The Tropical Fruit Forum

I managed to get a freshly cut Musa basjoo flower and a plant for my patio. The flower was just releasing pollen, and I was able to pollinate the M. velutina, which was already castrated (since its flowers are self-fertile with functional stamens). I picked them just before the bracts opened and saw that they weren't yet releasing their own pollen. I also had M. ornata, and I proceeded to pollinate its flowers. In this case, the ornata has non-functional stamens in the first few blooms, so it was easier to confirm that only the fresh pollen I obtained from the Musa basjoo could pollinate it. Then I tied the bracts so that no insects could touch the used flowers and covered them with white thread. We'll see if these very different species are compatible.

The goal is to confirm compatibility with other species, generate new cold-resistant varieties, and use *M. ornata* as a model, since it and *M. acuminata* are highly compatible. Genetically, they are similar, and this allows me to begin a preliminary analysis of whether combining edible *M. acuminata* with *M. basjoo* would be compatible. Crossing with *M. velutina* could overlap the advantageous characteristics of both, perhaps allowing their use in future crosses with edible bananas. *M. velutina* is dwarf, has a short growing cycle, flowers quickly, and produces pleasant edible bananas. It appears to be larger than *M. basjoo* and has smaller seeds. Furthermore, it is considered cold-resistant (-7°C), so the hybrid would increase the velutina's resistance. What do you think? Are there any records of crosses between *M. basjoo* and other species? I've never been able to find any information about it.

This question arose after showing the flowers of my Genoa Lemon x C. maxima hybrids. Let me start by clarifying that the Citrus Maxima I have are ancient, seed-bearing trees. They have white flesh and several seeds. When ripe, they release a strong grapefruit scent (I've heard of varieties that don't).

My first Citrus Maxima seed was grown using the technique in a Florida video. I think it's called RES, which is to stimulate rapid flowering in citrus trees.

This technique is easy: all branches are cut and the plant is forced to grow vertically until it reaches 3.5 m in height, at which point it is allowed to branch. This causes the terminal tip to age rapidly due to the rapid division of its cells, since all its energy is concentrated in the apical bud.


Many citrus fruits take an average of 7 years (depending on the conditions and whether they are grown in soil or pots), and can take up to 10 years.
The technique is uncomfortable because the wind blows the plants away and they have to be tied to a guide. It is also complicated for cold climates since they would be more exposed to the environment, but there are similar techniques using grafts. In my experience: I planted Citrus maxima seeds from a greengrocer in 2019, and they flowered in the spring of 2023, at 3.5m tall (as seen in the photo) without me realizing it, and from there the first fruit that I harvested in the winter of 2024 emerged. I took a bud from the branch that flowered and duplicated the tree by placing it in the ground to have a shorter clone (I pruned the main plant to use its root in another hybrid). Today, in the spring of 2025, my clone is flowering.

Redomestication of Cold-Resistant Bananas

To understand the domestication of bananas, we begin with two species that have an impact on today's edible varieties: Musa acuminata and Musa balbidiana.
About 7,000 years ago in New Zealand, a mutation appeared in some Musa acuminata ssp. bankssi plants, which produced fruit and pulp without needing to be pollinated (parthenocarpic fruit). This characteristic was passed from one plant to another, from this subspecies to others, and even to other species through hybridization, generating enormous genetic complexity in modern cultivars.
Sterility was an independent event, since if pollen from wild varieties was available, these cultivars would continue to produce seeds. One of the events that reinforce sterility is the triploidy mutation; therefore, most current cultivars are triploid.
Independently, further north, in colder regions like India, Musa balbisina was independently domesticated, enlarging the fruit and producing softer, often sterile seeds, thus enabling the fruit to be used in a variety of ways.
When the "cultivable" Musa acuminata was introduced alongside the balbisiana, they hybridized, generating AB plants, thus transferring parthenocarpy to this second species.
There were some plants that did not fit well with the classification and appeared to be fully parthenocarpic Musa balbisiana genetically, designated by some authors as BBB rather than ABB. Through recent genetic studies, it has been possible to elucidate that ABB cultivars may have a more complex history and appear to have originated from AB cultivars.
The ABs were backcrossed until plants with almost complete Balbisiana genetics were obtained, but they retained the Musa acuminata genes that generate parthenocarpy. A cross with Balbisiana was then carried out, giving rise to different lines of ABB cultivars. For this reason, some ABBs appear as BBB in analysis.
THIS TELLS US THAT WE CAN BRING PARTHENOCARPY TO DIFFERENT SPECIES OF COLD-RESISTANT BANANA, GENERATING ALMOST COMPLETELY PURE GENETICS, BUT WITH THE CORRECT GENES TO PRODUCE EDIBLE FRUIT.
THE PROJECT:
Taking these factors into account, we can develop strategies to accelerate this process, but using Musas with cold resistance and aptitude for cultivation in cold climates.
To begin, we can directly use the most cold-resistant and parthenocarpic cultivar: Bluggoe ABB.
Benefit: It is already cold-hardy, producing in my zone 9, and its height is 2.5 to 3 m at the time of fruit production. It tastes good when ripe and cooked.
Regarding its useful residual fertility: it is occasionally capable of developing viable pollen and easily forming seeds (when crossing it with Musa ornata, I obtained 1 seed for every 3 fruits).
Its seeds tend to have poor fertility, but if they sprout, they usually have diploid and "triploid" genetics, very rarely tetraploids.

Optimally cold-resistant parent:
Musa velutina:
Dwarf cultivar (flowers at 1.6 m), short seed-to-fruit cycle (18 months), possible to grow in a pot for winter protection, low light requirements (although it improves in the sun). Easy hybridization with acuminata, cold-hardy (USDA 7b).

So, what do you think of my project? What do you think? If anyone else wants to develop their own, I can pass on the information I've gathered over the years.

I would like to discuss a hypothesis that arose from the "Conestoga" experiment and its increase in cold resistance. A hybrid of Poncirus and orange gives the citrange, in this case C35, and its resistance could be like in Morton -15 ° C. Poncirus -24 + -4 (the orange) = average -14 ° C. This average is given by the coding of the genetics 🧬 of Poncirus and that of the orange 🍊. All the cold resistance genes of Poncirus are inherited through one set of chromosomes, and it seems to "Codominate" forming a proportional balance between both sets of chromosomes of the hybrid. But in the next F2 generation the Conestoga appeared, which gave greater resistance than their hybrid parent, this concluded that it must happen because in self-pollination the gametes form new chromosomes by mixing parts of Poncirus chromosomes and Orange chromosome, and when joining with their own gametes could both germ cells contain the same copy of the Poncirus resistance genes.  Basically, they have both portions of the Poncirus chromosomes repeated, which would express the Poncirus resistance characteristic, although other genetic/physical characteristics could come from the other parent, due to the same phenomenon. But that's not all. I've always found it strange that Morton and Citrangequat Thomasville both resist -15°C. If we think that the characteristics are mixed homogeneously and diluted like juice to which water is added, then Citrangequat shouldn't be that resistant. But based on Conestoga, I think that the phenomenon that happened was that, just like with the C35 F2s, the Citrange gametes inherited the entire Poncirus chromosome fragment, and that fragment (with all its cold-resistance genes) was the one that co-coded with the Kunquat chromosome, thus forming a hybrid that transmitted the resistance genetics. My hypothesis: This suggests that the mechanism of resistance transmission could be different; it would also be usable, as long as large populations of seeds are used (which was done with Conestoga).  hypothetically you could get a hybrid of hybrid by reducing the Poncirus genetics and including more Citrus genes. for example: you could cross Morton x orange and get a plant more similar to orange but with resistance like Morton (-15°C). it would be like saying that Citrange is -24° X -4° = average ~ -14°C, and if you use its pollen on another orange you could transmit only the -24° C expression of Poncirus, which with the orange ovule would express itself again = -24 X -4 = -14~ -15°C. you could also do it with grapefruit x citrange and get a hybrid more resistant than Citrange itself. and even an F2 of citrangequat to get both copies of the Poncirus chromosome fragment in the next generation and thus obtain a -24°C citrangequat.

Here is an illustration of how chromosome fragments are passed from one generation to the next (blue and red are two species) in the genealogy of ABB genetics bananas.

I thought about creating a red Kunquat, but I'm unsure if it can be achieved. I'm thinking of using the Ruby gene with different parents, but Bloodlime's problem is that its skin always turns red, so it's a genetic that I like more to use. I saw that the crosses I have with Kunquat generally improve the flavor of the skin depending on their dependence, Eutis limequat, calamondin, mandarinquat... but there's one that never becomes edible, although it may be tolerated to eat (this only happens when they are so ripe that they fall off the plant). So I think I can achieve something like a Eutis, but with red skin and partially edible, and with that particular and distinct smell of Bloodlime. Here is my first germinated seed of Bloodlime x meiwa.

Being deciduous, the Poncirus plant usually transforms its buds into a capsule ready for rapid action when the heat returns. This gives us the possibility of recognizing its buds before they sprout, while they are dormant. By observing them closely, we can see that the fat and round ones will generate flowers, while the scaly and slightly defined ones will only form branches. Furthermore, since they are dormant, we can store them in the refrigerator for a while, simulating an extended and artificial winter. This way, branches with flower buds could be sent and saved to graft when the pollen demand is highest, thus obtaining fresh pollen to coincide with other species. For my part, it has always been difficult to preserve pollen in ideal conditions, and one of the most complex is Kunquat, since it is the last to flower (it blooms in summer). If we want to cross Kunquat with Poncirus, we could take this strategy, or if your Poncirus hasn't flowered yet, they could share buds with you to make any hybrids you want.  For example, I realized that I grafted poncirus buds in the summer from a short, lateral branch, and what resulted was that those short branches first sprouted flowers.

In summary: short-growing branches = will produce flowers.
Swollen, plump buds = they produce flowers.

 Long branches with scaly, flat buds = they will produce branches.

If you save the flower buds = you can graft them and obtain flowers whenever you want.





buds that will not produce flowers, only branches:

The finger lime isn't really a lime like any other. Keep in mind that every lime and lemon are hybrids of C. medica and another Asian citrus fruit. It's called a lime not because of a relationship, but because it's acidic. But it doesn't have that "lemony" smell from Citrus medica. That's why I've always wondered what would happen if we gave it that characteristic smell? Also, I've seen hybrids with lime, with calamondin, with rampurg... but they've never used a lemon. 🍋 The lemon has a more elongated shape, with a nipple, like the citrus caviar. So wouldn't those characteristics combine well? And at the same time, it would give it genes that would contribute to improving size. So, here I have my first experience. I have two more plants. It was difficult, but at least one is doing well. It seems that this is difficult.  For the next challenge, it would be good to cross it directly with Citrus Médica 😁 so it would have something in common with the rest of the limes and lemons, and not just the name.

I feel very happy, after 6 years of work, I finally have my first hybrid created by me! 😊 Genoa Lemon hybrid 🍋 x Mandarin Lemon 🍊 (rampurg).
There you can see his parents and the hybrid in the middle.




The genetic mix is ​​this: Citrus medica, bitter orange, and mandarin. I've included the fruits for comparison. The yellow lemon is a cross between Citrus medica and bitter orange, and the rampurg lime is a cross between Citrus medica and mandarin.

you can see the features: the hybrid has a lemon scent 🍋, lemon color, and a flavor closer to lemon 🍋. but smaller in size, without a nipple, and thinner skin. plus the skin peels off the pulp easily. it's weird that it's full of rampurg-shaped seeds, but the first flowers it produced never had pollen... I don't know how it turned out. but it was very dry, the juice was kind of spicy and bitter, so this harvest seems to me to have turned out worse than its parents... but the good thing is that it flowered early... I think it took a year, although later I'll look at the photos to see how long it took until a fruit set.

I have a few Poncirus hybrids that I've tested and can use, and the one I found most impressive is Morton. It looks like an orange, so you could mistake any other for it, and the flavor, when ripe, is quite decent. So I decided to use it as the genetic basis for my crosses.

Morrón has 50% poncirus, is resistant to -15°C, and is as large as an orange, with thin, juicy skin. Decent acidity for juicing, but not completely sweet.

Based on this, I thought about crossing it with: C. maxima, to create a "grapefruit type" that is more resistant to cold.

x Okitsu: to improve flavor, reduce acidity, and achieve earlier ripening, and to overlap both cold resistances.

x Clementina Nules: to improve flavor, reduce acidity, and achieve a fruit with a strong orange flavor but more resistant to cold. (Clemenules is orange around the Okitsu season.) And being monoembryonic, it can produce more crosses for analysis than Satsuma, which is difficult to produce seeds and is highly polyembryonic.

x Nagami: This cross is intended to create a new citrangequat with cold resistance from both parents. Note that in some tests, both Morton and citrangequat Tomasville tolerated -15°C.

Satsuma I only got 1 seed and it is germinating, Clementina I have not harvested yet but I have only one fruit, C. maxima I have 2 fruits but it is still immature and Nagami I have 2 seeds planted and there is one fruit left on the tree to harvest.

Has anyone made any crosses with Morton? Or do you know what hybrids emerged? I've only seen one cross with its fruit, which was 5Star x Morton, and it came out small, like poncirus, but quite resistant.

Troyer:



Morton:

Okitsu:


We're in the middle of autumn, and Okitsu looks fully ripe, Troyer takes color before Morton, and Morton is very unripe. That's why it's so important to have the fruit early.

This is a project that I had in mind for years, since it is my favorite fruit, but more than a year ago I started to study its feasibility. I collected experiences from scientific work and from researchers specialized in its biology and improvement and they helped me take the last steps and this year I managed to do my first practices... I still have to see if the fruits start to gain weight 😊

I will start by presenting the tools that I managed to abstract from everything published that allows us to take a strategy:

Edible (seedless) bananas often have something called "residual fertility." This means that they may (sometimes) have some viable pollen and some functional ovules. This would be our main tool.

Yes! Even the Cavendish has been seen releasing pollen... rare but possible: hawaiibananasource on Instagram shows their experiences and photos.

So we have two options: we can use an edible banana as a mother or we can use one as a father. This is because important traits such as sterility (no seeds) and parthenocarpy (developing fruit even without seeds) are heritable and dominant traits.

Which one to choose? : The most fertile representatives are usually the diploids: groups AA and AB and tetraploids (such as FHIA). But there is also more fertility in those that have M. balbisiana genetics (AB, AAB and ABB).

What would be the other parent? : It would be a wild or fertile banana (with seeds). Some varieties that can be found are used for the garden: M. acuminata zebrina, Musa ornata and Musa velutina (those are the ones I have).

If we use triploids as pollen receptors: this usually gives mostly tetraploid plants. An example of this could be Blue java (ABB) x Musa ornata (OO) using ornata as a pollinator would give a banana: ABBO (tetraploid).

but nothing in biology is predicted, so reductions in ovule meiosis can also occur and diploid hybrids can emerge (apple banana (AAB from Brazil was crossed and gave an improved diploid AB) and triploids.

If anyone is interested, I can upload more information. It would be great to have an intervention with everyone to share experiences. In addition, there are not so many varieties in my country and therefore I won't be able to do certain things like use Blue Java, which is an interesting variety for me.

Grapefruit comes from the hybridization of C. maxima with an orange, but my question was what would happen if one of the parents was changed? So I proceeded to combine it with several species. Part of this is to create a more cold-resistant version, that’s why I used a large-flowered poncirus, but I also proceeded to mix it with something that has orange genes but is more resistant, that’s why I already have the hybrid x citrange troyer seedlings and this year the fruit of Máxima x citrange Morton (for me the hybrid most similar to an orange) is already fattening. I have 2 fruits forming and we will see later if I get enough seeds. This year I sent a friend seeds of the hybrids with troyer and poncirus and they arrived safely to the US, so he can try them in very cold conditions, maybe for the Máxima x Morton I can send some too.

Good morning! With this exhaustive research work I started to get interested in the genetics of citrus... but there is something I had overlooked, why was Poncirus used as an external group to Citrus, while all the other genera were reconsidered as synonyms of Citrus and for which it is proposed that they should be changed to Citrus. What reason makes a single branch, with a single species and perfectly interfertile with citrus, be placed as external to the genus? Before, it was considered that Poncirus could be Citrus trifoliata, that is, they included it. It should be noted that Severina is also another external group, but this is logical since Severina belongs to an independent branch in which other species of the genus Atalantia are found (basically Severina would be synonymous with Atalantia).
https://www.nature.com/articles/nature25447

Does anyone have a clearer idea of ​​why it is considered a "non-Citrus" here?

 
Good morning, I used these varieties in the graph because I wanted to compare shapes and sizes, although I don't have them to make a correct scale, and since they are the most mentioned, I mention their quality. Regarding their origin, I only have these parents implied, but I don't know the origin of the others. What information can you give me? Is any of them ripe before the frost? Which one has less resin, less acidity, less aftertaste of poncirus, less bitter and less resin. I only tried Swingle, but I would like to know which others are suitable for my breeding plan. I would also like to know about the proportion of zygotes.