The Tropical Fruit Forum

Ilya, I am thinking about it. I may test a cutting.

The climate here is special. In my childhood -20°C was very common, even for two weeks. Now, the lowest temperatures are about -10°C. Winters are cool and wet but usually not very frosty. Yet the growing season is still short (begin of April to end or mid of September) and late frost remains a problem. -10°C in April is well possible. That is a real challenge for Poncirus or citranges that have started to grow then. Yuzu does better in late frost. But its overall hardiness is not sufficient.

Only 30km away is one of the mildest areas of Germany (around Cologne and Bonn). Poncirus grows very well there and citrumelos did well for at least many years. The lowlands...

I consequently wrote the mother plant first (as is convenient in biology).

I do not castrate the flowers because I pollinate too much flowers. I have not the time to castrate them. It is then a bit more difficult to recognize the hybrids. But I am quite optimistic that I can do it nonetheless. Trifoliate leaves are only one characteristic of Poncirus hybrids. There are many others (paired first leaves or not, form of leaves, taste, leaf texture, leaf size etc.). I think it will become quite clear in the second year which are hybrids. Many can be recognized already now when you have a close look at the plant. The same is true I think for most other non trifoliate hybrids.

Regarding the Yuzu x Poncirus hybrid it was clear from the beginning that it is not nucellar. And some trifoliate leaves were then I clear sign that it is a Poncirus hybrid. It is indeed startling that it is mostly monofoliate. I also had a Kucle x Poncirus cross that was almost totally monofoliate. My supposition is that Papada genes can supress trifoliate leaves. Another example would be N1triVoss (Ichang Papeda x Poncirus) on the origin of which, however, some have cast doubt. The other explanation (or lets better say guess) of monofoliate Poncirus hybrids is that they are triploid. Now, my Yuzu x Poncirus does not look like a triploid I would say.

Regarding taste: Well, the taste may in many cases be far from our dreams. Yet I am optimistic. Dunstan Citrumelo has a very good taste. The other Citrumelo I used is not a culinary revelation but has high potential for it is very aromatic and even a bit sweet. Batumi Citrumelo is also tasty, as is Sanford Curafora. The Poncirus types I used are also better tasting ones that are in some year so good that you can almost eat them out of hand. So I am optimistic that at least some hybrids will taste better than Morton. Yuzu x Poncirus has no Poncirus taste in its leaves. That makes me also optimistic. The sole goal of all Chandler hybrids and of the one Sucrena hybrid is to get hardy plants with low acidity. My goal here is not to get tasty hybrids. I just want to take one step into the direction of hardy and sweet hybrids. Vainigla Sanguigno x Poncirus was also an attempt to create a hardy plant with low acidity. In that case my goal cannot be reached as I now know. Low acidity in Vainiglia Sanguigno is recessively inherited (defect NOEMI gene). In the case of Chandler (Siamese Sweet in background) I can reasoably expect that 50% of the crosses have only about 50% of the acidity of the sourest parent. My knowledge about Sucrena is more limited but I have hope. Sucrena is sweet because it converts acids into suggars more early and faster than normal sweet fruits.

I had a Calamondin bush of over two meters with plenty of fruits. My pollination of it was exceptionally loosy. While I normally take care that I am earlier than the bees I only pollinated from time to time my Calamondin bush without caring how old the flowers were. Under this circumstances I got about five hybrids per year. So I think you with your careful method should have a pretty good rate of hybrids - at least with Poncirus. I only got one single off-type seedling from Calamondin that had no Poncirus in its background. This is telling since Chandler and Limequat often bloom at the same time. The one off-type seedling has darker green leaves and grows faster than Calamondin. Leaf form and size is very close to pure Calamondin.

I do not have Taiwanica. I often wanted to get it but was never very keen on it. I think I already have better tasting trifoliate hybrids with more hardiness potential. Don't you think?

Some citrumelo seedlings. (Sacaton? Nursery confused names). From open pollination.



Poncirus x Batumi Citrumelo. There are hybrids among them but hard to recognize.






C. ichangensis x Amoa 8 (="Rubino" from Agrumi Lenzi). I would say one hybrid, the "big" one in the foreground.




Other pictures will follow...

...what would be an annoying problem for breeding.

I try to make crosses between Moro and C. ichangenesis and Amoa8 and C. ichangensis. I hope that helps. One hybrid so far but I don't know if it has the gene for coloration.

Concerning the genetics of the blood oranges, I have read the following:
1. All Sweet Oranges contain only one functional copy of the Ruby gene. It is though inactive in all of them except the blood oranges. The blood oranges possess a mutation that activates the Ruby gene under cold stress so that it produces the color of the fruits. Its original function seems to have been rather different, namely light protection in young shoots and leaves. 2. Poncirus possess two functional copies of the Ruby gene. Poncirus does, however, not produce red fruits because the Ruby gene is only active for light protection. 3. Mandarins do not posses a functional Ruby gene.

So all crosses of blood oranges with Poncirus contain at least one functional copy of the Ruby gene, the one from Poncirus. 1/4 of them should contain the mutation attached to the Ruby gene that causes red coloration of fruits. 1/4 posses the Ruby gene for light protection from Poncirus and a dysfunctional Ruby gene from the orange part.

So no F1 cross of Poncirus with Blood Oranges possesses more of the Ruby gene (with mutation) than Blood Oranges themselves. The difference is only that thoses F1 crosses having the Blood Orange gene also posses another functional copy of the Ruby gene in its original state, where Blood Oranges have a dysfunctional copy.

The big question is now why we do not have blood citranges. The answer can in my view be threefold: 1) By chance. When only 1/4 of all crosses have the genes for bloody fruits then we perhaps just had bad luck and got only the 3/4 without the desired genes. 2) The functional copy of the Ruby gene in its original state undermines the activity of the mutated Ruby gene. 3) Citranges just do not feel the cold stress that is needed for activation the Ruby gene from Blood Oranges.

So far my memories and conclusions. I am looking forward for your comments / critic, and sugestions.

Hmm. Then it can also be that the green embryos are from Yuzu selfpollination? Sounds plausible.
By "both parents" you mean the parents of Dunstan or the parents of the seeds, i. a. Dunstan and Yuzu?

All seeds of Yuzu pollinated with Staraji were pale.

Ok, I shall wait for the seeds to germinate and keep you updated.

At any rate my Yuzu seems to produce a greater number of zygotic seedlings so probably also hybrids.

Yes we have to be open for all possibilities that are backed by the observable facts. And it is good to be open for new phenomena.

I remember a very respected and experienced forum member of this forum and the old citrus forum who was absolutely sure that any Poncirus hybrid must have horrible taste and that any new hardy breed with Poncirus blood in it will not be worth tasting. Then Ilya began extensively posting and it became silent about this opinion. Indeed, the facts had changed and so why not changing one's mind?

I agree with Lauta_hibrid that purely zygotic varieties are the best starting point for anybody who wants a high percentage of zygotic seeds. The downside of such a choice is, however, that you have a very limited genetic pool for starting any breeding. It depends on the very special goals one has if that is a real downside.

As far as I know all oranges are mutations of a single ancient cross (Pumelo x Mandarine) x Mandarine. (I do not know what was father or mother.) On the one chromosome set oranges are pure mandarines, the second chromosome set consists of about 50% pumelo genes and about 50% mandarine genes. Oranges produce mostly nucellar seedlings. But there have been orange hybrids that are zygotic, namely: Sanford Citrange, Phelps Citrange, Clementine and Kijomi. There are also orange hybrids with a noteworthy percentage of zygotic seeds as C35. I conclude from that that all oranges are heterozygous for nucellar embryony. I would also assume that some citranges are only highly nucellar because of the Poncirus part of the cross.


Aside from these considerations, I would recommend to anybody who wants to make crossbreeding that he does not focus too much on the issue of nucellar embryony. I cannot boast to be a successfull breeder because most of my seedlings have not yet flowered. But I have produced a greater number of hybrids. So I can already tell from experience: Polyembryony and nucellar embryony are annoying but no real hindrance in many cases. If you believe that a certain plant has all the properties a good motherplant should have except zygotic seedlings then just try the cross. You may be surprised how many zygotic seeds you get! Or you may be disappointed. Then try it again with more flowers in more years. You will be likely to succeed. And when you succeed you will be faster as the one who waits the same time for getting a zygotic motherplant.

Today I harvested all my Yuzu fruits (very tasty by the way). Some had been pollinated by Dunstan Citrumelo. And surprise! About 1/4 of the seeds were green, the rest pale. That means that about 1/4 of all seeds must be hybrids and that an unknown number of the pale seeds must also be hybrids by the law of probability. (The green color comes from the citrus part of Dunstan Citrumelo, the pale color comes from Yuzu or the Poncirus part of Dunstan Citrumelo.) Ok, last year, I pollinated with Poncirus and had no hybrids at all, only nucellar seedlings. Does that matter? Only a year later my largely nucellar Yuzu gives my plenty of hybrids from a different but very interesting cross.
I got hybrids from 100% nucellar Calamondin, from 100% nucellar Tavares Limequat, from nucellar Vainiglia Sanguigno (very difficult though), from highly nucellar Dunstan Citrumelo, from Poncirus (nucellar seedlings unknown). Great, isn't it? But when I started my experiments I was so keen on getting zygotic mother plants. I was happy when I got Chandler. "Wow", I said to myself, "so many seeds in a fruit and all zygotic!" Yes, in theory. But I tell you something: Although my Chandler is full of flowers every year I got only one single fruit with seeds in it. All crosses were in vain except the one with "African Shadock x Poncirus". Poncirus pollen on Chandler - all in vain. Other pollen? All in vain. But Chandler pollen on allegedly nucellar Poncirus: one hybrid! I do not know what the problem with my Chandler is. Others were more successfull. But one thing I do know: There is a great difference between theory and practise. The good news is: Although the practise may laugh at your best theories, often it is more friendly to you than all earnest considerations.

And sorry. I was mistaken. I do NOT know how sweet the fruits on the photo are. I confused it with Chandler x PT (sibling of Swingle 5 Star??) an also almost unknown seedling from Bernhard.

In my experience, grafts of Poncirus and Poncirus hybrids usually flower after three years when the tree is at least 1,5m high. That seems to have something to do with the natural position of flower buds on short side shorts: In the first year the graft produces a long unbranched twig. In the second year it gets short side branches on which flowers appear in the third year.

Poncirus seedlings flower at about 2m high (from bottom to the tip of the highest twig).

Two grafted Citrumelos the budwood of which was most probably from mature trees flowered at about 1,7m-2m height. So there seem to be a mimimum height below which flowering is not likely.

I have forgotten what my Yuzu tree did. But I think it was not very slower. I have at least a "tree" only 1 m hight that does flower.

Two Kucle x Poncirus crosses bloomed at about 1m.

Growing conditions may also play a role. Drought stress or root problems may induce earlier flowering. That could have played a role in my glashouse in hot summers. Maybe your Yuzu tree is just too happy to flower :-).

Thank you for the photos! I believed Pumelo x Kaffir would be trifoliate because of old otherwise recessive genes. That is not true then.

Hello Lauta-hibrid,

thank you for your openness to give and share! And thank you for sharing information with us. You have a long list of interesting crosses. I am most curious to know how your Limequat hybrids develop. You are welcome to share any new observation about them.
I wanted to make crosses with makrut myself. But now I see that the leaf taste is largely not dominantly inherited. That is a very important information for me, though not the one I hoped for. I think you saved me a lot of time in that you did the experiment I wanted to do. I shall by oportunity only still check what happens when Markut and Ichang Papeda are crossed.