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

Seeds that are sort of immature just sprout at a lower rate. Anything that germinates is a success.

Bessie

MissyWeitzel the color of most of those look fine. What I've found is you can have a seed that's beyond the immature green stage, but if it is not filled with a mature embryo that can send out a root radical and a pair of leaves, it will not germinate/grow. I've opened up a few of my seeds that don't feel like there is any "innards", just to confirm my conclusions. Perhaps you can sacrifice a few seeds to dissect and understand what's inside. Just because there's a dark outer covering of the seed, there's not always the makings of seed viability. This seed viability issue can happen even in mature seed pods.
The grayish look is completely normal on the seed covering. I looked at it under a microscope a few days ago, and its an outer coating of whitish clear cells.

MissyWeitzel

Bessie thank you! I love how science minded you are. I'm almost ashamed to admit that until right now I hadn't heard the term 'root radical' at all, except for the punk song 'Roots Radicals' by Rancid. Pretty sure they're not talking about seeds. 🤪

In all seriousness, I do love learning more about this side of dahlia growing. It's so interesting and exciting!

KitCMC

Teddahlia This is very nerdy and full of questions you may have already answered elsewhere. I apologize if that’s the case.

It is surprising to me that there are any white dahlias at all given the number of chromosomes involved. The mutation(s) must be strongly dominant? Is it known whether the genetics affect the mechanisms behind the synthesis itself - ie. can’t produce a certain compound(s) - or alter the conditions in which the synthesis occurs?

Enzymatic reactions are very sensitive and highly specialized. Is that also why dahlia color expression varies so greatly depending on environmental factors (soil pH, ultraviolet radiation, temperature, etc.). Is anthocyanin synthesis, or its interruption, an origin of varietal sports? Which may also be why some are so hard to capture? I know you’ve mentioned irradiated seed being rumored to have been used, but what about on a plant itself? Has anyone ever tried growing under controlled manipulation to get a sport?

https://en.m.wikipedia.org/wiki/Anthocyanin

Bessie

KitCMC a plant growing under sunlight is being irradiated. That's part of why we wear sunscreen, the sun's radiation can be bad. Not sure if this is the right way to say this, but... The sun can cause mutations in our cells that damage the DNA and that may trigger skin cancer.
Same with plants getting DNA damage, strange things can happen.

Bessie

MissyWeitzel I love all kinds of learning, too. 😁
Check out https://forum.dahliaaddict.com/d/89-breeding-for-color/24

Teddahlia

"It is surprising to me that there are any white dahlias at all given the number of chromosomes involved."
Dahlias have two pigment classes.: (1)white and the variants of white and (2) Anthocyanin and it's variants. Anthocyanin is formed from the white pigment chemicals. The process takes several steps as different molecules are added to the white. If a step fails in the creation of anthocyanin, the flower will remain white. So in a way, all dahlias that have color, have the pigment for white. The prevention of the anthocyanin formation produces a "white" flower. White includes various versions and includes the yellows and even some darker almost orange pigments. If we know that two flower varieties were white for the exact same reason, we could cross them and get lots of white flowers. Trial and error may find the cross. DNA analysis is not currently a tool we have available.

Cosey

What has been your collective experience with viral symptoms in first year seedlings this season?

I grow my 1st & 2nd year seedlings in a separate field, manage insects well, and disinfectant between every plant. Nothing gets "harvested" from the seedlings to minimize cuts and possible infection from tools.

Out of around 1000 seedlings I culled 15 or so for suspicious symptoms throughout the season. I never tested them because it wasn't worth the money.

I decided to accelerate two first year seedlings and propagate via cuttings next season so I tested them for DMV. Unfortunately, 1 tested positive though it was asymptomatic. I did cull the seed parent variety this spring for symptoms.

I know it's been documented that at least one strain of DMV passes into seedlings, but I was wondering what your seeing in your seedling patches.

Bessie

Cosey if a seedling looks sickly within the first 6 weeks of growth and hasn't positively responded to a liquid fertilizer with micronutrients, then I throw it away. Poor growth after being planted out is another reason to cull. Since I don't test for viruses there's no way to know for sure if plants are infected. I have a mindset that resistance to virus is really important. Your one seedling that tested positive but was asymptomatic sounds like it is exhibiting resistance. I'd buy a Dahlia that grows nicely despite being infected. Only by breeding with a Dahlia with known "resistance" will the virus resistant gene pool grow. With all that being said, I probably had four seedlings that could of had virus out of around 80 seedlings.

Cosey

Bessie From my DMV testing last year, all asymptomatic DMV dahlias showed symptoms the following spring. I test in the fall for DMV. It was discouraging to see that. And to see symptoms and positive results in my 1st year seedlings (especially since I knew the seed parent variety tested positive last year) makes me nervous.

I don't know the percent of resistance or how long plants remain resistant but as a hybridizer seedlings are already 4-6 years old before I even begin marketing them.

This symptomatic timeline should be something those who bring seedlings to market need to be aware of.

Teddahlia

DMV has frustrated the virus researchers for many years now. Perhaps we will be hearing from them in the future. The issue is false positives as the dahlia has incorporated some of the DMV genes into it's genome. Those genes caused the false positives. I do not know that they have eliminated this issue, DMV used to be one of the worst ones for negative symptoms but this confusion implies that it may be something that may not cause symptoms in many plants. Our virus peron says the general rule is to test when you see symptoms.

Cosey

I spoke with two researchers this week and I'm sending off plant and seed samples for them to investigate. I'm sending both positive and negative plants, seedling siblings, and seed parents. Each researcher has a different objective but I would like to see if one will isolate which DMV strain is present.

I expect DMV+ results given it hasn't been tested for in previous seasons but I am alarmed at the number of asymptomatic positives in the first year seedling field.

In 5 years we'll know so much more.

KitCMC

Cosey thank you for your tireless efforts!

Cosey

A Bracken Glenda seedling. Seed sourced from a friend in Australia. BG has been a reliable seed parent for fully double formal decoratives. Tubers are 50/50 for being suboptimal or good.

Teddahlia

All first year seedlings have now been dug. Because this one was over 7 feet tall and still had nice flowers on it, today we stopped the digging and took some cell phone snapshots. Then we proceeded to disagree whether it was a waterlily or an informal decorative. Waterlilies are supposed to have only 7 rows of developed petals. This flower has a couple more than that. She says we can call it a waterlily and perhaps call it a waterlily type. The picture supports her appraisal of the form and I shall now agree with her. Orange color is very bright and evenly distributed. It had a very sturdy stalk too.

NCDahlia

Teddahlia I like this one whatever the form is lol I would grow it. Hope u grow it next year nice coloring for sure just in time for Halloween

calico20hill

Other then the fact of agreeing on what the perimeters of a form are, is there a good reason to restrict the number of rows on a waterlily? It seems like more rows would allow it more days as a cut flower...more rows to open and replace back petals as they die off....

Teddahlia

Waterlilies with few too many rows do make nice arranger's flowers according to Margaret. Perhaps an arrangement in competition could be called cut flowers on steroids.

Teddahlia

This seedling did especially well this year; over 6 feet tall, always several nice flowers on the plants. And it is a pleasing bicolor of lavender pink with light pink tips.

Juliarugula

Teddahlia what’s the bloom size on this one? I love the form and the color combo.

Emilyp

Teddahlia Very pleasing indeed!

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