Although my XXX Lemon
link
already looks to me as "growers dream" I'm thinking about hybridization possibilities and chances of cold hardiness extension below -10C.
I know that hybridization is a "long run" proccess and that is more or less all I know.

Please, can you share your thoughts about hybridization:
1) XXX -> Papeda (mother)
2) Papeda -> XXX (mother)

If that makes any sense,
is Ichangensis better choice of Papeda than Ichang Lemon?
Also, what is the best on-line source of information about citrus hybridization?

Ivica,

It seems that you made a great find with this XXX lemon. Even more encouraging is the fact that you want to go further and try hybridization with it.

I do not know if your lemon is giving zygotic (single embryo) seeds or it is largely polyembryonic.

The question is relevant, since you most probably is dealing with hybrid and by crossing it with ishangensis or its hybrids you will need to produce many seedlings in order to select hardy progeny.

If your lemon is mostly polyembryonic it will be difficult to find so many zygotic seedlings. In this case you probably should use it as a father and pollinate C.ishangensis that exists as zygotic clone.

If your lemon is giving many zygotic seedlings you have a higher freedom of choice and can use it in both ways as a mother or father.

For a choice between different ishangensis forms: from my experience Ishangquat ( see my post at cold hardy subforum) is more resistant than pure ishangensis that I had in the past.
This year it was largely unaffected after extremely severe winter with several episodes of long term freeze ( several weeks with frozen soil) with one night at -16C. It is a mature 4m tree that gave first fruits last year. I am not protecting it at all.
Pure ishangensis was frozen at much milder winter. The clone of Ishang Lemon that I had in the past was dead after -11C some time ago. It was giving plenty seeds that were monoembryonic, but with rather low germination rate.

In any case, in order to succeed you will need to produce literally thousands of hybrid seedlings and subject them to cold winter selection in order to find something valuable ( hardy and edible).


Wish you good luck,

Cool stuff, what is the best book to read on Citrus reproduction and cross-breeding? Is there anything that explains it without getting too deep in jargon?

The (mother) is usually called the seed parent, or similar. The other is the pollen donor or parent. You need to have simultaneous flowering of both, but more than that, you need to collect pollen from the donor, and apply it to a receptive female flower, before it is self pollinated, or cross pollinated.
This is usually done by pre- bagging the chosen female flowers, on the seed parent, and carefully discarding the male parts(stamens) before they begin to shed pollen. That eliminates self- pollination, and the bagging prevents cross pollination.
You can use stored pollen, if your trees dont flower simultaneously, or pollen from another location. It may be necessary to bag the male parents flowers, as insects could in theory transfer pollen to your pollen parent, and that foreign pollen could also end up in your crossing.
A good candidate for the seed parent, is one that reliably flowers, sets and ripens a high percentage of fruit under your normal conditions.

Thank you all for the comments.

ilyaC wrote:

It seems that you made a great find with this XXX lemon. Even more encouraging is the fact that you want to go further and try hybridization with it.

I'll post more detailed Final Report of Cold Hardiness Test for this winter and
Observations Summary of the tree characteristics in general later this month.
In a short, the tree seems to has several "unbelieavable" characteristics, "unbelieavable" even for me, the one who is looking at that last 9 months.
The most striking potential value comes looking from a grower perspective:
1) Exceptional fruit keeping characteristic turns the tree into Storage.
2) Everblooming character means constant refill of the Storage.
3) Fruit rind similar to standard lemon rind means possibility of long distance transportation.
4) Exceptional cold hardiness means having groves more north than usually.

Having the trees acting like a storage further means that grower does the harvest when the market price is optimal,
i.e. postponing harvest is natively supported by the tree.

With above in mind, every effort is approved and begs for more.

ilyaC wrote:

I do not know if your lemon is giving zygotic (single embryo) seeds or it is largely polyembryonic.

I have two tests on (very) small seed samples done:
1) Last summer I was testing viability of seeds taken from 2.5-3 year old fruit:
5 planted seeds resulted in 7 seedlings, 0, 1 or at most 2 seedlings per seed.

2) Seeds of this Lemon are weird on its own way. Genes pool seems to be very complex.
Three Green seeds was planted this winter:
One did nothing, other 2 resulted in 1 seedling per seed.

What should be done to get better clue about single/poly embryonic nature of seeds?

ilyaC wrote:

For a choice between different ishangensis forms: from my experience Ishangquat ( see my post at cold hardy subforum) is more resistant than pure ishangensis that I had in the past. This year it was largely unaffected after extremely severe winter with several episodes of long term freeze ( several weeks with frozen soil) with one night at -16C. It is a mature 4m tree that gave first fruits last year. I am not protecting it at all.

I'm still unaware of any mature papeda tree in my "neighbourhood".
If I'll have no other options and if/when I decide to do hybridisation try,
is it possible that I got polen from your Ishangquat?

Judging solely on minimal temperature (2m level) this winter locally is USDA 7a.
Judging on low temp duration, ground coverage by snow... this winter seems to be the most hardiest in the last 60 years (just heard that from the local weather synoptic man).
I did some rough statistic:
since 1st November till 1st March we had 711 hours with temp <= 0C, 369 hours with temp < -4C.

ilyaC wrote:

In any case, in order to succeed you will need to produce literally thousands of hybrid seedlings and subject them to cold winter selection in order to find something valuable ( hardy and edible).

That could be the problem, with so many seedlings needed I see the only possible solution to have them planted into ground
but local winter extremes could make real obstacle to that...
A shortcut could be planting a smaller number protected from weather extremes and test my luck.
Things happens, let me cite DAD from H2G2:

" Mostly Harmless


Anything that happens, happens.

Anything that, in happening, causes something else to
happen, causes something else to happen.

Anything that, in happening, causes itself to happen again,
happens again.

It doesn't necessarily do it in chronological order, though.
"

Where is the best Citrus Research Center in Europe?

Greetings from Siscia,
--ivica
P.S. Siscia Lemon will be the name of XXX.

Jrb, thanks for the information.

ilyaC wrote:

How many months does it take for your lemon to mature from flowering? Are the fruits also resistant to freeze?

The best I can say at this stage of research is expectation based on observations done so far and cultural practices applied to those trees:

1) Could be something similar to standard lemons, 9-15 monts.
What happens inside the fruits after that is beyond me...
One difference is noted already, so far I saw Green seeds in young (a year) fruits only.

Loud and weird thinking follows, what if those fruits have two rippen stages:
Normal stage: Over-rippening means -> Green seeds sprouts and decline.
Exceptional stage: Over-rippening means -> fruit decline.

2) Fruits are resistant to freeze, how low temp can go is opened question.
Here is the event catched last autumn, 2009-11-02: Minimal temp was -4C. Please, see my posts dated:
"Mon Nov 02, 2009 5:54 pm"
and "Tue Nov 03, 2009 9:20 am" at
link


My candidate for future Freeze tests is the graft hosted by P.T. tree:
(photos taken today)
Improvized cover destroyed by wind:


Peeking inside:


I plan to build proper frame arround the tree, leaving upper canopy of P.T. out of that. Lower growth is for my tests.
A lot of sprouts there, some of them could be grafted with budwood from mature trees interesting for further hybridization. The frame should protect all them from weather extremes.
What do you think about that idea?

ilyaC,
I had phone conversation (also we did partial tour here) with Dr. Gatin today.
(Zorica Rana - very early ripening Satsuma - is his findings, that happened 1974. when he was 51 year old)
He got me this data as freeze temps for standard lemon:
-1.8 C for fruit, -1.5 C for fruitlet, duration - several hours.

During events "Mon Nov 02, 2009 5:54 pm" and "Tue Nov 03, 2009 9:20 am" the trees was in the position as shown on the coresponding photo.
(link in post above) The official min temp was -4C, lets attribute 1C to microclimate of yard position, how much we can attribute to the tree position inside yard ? (the trees was under roof more-or-less)
In a days after that I was there several times, the trees had flower buds, flowers, fruitlets... I found nothing fallen on the ground.