That's why I'm thinking if I crossed Dunstan citrumelo with citron I might get something very similar to a lemon -- albeit one that's a lot more cold-hardy.

"not true to seed" takes a little bit of explaining. Unlike many other common citrus varieties, Meyer produces all zygotic seeds, meaning they all resulted from sexual reproduction. Whenever this happens, the genes get mixed around. It will not be genetically identical to its parent. That being said, for some types of citrus, especially sour types, even if it is not a genetic clone it will likely still have fruit extremely similar to its parent (assuming the seed did not result from pollination with a different variety). Meyer lemons grown from seed are usually not as good, there's a 50% chance it will not be as sweet, and a 50% it will be insipid. Furthermore, when you grow from seed and the little tree has never been grafted onto different rootstock, it will take a very long time before the tree ever begins producing fruit, and the tree will be quite big at that time. (You see the dwarfing effect of rootstock induces a tree to begin producing fruit earlier in its lifespan, this is true with many fruit species, not just citrus)

Usually, for the home grower, it's not worth the effort, risk, and time growing from seed. But it can be done. And sometimes (in rare cases) you get a new variety that's better than the original.

If I can add, 'kao pan' is the same variety as 'Siamese Pink', and also sometimes goes under the name 'Nakhon' or 'Nakon' after the province in Thailand where these are grown. It's often and generally considered the best tasting variety in Thailand, though that's subjective. (Keep in mind Thai category pomelos may not be as sweet as the other varieties we know, especially when grown in a climate that does not have year-long heat that Thailand does)

Correction: Nakon was the name given to a seedling of kao pan which was grown in Florida. It's probably very similar to its parent though.

Let me again point out that even though this may theoretically be the variety with the "best" flavor, I do not recommend it for most of you. Almost everyone outside of Southeast Asia prefers more sweetness. What a pomelo should be like is viewed a little bit differently in Thailand, since there are already so many other very sweet tropical fruits readily available, and pomelos are often used in salads or combined with sweet spicy sauces, rather than just being eaten as a dessert fruit. And even climates like Southern California may not have enough heat throughout the year to truly fully ripen these Thai varieties to full sweetness. Which is probably why as you start going North to Southern China the types of pomelos they grow look a little different, "Honey pomelos" with more golden-yellow colored skin. "Chinese grapefruit" may not be all that bad of a translation. They do have a very sweet variety in Thailand but the flavor is also very insipid because it lacks all sourness. This is where 'Siamese Sweet' originated from. (I also think it is lacking in fragrance and aroma but can't absolutely vouch for this)

I have for a long time been wanting to get the Japanese variety 'Banpeiyu', which has the distinction of having the largest size of all the citrus fruits, but from what I've read it's not really the most excellent eating quality. It's more of a novelty in Japan, or left floating in hot tubs to add fragrance at expensive ryokan inns.

There are several pomelo varieties cultivated in Japan, and of these the most commercially popular is Suishō buntan (水晶文旦), which translates as "Crystal". (Hirado Buntan comes in a distant second) However, grapefruit imported from the U.S. has mostly replaced the more traditional pomelo fruit in Japanese supermarkets. (Price may be a significant factor. Japan imports 15 times more weight in grapefruits than the entire domestic harvest of pomelo)

I don't know, I wonder if the Chinese Orange could be partly descended from C. indica, which can still be found growing in the wild in Northeastern India. I'm also thinking that Meyer lemon has a lot less C. maxima in its ancestry (if any) than Orange.

I'd be really interested in citrus hybrids that didn't have any mandarin in their ancestry, since virtually all citrus hybrids are descended from mandarin.

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.

I planted several seeds from store bought mangosteen one month ago, placed them in a plastic bag with moist soil, and put them in a place they wouldn't get too cold at night. None of them germinated. I just checked on it right now.

On the other hand, I didn't have any problem germinating seeds that were not from supermarket bought fruit, so I can tell you mangosteen isn't that hard to germinate. I'm pretty sure it probably has to with freshness. Also make sure to use distilled water because the water coming out from your faucet may have too much chlorine and mangosteen seedlings are sensitive.

They're not exactly "fresh off the tree" fresh but those are the best looking mangosteens I've ever seen sold in a supermarket. Generally the odds of being able to germinate store bought imported mangosteen are not good. I don't know whether it's because of long-term refrigeration (the seeds inside the fruit are quite vulnerable) or whether it's the irradiation all imported fruit go through. Still, I've had success germinating store-bought lychees that were imported, and surely that goes through everything that mangosteen goes through.

I'd say your chances of being able to grow any plants from those mangosteens are not good, but I do think you have a chance, if you're willing to go to the trouble knowing you will most likely meet in failure.

Another issue, I'm not sure about it, I think the mangosteens for export might be picked just a little underripe to prolong shelf life. Unfortunately that means the seeds are not all the way fully formed and are not as big as they would have been later, so this could be a factor. (I'm really not sure)

Etrog citron seed sprouting



I don't think breeding with citron is "taking a step backwards". After all, citron is the ancestor of modern-day lemon, and, while it doesn't have a lot of pulp inside, the fruit of the citron is very fragrant. Citron fruits can be pretty big too.

Another advantage? Being an original species, citrons produce all zygotic seeds. Edit: after looking it up, it apparently 50-60 percent of the seeds in citron are zygotic.

It's true that lychee is known to be susceptible to drying out (especially small seedlings), but lychee plants in the ground and kept well watered can take sun. I bought this little guy only 2 feet tall and planted it out in the sun. I was afraid it might get scorched in the heat, but it seems to be making it.



It's mulched around the soil and being kept well watered.

 Southern California

This may be interesting for some of you. As many of you know, many types of common citrus cultivars are considered to be polyembryonic (that produce seeds which are genetic clones of the parent). This can cause problems for breeding because most of the seeds in a polyembryonic cultivar will just be clones of the parent, rather than inheriting any traits from the parent the tree was pollinated with. However, not absolutely all of the seeds in a polyembryonic citrus variety will be clones, a few will be zygotic (the result of sexual recombination).

seed parent ... Seedlings/seed ... % nucellar
__________________________________________
Lemon: Eureka, Lisbon, etc ...  1.05-1.06 ...   32-33
Rough Lemon ...  1.24-1.96 ... 54-98
Mexican Lime ... 1.29 ... 78
Mandarin: Dancy, Kara ... 1.37-1.71 ... 100
Mandarin: Satsuma ... 1.44 ... 90
Mandarin: Kishu ... 1.00 ... 0
Mandarin: King, Ponkan ... 1.01-1.42 ... 21-98
Grapefruit: Marsh ... 1.08 ... 96
pummelo: 11 cultivars ... 1.00 ... 0
Sweet orange: 4 cultivars ... 1.09-2.00 .... 39-97
Sour orange ... 1.21 ... 85
Tangelo: Orlando, Minneola ... 1.31-1.49 ... 83-97
Trifoliate orange ... 1.03-1.26 ... 13-73
__________________________________________
data in this table comes from Frost and Soost (1968)

As can be seen in this table, pummelos produce all zygotic seedling, while almost all of the seeds in a Marsh grapefruit will be nucellar (clones of the parent)

So it is possible to use polyembryonic parents as the seed parent in breeding, but you just have to grow a lot of seedlings and see what they all become. This might not be practically possible in Dancy and Kara, however, because there were none of their seeds that were not nucellar in this experiment.

Well there's nothing sweeter and juicier than a tangelolo (but that's more of a tangelo flavor than grapefruit).

You are right to be concerned that your citrus is a standard blah variety and question whether there's something better out there. However, in the case of grapefruit the standard ones are pretty much the best. Have you considered an Oroblanco grapefruit though?

My personal take on Oroblanco, it seems to have just a little less flavor and aroma than regular grapefruit, frustratingly, but the flavor it does have is excellent. They tend to have a bit less bitterness than other grapefruit (although I still think environmental factors make as much difference as variety here).

I might also add that some citrus enthusiasts are huge fans of Tahitian pummelo, if you like lime flavor. It's sweeter and juicier than other pummelos (probably because it's more like a grapefruit than a true pummelo).

You will need a heated environment during the winter and be able to maintain a fair level of humidity. And it will still need lots of light during this time.
Just treating it like a normal house plant and setting it by the window isn't going to work. And if conditions are not optimal, it may take a very long time before you ever see any fruit.
(Why is it not going to work? The inside of your home gets colder, dryer, and has less light exposure than most people trying to grow plants inside realize.)