Hi, four,

I don't blame you for not owning those labels/annotations. They seem to use "flower" and "floret" interchangeably, and they aren't really the same.

Some of my zinnias have petals that resemble florets. These two blooms happen to be composed of petals because they contain stigmas. You don't see any pollen in them.

If it contains a stigma, it's a petal. If it contains an anther, it's a floret.

ZM

There are zinnia stigmas for petal seeds (peripheral), also there are zinnia stigmas for disk /core seeds.

Hello everybody,

A little advice to anyone considering doing some zinnia pollination or hobby zinnia breeding next year. Don't pay any attention to those who say never to cross F1 hybrids with F1 hybrids. There is a lot to learn about practical zinnia genetics. Zinnia DNA strings, like all DNA strings, have specific sequences of Adenine, Guanine, Thymine, and Cytosine that code as genes, but separating many of those "genes" are partial sequences, many of whom, perhaps all of whom, consist of gene fragments from prehistoric genes. Genes can be struck by cosmic rays, and some of those strikes can be energetic enough to fracture the gene into two or more parts. There may be other causes of gene fragments as well.

Hybridization of hybrids may occasionally recombine some of those gene fragments with other different gene fragments. Many of those combinations are just different fragments, but occasionally the combination could recreate a viable "lost" gene or even a prehistoric gene, or such random combinations could create altogether new genes. Ancient lost plant traits could be restored, or wholly new traits might be created. The key to those possibilities is lots of cross-pollination. Which is relatively easy to do with zinnias. The ability to recover prehistoric genes or to create altogether new genes is kind of mind-boggling. So make hybrids between hybrids ad nauseam, and prepare to be amazed. Hopefully, you won't get anything too amazing, like, maybe, intelligent zinnias (grin).

If I were to try some zinnia breeding here in an apartment in town (and I am considering that), I would try combining some closed-tube petal zinnias with other zinnias. These are some of the closed-tube "finger-petalled" zinnias I am referring to.

As always, you can click on the photos here to see larger versions, which you can close by clicking on their "X". The reason for using those odd zinnias in some crosses with other zinnias is not so much that I like the closed tube look (although I kind of do), but there are some different genes there that could recombine with existing zinnia genes to create some altogether new genes. And these altogether new "finger-petalled zinnias" may themselves already be products of such new gene creation. Let the good times roll. I am always up for "altogether new".

ZM

Hello everybody,

These are a few more zinnia variants that are somewhat similar to the finger-petalled forms.

Several of those specimens show probable new gene creation via multiple hybridization.

ZM

The last one (nice) looks like things that we see inside some aquaria.

The many upright petals might give it an advantage for collecting pollen that would fall off insects when the insects inevitably would bump into petals.

Hi, four,

" The many upright petals might give it an advantage for collecting pollen that would fall off insects when the insects inevitably would bump into petals. "

I hadn't thought of that, but those upright petals could give it that advantage. Although, for good breeder specimens like that one, I frequently intervene and do some self-pollination.

And for tubular petals like that one, that means snapping off the petal, similar to snapping a green bean, to expose the stigma inside. With no intervention, those skinny petals probably would not develop viable seeds at their bases. But as an amateur plant breeder, I do a lot of "intervention".

That allows me to get results that don't normally occur.

ZM

Hello again,

This is another variant Zinnia that I liked.

Its petals resembled pollen florets with red tips.

ZM

So many of them in photos here are delightful. Have you propagated some /all /none of them?

Hi four,

" Have you propagated some /all /none of them? "

I moved to an apartment a few months ago, so I didn't have any available growing space this season. I think I will experiment with growing a few zinnias indoors in the apartment this Winter. This move was not my idea. The owner of the farmhouse we were renting decided to sell the property and asked us to leave so they could prepare the place for sale. There were two "secrets" to my success with zinnias. I did a lot of cross-pollination, and I grew a lot of zinnias in a large garden space. It remains to be seen what I can do in my present limited circumstances. I have had some experience growing zinnias indoors.

It remains to be seen how much I can do in this apartment. There are actually a few advantages to indoor zinnia culture. But space to grow large numbers of plants is not one of them.

ZM

I understand.

A school's garden. A community garden. An acquaintance's garden. None of those exist? Build it.

Hi, four,

All good ideas. We can have a killing frost any night now in this part of Kansas. But I am going to plant a few zinnias indoors. I think I might plant a few this evening. A few more photos of past "glory". These really benefit from being clicked on to see their expanded versions.

Zinnias have a lot of possible flower forms. And plant habits, as well. I will show some possible variations in zinnia plants in subsequent photos.

ZM

Hello all,

I've haven't posted very much here, but I'm very interested in what you all have going on. I communicated with ZM over email a few months back.

I'm curious what you all have learned over the years about color inheritance. If I cross a pink with a white, do you find that pink is dominante and that subsequent generations segregate into pink (dominant) or white (recessive). Or do colors tend to blend and produce in-between tones of color?

Just curious what you have observed...

Thanks!

Weston Adams

Hello again, Weston,

You are very welcome here. I have a few comments on the dominant-recessive zinnia color thing.

Zinnias have a very wide range of colors, based on a fairly small range of basic pigments, but unfortunately no true blue or any colors depending on the presence of at least some blue pigment or dye.

I have found zinnia genetics to be much more complex than the Mendelian dominant or recessive thing and it is interesting that you mentioned white as a potential recessive. Like white snow, there is no white pigment in zinnias. White is a structural thing in the petal cell structure. It is an inheritable factor. And it may be a dominant factor.

White is one of my favorite zinnia "colors" because it is structural, and crosses with white can lead to some "looks" in zinnias that I really like. These zinnia hybrids had white parentage and a unique look that I liked. You can see them much better by clicking on these "thumbnails" to expand them to "full size", which you can then collapse by clicking on the "X".

They share a "sheen" of structural white color. They also had "scabious" parentage. But in my opinion, zinnia genetics are much more complex than Mendel's experiments with peas.

ZM

OK. Thank you very much for this information.

Would I be correct in saying that white is the absence of any other pigment?

Hi Weston,

"Would I be correct in saying that white is the absence of any other pigment?"

Not strictly correct. "any other pigment" implies that zinnia white is a pigment. Zinnia white is just a complex cell structure of transparent or translucent cells and, like white snow, no white pigment is involved. But it is a special cell structure, and white zinnias have it, and "regular" non-white zinnias don't have it unless they are white hybrids like the two zinnias above.

ZM

OK thank you very much. I would enjoy doing some crosses with white zinnias soon.

Hi Weston,

You wouldn't want all of your zinnias to have that white-crossed "look", but you could create strains of zinnias with the look. As regards doing crosses "soon", if outdoors currently, that would imply growing south of the equator, like maybe Australia or New Zealand. Or indoors.

I am thinking of experimenting with hydroponics as a potentially scaled-down way of conveniently growing zinnias in my small apartment space. I have some books from Amazon on that subject coming today.

In past years, I was able to grow some relatively tall blooming zinnia plants under fluorescent lights in 4-inch "clear" plastic pots. They were rootbound, so I repotted them in black 8-inch square plastic pots. But I think it was kind of amazing that they went from seed to bloom in those tiny pots. These photos also benefit from being clicked on to see their expanded versions.

I hope to do as well in my present more limited circumstances. Incidentally, I went for years using "clear" 4-inch square plastic "orchid" pots but discovered a tendency for green "moss" to take advantage of the light transmitted by the translucent plastic, so I switched to black plastic in my little 4-inch seed starter pots.

ZM

Yes, my current zinnia efforts are indoors! Very inhospitable to zinnias outside right now.

I’ve been thinking about something else too…

With all of the cross pollination that you have done, when you finally find a zinnia you like and you self pollinate it, what levels of stability do you find in the progeny?

Do you find that highly-hybridized zinnias generally come roughly true to type when self pollinated? Or do you find that they revert back to various versions of the zinnias in their ancestry and display a high level of genetic instability?

Hello Weston,

" Do you find that highly hybridized zinnias generally come roughly true to type when self-pollinated? "

That is really a very good question. There can be quite a bit of variation. It can take at least one generation of selection to "purify" a new strain, and depending on the degree of uniformity you are going for, it could take more than one generation of "purification". Some gardeners do like to have some variation. But some recent commercial introductions of new zinnia varieties have had a surprisingly bad level of impurity. I planted an entire flower bed of white Zinderella zinnias, and not a single specimen had that unique flower form. They all had white blooms, but not even one had that true scabious-looking "Zinderella" flower form.

" Or do you find that they revert back to various versions of the zinnias in their ancestry and display a high level of genetic instability? "

I wouldn't say that they all "revert back". Sometimes they "revert forward" to actual improvements. I liked the look of some of my tubular petalled specimens, so I split their tubes and selfed them. In those selfs, I got some more extreme forms that I considered to be unplanned improvements.

It is standard practice for zinnia seed producers to hire people to go into their seed-producing fields to "rogue" them by simply destroying any specimens that differ too much from the norm. I fear that many interesting new varieties of zinnias have been lost that way. However, as they say, "Beauty is in the eye of the beholder" and that may apply to zinnias as well.

" my current zinnia efforts are indoors! "

You might be interested in this book on LED plant lights.

ZM

Yes this makes sense. Thank you so much. I will try to keep you updated!

Hey ZM,

I remember hearing at one time that you attributed part of your success to working with large populations of zinnias in an outdoor garden.

If I may ask, how large was your population? How many zinnias could you fit in your garden?

Thanks so much!!

Hi Weston,

" how large was your population? How many zinnias could you fit in your garden? "

Tens of thousands. I was renting a farmhouse whose "grounds" were multi-acre. I bought a hoop bender and created hoop houses to extend my growing season.

I only "messed with" maybe one zinnia in a hundred. Those were "the good old days."

ZM

Hi ZM and all,

Wow, I did not realize that your scale was this large.

I am getting the idea that a successful breeding program ebs and flows significantly over the course of the year. Suppose a person is working with 4 generations/year. Two of those generations could be grown outdoors. These would be massive populations and they would allow for extensive pheno-hunting. The other two generations would be grown indoors under lights. By necessity, the breeder would have hone everything down to his #1 or #2 priorities over the winter. Through careful timing and climatic control, he could theoretically advance his top priorities by two generations over the winter. If all goes as planned, he should be ready to launch another large population in March.

Now I'm going to change subjects...

There is something that I've been wondering about, but I don't recall anyone discussing it here. Once a variety has been bred and stabilized (to a reasonable extent), the next step is large-scale production. From the research I have done, it's a recognized fact that zinnias drift toward single flowers if they are open pollinated and grown for successive generations without selection. I may be prying into someone's trade secret, but I can't help but wonder how large-scale seed growers keep the percentage of double zinnias up in their seed lots. Perhaps they are only saving seed from fully double heads, and just tolerating the singles as pollenizers? Perhaps they have another trick of the trade.

According the English summary of a Japanese article I was just reading, there are 3 Mendelian genes involved. Apparently, these genes are recessive, because in the F2 generation of a cross between a fully double flower and a fully single, they were reporting 1 in 64 flowers recovered the fully double phenotype. Here's the article: ジニアに於ける八重咲性の遺伝 (jst.go.jp)

I wonder how this works in real life zinnia seed production...

Hi Weston,

Your four-generation per year zinnia breeding scenario is spot on.

" It's a recognized fact that zinnias drift toward single flowers if they are open-pollinated and grown for successive generations without selection. "

" From the research I have done, it's a recognized fact that zinnias drift toward single flowers if they are open-pollinated and grown for successive generations without selection. "

" I may be prying into someone's trade secret, but I can't help but wonder how large-scale seed growers keep the percentage of double zinnias up in their seed lots. Perhaps they are only saving seed from fully double heads, and just tolerating the singles as pollenizers? Perhaps they have another trick of the trade. "

I think it is safe to assume that there are several "tricks of the trade", some of which are actual trade secrets. But the single-double thing is just one issue. The recent Zinderella debacle is an example of a seed company being totally incapable of delivering seeds that produce results that even remotely resemble the picture on the packet. Seed companies need to mechanize selections that breeders can do manually. It's a lot more demanding than just blowing out the chaff, stem pieces, petals, and what-have-you. One "secret" that I employed is the manual selection of unusual seeds.

Zinnia seeds will occasionally have a variety of "horns" and such that get knocked off in automatic processing machinery. Zinnia seeds have other shape variations, in both the petal and floret seeds. I suspect that some seed companies may have proprietary seed-sorting devices that could amount to trade secrets. Digital computers and artificial intelligence could be involved.

ZM

Yes, that makes sense. There is much to figure out, but I am excited about this project!!

Hi again, Weston,

I am a bit excited about your project, myself. The commercial side is totally away from my area of expertise, but I don't mind making some "educated" speculations (guesses).

Returning to the phenomenon of double zinnias "running out" into singles and how the current seed companies avoid that, I am under the impression that at least some seed companies do not take next year's seed stock from this year's production fields. Instead, they have smaller isolated zinnia patches that produce the seeds that are used to plant the production field(s).

Those smaller patches can be carefully hand rogued to remove any plants with single or less than fully double blooms so that only fully double zinnia plants produce pollen and set seeds to be used to plant next year's seed fields. That does not necessarily eliminate the practice of hiring people to go into the production fields to "rogue" them, but it greatly reduces how many zinnia plants they need to kill. And more individual care can be given to those plants in the isolated patches that produce the seeds to plant the production fields.

Maybe an obvious question to ask here is where the seeds come from that are used to plant next year's isolated patches. Maybe just a random selection from this year's isolated patches, or maybe superior specimens are tagged for that.

This technique can be used to preserve other zinnia quality features like plant height, color purity, leaf shape, and so on.

ZM

That makes sense. Yes I am sure that they have a system.

Another topic…has anyone ever seen ”albino” zinnias? I expect the seedlings in this photo to die from lack of photosynthesis. But they are interesting nonetheless. From Dawn Creek germplasm.

Hi Weston,

I occasionally see an "albino" zinnia seedling, but they are very rare. I have never seen more than one at a time. You apparently have three in a grouping, and that seems a bit freakish. It is normally a fatal mutation because, without chlorophyll, the albino seedlings die fairly early in their development.

You have an opportunity to do an interesting experiment. You could foliage-feed the seedlings with sugar water to see how far you can extend their development. I would guess that one tablespoon of sucrose (table sugar) per gallon would be an effective foliage feed. As an experiment, you could include conventional inorganic nutrients and maybe a little glycerine to further sweeten the feeding.

You could spray the foliage feed or apply it with a watercolor brush. The objective would be to see how far you could extend the development of these albino zinnias. Maybe all the way to bloom development and beyond. Foliage-feeding zinnias is a good cultural practice, so augmenting that foliage feed with organic ingredients like sucrose and glycerol would not be too far-fetched. You could get some remarkable-looking zinnias.

ZM

Yes, I may try doing that. However, even if we get these zinnias to maturity, they will not be viable for our customers, who will not be foliage-feeding their plants.

But it would be an interesting experiment for sure

Hi Weston,

" However, even if we get these zinnias to maturity, they will not be viable for our customers, who will not be foliage-feeding their plants. "

I would expect that some of your customers already practice the foliage-feeding of their zinnias because foliage-feeding works rather well with zinnias, and with many garden plants in general. And you wouldn't be out of Iine to recommend foliage feeding to your customers.

As a general practice, I foliage-fed my "regular" zinnias with Miracle-Gro Tomato food because that soluble nutrient product worked rather well as an affordable foliage feed. I also added a teaspoon per gallon of Physan 20 to protect my zinnia foliage from diseases and the Physan served the additional function of being a good wetting agent for the foliage feed. During periods of unusually cloudy weather, I added some sugar to the mix to compensate for the lost photosynthesis from decreased sun exposure. So I was "babying" my zinnias.

So if Albino Zinnias did become a "thing" that required "baby formula" foliage feeding, that might be an acceptable requirement for many gardeners. If you do decide to keep your pale babies growing with some baby formula, keep us posted with photos.

ZM

I've been looking at some of the indoor zinnnias I've got going and noticing some interesting foliage differences even within the same lot. Look at the "basil leaf" structure of this plant! And compare it to the other plant in the same lot! Very pretty. Pardon the photo colors...that is from the spectrum-specific grow lights we are using.

I'm assuming that this leaf-structure difference is purely genetic, but does anyone else have other ideas as to what might cause this?

It's quite a desirable phenotype in my opinion.

Blessings,

Weston

Hi Weston,

"I've been looking at some of the indoor zinnias I've got going and noticing some interesting foliage differences even within the same lot."

You are wise to be looking beyond the characteristics of the zinnia blooms to observe foliage and plant features. I have noticed that zinnias almost always have leaves in pairs and I think that leaves in threes or even fours might lead to more balanced plants. And since side branches normally arise from the leaf attachment points that could lead to a fuller stem structure of the zinnia plant.

However, my best zinnia plants were the triploids.

It would be good to have desirable zinnia plants that were not triploids. I have my doubts that really good non-diploid zinnia plants are possible, but I could be wrong about that.

ZM

Hi everyone,

This super-cold weather keeps me indoors in our apartment pretty much all the time. We currently have snow on the ground in the apartment complex. I have a few zinnias indoors under fluorescent lights. I haven't upgraded to the new technology. I'll post a few photos of in-the-past zinnia specimens.

More later.

ZM

For some imaginary exhibit of specimens in categories, those could go into "Elegant Beauty".

ZM,

I was thinking about you yesterday. We have just had the most brutal storms. High winds, then record snowfall (we get hardly any snow in Nashville, so 8.5 inches overnight was crippling), and then single digit weather. During said storm, my seedlings under lights grew exponentially. Potted them up to give me something to do while stuck indoors. I'd say I have 30 of the 50 that have germinated ready to be pinched soon. I have never done that. Then I thought, I should probably search ZM's post. I bet he has suggestions. All that is to say, I'm glad to see you're still growing strong!

We have switched are in the 50s and 60s for the next week, save a couple of days, and now, my potted up babies are on a fieldtrip on the back deck. They're really happy. I hope you have a great growing season

I've been looking through this thread and viewing all of the "tubular" petal variations once again! So pretty. (Thanks for this photo, ZM).

One thing I'm wondering is whether these forms could ever stabilize into open-pollinated lines. Are the stigmas accessible to insects? Or do they require "surgery" in each generation to access the stigmas and successfully pollinate them.

I've had similar thoughts about scabiosa-type flowers. But apparently scabiosas are accessible to insects...because they surely aren't all hand pollinated!

Blessings,

Weston

Hi Weston,

"One thing I'm wondering is whether these forms could ever stabilize into open-pollinated lines."

Well, yes, that is a very good question. I think the answer is yes. There is always one safety net, and that is those yellow fuzzy starfish--the florets--whose pollen selfs themselves internally unavoidably with their own pollen and unavoidably produces a selfed seed. That occurs even if the stigmas inside the tubular petals themselves are sealed into tubes that make them inaccessible to fertilization by natural means. Pollen florets can save the day, even when the petals are naturally sealed up.

Propagation by high-tech means might possibly propagate a specimen that does not produce any pollen at all. Tissue culture could be used and possibly eventually be automated to produce so-called artificial seeds. But for the time being, that is a little too science-fictionish for practicality.

There are some closed-tube zinnia variants, or some whose petals are so long and narrow that they are effectively closed, that are of interest. To me, at least.

That little guy is trying to help. It may be that tubular zinnias that are not cooperating in producing pollen can be sprayed with a substance that will stimulate them to produce pollen florets. All those pictured did eventually produce a few pollen florets. Finding a hormone or plant growth regulator that stimulates pollen production might be possible.

ZM

Very interesting ZM. Thank you for these thoughts.

Based on what William Hazzard (breeding zinnias at UC Davis) says, zinnias don't like to be selfed over successive generations. Seed set will drop off around the S4 or S5 generation he says. I don't have personal experience with this, but I know that Zinnia is a widely outcrossing genus.

Do you think that it is realistic to develop a full line of OP zinnias that entirely relies on self-pollination?

Hi Weston,

" Do you think that it is realistic to develop a full line of OP zinnias that entirely relies on self-pollination? "

Excellent question. We could take a look into nature to see if there are examples of that, and how successful are they? For example, the Redwood Trees in California. People just want to cut tunnels in their trunks and drive cars through them. Many of our native plants have been selfing themselves for centuries, if not eons. There is that weird "giant flower" in public plant displays that has no one to cross with besides itself.

All that said, you raise a valid question, and I kind of wonder about that myself. Most farmers are growing F1 hybrids, and they are "feeding the world".

ZM

It's true that plants like tomatoes and beans self themselves all the time. But zinnias are designed more as outcrossers...so I'm not sure. So much needs to be researched!

Hi Weston,

" But zinnias are designed more as outcrossers..."

But if it is a reasonably pure variety, its neighbors in the production field are just like it, so it doesn't matter whether it selfs itself or outcrosses to an identical neighbor. A seed company is only responsible for what goes on in their production facilities and can't be expected to prevent a customer from cross-pollinating their product or make their product somehow proof against outcrossing by a bee working for their customer in a home garden. After all, the seed company may employ the bees to improve the pollination and hence the seed production in the company's seed production fields.

Corn can outcross (wind happens), but that doesn't discourage the corn seed producers.

ZM

Hey :) im new here and i have some newbie questions. i want to start breeding zinnias this year. now can i just randomly buy zinnia seeds i like and then keep going from there? how do i make sure they are not tetraploid or my offspring is tetraploid and infertile?

and would be the zinnia breeders handbook a good starting point?

i like multicoloured zinnias like carousel or persian carpet an throw in some white ones and see what happens..

Hi HU,

Welcome to your zinnia project.

" how do I make sure they are not tetraploid or my offspring is tetraploid and infertile? "

I think you meant if your offspring is triploid and infertile because tetraploids are fertile. That is a valid concern because seed companies do not always label tetraploid zinnias as tetraploids. I do not always know or know how to learn about zinnia tetraploidy. For example, I have doubts about the zinnia named "Pinca," but right now, I don't know of an authoritative source about its "ploidy."

I don't know what "starting point" to recommend. In my case, it was a very expensive book

Flower Breeding and Genetics

(that is a link to Amazon's offering of the book.) Chapter 12 of that book is devoted to Zinnias.

I have an assortment of tweezers and small forceps that I use to grasp and manipulate zinnia pollen florets. I would suggest a lightweight chair that you can carry around and place near the zinnias that you are "working on," including gathering pollen or applying pollen (being the bee).

You have a good idea to include multi-colored zinnias in your breeding. I recommend Whirligig as a good strain because it was derived from crossing two different zinnia species, giving all of your zinnias a wider genetic range and more potential for variation. And you would be justified in calling them Zinnia hybrida.

I wish you every success, and will gladly continue our discussion here.

ZM

Hello! Maybe ZM will chime in too, but the majority zinnias are diploids. State Fair Mix (from GeoSeed) is a tetraploid line, and so is the Super Cactus Giant Mix (same source), but my read on the situation is that otherwise you can assume zinnias are diploid.

Tetraploid zinnias are fertile, the only sterile ones are the triploids (crosses between tetraploid and diploid).

Hope that helps

So I've got two mysteries I'm trying to solve. Here's the story....

This winter we grew quite a few zinnias under CMH lighting. We had to battle powdery mildew, but the plants grew well and flowered profusely.

I found a single plant that was producing very impressive blooms. Image is attached. This plant exhibited an iridescent peach color--quite spectacular. I definitely wanted to work more with this plant! But I ran into two mysteries which I'm now trying to solve.

Mystery #1) This plant produced basically no pollen! When I went to collect pollen from it, I found almost nothing. I checked back numerous times throughout the blooming season (even checking numerous blooms) and even though nearby plants were producing pollen well, I was never able to utilize this specimen plant as a male in any cross! So, I decided to use it as a seed parent to receive pollen instead.

Mystery #2) Since I had experienced irregular seed set on zinnias before, I decided to document my pollination activities more closely and correlate them to seed set. I chose one bloom on this specimen plant which I would observe very carefully. I pollinated each receptive stigma on this bloom with pollen from other plants. I came back in the next day or two and saw that nearly all of the stigmas I had pollinated were withered and shriveled up--a good sign of successful pollination. Then I carefully marked each stigma that had shriveled by snipping off half of the petal. By doing this I would know which achenes had been pollinated and apparently successfully been fertilized.

Yesterday I saved seed on that bloom. In accordance with the irregularity I've seen over the winter, only about 15% of the shriveled stigmas actually set seed. I pollinated maybe 26 stigmas and they all shriveled down nicely (indicating successful pollination) but of all those "successful" pollinations I only got maybe 4 filled seeds. This is a mystery to me which I hope to solve. If anyone has pointers or tips, I'm all ears!

Hello Weston,

Mysteries, mysteries.

Powdery mildew is obvious in your photo, which could be a factor. Is there temperature control, and what are the settings? What photoperiod(s) are you growing at? CMH lighting may be providing less red spectrum than the zinnias would like.

Apparently, something other than the seed set is causing the death of the stigmas. The question is, what??? A possibly early attack by Powdery Mildew by the sticky stigma trapping a mildew spore instead of a pollen grain. A working hypothesis is that PM onto stigmas might be causing a false appearance of fertilization of the stigma. Is there any other source of non-zinnia pollen present?

My theory about false pollination may not be the only explanation. Your zinnias may prefer a more red spectrum than the CMH provides. More later.

ZM

Hello again, Weston,

" Mystery #1) This plant produced basically no pollen! "

An even bigger mystery is that your photo shows an abundance of pollen-bearing florets. I see at least a dozen florets in your photo. Those had the potentiality of a selfed seed at the base of every floret. Were there any of those? Floret seeds are frequently an important seed source for me, especially in the case of those blooms that consist entirely of modified florets.

"I pollinated maybe 26 stigmas and they all shriveled down nicely (indicating successful pollination) but of all those "successful" pollinations I only got maybe 4 filled seeds."

If the Powdery Mildew is the culprit, I would focus on that. You can afford to treat a unique specimen plant like this with a systemic fungicide, like BioAdvanced Disease Control for Roses, Flowers, and Shrubs. Just out of curiosity, what is the status of that plant today? Did you tear the bloom apart, looking for seeds? Or did you pluck it, petal by petal? If you still have the seedhead, or it is still attached to the plant, it may contain some viable floret seeds. If so, they are obviously selfed. Or the seedhead may still be developing or maturing. And hopefully the plant will put out additional blooms.

Incidentally, that bloom may be a cross between a pastel-colored zinnia and a white zinnia. I have discussed that no-white-pigment thing before.

ZM

Hello,

Yes, this plant produced loads of disc florets. Many of the other plants nearby had plenty of pollen in their disk florets, but this plant had anthers that (to appearances) were empty of pollen. The plant produced at least 4 blooms over the course of a couple months, and none of the blooms ever produced good pollen even though disc florets were present.

Yes, we have dealt with powdery mildew. I'm attributing it to the variable temps (cold/cool nights in the greenhouse). We've been able to keep it at bay with Physan 20, but we didn't totally eradicate it--especially on older plants. Personally, I don't believe the powdery mildew is the culprit. I've had other plants with plenty of mildew that produced good seed set.

The plant has declined and been disposed of, but I was able to collect perhaps 20 seeds from about 4 blooms before we disposed of it. So we still have the genetics.

This summer I hope to do more experiments to establish a base level success rate for pollinations. In your experience, is there normally a strong correlation between a withered stigma and successful embryo development? If you make 18 pollinations, and you see all 18 of the stigmas wither in the next day or two, would you expect to have 18 good embryos in a few weeks? Or would it be a lesser percentage?

Thank you so very much.

Have a blessed day,

Weston

Hello Weston,

Since this message thread has become so long, I will continue my response to your message over at a new part of this message thread. See you over at

https://www.houzz.com/discussions/6431599/it-can-be-fun-to-breed-your-own-zinnias-part-58#n=0

ZM

So another thought...

As the seeds were developing, I would occasionally pull back slightly on a petal to observe the developing achene and see if there were embryos forming. The motion was very gentle and it didn't dislodge the developing achene in any way. However, I wonder if this motion would have caused the developing embryo to abort. I should experiment more with this.