The Tropical Fruit Forum

I have 10 varieties of bananas
Musa acuminata (AAA) ‘Dwarf Cavendish’
Musa sikkimensis (Darjeeling Banana)
Musa sapientum Linn. (AA) 'Kluai Leb Mu Nang'
Musa balbisiana ‘Kluai Tani’
Musa basjoo
Musa (ABB) "Dwarf Orinoco"
Musa (AAB) "Dwarf Puerto Rican" (plantain)
Musa acuminata (AA) 'Siam Ruby'
Musa (ABB) ‘Kluai Nam Wa Dam’
Musa (AA) ‘Kluai Khai’ ( Sucrier)

Can any of those grow outside where you live? (I mean left in the ground during the Winter)

I have read that optimal citrus growth occurs at around 86F

Maybe in humid climates like the South.
The Summers on the West Coast (including the PNW) are far too dry for citrus to do well in that heat, the leaves can get kind of baked. I think the optimal temperature range might be closer to 76-83.

There may be another way of obtaining a tetraploid banana without Colchocine or Oryzalin.

"Crossing of a triploid banana with a diploid variety generates diploid, triploid, tetraploid, aneuploid and hyperploid progeny"

I believe this may be because sometimes an unreduced gamete escapes, and in the case of triploids, an unreduced gamete (still with all 3 sets of chromosomes) is much more likely to escape meoisis intact and be viable than a triploid that underwent chromosomal division.
So an unreduced 3n gamete from pollen + a normal haploid gamete from the female parent = a tetraploid offspring 4n

https://www.sciencedirect.com/science/article/pii/S0254629905000463#bbib22

I know the same thing can occur in citrus but it's usually only somewhere around 1 out of 25 offspring.

Another article seems to suggest with bananas it may be as high as half:
"On the assumption that Cavendish cultivars have low fertility, the Banana and Plantain Breeding Program at the Honduran Foundation for Agricultural Research (FHIA), starting in 2002, pollinated 20,000 bunches, approximately 2 million fingers, of the Cavendish cultivars ‘Grand Naine’ and ‘Williams’ with pollen from 10 Cavendish cultivars for the development of Cavendish tetraploids. As a result, 200 seeds with 40 viable embryos were obtained, from which 20 tetraploid hybrids were developed. These results confirmed the assumption that Cavendish cultivars have low fertility, which allows their use in conventional breeding methods to create new progenies. The selected tetraploid progenies were crossed with improved FHIA diploids for the development of second generation triploid hybrids."
http://www.fhia.org.hn/dowloads/banano_y_platano_pdfs/Improvement_of_cavendish_banana.pdf

much of this is because seeds that would have had problematic chromsomal abnormalities don't form in the first place, i.e. half the seeds that do manage to grow from a normal seedless banana, out of the very few number of seeds, will be tetraploids. Then these tetraploids can be crossed again with a normal (diploid) seeded banana to give a seedless banana offspring.

still growing, very warm sunny day today,
stem of the smaller branch stem beginning to thicken

I have another idea also.
Take a regular seedless banana (3n), double its chromosome set number to 6 (hexaploid), then breed it with another banana.
Once the chromosome set number has been doubled from 3 to 6 it should then produce seed because 6 is an even number (and the chromosomes can be evenly split during meosis).
Hybridizing a 6n (hexaploid) with a seeded 2n (diploid) should give a 4n (tetraploid) banana (also seeded), which could then in turn be hybridized again with a 2n seeded banana to give a seedless 3n triploid.
I believe it could also be possible to use seedless (3n) banana pollen to fertilize a hexaploid (6n) flower, also resulting in tetraploid (4n). I'm not exactly sure about bananas but this type of phenomena can work in citrus. There are some issues with trying to breed triploids but in general some normal (1n) haploid gametes are able to form from the meosis of triploids, and the majority of offspring able to form from triploids will be the same as if they came from a normal diploid parent (though the rate of fertility is normally substantially lower). Basically 3 is unable to split evenly into two, so some 1n gametes are able to escape from the division intact. Maybe someone with more knowledge than I will be able to give some input about whether seedless bananas have fertile pollen.


Edit: A quick search reveals triploid bananas can produce fertile pollen.

"Pollen viability was examined by recording the number of viable as well as non-viable microspores in anthers just before anthesis, as it could be an efficient and rapid indicator of female fertility. It was thought that competency in meiotic restitution in microspores could indicate similar competency in megaspores. Pollen fertility was compared among seeded diploids and edible triploids of Musa and correlated with ovule fertility. Viability was examined using the Alexander's pollen stain procedure. The seeded diploid species M. acuminata, M. balbisiana, and M. ornata had 3 times more viable pollen than the edible tetraploids (AAAB). M. balbisiana and M. ornata had significantly more viable pollen than M. acuminata. The tetraploids contained 3 times more viable pollen than the edible triploids AAA […] The AAA triploid Gros Michel had the highest percentage of viable pollen at 13% […] "

Pollen fertility in Musa : Viability in cultivars grown in Southern Australia, J. A. Fortescue, D. W. Turner, Australian Journal of Agricultural Research, January 2004

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: http://hortsci.ashspublications.org/content/43/7/2248.full


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."
https://www2.palomar.edu/users/warmstrong/hybrids1.htm

Below is a Duncan grapefruit growing in Bouches du Rhone, Southern France:


Duncan was one of the first grapefruit varieties to be commercialized. It has very good flavor but does has a fair amount of bitterness.
It is a very vigorous tree, which has a power of recovery after a frost, quite exceptional. Its resistance to cold is -8 °C (23F). For a specimen like this particular tree, its resistance to cold seems to be more like -10 °C (14F).

The tree froze back at -14 °C but has recovered. Currently it will still bloom (send out blossoms).

Pictures and text translated from http://www.agrumes-passion.com/pamplemoussiers-pomelos-f6/topic337.html


From the picture, it looks like the tree is at least 20cm in diameter. The top has been cut back, obviously because it was freeze-killed back, but plenty of vigorous branch growth coming out below the cut. You can see the graft line about 40cm above the ground, and the total height to where the cut is looks to be about 100cm (the tree is more than 3ft high).

Most of France, including the South of the country, is in the equivalent of USDA climate zone 8, with a narrow stretch of zone 9 right along the southern coast, so I would probably estimate the location (in Bouches du Rhone) probably being 9a, or solid zone 9.
Although the temperature lows mentioned are more characteristic of zone 8, and a small part of Bouches du Rhone is in zone 8.

I decided to cover the little keraji seedling in the ground with a cut transparent plastic water container, as part of an experiment to see if they will be able to survive, or if it would help extend the growing season in this cool climate.

The little keraji seedling has actually put on some noticable growth since being covered with the plastic container. Here it was at the end of August, not having been covered yet:



Here's the transparent plastic container that was put over it:



Here it is on September 20, temporarily with the cover off so you can have a clear view:



And now here's another picture taken today (September 26 ) and you can see it's noticably put on even more growth:



Obviously the plastic container coverings are working.

I think it's helping for three reasons.
First of all, the container holds in the humidity. This may not be an issue in the South, but in this climate when it's warm and sunny it also tends to be fairly dry. As temperatures are cooling down, that ironically is also going to contribute to dehydration since as the leaves are warmed by the sun's light they will be slightly warmer than the surrounding air, and when you have an object that's warmer than the surrounding air a drying effect occurs (analogous to freeze drying). That's one of the reasons most trees in the Pacific Northwest are conifers, by the way, with needle-like leaves for maximum passage of air to cool off so they do not become warmer than the air (which tends to be cooler from the air blowing in from the ocean).
The second reason is insulation that helps the wind from carrying away heat (this is somewhat like the windchill effect). It might not sound like much but just a simple plastic layer that prevents the blowing of air through the leaves can help raise effective temperatures by a few degrees. This is important with the cool climate here and the growing season coming to an end.
The last reason is the greenhouse effect. Sun light that enters hits the plant or the ground as is converted to heat. Light can enter through the plastic more easily than heat can leave, so as a result the temperature inside a greenhouse rises while the sun is out. This can be a pretty strong effect. A simple plastic container may not really function as the most effective greenhouse but I suspect temperatures inside the container may be 5 or 6 degrees warmer than the immediate area outside (at least while the sun is out and shining on it). This greenhouse effect is far less effective at keeping temperatures up after dark, but warmer temperatures in the middle of the day can mean a longer growing season for citrus, since temperatures are about now dipping just below what citrus needs to grow in. The season is already beginning to cool off.

The thing to fight in the PNW is cool temperatures (cold-cool), not so much extreme cold events. That's why I think this type of strategy is probably a lot more effective here than it would be in the South.

Crimea fruit


Before cutting it open the outside has a faint fragrance of pear and vanilla. Aftering cutting it open there's an apple aroma. The texture inside of this quince is like a Granny Smith apple (that's very tender for an uncooked quince fruit). Just in terms of texture, I had absolutely no problem eating a slice of this quince. It didn't have to be thin sliced. There was some slight to moderate level of astringency though. Slightly less than half as astringent as a regular quince. I would say that overall, this rises to a level close to edibility raw.

After being cooked, it wasn't really all that amazing. Almost kind of potato-like.
It didn't turn pink during cooking at all, probably because of the lower level of tannins in this variety. Has a slightly lemon-like aspect to the flavor.


Kuganskaya fruit


I tasted an unripe Kuganskaya (still mostly green). This has surprisingly tender texture. If Crimea was like an underripe Granny Smith Apple, Kuganskaya is like a ripe Granny Smith that you would find in a supermarket.
The texture is not just tender it's also very smooth, almost "buttery". No fibrousness. If someone handed a slice of this to me and I closed my eyes, I almost wouldn't know it was a quince. Unfortunately it does have some astringency like a Hachiya persimmon.
I give this a 10 out of 10 for texture.

Before cutting open, the fruit exuded a slight caramel pear fragrance with vanilla. Kuganskaya definitely leans closer in the direction of pear flavor than Crimea. The cut fruits almost had a "cooling" pear smell to them (something I did not notice in cut Crimea fruit), although it was kind of subtle.

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.

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.

https://www.wacotrib.com/news/north-waco-family-s-orange-tree-a-miracle-on-th/article_3928e5be-b811-52ef-8dee-465b5788e6ae.html

________________________________________________________________

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.

level of cold hardiness order for kumquat and common related hybrids

kumquat > mandarinquat > calamondin


Some more information on relative cold hardiness of different citrus, now going into some of the varieties that are not very hardy

Citron is basically the ancestral species from which lemons descend from. (ordinary lemons)
Citron has even less cold hardiness than common lemons. Common lemon varieties in turn do not have as much hardiness as Meyer lemon, which is believed to have originally resulted from hybridization between mandarin and citron in China, and has a separate (but somewhat similar) ancestry from other lemons whose history dates to Southern Europe.

Limes have less hardiness than lemons, making them the least hardy common citrus group. Limes are mainly descended from an the citrus species C. micrantha, which has even less cold hardiness than limes.
One exception, Kaffir lime is in a separate group, believed to be descended from an origin citrus species known as Khasi papeda (C. latipes), and has some small degree of cold hardiness, more than lemons.

In form, the fruits of citron appear quite similar to Ichang papeda, in fact the two species may be less distantly related to each other than to other citrus species, but whereas Ichang papeda is the second most cold hardy citrus species, citron is the second least cold hardy species. (so quite a difference in terms of level of cold hardiness!)

I've been wanting to attempt a hybrid between citron and Ichang papeda as the first step in trying to breed a lemon (a true lemon) with more cold hardiness.
Maybe the 2nd step would be to cross the result with Duncan grapefruit or pomelo, or something like that.

While Meyer lemon is the cold hardiest of the true lemon varieties, and I am a really big fan of lemons, I'm just not really a big fan of Meyer lemons.
(But that's personal preference, some people say Meyer is their favorite lemon variety)

Citrumelo (has survived in zone 7b in the South, and a few cases growing in zone 8 England)
Ichang papeda (cold hardy down to the border of zone 8a/7b in the South, zone 8a in a sheltered location in the PNW)
Yuzu 10 F
Changsha 10-12 F
Arctic Frost 10-13 F or 10-15 F (this is a Changsha x Satsuma cross, a few people have suggested this may not really be much hardier than regular Satsuma)
Ten Degree tangerine 11.5 F or 10-14 F (this is a Clementine x Yuzu cross)
Keraji 12-14 F

Indio mandarinquat 14-23 F probably
Bloomsweet 18 F or 15-23 F probably (might be just slightly hardier than Satsuma)
Nippon Orangequat 14 F or 10-16 F

Ichang lemon 15-20 F (or might have close to the same level of cold hardiness as Yuzu, genetic studies have suggested this is a Pomelo x Ichang papeda cross)