Hybridizing Dahlias

Bessie · 2023-09-14T03:43:02+00:00

Krista to discover if seeds are growing in the seed pod, after there are no remaining anthers on the pod, gently squeeze the pods between your thumb and fing...

AndreaB

Teddahlia I REALLY like this one ❤️

Teddahlia

I am responding to Bessie who wanted to see seedling pictures.
I took some pictures of some "random" seedlings. Which one(s) would you keep?

Bessie

Teddahlia 😁, thank you! I was wondering if all of your seedlings were incredible. Even though you have said a tiny percentage of seedlings are saved, I was losing perspective.
I guess I'm a visual learner. Thanks again.
Oh, I almost forgot... The orange waterlily is an obvious keeper.

Emilyp

Teddahlia Very pleasing indeed!

Teddahlia

We have not talked about collecting seeds very much. With no seeds there are no seedlings. Over the years some of our very best ones have come from the hand crosses done by Margaret. Alas, this is a year off for her, as it takes well over 100 hours of work to do a decent batch of properly done hand crossed seeds and we must be satisfied with collecting seeds from her hand crosses from previous years. The preparation for the dahlia tour wore her out. Seeds from hand crosses is a new "trick of the trade" as we decided that if all these hand crossed waterlilies that may or may not be really good ones, came from only from only good seed parents, We went through the hand crossed seedlings and selected seeds from the ones that had things we like and not too many things we did not like. An example would be an exotic color combination or a really vigorous plant. And of course we collect seeds from our named plants planted strategically by other special plants too. We need enough seeds to produce about 1050 seedling plants.
Every year I see people saying, "I just want to plant some seeds to see what I will get. I do not care if they have perfect form and I know there will lots of different colors. " I believe that the most experienced breeder has a streak of this philosophy. I have a row for the giants and large dahlias. Somehow a Hollyhill Snowcap pom tuber was planted in that row(and grew taller than the giants around it) and I collected some seeds from it. Not very many seeds were there but what will these special seeds make?

Bessie

Teddahlia

Not very many seeds were there but what will these special seeds make?

Ted, thank you for your insights. That question you asked is what keeps me going!
I've decided I can't grow hundreds of seedlings (at least how I grew 88 seedlings this year), so going forward I will need to concentrate on hand crosses of the best perceived seed parents with desired pollen parents.
I have not marked any of the crosses I've performed. However, every day I'm home, I try to go out twice a day(I'm retired) and collect pollen and then transfer it to what looks like mature, receptive stigmas.
At the beginning of the season I made some collection envelopes ( one for each variety) out of cardstock paper, so that I could reuse them. But, after a few weeks, I realized that storing pollen overnight (which I sometimes do) did not work very good. I dug out the little plastic containers I purchased last season for pollen storage. I have found them to work really well for collecting, moving pollen around my yard, and storing pollen.
36 Pieces Rectangle Clear Plastic Containers Transparent Beads Storage Containers Box Jewelry Storage Box Case with Hinged Lid for Small Items Beads Jewelry (1.3 x 1.3 x 0.7 Inches) https://a.co/d/cgv4x7e

Teddahlia

When we first started to handcross. I attempted to compare them to our other seedlings . I found that it increased the odds by about 30% that we would retain a seedling a second year. In those days we were crossing named varieties not bred by us. Last year Margaret did quite a few hand crosses and I would say the percentage of keepers was a bit more than 30% . But there are keepers and there are KEEPERS. That means the very best are much better than what could be achieved by the bees doing the work. And our non hand crossed seedlings are now 4, 5 or 6 generations of our breeding and are much better too. Some really nice ones are bee pollinated (and even some waterlilies) and are very good. and comparable to the hand crossed results. It is just that there there is lower percentage of them but since we grow more of the non crossed seedlings, we select more non hand crossed seedlings to keep than hand crossed seedlings. It is still a matter of growing lots of seedlings because the octoploid dahlia is so variable. Diploid breeding is a snap compared to octoploid breeding.
Getting ready to place flagging tape on a waterlily seedling

Cosey

A very important picture of we are discussing seeds. Here you have a full view of the stigma (upper V portion) that's part of the female reproductive system. It is fully mature and ready to accept pollen. Once compatible pollen is presented it will travel down the pistil to the ovary at the bottom.

Meanwhile, the golden yellow surrounding the stalk of the stigma (or sometimes called style) are immature stamens with pollen anthers (the yellow portion) that haven't begun to produce pollen. Historically, there are always 5 pollen anthers in dahlias. When fully mature they unfurl from the pistil and elongated to display the pollen for visiting pollinators.

This seems to be a method to ensure self fertilization does not occur in this specific variety. At least between this localized disc floret.

Bessie

Cosey what I see in Dahlias is the pollen ripening before the stigma. As the stigma pushes out, it transports the ripening pollen. The stigma becomes receptive after the pollen matures and is no longer present in mass on the stigma. The stigma, once mature, produces a sticky substance that will allow pollen to adhere. I have observed this clearly in Alstroemerias, and think it applies to Dahlias too.
The photo below is of a bagged bloom, the newly emerged sigmas(red arrow) in the middle of the disk, are covered with self pollen. The older stigmas(blue) are ready for foreign pollen.

Cosey

Bessie I'm guessing that different cultivars mature pollen differently. I had to take apart a series of blooms this fall and the image I posted above seemed to be a unique feature of this particular variety.

Alas, my season is done and I'll continue my observations in 2024. I'll look up the other flower you mentioned.

Cosey

Bessie Were you trying to see if this bloom would self pollinate? Any seeds?

Bessie

Cosey I had the bag over the bloom to collect pollen, and keep moths from depositing eggs that turn into the worms that destroy the buds. I've still got 7-8 varieties blooming that I am hand pollinating.

Cosey

Bessie

I dissected a few more blooms today. I found more cases of repeated maturing stigmas before their pollen anthers developed pollen AND one case of maturing pollen before the anther fully developed.

Example of stigma maturing before pollen anthers.

Example of both the stigma and pollen anthers developing around the same time.

Next season I'll have to cover a few blooms on these varieties to test my hypothesis that the variety who matures pollen at the same time as the stigma can self pollinate.

Only 1 out the the 5 varieties I was looking at showed evidence of mutual maturation. Now, disc florets mature at different times, so it was possible on all examples that pollen anthers from a neighboring disc would be matured at the same time an another was maturing on another disc.

Teddahlia

California growers have a long season for ripening pods. Jack Almand was a breeder a few miles south of you and was one of the premier breeders of giant dahlias. He bred our favorite giant-large dahlia called Show-N-Tell. By the way it does not even sort of, maybe, perhaps ever, make seeds for us. I have checked every year and wasted my time. We grow lots of it and it is a good tuber maker too. When a grower starts showing dahlias(some never do) they have novice class for beginners. I have seen many, many magnificent Show-N-Tell entries from novice exhibitors. It is a sure winner for a novice if grown and staged well. In the open classes, they want dahlias with more traditional form and it does not do well.

Bessie

Teddahlia we do have a long growing season, especially this year. There will be a few days of rain coming up. I think a problem I've had so far, is picking the seed pods too early. So the remaining seed heads that weren't decimated by the borer worms, will stay on as long a needed in an effort to become very mature. I'm very foolish/optimistic and am still hand pollinating. Time will tell if these late pollinated blooms give any viable seed. Hollyhill Daydream has been a bloom machine, and it's very, very exciting that it is setting seed.

SteveM

Cosey Next season I'll have to cover a few blooms on these varieties to test my hypothesis that the variety who matures pollen at the same time as the stigma can self pollina

I always assumed (not based on science) that the mechanism that caused some dahlia varieties to be self-fertile, and others not, was something genetic but never looked into the actual mechanism. It would be nice to know if a variety was self-fertile by observation before it was used in a breeding program. I can imagine instances where you might want to use either case depending on breeding goals. Dr. Keith Hammett would likely have the answer and might be worth contacting. If I remember correctly, he developed a line of fully double dahlias that came true from seed decades ago. I would think this would use self-fertile varieties to inbreed but I don't know for sure.

calico20hill

I had an excellent year for blooms but a bad year for seeds. Most of the pods rotted before the seeds were ripe. Because of that I collected seeds that were a bit less mature trying to beat the next rain storm. Ah well, I had so many really nice seedlings this year I will just count my blessings and sow what seeds I have.

Cosey

SteveM
It would be incredibly fun to chat with Dr Hammett. I wasn't looking for this specific information but when it repeatedly presented itself among a variety and was repeatedly different in another variety it stood out.

It could be nothing. It could be something but it's something to look into again next season.

If anyone has HH Code Red or HH Ms White I would check to see if the pollen and stigma mature at the same time. They repeatedly produce similar seedlings for me in size and petal shape though they are never better than the parent. Unfortunately they got swept into the culling in the last 2 years.

Bessie

I read this article a few months ago, but forgot about it. The American Dahlia Society Bees Don’t Care – Hybridizers Should. It goes into a bit of detail on Dahlia anatomy and the article mentions the anther/stigma maturation process.

https://www.dahlia.org/docsinfo/articles/bees-dont-care-hybridizers-should/

https://www.dahlia.org/wp-content/uploads/2020/08/dehis.jpg contains the "DRAWINGS" referenced in the article, and I captured this screenshot:

From [Wikipedia]https://en.m.wikipedia.org/wiki/Dehiscence_(botany)):

Anther dehiscence is the final function of the anther that causes the release of pollen grains.

Teddahlia

I was going to post this on Facebook but this is a better forum for random thoughts: There are two dahlia activities that are mutually exclusive: Collecting seeds and digging the dahlias. Seed harvesting only happens before you dig the dahlia clumps. We do a final check for nice seed pods just before we chop down the foliage. However, we have been gathering seeds for about 6 weeks by then and anything we collect is just a bonus crop. Having said that, there are many, many seed pods that are not harvested here. Some varieties have been proven to have inferior seedlings yet they make a bazillion seeds. I see the huge over packed seed pods of one particular variety and wish that it was a good seed parent as collecting 1,000 seeds from a half dozen plants would be possible. Digging the Giant and Large row of flowers takes extra time as we check nearly every plant for seeds. Once in awhile, a giant will surprise you with seeds but some of the giants do not ever make seeds. Every year, I check Show-N-Tell for seeds pods but after 10 years of checking there never has been any seeds. I have noticed that seed pods collected after a frost are real crap shoot. Many of them have been partially frozen and rot sets in quickly, especially when you bring them into the warm house. The very ripe pods do much better but it is hard to to distinguish a sort of ripe pod from really ripe one while you are concentrating on digging.

Bessie

Teddahlia thanks for the advice! I appreciate your random thoughts, as a newbie hybridizer.

AndreaB

Teddahlia your pups look bored!

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