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...

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!

Teddahlia

I divided a first year tuber clump and got 9 tubers. I looked it up and it was one of those that got marked for retention but there was not enough enthusiasm to write any remarks. Now it has one very positive comment: "makes lots of tubers" . Perhaps, if we ever sell it, I will post a picture of the tubers instead of the flower. I bet that it will be one of the second year seedlings that we do not dig but it deserves another shot at glory.

I wonder if it was this one that had it's picture taken more as a prank Actually, this is a "Bill Mishler" picture as he would bring an over the hill, open center flower to a dahlia meeting and say: "You should have seen this one before it went over the hill,." Margaret wanted a picture and this was the only flower and I bet she would say it was a good one.

blown_dry

Teddahlia "You should have seen this one before it went over the hill,."

I love this. "The one that got away!" dahlia style.

Teddahlia

I have a habit of posting progress reports on the dahlia activities. Digging is done here but the dividing is in progress. Dividing takes many,
many hours more time than digging. I divide in this order: first year seedlings. second(multi years as some third year in there) year seedlings, all the rest and that is the bulk of the dividing and it includes the named varieties grown in our main garden.
I finished the first year seedlings and marked 124 to grow another year. One clump(a yellow waterlily with a nice flower) set a new record of 14 tubers, beating the previous record of 12 tubers last year. I will not take cuttings as there are enough tubers. By the way, we mark the best of the best and take cuttings from them to be sure we have enough of them to evaluate and if it is a good one, we have headstart on tuber production. I do not have the count on the best ones as that is a joint decision with Margaret but it is usually about 15- 20. By the way, there is never enough information written on most of the seedlings. Even the best ones get a short write up. Pictures are taken and then often not labeled as to which one it was. We always say we will do better on these issues but in our "dahlia seedling frenzy" when we are jointly evaluating them, we fail to do enough record keeping.
Pictured is HH Pink Martini with HH Serenity behind it. Both seem to be pretty good seed parents. Serenity was hand crossed(line bred)and the result was a 7 foot tall red waterlily with very good form.

Teddahlia

We need some posts on these frigid winter days. 28F this morning. Does this seedling look like Kilburn Glow?

k like Kilburn Glow?

calico20hill

As far as I can remember, Yes it does. It is also very pretty and I would be delighted to grow it. And it was 24 degrees here this morning which makes your 28 sound balmy! The days have been beautiful lately with clear skies and sparkly frosts in the morning, and that big full moon moving across the sky at night.

AndreaB

Speaking of the full moon… did anyone see the rainbow ring around it this morning? There were actually 2 if you look closer. Lasted all of 6 minutes and then they were gone. Pretty while it lasted.
It was a crisp 14 degrees here!

Krista

AndreaB Wow what a spectacular capture! Lucky to have been in the perfect place at the perfect time - thanks for sharing with us!

Emilyp

AndreaB We saw the halo around the moon here in Wisconsin. It was lovely, and quite chilly.

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