Breeding for late flowering?

[gilbert]

I'm getting ready to start my landrace hybrid swarm tree breeding project; some species will be planted this year, for others I'm still tracking down genetics. Is it possible to select peaches, apples, etc. for late flowering, i.e. for plants that sleep through early warm spells? Or would I inadvertently select for weakness or high chilling hour requirements, and thus low production? 

[fliver]

I might be wrong but I believe that what you are wanting are plants which have about the same chill requirement as the environment they are living in. Here in Missouri we have more chill hours (about 2000 hrs) than they have, say in Mississippi, and we have winter thaws where the temperatures get almost summer like. If I bought peaches with a chill requirement of 200 hours, then during a February thaw my peaches might bloom. Then when winter returns the blossoms would be killed by frost. If I bought peaches with a chill requirement of about 2000 hours they would sleep though the February thaw to bloom in spring and produce peaches for me.

[mskrieger]

I agree with fliver. High chilling doesn't correlate with low production unless you live in an area with very little cold. I kind of wish we could indeed breed peaches and apricots with very high chilling requirements--it would make crops here much more reliable!

However, in apples at least, I believe it is possible to breed for later flowering without breeding for high chill hours. In places with long, slow springs, it's possible for the first apples to bloom more than a month earlier than the late varieties. Those trees won't pollinate each other. Plums can have widely varying bloom as well--there is a plum breeder in the upper Midwest US who has varieties with quite variable bloom dates. He plants them in tubs and manipulates the environment (keeps some in cold, dark outbuildings to delay bloom while others go in the greenhouse to speed it up, for example) in order to cross certain varieties that normally wouldn't bloom at the same time.

[Joseph Lofthouse]

I see a lot of variation in flowering times on seed grown fruit trees. A seed grown apricot tree lives in the yard of a family member. It flowers a week or two later than other apricot trees. That's a great trait to have, cause the flowers/fruit are much more likely to survive the early spring frosts.

A few weeks ago, I transplanted 27 seed grown apricot seedlings into a nursery row. I'm looking forward to following their progress.

[gilbert]

I agree with fliver. High chilling doesn't correlate with low production unless you live in an area with very little cold. I kind of wish we could indeed breed peaches and apricots with very high chilling requirements--it would make crops here much more reliable!

I am in an area with unreliable cold. If I bred in high chilling requirements, I might not get them met most years. In theory, Denver gets 1650 chilling hours, so an apricot with 1000 chilling hours requirement could stand some improvement. But, I'm not sure we actually get that much. Average high temperatures in Denver are above 45 degrees all year around. Average lows are above freezing for 8 months of the year. And winters seem to be getting warmer. Meanwhile, we still can get frosts till the end of May, sometimes in June. 

It is good that in some species that two variables are independent.

I suppose if I selected for late flowering trees, I'd simply have to do another round of selection for abundant fruit after a warm winter? 

[walt]

OK.  I'll come out of the closet on still another breeding program I have.  Late-flowering apricots.
Apricots in general are plenty winter hardy, but they bloom too early here.  About 4 out of 5 years late freeze kills the flowers without hurting the tree.
So I decided to cross apricot x P. besseyi "Hanson's Bush Plum", AKA "Hanson's Bush Cherry".  P. besseyi blooms as much as 6 weeks later than apricot here, depending on the year.
I also got Nana beach plum from Oikos tree crops.  It is also supposed to be very late blooming.
My new P. besseyi died this winter, I think.
Both Nana and Hanson's are also very precocious.  Precocity is very useful breeding trees.
So last summer, someone bought my neighbor's orchard and cut down the apricots, which I'd planned to use as pollen donors.  Bummer.  Next nearest apricots I know of are 40 miles away.  Well, 40 miles is worth it, but I must aquire my own apricot tree now.
So my plan is to cross the apricot with the two late-blooming plums.  Grow the F1 seedlings and backcross to apricot.
Depending on the segregation in the backcross, I'll either intercross the F2 seedlings and select for late bloom, or select among the backcross 1 seedling and pollinate the late bloomers with apricot again.  And so on.

Enough apples do OK here that I won't be breeding apples for late bloom.  But if I did need later bloom, Court Plat Pendu, AKA Wise apple, blooms very late.  I'd be putting pollen from the best apples on it, if I wanted later bloom.

An alternative method, for any kind of fruit tree, would be to grow a lot of seedling, and select latest bloom in each generation.  But I don't know if there is enough genetic variation for bloom date in available apricots.  And I'm too old to go for 2 or 3 days later per generation.

[mskrieger]

I love your apricot project, walt . Beach plums are native to my region, and very reliable. The fruit tastes like a cross between a plum and a sour cherry. Why do you think they might be compatible with apricots? It would be lovely if they were. We like them, my parents planted a hedgerow at their house on the water and most of the fruit gets eaten as a snack in between jumping off the dock.

Um. Maybe I should try crossing them at my place. Or maybe with sour cherries. Hm.
Just found this publication, summarizing the Geneva breeding station's work on producing cherries and plums more reliable in the New York state climate: reeis.usda.gov/web/crisprojectpages/0130980-stone-fruit-breeding-for-new-york-tree-fruit-industry-diversification.html

[walt]

P. besseyi is in Prunus section microcerasus.  I probly miss-spelled that.  But that section has been successfully crossed with every other section of genus Prunus.  And more specificly, P. besseyi has been successfully crossed with every section of genus Prunus.
I did some serious googling before I got too involved in this project.

Excuse me.  On re-reading your post, I saw that you didn't ask about apricot x P. besseyi.  Rather you asked about apricot x Beach plum, P. maritima.  Quite a different question.  It may be in section euprunus, I'm not sure.  But apricot x euprunus has given us plumcots, apriums, pluots, and plums.  Which of these classifications a given hybrid goes in depends mostly on the breeder's whim.
Dr. Hanson, over a century ago introduced "plums" that were 1/4 apricot.  
One modern breeder, whose name I don't recall right now, calls his 1/4 plum:3/4 apricots apriums, his 3/4 plum:1/4 apricots he he calls pluots.  Perhaps I have that backwords.
All these hybrids give seedlings that are at least somewhat fertile, if both parents are diploid.  And almost all apricots, beach plums, and Hanson's Bush Plums (Cherries) are diploids.

So do you want anyone to send you apricot pollen to use on your beach plums?  It might be too late this year to collect apricot pollen here.  But someone might have some.

[mskrieger]

Kind of you to offer the apricot pollen, walt , but I can source locally if I am so motivated. And this spring is so unmotivating. Although it might be the best spring to do it, as it's been so cold that none of the prunus species have bloomed yet. They might all bloom at the same time when spring finally comes...I should be alert to that.

I could potentially cross both apricot and sour cherry onto beach plum, and beach plum and apricot onto sour cherry, and see what happens....

[reed]

Apr 19, 2018 11:32:55 GMT -5 mskrieger said:

 They might all bloom at the same time when spring finally comes...I should be alert to that.

I don't know much about this topic but my peaches all bloomed at the same time this year and they did not get frosted at least not yet.  I'v never seen the little wild ones bloom till after the others have all faded.

I'm in hopes they crossed some but even though it didn't freeze, it was pretty chilly and I did not see much pollinator activity.  

[nicollas]

You could select for flower hardiness too i guess

[walt]

Apr 19, 2018 11:32:55 GMT -5 mskrieger said:

Kind of you to offer the apricot pollen, walt , but I can source locally if I am so motivated. And this spring is so unmotivating. Although it might be the best spring to do it, as it's been so cold that none of the prunus species have bloomed yet. They might all bloom at the same time when spring finally comes...I should be alert to that.

I could potentially cross both apricot and sour cherry onto beach plum, and beach plum and apricot onto sour cherry, and see what happens....

I believe sour cherry is tetraploid while sweet cherry is diploid.   All the other species mentioned here are also diploids.
The besseyi x tomentosa hybrid is one I've thought might be good.  Besseyi could use a little tartness.
And sweet cherry x tomentosa (Nanking cherry) could give good results.  Sweet cherries don't take our winters very well.  And Nanking cherry could use size and sweetness.  Nanking cherry is quite precocious too.

[walt]

Another interesting, to me, discovery.  
Some years back Some California peach breeders published that, after generations of selection in peaches which included selection for precocity, they had arrived at a point where enough of their seedlings bloomed by their second year that they would no longer concider any seedlings that did not bloom in their second year from seed.  Of course, they have a longer growing season than most of us, so the same seedlings might not bloom in their second or even third year.

Apple breeders long ago went to 2 years per generation.  The seedlings are grown in greenhouses in perfect temperature, etc., for rapid growth.  And most apple seedlings will bloom without going through a winter, neither natural nor artificial.  But giving them a cold spell does make them bloom together for more crossing.
After first bloom, most apples need a winter to make more bloom.

Time from seed to bloom is positively corelated with time from graft to bloom in most, if not all, non-tropical fruit species.

I love reading (and writing) about fruit breeding.

[Joseph Lofthouse]

My general attitude, is that I don't care how the plant gets to the desired goal... My primary breeding priority, is that a plant must produce seeds to stay in my breeding program. That's wonderful for a fruit crop, cause it tends to correspond with productivity.

[imgrimmer]

Apr 20, 2018 12:19:52 GMT -5 walt said:

Another interesting, to me, discovery.  
Some years back Some California peach breeders published that, after generations of selection in peaches which included selection for precocity, they had arrived at a point where enough of their seedlings bloomed by their second year

I wonder if it is possible to reach that level of precocity in Citrus too? I am almost sure but not sure about the right way.