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...

Teddahlia

Bicolor is vexing for breeders.
This one makes lots of tubers. We like lavender flowers too.

Teddahlia

Variegated flowers can be interesting. Wicked Witch does not have much form but it's colors are gothic.

Teddahlia

Pulling pot tubers and tubers for material to take cuttings. There are too many to remember and I go off our notes. We need to do a better job of notes on the second year seedlings that we keep over for a third year. The fact that we have dug and divided the tubers is good indicator but notes would be a lot better.

BackyardBouquets_17

Some of you may recall this scented seedling from last yr. So far it looks like it stored well ( I don’t baby them, if they dont make it without babying that’s just to bad) I do not grow any anenome but am wondering, would it make more sense to cross it with say something like Polka instead of a fully double since the strongest scent is at pollen shed or would that not necessarily make much difference?

I’m really anxious to see what it does/smells like this yr as last fall I could smell it just walking by the row. There were a few other less desirable ones that had a fairly strong scent that I’m now kicking myself for not saving to experiment with.

SteveM

BackyardBouquets_17 It's my understanding that scent is strongest when the plant (in general) is trying to attract insects so this would correspond to the pollen stage. However, I think the actual scent comes from the petals (or foliage) and not the pollen. You could find out if this is true for dahlias by picking off all of the florets from a bloom at pollen stage and smell them separately from the pollen center. Is it possible a fully double dahlia could have a scent, but only in the Fall when it goes open-centered? Dahlia blooms with scent are mostly (all?) open centered varieties and your chances of getting another scented dahlia will have the best odds if you cross with another scented dahlia.

Teddahlia

Dr. Hammett, the most important thing we learned: goals. You must define your breeding goals specifically as to the exact flower you want to breed and work towards that goal and that process may take many years. He said people who collected seeds from named varieties without any particular goals were breeding "mongrels". Yes, once in awhile a mongrel can be an excellent dog but it is rather worthless for breeding purposes as the genetics come from disparate backgrounds. This is an interesting theory and probably there is lots of truth there.

SteveM

Teddahlia This is an interesting theory and probably there is lots of truth there.

That theory would hold true when breeding for show dahlias but not always when breeding for cut or garden dahlias. If, for example, we are breeding for a new dahlia form then a "mongrel" can be what we re looking for. The desired recessive genes have been buried by decades of purposeful breeding. One way to rediscover them is to randomly cross different forms/shapes/sizes and hope for a mongrel with teeth.

But, I suppose "not having a goal" is a goal in itself.🙂

Teddahlia

You are quoting "hybrid vigor" as when you cross two inbred lines together the plants have extraordinary vigor. If you remember a post I did long ago, I asked Dr. Hammett if there was hybrid vigor in dahlias. He refused to answer immediately and an hour or so later, said a one word answer: "No".

For a few hundred dollars and a 6 month wait he would tell me why. Actually he just said no and allowed no further discussion as to why.

Bessie

Teddahlia I question the validity of science assertions, meaning that until proved, it's just an hypothesis. I've always been curious and exploring, and experimenting.
Food for thought...
It's now discovered, through the Dahlia project, that Dahlias are now considered tetraploid with 92 chromosomes per cell, not octoploid as once thought. Also, their nearest relative is the Sunflower(from April Newsletter of the Dahlia Society of California).

With that in mind, I asked Gemini AI:

Can Sunflowers exhibit hybrid vigor even though the two seed parents are not inbred

Excerpt from the Gemini reply:

Therefore, while inbred lines are very useful in producing high levels of hybrid vigor, it is still possible to have hybrid vigor occur when crossing non inbred parent plants.
In summary, while inbred lines are a powerful tool for maximizing hybrid vigor in sunflowers, it can also be observed when crossing non-inbred parents.

Ludmila

Teddahlia my understanding of hybrid vigor is that it's mostly an absence of inbreeding depression.

SteveM

Bessie Dahlias are now considered tetraploid with 92 chromosomes per cell, not octoploid as once thought

How did they get the "92 chromosomes" number?

Teddahlia

"One surprising discovery they made is that cultivated dahlias may actually be tetraploid (four sets of chromosomes) rather than octoploid (eight sets), as was long believed. This finding could have significant implications for breeding strategies and evolutionary studies, though additional genome analysis across different dahlia varieties will help confirm these insights. " March 25th
https://www.hudsonalpha.org/natures-palette-how-dna-shapes-the-flowers-we-love/

Bessie

SteveM how they got "92" is a good question. Also, FYI , the November report of the Dahlia Project is on the ADS website and mentions tetraploid dahlias. But since you asked the question, thinking about it, I asked Gemini AI...😀

The tetraploid version then has four sets of these 23 chromosomes, resulting in 92 chromosomes (4n = 92).

Gemini Prompt: How can a plant that's tetraploid have 92 chromosomes
Public link to full response:
https://g.co/gemini/share/8eabc509c4a9

Teddahlia

I remember from the "old days" they would stain the sample and place it under a microscope and count the chromosomes. Perhaps they could not count in the old days or they were right and the new way to do it is more accurate. However, in my quote they use the word "may" for their conclusion. We will see. Tetraploid is only somewhat better for breeders and does not change much.

SteveM

Teddahlia When a dahlia was believed to be an octoploid I thought the number of chromosomes was stated to be 64. That would make a tetraploid dahlia 32. I don't see any math that will give a dahlia 92 chromosomes.

Teddahlia

"my understanding of hybrid vigor is that it's mostly an absence of inbreeding depression."
Inbreeding is very difficult for tetraploid or octoploid organisms. I could be done but it would take many years of breeding.

Ludmila

Teddahlia

Inbreeding is very difficult for tetraploid or octoploid organisms. I could be done but it would take many years of breeding.

Yes, that's a whole point! There is no inbreeding depression, so no hybrid vigor either.

SteveM

Bessie Gemini Prompt: How can a plant that's tetraploid have 92 chromosomes

It is possible for a plant to have 92 chromosomes in a cell but it is not the case with dahlias.(I'm pretty sure).

What does Gemini say with this prompt:
what is the haploid number for dahlias

The chromosome number is more of a curiosity since it has very little to do with the choices we make as breeders. We are more interested in the genes and their alleles.

Teddahlia

A PhD corrected me when I kept saying genes when the proper word for that sentence was allele. They like to split hairs. Genes are what we think of but an allele is word for one of a set of genes than can "fit into the same spot" So, a sentence would go from: " there are many genes that can affect that trait " to "there are many alleles that can affect that trait". Dahlias have lots of genes and lots of alleles. So for a trait there may be 3 or 4 or more alleles for that "spot" and since they are tetraploid,(I wonder about that) there are 4 positions for alleles and all 4 could be different. When they are octoploid(they have not yet said for certain) there are 8 positions but I doubt there are many with as many as 4 different alleles and so whether tetraploid or octoploid it is very complicated. Theoretically. a tetraploid could be made homozygous(all alleles the same) twice as easy as an octoploid. But twice as easy is still nearly impossible.
Boring, boring, boring says Margaret. She says that observing traits and crossing two with that same trait gives you more flowers with that trait. She says that it is so obvious that anyone would know that. One cannot argue with results.

Teddahlia

Taking cuttings of everything good. 2024 best seedlings included. Three taken from the very best one.
Yes, this one.

Juliarugula

Teddahlia I remember a few years ago you commented that you and Margaret had a seedling that you were both super excited about and hoped to release in a few years. (I realize that’s sort of non specific, but you seemed to think it was really something special, so maybe you’ll know what I’m talking about). Is it a variety that has been released now that it’s been a couple of years, or is it still being evaluated. (Or did it get lost or not make the cut?).

I may need to see if I can find the old post…

Edited to add…. I gave up. Just crossing my fingers now!

Teddahlia

Juliarugula That happens every year. The pink one is a close up of Margaret's favorite one from 2024. No full frame pictures of the best first year seedlings as they have to prove they are still good a second year. HH Cheerio and HH Sincerely are "not waterlilies " that I love and Sincerely is released and was sold and Cheerio is being held back to accumulate tubers for next year. It was mis-labeled by me at our trial garden but passed with high score at the other trial garden. It is really nice but Margaret will say not as nice as her waterlilies and two of them are in the trial gardens this year.

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