The Tropical Fruit Forum

If you don't want the terminal bud, trim it.  But having many side branches will slow down the terminal bud.  Either way works.  One way leaves a central leader, the other doesn't. 
Yes, the end bud on a branch does act as a new terminal bud, but to a lesser degree.  And I think that in general, the more horizontal a branch is, the less effect the terminal bud has.  But this isn't always true.  We have all seen weeping willows, weeping cherries, etc.  Twigs are growing straight down yet not branching much.

Congratulations.  Will you be planting the seeds?  If so, good luck and keep us up to date please.  If not, there are people who would like to grow them. 
I'm surprised it is winter hardy that far north.  That's very encouraging.  Walt

"Hybrids of "F1 Poncirus hybrids" with Ichang Papeda grow much better than pure Poncirush hybrids for me. But that is just my observation and only refers to my climate. It may not be helpful elsewhere...."

I'll have to check this out.  Hybrid vigor can be a very useful tool.
I now have P. trifoliata from 5 sources.  I'll be comparing them for vigor, winter dieback, brix, acidity, and every other trait I can think of.  An important part of plant breeding is exploring your options.

Ichang Papeda isn't hardy enough for my location.  I thought about using both it and Pt.  But that would dilute the percentage of mandarin genes in my population.  That's a judgement call that others might disagree with.  But I take my best guess and go with it.

I wonder what a hybrid swarm from Ichang Papeda x Pt would be like.  But I must limit my efforts if I am to get anything done.

I do like it when other people give comments, offer additional ideas.  Its not like I know all about this.  I just make my best guesses and act on them.  And as I said before, Kumin showed that I was wrong about how quickly one can get hardier citrus.  Others may show that I could have gotten better or quicker results going a different way.  Good.  As long as there is progress, I'm happy.

Ponciris+ iseported to lack the acrid flavor of other ponciris and to have at least some zygotic seeds.

Thanks for the offer.  It will be at least a year, maybe more.  W

I've been thinking a lot about hardy citrus breeding for some years now.  But new information and experience is changing my mind about several thing the last few weeks,

Ponciris trifoliata is hardy enough for my area,  And it is the hardiest citrus relative I know of that is readily available.  It crosses easily enough with good citrus, and I've always thought breeding from such crosses was the way to go.  The ONLY way to go.  People have told me they want to select within the pure P. trifoliata, and I thought that was stupid.  There isn't enough variation to make that way successful, I thought.

But what is really the problem with P. trifoliata as a crop?  The nasty-smelling resinous flavor, of course.  But there is at least one mutant without that problem.  Ponciris+.  And P. trifoliata is mostly nucellular.  Again Ponciris+ is zygotic so that is at least less of a problem.  In addition, P. trifoliata, its F1 hybrids, and backcrosses to mandarins (mandarin x P. trifoliata) x mandarin, are too sour and lack sweetness.  Granted, I've only tasted one mandarin backcross, Clemtriclem.  It is (Clementine x P. trifoliata) x Clementine.  And Clementine is not the sweetest mandarin.  But I have not read of any improvement over Clemtriclem.  Another problem is the size of Ponciris fruit.  They are small.  But that is a minor problem compared to flavor.

But all this means, really, is that more sugar (higher brix) and less acid (higher pH) is the whole breeding problem.  Or at least most of it.  Precocity, short time from seed to bloom, would be valuable, as with a certain set of breeding stock, progress will be set by population size, ability to measure brix and acid, and the number of generations.  Keeping generation time short would be very valuable.

But to select within P. trifoliata seems a dead end.  There isn't much variation in brix or acidity to select from.  At least I haven't found information that would make me think otherwise.  So crosses with other citrus is the only way to get the needed genes.  Fortunately, such crosses have been made.  Kumin and I and others have acquired such hybrids.  US 1279, US 1281, US1282, Us 852, 5*, are useful as seed parents as well as pollen parents.  Other varieties might be used as pollen parents if desired.  Citrangequats can't be ruled out, though they wouldn't be my choice.  Bringing in Kishu Seedless as a pollen parent seems worthwhile, as it has a dominant gene for seedless, and is said to be exceptionally sweet.

New hybrids could be worthwhile.  Precocity might be brought in from Laaz's Fast Flowering Ponciris, Etrog, or Hong Kong kumquat.  None of these are of proven value, but I am checking them out.

Hybrids of various citrus with Ponciris+ could speed up getting rid of the  Ponciris flavor.  Though a generation or two of selection should get rid of it where Ponciris+ isn't available.

The amount of Ponciris in a breeding population should be determined by your climate zone.  Zone 8, maybe zone 7, 1/4 Ponciris could be enough.  This would speed up the breeding in those areas.  I plan to make such seeds available in a few years,  when my breeding stock is older.  Kumin, in zone 6, has had some success with 1/2 Ponciris in zone 6.  What he does in the future is up to him.  He has already done in one generation what I thought would take several generations, so I'm not the one to tell him what to do.

I'm also in zone 6, and will be working with 1/2 Ponciris.  But I will also make some crosses of those 1/2 Ponciris with pure Ponciris.  This will give me a big population that can be grown without protection.  This population will include seedless plants from the Kishu Seedless mandarin ancestor, fruits lacking Ponciris famous flavor, various levels of brix and acid, and fruit size.    Of course, I'll be working on the 1/2 Ponciris population, but I'll have to provide some protection to keep seedless and some other genes in the population in the early generations.


Breeding stock I now have on hand include:

Ponciris trifoliata
Ponciris+ which doesn't have the undesirable Ponciris flavor and does have zygotic seeds.
FFP, Laaz's Fast Flowering Ponciris, which doesn't pass on its fast flowering to its seedlings when crossed with other citrus..  But it may pass it on to its grandchildren.  If so, it would speed up generation time.
B and J.  Bigger and juicier P. trifoliata.  100 seeds from Kumin.
Many seeds from a wild population.  Sent by orangedays.  These trees give monozygotic seeds.  These are to broaden the genetic diversity of my breeding population.   

Mandarins
Kishu Seedless.  Very small, but very sweet and has a dominant gene for seedless.  It can only be used as a pollen parent.  Half of its seedlings will be seedless.
Changsha.  Good flavor, good size, more cold tolerant than most mandarins, zygotic seeds.

Citandarins
US 852  85% zygotic seeds
US 1279  More than 95% zygotic seeds
US 1281  More than 95% zygotic seeds
US 1282  More than 95% zygotic seeds
Bishop Citandarin  Seedling of US 852.  An improvement in flavor.


Citrange
010 Citrange  Survived 3 winters in Pennsylvania.  Zone 6  Fruit quality unknown.  % zygotic unknown.
058 Citrange  Survived 3 winters in Pennsylvania.  Zone 6  Fruit quality unknown.  % zygotic unknown.
067 Citrange  Survived 3 winters in Pennsylvania.  Zone 6   Fruit quality unknown. % zygotic unknown.
These 3 are seedlings from the same tree, C-35.  Mother tree was 15% zygotic.  These were all grown and selected by Kumin.  He has reported his work elsewhere on this forum.  Very impressive work.

I recently got precocious trifoliata.  Since you say it has weak roots, I'll try grafting it on regular trifoliata.  I was thinking of doing that anyway.  I want to make crosses with it and see how the F2 generation does.

Baker creek Seeds offers chiltin seeds.  I bought some but haven't planted them yet.  I don't know, but somewhere I got the idea that these produce earlier in the summer.  They don't list them as being late bloomers, and from dealing with them for many years, they would say it if they were late bloomers.
Once established, I've found chiltipin seedlings to be easy to keep going.  I do have lots of summer heat, but my house is very cool in the winter.  My seed always came from Native Seed Search and have been late bloomers but easy to grow.

Good job.  Good, useful information, though it is still incomplete, and may remain incomplete for more years.
Thank you.

They don't have to flower at the same time.  Citrus pollen can be stored for some time,  Keep it cool and dry.

Seedless Kishu has a dominant gene for seed abortion.  So using its pollen, about half of its seedlings should be seedless.