura lemandarin is sour, like a lemon.
Seems to be a vigorous growing variety. Supposedly when it was high grafted onto poncirus it managed to survive a brief 6 °F event with branch die-back, according to one report.

According to genetic marker studies, Tiwanica lemon seems to really be a sort of sour orange, with pomelo-type gene indications. It originated from Taiwan, and was named Nanshodaidai in Japan. The fruits are as sour as a lemon.
Both Keraji and Satsuma are closely related in ancestry, Keraji having even more cold tolerance than Satsuma, though smaller more sour (and seedy) fruits.

Glen citrangedin- This was an early citrange x calamondin cross.

" The first hybrids were between Poncirus trifoliata and varieties of the cultivated orange. They were called "Citranges" and while they received a good deal of publicity when they were first introduced they may be said to have been more encouraging than useful. The fruit, though beautiful to look at, was scarcely larger than that of the Trifoliate Orange, and while the juice, taken by itself, could be used as a substitute for lemons, there was even in the hybrid so much musky oil in the rind, that special precautions had to be taken in opening the fruit. Another bad trait of the hybrid was its too quick response to warm weather in the early spring. It was, therefore, crossed with two other citrus fruits, which, though not so hardy in other ways, were slower to start into growth m the spring. These were the Kumquat, Fortunella japonica, and the Calamondin, Citrus mitas, a tropical citrus fruit from the Philippines. The triple hybrids which resulted were called "Citrangequats" and "Citrangedins" respectively. The most promising hybrid yet introduced is among the latter group and has been named the Glen Citrangedin, from Glen St. Mary’s, Florida, where much of the breeding work has been done. It has small fruits about the size and flavor of a lime, but colored like an orange. The rind is without even a trace of the musky oil which characterizes the original hybrid and the tree is hardy at least as far north as southern Georgia. This artificial cosmopolite, uniting the possibilities of the Chinese Poncirus, and Philippine Calamondin with the common orange, is the "farthest north" which has as yet been achieved by the plant breeders. "
Arnold Arboretum Harvard University Bulletin of Popular Information, Series 3, Volume VI, November 5, 1932, article: Growing Orages in Boston, page 45, Edgar Anderson

I don't know about good tasting though. I was given two of the fruits and they had an unpleasant aroma, like rubber and baby wipes that made them inedible to me. The same with many other poncirus hybrids.
If they had been grown from seed it's possible they just reverted to a more bad flavored type, so I can't be completely sure if the fruits were truly indicitive of the original Glen citrangedin. Fruit size was also incredibly small, tinier than big sized kumquats.
Thomasville citrangequat was infinitely better.

MIC (Minneola x Ichang papeda x CiTemple Edible) -
I believe this was bred by Dr. Brown, who first crossed Ichang papeda with CiTemple Edible, and then crossed that with Minneola Tangelo.

(I have a seedling cultivar of this, may or may not be exactly the same as the original MIC, but unfortunately haven't had the opportunity to see any fruits yet)

Minneola tangelo isn't exactly a real cold hardy variety, but they are a bit hardier than oranges.

Fresh seeds available, several different varieties, only available for the next 5 days
$5.50 for >5 seeds, probably more

White grapefruit (probably Duncan or Marsh) - gold standard of grapefruit flavor
Ugli Fruit
Satsuma mandarin (only 3 seeds)
Yuzu (only 3 seeds)
Kaffir lime (not a true a lime, cold hardier than regular limes, down to zone 9)

For best chances of germination and fastest germination time, begin sprouting as soon as you receive them
You are most likely to have 100% germination rate with these (although the Yuzu has been in the refrigerator for over 3 weeks now, which might affect chances of germination).

Also willing to trade, if you have any super cold hardy variety seeds (or will have them in the future)


Apparently Haggen is carrying "Yuzu Lemons".
probably only for a short seasonal time

They don't look very ripe, but they are loaded with lots of fresh seeds inside.

Last week they were also carrying Buddha's Hand citron.

Some of you may have seen my thread "Karp's Sweet and other Edible Quinces for Eating Raw"

available: 2 free seeds 

Crimea or Kuganskaya variety. These quince are possible to eat raw, very little or almost no astringency. The fruits are very tart and kind of acidic though.
Quince is kind of an obscure fruit species now. These particular cultivar varieties are even rarer.

You'll probably need to grow the seedlings and then later graft them onto rootstock, if you don't want to be waiting around forever to get fruit.

Tropical Fruit Discussion / SF Bay Area Tropical Fruit Experiment
« on: October 20, 2018, 09:03:54 PM »
I don't know if any of you have seen this. This guy is around the San Francisco Bay area, zone 9b

Quick summary of what survived and what didn't:

Longan (although one of the trees died)
Jaboticaba (several different species)
Suriname Cherry
Cherry of the Rio Grande
Cherimoya (although one of the trees died)

Damaged but did not completely die:
Cinammon  (half of the new growth died back)
some of the mangos

Died or mostly died:
Green Sapote
Luc's Garcinia
Black Sapote
Peanut Butter Fruit
Cinnamon Apple
Wax Apple (note about the Wax Apple, I am aware of a few people with thriving Wax Apple trees in Southern California, zone 10 )
Bay Rum
most of the mangos

The lowest the Winter temperature got down to was 28 F. There was some frost on the surface of the soil.
He didn't bother protecting any of the plants.

His bananas also look good too.
He's also growing oranges and a macadamia nut tree.

Tropical Fruit Discussion / How to breed Bananas for Temperate climates
« on: September 28, 2018, 07:33:19 AM »
This post is about how to breed seedless bananas for temperate climates, a rough outline idea.

Select a cold-hardy banana (such as Musa basjoo) and then select another "edible" (good tasting, but seeded) banana which is very early ripening (perhaps Helen's hybrid).

Treat the apical bud with either Colchicine or Oryzalin to double to chromosome number, obtaining a tetraploid.

"Tetraploid plants were induced successfully from diploid bananas Musa acuminata ‘Kluai Leb Mu Nang’ and ‘Kluai Sa’ (2n = 2x = 22) with in vitro oryzalin treatment. Calluses from in vitro-grown shoot tips of both cultivars were treated with oryzalin at concentrations of 1.5 or 3 mg l−1 for 24, 48 and 72 h, respectively. The oryzalin treatments produced tetraploids at a frequency of 15.6% in ‘Kluai Leb Mu Nang’ and 16.7% in ‘Kluai Sa’ as detected by flow cytometry. Chromosome counting showed that the tetraploid plant chromosome number was (2n = 4x = 44). The selected tetraploid plants were transplanted in the field and variations in the morphological characteristic of leaf shape and fruit bunch compared to normal diploid plants were found under the same growing condition even after 3 years of cultivation."

In vitro induction of tetraploid plants from callus cultures of diploid bananas (Musa acuminata , AA group), Kluai Leb Mu Nang, Kluai Sa

Here's another relevant article as well:

When a normal diploid is bred with a tetraploid, the result is a seedless triploid variety.

"Most bananas purchased at your local supermarket came from sterile triploid hybrids."

This is a coconut palm growing in a pot in Santa Ana. It had been outdoors for 3 years, at the time this picture was taken (Sept 2010). The half whiskey barrel it is planted in is filled with pure sand, the idea being to make sure the roots are well drained. Trunk is 2 inches thick and tree is about 4 feet high.

Here's a picture of the same coconut 5 years later, in 2015:

Looks bigger and healthy with four large fronds.

Mark M. of South Oceanside Palms nursery bought and nursed a little coconut palm for 3 years, then planted it in the ground against a south facing wall on the side of a building. After 8-9 more years it grew to about 13 feet.

In Desmond Muirhead's book titled "Palms", he points out that the Coconut is of the tropics and that it remains stunted on the Baja down to La Paz. He goes on to point out that it is not the extreme low temperatures that doom the Coconut in California but rather the extended cool time frames.

Numerous attempts were made by many businesses in the 20s to 40s to try to import and grow coconut palms in California without success. But perhaps the regional climate of Southern California has warmed due to all the development that has taken place over the years. For example, Blenheim Apricots that used to be commercially grown in orchards 70 years ago now seem not to do as well and do not get enough chill hours.

There were several coconut palms growing near the inland Salton Sea (in proximity to the southwest shore). The fronds didn't look very lush but they seemed to be doing okay. A number of years later, however, they all died due to not being watered. Renters moved in (you know how that can go) and the palms didn't get the care they needed. Then the house became abandoned after the area fell into economic decline right after the housing crash.

I think coconut palms don't need that much humidity, they would do just fine anywhere within 15 miles from the coast in Southern California if it weren't for the extended cool winter temperatures.
I think cool and wet is what does them in. Maybe they'd be able to survive here if we had our dry season in the winter instead of the summer. Of course they like a bit of humidity if it's warm.

Cold Hardy Citrus / Orange tree in zone 8
« on: September 17, 2018, 01:49:26 PM »
This is based on a previous thread, and I thought to make a new thread on the topic, sharing some of my knowledge and thoughts.

Some of you living in zone 8 may be wondering if it's possible to grow an orange tree outside, or whether there's any kind of orange tree hardy down to zone 8a.

Well first, let me explain something. The most common citrus that people normally want to grow, oranges, regular lemons and limes, these are some of the least cold hardy citrus varieties. It's no wonder then that there's a common perception that citrus doesn't grow in zone 8, because normally when people have tried growing citrus, these are the types they have tried.

Now, before I explain further, I would like to share an optimistic story with you.


North Waco family's orange tree a miracle on 15th Street
by J.B. Smith, January 2013

A tree that Juana Delgado grew from the seed of a grocery store orange has become a miracle on 15th Street.

This month, Delgado’s family has harvested an estimated 600 oranges from the tree she planted 15 years ago when she moved into the Habitat for Humanity home near North 15th Street and Colcord Avenue.

In recent weeks, the family made big jugs of orange juice, shared fruit with passing vagrants and sent their children door-to-door to give away large bags of juicy oranges.

The tree has defied the conventional wisdom that oranges can't survive the Central Texas winter, when temperatures usually dip into the low 20s.

But the tree has soldiered on, even through a January 2010 cold snap when temperatures plummeted to 8 degrees.
"Many people said it’s not possible," Delgado said in Spanish. "I say, 'Come look. It's possible.'"
Mark Barnett, a McLennan County master gardener and a landscaper by trade, said he has seen many people try to grow citrus trees they bought from big box stores, but the trees usually freeze and die.

"It's very unusual for it to have survived that long without protection," he said. "We've had some extremely cold winters that should have killed it."

Delgado started the orange tree in a pot using a seed from an orange she bought at an H-E-B supermarket. Most table oranges are improved hybrid varieties and tend not to reproduce faithfully by seed, Barnett said.

But Delgado's oranges turned out sweet and flavorful. Delgado has been harvesting a few oranges a year during the last decade but got her first big harvest two winters ago: A basket and a box full. In the 2011 drought, she kept the tree alive by watering it but ended up with only three oranges that season.
This year, she hit the jackpot. Her children and grandchildren climbed ladders to pick the fruit and filled six boxes with about 100 oranges each.


Waco, Texas, is in zone 8a, and is just a little south of Dallas. Although in recent years the 8b zone has been moving north, first the southern half of Waco was reclassified into zone 8b, and now on the latest maps zone 8b has engulfed the entire city.

I've also speculated in another thread that citrus grown from seed may have more cold hardiness in zone 8 than the usual citrus on rootstock. (This doesn't necessarily apply in zone 7 though)

So now you know there's some hope an orange tree may be able to survive in zone 8. But don't get your hopes up because this is zone 8 in the American South and Texas. All the heat during the growing season (mostly because the growing season is longer) helps the citrus put on a lot of growth and better recover from the Winter. And there may be the odd year once in a while, with an exceptionally cold Winter, where your tree is going to killed to the ground. That's the type of climate that exists in the Southeast and Gulf Coast.

But now going back to the original topic. Are there any type of Oranges that are more hardy? Or are there any orange-like citrus that are more hardy?

The only actual orange that I'm aware of that has a good chance of surviving in zone 8a is Chinotto orange. It's actually more of a sour orange, the type good for making marmalade. You can eat it, but it's not as good eating quality as a regular orange.

Then there is Bloomsweet grapefruit. It's not really a "real" grapefruit. In form and flavor it's more like something halfway between an orange and grapefruit. The eating quality isn't bad but the eating quality isn't really quite as good as the oranges or grapefruits you can find in a supermarket, and it is full of seeds. (It is believed Bloomsweet may have come from a variety in Japan named "kinkoji", and a genetic analysis has shown it to be half-sibling to the popular variety Satsuma)

Tangelos have more cold hardiness than oranges. I'm not saying a tangelo is going to grow well in zone 8a, but it's probably going to have a much better chance than orange. Minneola tangelo has great flavor, but Orlando tangelo is known to have slightly better cold hardiness than Minneola.
In general, mandarins (sometimes called "mandarin orange") are more cold hardy than oranges. Not incredibly cold hardy, but mandarins can be commercially grown on the border between zone 9a/8b.

If you're interested in juicing, FF-6-15-150 is a newer one that came out of a USDA breeding program in Florida, and is rated to be as hardy as the cold hardiest commercial mandarin varieties. It was in large part bred from Orlando tangelo, is said to have great flavor, though seedy and on the small side for an orange. But it's not commonly available to the public and may be difficult to get your hands on.

Calamondin is believed to have originated from hybridization between kumquat and orange. It has more cold hardiness than orange, can grow in zone 8b, and has a chance of growing in zone 8a (maybe not as well). Mandarinquat is similar, it's a hybrid between kumquat and mandarin, and has slightly more cold hardiness than calamondin. The inside flesh of a mandarinquat is better than a kumquat, but although it can be eaten like a kumquat, the skin is a little bit tougher and not as good. And of course this section wouldn't be complete without making quick mention to Nippon Orangequat (a hybrid between kumquat and Satsuma mandarin). It has the best chance of doing well in zone 8.

Changsha mandarin and Citrange (a cross between Orange and bitter Trifoliate Orange) are two more pretty cold hardy ones that are distantly orange-like, sort of, if you're willing to drastically lower your expectations of fruit quality and flavor.

There are many other citrus varieties that have more cold hardiness but none of them are really "orange-like", so we won't really go into that discussion here.

Cold Hardy Citrus / Grapefruit that grows outside in England
« on: September 17, 2018, 01:27:39 PM »
There is a grapefruit tree growing outdoors, and which produces fruit, in the Chelsea Physic Garden, located in London.


A little bit of information about this grapefruit, it started off as a seedling sown in 1948 and kept in a pot until 1990, when the original owner died. It has fruited regularly every year since 1998.

It has been nick-named 'Aunt Queenie'.
The tree is located in a sheltered corner up against a brick wall under the protection of a large olive tree, and produces regular crops of large yellow fruits that hang for months on its branches.

With the thick pith and small fruit size, it doesn't look like those fruits are ripening very well in the cool climate.

A couple of possible factors that may be contributing to it being able to grow so far North: it is located in the center of a large city which probably has an effect on the localized climate, the garden is located next to the Thames river which may be having a moderating effect on the nearby temperature, the tree is growing in the corner of a sheltered walled garden. The fact that it was grown from seed and is not grafted onto a different rootstock might also be making the plant more vigorous and resilient to the cold. Since it is a white grapefruit, the variety it was sown from was most likely Duncan or Marsh, which are a bit more hardy than other common grapefruit varieties.

I have theory. I don't have any evidence for it, but let me share the reasoning for it.

Among different citrus varieties there are some which produce a higher percentage of nucellar seeds than others. Some citrus species produce entirely zygotic seed, while other varieties produce almost entirely nucellar seed, and there are several varieties with percentages in between. If the seed is nucellar, it will be a genetic clone of its parent. Not really a good thing if you're trying to hybridize new citrus varieties, but a good thing for those growing rootstock from seed, where uniformity is important.

The reason, it is believed, some citrus varieties form nucellar seed is that the sexual gamete cells inside the seed are not vigorous enough and can't compete with the nucellar cells.

The original origin citrus species are, almost entirely without exception, all zygotic. But when different citrus species are hybridized the percentages of nucellar seed shoot up. This could be because the hybridization between different species (which are not entirely compatible) results in a weaker gamete (megagametophyte), and so the nucellar lining takes over.

My theory is that if a hybrid citrus flower is pollinated with pollen from one of the original two species from which the hybrid originated from, the percentage of nucellar seed is likely to be lower. This would be because, the genetic composition of the megagametophyte would be less heterogenous, and thus presumably have more vigor.

So, for example, if Yuzu were pollinated by C. ichangensis, there might be some zygotic seeds form in the Yuzu fruit.

If this theory is true, this may confer some advantage to hybridizing new citrus varieties, since normally trying to hybridize a variety that is highly nucellar and using it as the female parent presents some pragmatic challenges.

How many of you here have cold-hardy citrus that you grew from seed?
I ask because this could lead to new hybrids. Seedlings don't always have the same genetic mix as their parents. Sometimes a seedling will have better tasting fruit or be more cold hardy.
It's also a simple cheap way (although time & effort intensive) to propagate more plants.

Cold Hardy Citrus / a few pictures from the Pacific Northwest
« on: July 09, 2018, 07:55:17 PM »

Bloomsweet grapefruit

Duncan citrumelo

Keraji mandarin (small seedling)

I was told this hybrid (on grafted rootstock) was originally grown from a seedling that was some sort of hybrid that included C. ichangensis and Minneola tangelo in its lineage. It's very probably a M.I.C.

I don't have all the info about this variety, but it's very likely the result of several select hybridizations by cold-hardy citrus grower enthusiasts over many many years, a real labor of love. I'm expecting it will have a good balance of cold hardiness to edibility.

I'm in zone 8a, but we have a long cool season that doesn't really begin warming up until late May. So the growing season for citrus is very short.

Just thought some of you might be interested in some unusual varieties of cold-hardy citrus growing in a part of the country people normally don't try to grow citrus. (Olympia, WA)

Right now it's humid, overcast, and warm, but it hasn't significantly rained for the last few weeks. Very low precipitation in the Summer.

Cold Hardy Citrus / Arctic Frost beginning to come back
« on: June 26, 2018, 03:21:27 PM »
planted out in the ground in mid-March, while the little tree was just beginning to set fruits. The tree could not take the cold temperatures (not freezing though) and completely defoliated, all except one tiny leaf. Most of the branches died back.
But now it's beginning to push out growth.

Pacific Northwest, zone 8a

(will have to show pictures later, it's too slow right now)


Just got it into the ground.

location is about 12 miles from the coast, so I would consider it solid zone 10 (between 10a and 10b)

That's a lychee and tree fern you see up in the top left in the picture.

This is a bigger specimen than most people have tried, so it already has a well developed root system and may have a better chance of surviving. This guy wasn't cheap. But it's a big beautiful plant. (yes, purple mangosteen)

Here's G. mangostana growing in the same container right next to G. hombriana.

The first picture was taken April 4, the second one was taken today. (That gives you some idea of how much they grow, or don't grow, in two months time)

I plan to approach graft them later.

G. mangostana, as a younger seedling, is really hard to grow. All the conditions are optimized, it's inside an enclosure with high humidity, temperature controlled with a thermostat at 77-79°, and LED grow lights (combination of both red/blue/white), and not too much light either I might add, as I seemed to run into that problem with G. mangostana earlier.

Obviously G. hombriana is the plant that's doing better in the picture.

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."

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.

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.

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.

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.

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

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

the one in the very front is a citron

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.

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

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:

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.

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