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Author Topic: Long term cold hardy citrus breeding project  (Read 15246 times)

Ilya11

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Re: Long term cold hardy citrus breeding project
« Reply #75 on: July 12, 2018, 04:37:15 PM »
Given good conditions it will bloom next spring, but fruit formation will depend on  formation of complete flowers with mature styles.
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SoCal2warm

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Re: Long term cold hardy citrus breeding project
« Reply #76 on: July 19, 2018, 07:52:16 PM »
Those made me think it was easy, but for all I know they resulted from thousands of attempts.

I think the main barrier, in many citrus types (and this tends to be particularly true for hybrids) is a high percentage of nucellar seeds, which means that the majority of the seeds grown will be genetic clones of their parents. Grapefruits tend to be somewhere around 70-90 percent nucellar, for example.
That means you have to grow all the seedlings and you may not know if any are actually hybrids until much later when they begin producing fruits. Although of course there are several strategies to be able to help identify seedlings that are different from their parents.

For example might be using trifoliate citrange pollen on a grapefruit as the female parent. If any of the seedlings have trifoliate leaves, you know they are citrange-grapefruit hybrids. Or possibly the reverse of that could be possible: If any seedlings from a citrumelo don't have trifoliate leaves than they are probably hybrids of the other pollination parent that has ordinary leaves.


Another topic with more information on which citrus types tend to be nucellar: "Thread for Citrus Breeders"
http://tropicalfruitforum.com/index.php?topic=24518.0

« Last Edit: July 19, 2018, 07:55:21 PM by SoCal2warm »

SoCal2warm

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Re: Long term cold hardy citrus breeding project
« Reply #77 on: August 04, 2018, 11:24:40 AM »
((C. ichangensis x Duncan grapefruit) x Satsuma mandarin) x Duncan Citrumelo)

(C. ichangensis x Satsuma) x (Satsuma x trifoliate)

(C. ichangensis x (Satsuma x trifoliate)) x ((Satsuma x trifoliate) x pomelo)

Duncan citrumelo x Bloomsweet

Just some ideas


« Last Edit: August 04, 2018, 03:40:07 PM by SoCal2warm »

Walt

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Re: Long term cold hardy citrus breeding project
« Reply #78 on: August 04, 2018, 02:34:24 PM »
Are these crosses that exist, or crosses you plan?

SoCal2warm

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Re: Long term cold hardy citrus breeding project
« Reply #79 on: August 04, 2018, 03:46:58 PM »
I do have some Page mandarin & Shasta Gold seedlings, so it would be interesting to eventually try to do something with that.
Two of the most delicious mandarin varieties, btw.

With the exception of Satsuma of course (but that's just individual personal preference talking).
Kishu produces 100% zygotic seeds and is also a very very good one. Believed to be one of the parents of Satsuma, although it doesn't have anywhere near the cold hardiness of Satsuma. Still, it would be a very easy one to cross. Satsuma produces about 90% nucellar seeds, on the other hand.
« Last Edit: August 04, 2018, 03:49:38 PM by SoCal2warm »

Millet

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Re: Long term cold hardy citrus breeding project
« Reply #80 on: August 04, 2018, 10:48:16 PM »
Kishu is indeed a good tasting cultivar.  I used to have a kishu tree, but I removed it to plant another cultivar.  The main problem with kishu is that they are a such a very small fruit.  I also have a Page fruit, great for juicing, but it is also a small fruit, but larger than Kishu.

SoCal2warm

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Re: Long term cold hardy citrus breeding project
« Reply #81 on: August 06, 2018, 01:06:49 AM »
The main problem with kishu is that they are a such a very small fruit.
Yes, but it's kind of a novelty. They make up for it by being seedless (if the blossoms were not pollinated) and effortless to peel. Little fruits would be frustrating if it took some effort to peel them, but with Kishu that is definitely not the case.

SoCal2warm

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Re: Long term cold hardy citrus breeding project
« Reply #82 on: August 06, 2018, 09:56:52 PM »
A couple grown from seed:



SoCal2warm

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Re: Long term cold hardy citrus breeding project
« Reply #83 on: August 17, 2018, 11:42:40 AM »
I'm thinking if you try second generation hybrids (F2) you might start seeing some interesting traits of much better edibility and higher cold tolerance appear.
For example citrange x citrange, or citrandarin x citrumelo.

This is because some of the genes for cold hardiness could be recessive, so there would have to be a trifoliate ancestor from both parental lines for these genes to be expressed. In other cases there may be a gene in the normal citrus parent which is dominant and detrimental to cold hardiness, so if using a pure normal citrus in even one parent side, it would be impossible for the immediate offspring to not have the dominant gene.

Doing some very basic math, if there were two of these genes (either beneficial recessive, or detrimental dominant, or just a combination of recessive genes, one for edibility and one for cold hardiness, for example) the probability that both would get expressed in the offspring together (assuming this is only out of the zygotic seeds of course) would be 1/16.

Walt

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Re: Long term cold hardy citrus breeding project
« Reply #84 on: August 17, 2018, 01:57:44 PM »
I wish that were true, that some F2 plants were more winter hardy than the F1.  But I doubt it.  Not that I know of any F2 Ponciris x Citrus.  But I'll give my thinking, as you gave yours.
I assume that P. trifoliata has many genes involved in winter hardiness.  Many are incompletely dominant, as shown by the F1 which are more winter hardy than their citrus parent, but less winter hardy that the Ponciris parent.
I have read in an old publication from government citrus research, that the F2 is less winter hardy than the F1. and that it decreases in later generations. 
Now I don't believe that last statement, about the F3.  I have seen no reports on growing a large F3 generation from a large F2 population.  I would think that at most they selected the best F2 and grew out some F3 plants.  If they selected the F2 for eating quality, then the citrus genes for flavor, etc., would be linked to other citrus genes for less winter hardiness.
Don't forget gene linkage when planning crosses!
I'm am not saying not to do the crosses you have in mind.  They are much like I've planned.  I'm saying not be discouraged if what you have in mind isn't in the F2.  I for one, plan to continue select for cold tolerance and good flavor in Ponciris x Citrus in generation after generation, as long as I live.  I certainly don't want to talk you out of doing what you are doing.  I just think it will take longer than one generation.
I think you are in a milder climate than I am.  I think you can succeed quicker than I can.
Good luck.

Ilya11

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Re: Long term cold hardy citrus breeding project
« Reply #85 on: August 17, 2018, 05:48:06 PM »

I am not fully agree with your reasoning for rejection of of the progeny of direct hybrids between poncirus and edible citrus.
Of course, if you consider all the plants in F2, F3 and so on generations, they become more and more heterogeneous in respect of the presence of genes for hardiness, but due to the chromosome crossing-overs the two genomes will be progressively  present in the smaller and smaller intermingled fragments finally resulting in the separation of genes for bad  quality of poncirus fruits from the genes of hardiness in particular plants. This will be less possible in your pop3 and pop2 populations.

If you select for extreme hardiness ( comparable to that of poncirus ) in each subsequent generation of intercrossing inside pop5 population, and simultaneously keep selection for better and better  fruit quality, discarding the rest, you will produce hardy plants with higher and higher proportion of edible citrus genome.
Last year I obtained around  400 hybrid seedlings of 5star citrumelo crossed to Morton citrange and Batumi citrumelo. After selection for the absence of poncirus taste of leaves. I have around 50 plants of each cross growing in the ground.
Now I need a good cold winter  ;D to see to what extent cold hardiness  and nasty poncirus aftertaste are linked.
« Last Edit: August 17, 2018, 05:51:43 PM by Ilya11 »
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starch

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Re: Long term cold hardy citrus breeding project
« Reply #86 on: August 17, 2018, 07:04:46 PM »
Last year I obtained around  400 hybrid seedlings of 5star citrumelo crossed to Morton citrange and Batumi citrumelo. After selection for the absence of poncirus taste of leaves. I have around 50 plants of each cross growing in the ground.
Now I need a good cold winter  ;D to see to what extent cold hardiness  and nasty poncirus aftertaste are linked.

Wow, that is an ambitious project and a lot work! I hope some of those pan out for you!
- Mark

SoCal2warm

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Re: Long term cold hardy citrus breeding project
« Reply #87 on: August 17, 2018, 11:10:21 PM »
Last year I obtained around  400 hybrid seedlings of 5star citrumelo crossed to Morton citrange and Batumi citrumelo. After selection for the absence of poncirus taste of leaves. I have around 50 plants of each cross growing in the ground.
Ilya, be aware that if citrumelo was the fruit parent, likely 70-90 percent of the seeds are nucellar. You may not necessarily be able to tell which ones are nucellar. If citrange was the fruit parent, the percent will be even higher (probably above 98-99 percent).

Unfortunately, that means a lot of the seeds you have may not be second generation hybrids. That means you'll have to wait to find out, if it shows more cold hardiness or better fruit quality than either of the parents (or even if the fruit just looks different).

What perhaps should have been done was to breed a monofoliate hybrid with trifoliate leaf citrumelo, and then identify the seedlings from the citrumelo which are monofoliate (since they must be hybrids).

Ilya11

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Re: Long term cold hardy citrus breeding project
« Reply #88 on: August 18, 2018, 03:43:15 AM »
SoCal2warm, beware  that 5star citrumelo when castrated and cross-polinated is giving more than 90% of zygotic seeds and rare nucellar seedlings can be  readily identified.

Before making such remarks as "Beware that ..." you have to acquire your own solid experience in citrus growing and hybridization. (just a friendly advice) >:(
« Last Edit: August 18, 2018, 03:53:01 AM by Ilya11 »
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                       Ilya

Ilya11

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Re: Long term cold hardy citrus breeding project
« Reply #89 on: August 18, 2018, 03:52:31 AM »
Wow, that is an ambitious project and a lot work! I hope some of those pan out for you!

Yes, I find that  it now looks like a full time job, but luckily  I am retired :)

I still believe , that current number of seedlings is not sufficiently high.
I read somewhere that even when crosses are made between two high quality citrus varieties you need at least 200 hybrids to select something new and valuable.
Best regards,
                       Ilya

Radoslav

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Re: Long term cold hardy citrus breeding project
« Reply #90 on: August 18, 2018, 09:45:20 AM »
Last year I obtained around  400 hybrid seedlings of 5star citrumelo crossed to Morton citrange and Batumi citrumelo. After selection for the absence of poncirus taste of leaves. I have around 50 plants of each cross growing in the ground.
Now I need a good cold winter  ;D to see to what extent cold hardiness  and nasty poncirus aftertaste are linked.

I have a strong feeling, that they are linked to each other. My opinion is that nasty poncirus oil is someting like antifreeze liquid fot the car radiator.
But time will tell .
« Last Edit: August 18, 2018, 09:48:39 AM by Radoslav »

Walt

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Re: Long term cold hardy citrus breeding project
« Reply #91 on: August 18, 2018, 12:40:28 PM »
I still believe , that current number of seedlings is not sufficiently high.
I read somewhere that even when crosses are made between two high quality citrus varieties you need at least 200 hybrids to select something new and valuable.
[/quote]


Most citrus breeders aren't using P. trifoliata as a grandparent.  While larger population is better, I would expect some of your seedlings will not have the Ponciris flavor, mot even a little.  That would be an improvement right there.
Look at Dr. Brown's work.  His populations were about 10% of yours.  But he is said to have had improvement over what was available.  Of course, I don't know first hand.  But I find it encouraging.
That said, I working toward populations of about 200. but so far I have mostly populations of zero.  So you are way ahead of me.

Walt

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Re: Long term cold hardy citrus breeding project
« Reply #92 on: August 19, 2018, 03:10:09 PM »
SoCal2Warm.
Ilya wrote that he had discarded all seedlings with the leaf smell of P. trifoliata.  I think that got rid of all nucellar seedlings and left only zygotic seedlings.
I think he also got rid of some zygotic seedlings, as not all zygotic seedlings would lack that smell.  But while the discarded zygotic seedlings might have some good traits, one does have to set standards and stay with them unless something unexpected turns up.  Space is always limited.

SoCal2warm

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Re: Long term cold hardy citrus breeding project
« Reply #93 on: August 19, 2018, 04:47:54 PM »
Yes, leaf smell is interesting. Ichang papeda doesn't have the same leaf smell as Yuzu. Ichang papeda leaves smell very mild and slightly lemony, Yuzu leaves smell more intense and spicy. The difference is obvious, despite the fact Yuzu is believed to have descended from Ichang papeda.

Sylvain

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Re: Long term cold hardy citrus breeding project
« Reply #94 on: August 20, 2018, 06:37:58 AM »
> Yuzu is believed to have descended from Ichang papeda.
It is not believed anymore.

mikkel

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Re: Long term cold hardy citrus breeding project
« Reply #95 on: August 21, 2018, 09:05:55 AM »
populations size is what me makes think about the most. I am just in the beginning of everything and did only my first small scale hybridisations. That is fine for the start but I know that I need (and want) more seedlings to do selection.

I see 2 main issues in practical work. In the south it would be easier to produce large amount of seedlings but you have to wait for the chance of frost tests. That means you keep more seedlings as you need. (fortunately not my position  ::) )
In the north (like me) it is much more difficult to produce enough seedlings for frost tests. Due to limited space in greenhouse etc. Most seedlings grow very slowly in their 1st season here in our climate. So it is probably better to do frost tests in the 2nd season but that is a matter of space. Small seedlings will be killed for sure whether potentially hardy or not. Too small is too small :(
So it is even much more unlikely to find a hardy one among the small number of seedlings. To talk about edibility is a whole other thing...

I was thinking about a garden in the south, dreaming of Ventimiglia, Italy were I once lived for a short time, but that is far from reality for me. Theoretically it would make it possible for me to produce a lot of seedlings  without to worry about the winter and do large scale frost tests here in the north.
I am still thinking about this possibilty but it only will come in reach in far far future. Now I barely manage to handle my 2nd home and work 160km from here.

Still only spinning around but I keep thinking about that. Especially about how to handle it now...not in future.


Walt

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Re: Long term cold hardy citrus breeding project
« Reply #96 on: August 21, 2018, 03:27:54 PM »
My plans are to aim at growing 200 per generation.  They will spend their first summer outside, in pots, then their first winter in the greenhouse.  Outside again for their second summer, then back into the greenhouse, but take cuttings which will be labeled, then packed in moist sawdust, then put in a freezer set at a temperature to be determined later, but the temperature chosen to kill some but not all of the cuttings.  Then the cuttings will be grafted back onto their origional plants to see if they survived.  Or perhaps I'll try to root the cuttings, or maybe I'll learn to identify freeze damage just by look or feel.  I am open to everyone's ideas.  Most of you have much more experience than me.
I do see problems with my plan.  Weather before taking the cuttings will determine degree of hardening off.  And different genotypes will respond differently to the hardening off.  I'm studying work done in apple breeding for ways to select for winter hardiness.  Again your ideas are welcome.

I will also be selecting for % zygotic seeds, precocity, and flavor, so I plan to keep most of the seedlings to bloom, or at least for a few years and then dump those that haven't bloomed.
I expect to build an additional greenhouse each year for 4 years.  I expect to start a new crop of seeds each year, 200 per year. 
Now, if my breeding stock would just bloom already.

SoCal2warm

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Re: Long term cold hardy citrus breeding project
« Reply #97 on: August 22, 2018, 01:14:13 PM »
I see 2 main issues in practical work. In the south it would be easier to produce large amount of seedlings but you have to wait for the chance of frost tests. That means you keep more seedlings as you need. (fortunately not my position  ::) )
In the north (like me) it is much more difficult to produce enough seedlings for frost tests. Due to limited space in greenhouse etc. Most seedlings grow very slowly in their 1st season here in our climate.
That's why it is probably more pragmatic to have two different people living in different locations collaborate. One would be in a position to grow out the plants, the other would be in a better position to test them.
This just involves some coordination between different breeders, and exchange of seeds/scions.

Walt

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Re: Long term cold hardy citrus breeding project
« Reply #98 on: October 18, 2018, 04:55:28 PM »
I see that citrusman99 is offering fruit of US852.  I've ordered 14 of the fruit.  US 852 is said to have maybe 50% zygotic seeds.  That means I will have at least 280 seeds, over 100 zygotic.  T
his puts me a generation ahead of where I was this morning.
I'm still getting a tree of US 852 for crossing with mandarin and with trifoliate orange.  I'm wanting to see the variation in the 3 populations, the F2 and both backcrosses.
Isn't citrus breeding fun?    Actually, I am one of the few who think so.  But as Shakespear said, "We few.  We happy few."

 

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