This summer I attempted an argyrosperma X pepo cross. I would like to combine the naked seed trait from the pepo, with the insect resistance (esp. to squash vine borers) of the argyrosperma. Each parent was genetically variable, which I hoped would help with getting at least a few good seeds. The argyrosperma was a F-1 plant of Tennessee Sweet Potato X Mexican Wild Green, a cross I did last year (2023). I have a naked seeded pepo population, which came from crosses done ~20 years ago between Lady Godiva, Styrian Hulless, Erken, and pepo ornamental gourds; that has almost all naked seeded plants now. I used flowers from two different plants of the naked seeded pepos to pollinate. By chance the the first flower on the argyrosperma was a female flower, there were no male argyrosperma flowers present. The hulless pepo were blooming vigorously with both male and female flowers. I did a first pollination early, a day before the argyrosperma flower would have opened, protected the flower from bees with Reemay, and then pollinated it again the following day, again protecting it. I left the Reemay on for a week to be sure no pollinators got in.
A fruit developed, which I hoped was not parthenocarpic. When I havested it, it was full of seeds, which all appeared to be good. But when I sliced one seed in half, it just had water inside. Disappointing, but I took out all the seeds, and let them dry. It turned out that of the hundreds of seeds, there were 6 that were filled, three about half filled and three plump and normal.
So my question is, when I plant those possible interspecific hybrid seeds, can I tell by the appearance of the seedlings that they are definitely interspecific? Do I need to grow them all the way to flowering to know for sure?
I have photos of the fruit that contained the crossed seeds, it's interior, the possible F1 seeds it contained, and the seed appearance of Mexican Wild Green, Tennessee Sweet Potato and 8 plants of my hulless pepos. The possible argyrosperma X pepo seeds look exactly like open pollinated seeds from other fruits of that (TN Swt Pot X Mex Wild Grn) plant. This is to be expected, as the seed appearance is determined by the female, right?
The leaves of argyrosperma and pepo look dramatically different. I expect an F1 hybrid between them to have a leaf shape that looks half-way between.
That's good. I will be starting pepo and argyrosperma as well, for backcrossing, so I could compare their leaves to the possible cross.
I had also tried crossing argyrosperma X moschata this past summer, and got one fruit. It wasn't planned, I just crossed what I had growing to see if it would work. The argyrosperma was a F-1 plant of Mexican Wild Green X Tennesse Sweet Potato, the moschata was either Burpee Butterbush or a F-1 plant of Burpee Butterbush X Ithanga. There were a lot of seeds in the one fruit, most half filled with endosperm or less. The seeds did look different from other open pollinated fruits on the MWG X TSP plant, as you can see on the photo below, which is a good sign for a species cross. Instead of waiting for next summer to know for sure, I decided to start a few seeds indoors (on 12-23-24, seeds soaked a few hours, then planted on heat mat), and see if I could confirm a species hybrid by the appearance of the seedlings. I planted one seed of the possible cross, and one seed each of it's parents. I didn't have enough of the argyrosperma X pepo seeds that I mentioned in the first post (just 6 seeds) to risk in this experiment, so that will have to wait until spring.
They've just germinated, and I noticed a difference in the hairiness of the stem below the cotyledons. The possible hybrid is intermediate in hairiness between the two species. It will be more definitive when the true leaves start developing. I didn't pay any attention to this detail of appearance when growing the various parents a few years ago. I will in the future!
The photo labelled Argyrosperma is a seed from a selfed fruit of the F-1 MWG X TSP I grew this last summer. The photo labelled Moschata is a seed from a selfed fruit of the F-1 BB X Ithanga I also grew last summer. Argyrosperma X Moschata is the possible species hybrid. The possible species hybrid plant appears to be hairier (maybe longer hairs) on the seedling stem than the argyrosperma plant.
I will keep growing them until true leaves develop, which should tell the tale. I also have a possible pepo X argyrosperma that I am watching, but it is developing slower and will take longer to evaluate.
Many of the possible pepo X argyrosperma seeds I have are underfilled and probably will be weak to germinate. Does anyone have experience with trying to start weak seeds on agar? Is this a good idea? Thanks!
Great observation!
I've noticed that Tetsukabuto F1 descendants can be weak seedlings. My thought on that observation was to give them plenty of space do they don't get overrun by more vigorous seedlings.
It is pretty easy to use a seed as an explant in plant tissue culture. So as long as you have the equipment and good sterile technique starting a seedling on agar media would be pretty straightforward. Seeds are easy to surface sterilize. You would want a large culture container for a big squash seedling. You might also have to tweak things to make sure you had enough nitrogen for a squash seedling. Transfer back out of culture must be done with care.
I used a small laminar flow hood and microwaveable food containers for many of my experiments trying to grow a lily in tissue culture about 15 years ago.
My advice would be to use some excess normal squash seeds to practice with first well before spring planting time to make sure that everything works as you hope before you try important seeds at an appropriate time. Even seeds from a grocery store squash would work for practicing with if you don't have an excess.
I got started with advice from:
https://kitchenculturekit.com/
I bought my flow hood from:
https://fungi.com/products/the-series-i-laminar-flow-hood?srsltid=AfmBOoqRCKNZmem6O--HX8GGa2E9fENMDropMGuEG7Wv8jTLmHpEI7AL
Would pay to shop around though this looks half the price:
https://www.midwestgrowkits.com/bonsai-99-99-hepa-horizontal-laminar-flow-hood-natural-clear-coat-finish.aspx?feed=Froogle&utm_source=google&utm_medium=paid&utm_campaign=21182868184&utm_content=&utm_term=&gadid=&gad_source=1&gclid=Cj0KCQiA4L67BhDUARIsADWrl7FJZhzhMSQGIVwPoGuZ_kI1ZSfmKGfeZVFun0VsSsJPXcRzVdcAsh8aAkImEALw_wcB
The plants from Test tubes book is a useful read.
https://www.amazon.com/Plants-Test-Tubes-Introduction-Micropropogation/dp/1604692065/ref=asc_df_1604692065?mcid=ad3e6ee6da8b3bdd8d2175db799c65e6&tag=hyprod-20&linkCode=df0&hvadid=693033695481&hvpos=&hvnetw=g&hvrand=7637217914482315647&hvpone=&hvptwo=&hvqmt=&hvdev=m&hvdvcmdl=&hvlocint=&hvlocphy=9222754&hvtargid=pla-522112325482&psc=1
For the germination of my F2 with tetsukabuto, i was sanded the seeds at sand paper.
Two problems with thoses seeds:
-The seed coat will sticked at the cotyledons.The molds will attacked the cotyledons if the seed coat stayed stiky too long time.
-the root can stopped his développement if the soil humidity is not optimal.
I have noted that the germination rate is more important when they are sowed deep (1,5-3cm) in a very draining soil.(I use Coco peat )
Thoses seedling also will less lenghtening that normals seedlings.
William,
Thanks for the comprehensive info. It sounds like completely sterile technique might be pricey for me, with the laminar flow hood. Sterilizing the seed surface would be valuable, though. The complication is that the crossed seeds are naked seeded pepo. There isn't the solid seed coat you would normally have. I assume bleach solution might be toxic? Or would hydrogen peroxide work? If I sterilized the seed surface, and sprouted them on paper towels with distilled water, then transferred them to a pot when a root showed, maybe that would work.
Adrian,
I know what you mean about the seed coat sticking, I've had that happen in the past. Sometimes the seed wasn't strong enough to break open the seed coat all the way, and I've had to try to cut it off with scissors. I can see that sanding it around the edges might help the seed absorb water, and also break out of the seed coat. Planting it deeper helps it break out of the seed coat if the seed is strong enough to get to the surface. I planted mine a bit too deep in the pot, I scraped the surface soil off to check if they were germinating, and when I saw they were I just put back a little soil. So that even though they were weak, they still made it to the surface.
I would try the various surface sterilants on some less special naked seeded pumpkin seeds first. I used to do something like a minute of 10% bleach with a drop of free and clear dish soap as a surfactant and then a minute of hydrogen peroxide. Then a one minute rinse. Stirring during the treatments. My understanding was that the bleach cleans and then the peroxide helps remove the bleach. It might be fine to do that even without a protective seed coat but testing on less important naked seed would tell you.
I will try that, and I do have other hulless pumpkin seeds to test it on.
That argyrosperma x moschata cross looks like a fun accidental side-project. I'll definitely be curious to follow that one, as well as your argy x pepo hybrids as well.
Here's an update. I've transplanted them to larger pots. One thing I noticed about the the argyrosperma, the cotlyedons took longer to uncurl and flatten out. They must be folded up more inside the seed. The veins on the cotyledons definately look different between the argyrosperma, the moschata, and the possible cross. The cross germinated first, that's why it is farther along in development than the others.
The pepos are all naked seeded, from crosses I did ~20 years ago between Lady Godiva, Erken (I think a Turkish bush zuchinni supposedly borer resistant, memory?), maybe other hulless varieties, and ornamental pepo gourds. I included seeds from two different plants as there is a fair amount of variation in my population, although they are all hulless and fruits mostly round green and orange camouflage pattern of different sizes. The short vine plant was one I noticed this year that had the leaves much closer together, so vines only got 5-6 feet long, and I selfed it. The large seed one had the biggest fruits and seeds, and vines 12-15 feet long, open pollinated.
The main reason I'm not sure if the PepoXArgyrosperma is a cross, is that I might have pollinated first with Arg. pollen, and the next day with Pepo pollen, with the thought that I would be able to tell the seeds apart, and the pepo pollen might help the fruit develop, and still carry some Arg. crossed seeds. As it was, all the seeds were hulless, although there were a lot of twisted and poorly developed ones. If it was picked too early, that could also cause poorly filled seeds. I didn't want to leave the fruit on too long, as sometimes the hulless seeds start sprouting in the fruit. So, too many variables! Even if this one seed is not a cross, there might be other seeds from the fruit that are, maybe especially the poorly developed ones.
I think it is too early to tell if the PepoXArgyrosperma is a cross. I need to see the true leaves. I don't want to judge by the different shaped cotlyedons, as it was a stunted poorly filled seed compared to the other two pepos.
Now that the true leaves have grown more, I'm pretty sure the argyrosperma X moschata plant is an actual interspecies hybrid. The biggest difference I notice between it and the argyrosperma, is the lack of toothiness of the outline of the true leaf. Another difference is in the moschata and the argXmos the silver flecking follows the main leaf veins, where in the argyrosperma the silver appears more in patches.
It's not looking good for the possible pepo X argyrosperma, so far the true leaves look just like the other two pepos. From what I have read, there is much less or no success doing pepo X argyrosperma, compared to argyrosperma X pepo.
I'm tempted to try to keep growing the argyrosperma X moschata indoors through the winter under plant lights, to try to get a fruit. If successful, it would save a year in the plant breeding process. If it matured by April or May I could plant seed from it outside in the summer. I would need to prune it a lot to keep it from getting too large inside. The parents grew 12 feet plus in the garden! I wonder if you can still get a fruit from a severely pruned vining squash? Does anyone have experience with this? My plant light could give strong light over a 3'X3' area. The key would be getting a female flower. I might grow the moschata as well, just to get male flowers for backcrossing. It probably wouldn't need as nice conditions, to get male flowers. Any resulting seeds would be 1/4 argyrosperma, 3/4 moschata.
Hi Mike Deyo,
I don't think that the most big problem will be the light in indoor but the fertilisation and watered for got a fruit.
In my experience a red light benefits at the fructification and a wight light spectrum benefits at the grow.
If yours plants are a nutrients defisciency the leafs should be becoming yellow and the grow can stopped.
You should fertilisated at least each the two weeks for squashs plants in planter for 15L of soil by plant.
I put chicken manure for the grow and beet vinasse at the flowered.
Hi Adrian,
The led light I have includes some red light, to help with flowering. I can also put it in a window where it would get some sun. I will use a large pot and fertilize when needed. What I don't know is if it will produce female flowers, on a plant that is much smaller than it would grow outside, with it's roots in the ground and free to spread. I guess I'll have to try and find out.
Update on the squash I started in December to try to see if I could tell if they were successful interspecific crosses. I ended up discarding the pepo X argyrosperma plant, as it exactly resembled the pepo plants. I will try more seeds from that cross this spring, just in case there are a few obvious hybrids. I kept the argyrosperma X moschata plant, and the moschata plant, transplanting them into larger pots under led plant lights indoors. My thought is I will try to backcross with pollen from the moschata plant. In an attempt to encourage earlier production of a female flower in the arg X mos plant, I pruned off any male flower buds, and most of the side shoots developing from leaf axils. I was pleased to see a female flower has developed! There are also male flower buds on the moschata plant. I will have to cross my fingers that the timing of blooming will work out to get a pollination.
In the first picture, the moschata plant is in foreground, and the arg X mos is in background. The latter is in a 18 inch pot. The second photo shows the female flower bud on the arg X mos plant.
This is all very experimental, I have no idea if I can mature a fruit in a 18 inch pot, when the parent plants had large vines when grown in garden.
I look forward to seeing what it ripens into. I'm always curious about potential leads that might improve my moschatas in the future.
I'm curious to see what it does too. Even if I don't succeed with a pollination growing under lights, I know I can try again growing outdoors this summer.
This present cross, I'm showing in the photos, is more about improving/changing argyrosperma, since argyrosperma is the female plant. On the moschata side of the cross, which is itself a cross: Burpee Butterbush X Ithanga, I will be planting ~20 or so F-2 seeds this spring, with the hope that I can pick out bush plants while they are seedlings. Then I will just grow out the bush plants, selfing them and hoping to get some of the fruit flesh quality of Ithanga in a bush moschata like Burpee Butterbush. I could use one of those bush plants as a male to back cross pollinate my interspecific cross (Tennesse Swt Pot X Mex Wild Green) X ( Burpee Butterbush X Ithana ). It would be neat if I could get the bush gene into the argyrosperma, as well as some fruit flesh quality from the moschatas.
Here in Ohio, argyrosperma is the most resistant to squash bugs. This past year they barely touched them. Moschatas can get a lot of squash bugs, but they don't seem to slow them down very much, especially if you lower the load by finding and crushing eggs. Pepos get a lot of squash bugs, and they can be weakened even by a small number of them. It's a race somethimes to get mature fruit. Even worse on the pepos are vine borers, which I haven't seen on moshatas or argyrosperma.
I do love those Ithanga you showed off, with those enormous sepals/calyxes(?) they had.
It looks like this female flower on the argyrosperma X moschata plant is about to bloom. Unfortunately, I don't have any male flowers ready to bloom. I included a photo of one of the male moschata flowers that is farthest along.
The female flower doesn't appear to have a butternut shape like the moschata pollen parent. I don't remember if the two argyro's that went into the cross had sepals like that, or whether that came from the Ithanga in the moschata half of the cross. You can see the big leafy sepals in the male moschata flower, although it's magnified by the camera a bit compared to the first photo.
I think this female flower developed quicker because it was close to and above a smaller plant light I am using for some dwarf tomato crosses below. The air is warmer there. Luckily there is another female flower on the ArgXMos that is in a cooler location and developing slower. Hopefully it will line up with some of the male moschata flowers so I can make a pollination.
The female flower opened on the possible argyrosperma X moschata cross. This would be a F-1 interspecific plant. Does anyone have experience with what the flowers would look like on a cross like this?
Traits on F1 plants tend to be mid-way between the phenotype of the parents. The previous photo looks like a hybrid to me.
If I notice that I'm getting a female flower near blooming without any male flowers, I'll wrap the female flower with something to cover it from the sun and pests, and it typically gets me an extra day, which is usually enough time to get a male flower that might not be open, but should have some pollen.
But yeah. Getting a fruiting flower with no pollen source is one of the more frustrating things to deal with in squash breeding like this. Forces some emergency decision-making.
Quote from: Joseph Lofthouse on 2025-02-04, 06:57:29 PMTraits on F1 plants tend to be mid-way between the phenotype of the parents. The previous photo looks like a hybrid to me.
Thanks, Joseph. That's good to hear. Even if I can't get a back cross done on this plant growing indoors, I know I can do it outside this summer. I will probably try both moschata and argyrosperma as male parents, since I don't know which might work best.
Quote from: Mica Winnower on 2025-02-05, 12:47:24 PMIf I notice that I'm getting a female flower near blooming without any male flowers, I'll wrap the female flower with something to cover it from the sun and pests, and it typically gets me an extra day, which is usually enough time to get a male flower that might not be open, but should have some pollen.
Mica, your suggestion gave me an idea to try. I have 4 male flower buds on the moschata plant that have just been sitting there, not progressing to blooming. I'm going to try to accelerate their development. I chose two, wrapped aluminum foil around the base of the flower to reflect more light on them, and covered the top with plastic wrap to enclose it and maybe have a warmer environment around the flower. I never thought my problem would be a lack of male flowers, but that is how it has turned out. Another thing I have read about, is cutting a male flower that is opening in the morning, and storing it in the refrigerator in a ziploc bag for a few days max, to pollinate a later developing female flower. I will try that with any male flowers that bloom if I don't have a female flower ready.
I finally got a male moschata flower to bloom, actually two this morning. I also had two female flowers on the argyrosperma X moschata plant that opened yesterday morning. I taped them shut yesterday, in the hope they would stay fresh enough to take pollen this morning, one day after anthesis. I could tell by the appearance of the two male moschata flowers that they would open today. So, fresh pollen on one day old female flowers. I pollinated both arg X mos flowers, I'll just keep one. I hope the fruit will mature and I will be curious if it shows more evidence of a species cross.
The male flowers on the moschata had been present for more than two weeks, but seemed to have stalled in development. They had developed early, and close to the base of the plant. I had 4 female flowers grow from tiny buds to blooming during that time, but with nothing to pollinate them with I picked them off. I tried putting a heat mat under the male flowers, but it didn't speed up development that much. What finally seemed to work was some radical pruning of the moschata plant. I cut off all vine tips, some old leaves, and all small female flower buds. The first two male flowers opened about three days later.
To review, I have two squash plants growing indoors under lights that I started in December. One plant, the female in today's cross, is itself a cross between an argyrosperma and a moschata I made this summer. The parentage is a bit complex, as the argyrosperma was an F-1 plant of Mexican Wild Green Cushaw X Tennessee Sweet Potato, and the moschata was either Burpee Butterbush, or a F-1 plant of Burpee Butterbush X Ithanga. So the female in today's cross is (MexWildGrn X TnSwtPot) X ( BBB or BBB X Ithanga). The male in today's cross is an F-2 plant of Burpee Butterbush X Ithanga. An interspecific cross argyrosperma X moschata, that today I back crossed to moschata.
I don't know if I will have space to fully investigate this cross, but it will be interesting to see if the bush growth habit and good fruit quality from the moschata parents can be introduced into a pest resistant argyrosperma background. The Mexican Wild Green Cushaw is not helpful in this goal, as it is grown for eating the seeds only, probably poor fruit quality.
The first photo is of the two male moschata flowers that opened today, and the other two are the agyro X mosch that opened yesterday, and were pollinated today.
Update on the fruit developing on my F-1 argXmos plant. The pollen came from a moschata plant. So it is a backcross. The pollination was done on Feb.15. I had pollinated two female flowers that day. I pruned off the one that was developing slower, after a week. The fruit that I saved is developing unevenly, one side not swelling out as much. I'm guessing there are no seeds on that side. I'm planning to wait to pick it til ~60 days after pollination, which would be April 15. As long as the plant lives til then. I am hoping for seeds inside, and it will be interesting to see what the flesh is like.
Of the parents, Tennessee Sweet Potato had a white skin with a slight greenish tone, shape sort of pear like. Mexican Wild Green Cushaw had a flattened globe shape with white skin and green stripes/flecking. Ithanga had immature fruits that were mottled dark green and light green, that ripened to tan, a short neck butternut shape. Burpee Butterbush is a typical butternut shape and color. This fruit appears to have the shape of Mexican Wild Green Cushaw, with the color of the butternuts, although the tan color seems a bit lighter.
About 10 days ago I decided to harvest the crossed fruit. The plant's leaves were yellowing, and then getting brown edges. Any ideas as to what that might be? The leaves were yellowing well before they got old. The youngest leaves were still green, and the plant was still growing and blooming. I figured it wasn't contributing much to the fruit. I stored the fruit in a warm room for 10 days where I was starting tomatoes and peppers (~80F). Hopefully to help the seeds mature. When I rapped it, the fruit felt hard as a rock. Photo is of fruit just before I opened it today. It was 58 days since pollination. I used a hacksaw to circle around the rind, which was ~1/8 inch thick. This was surprising since none of the parents have that thick a rind. The flesh was not bitter (tasting raw), and appeared to have a smooth non-grainy texture. Most of the seeds were completely undeveloped. Luckily, there are 10 seeds which appear to be good. I will know for sure once they dry. It looks like the seeds have an enlarged edge, similar to the Mexican Wild Green Cushaw, but not the corky surface. They are much larger than the seeds of either of the moschatas in the lineage.
To review the plant's history, grown this winter under lights, it's seed came from a fruit on a F-1 plant this past summer (Mexican Wild Green Cushaw x Tennessee Sweet Potato), that was pollinated by Burpee Butterbush this past summer (or possibly a F-1 plant of Burpee Butterbush x Ithanga). That's argyrosperma x moschata. The seeds on the plate were pollinated this winter by a single F-2 plant of Burpee Butterbush x Ithanga, so a backcrossing to moschata. The pollen parent was grown under lights as well, and once I saw the pollination was successful, I got rid of it as there wasn't room to grow it to maturity as well.
I think I will try to grow one of the seeds this summer, and see if I can successfully self it. There should be a lot of variety in the F-2. I don't know if I have enough garden space to pursue this cross fully, but I will be interested if any bush plants like Burpee Butterbush emerge, in a at least partial argyrosperma background.
I was not able to germinate any seeds from the crossed fruit I grew indoors. There were only two seeds that were filled. They were not fully filled. After a week of no sign of germination, I peeled the seed coat off. There was an embryo inside, that had absorbed moisture, but no root. I tried the embryo for another week in peat moss, and there was no germination, it eventually rotted. So either the seed had not developed enough, or the second crossing with moschata led to an embryo that would have needed embryo rescue. I have planted three seeds in the garden from the argyroXmoschata fruit of last summer, I will try pollinating it with pollen from an argyrosperma- Papalote Ranch, and also try selfing.
The main interspecific cross I was interested in last summer, was argyrosperma x pepo, where the argyrosperma was one of the silver seeded varieties (large seeds), and the pepo was hulless. I would like to get the hulless trait into argyrosperma, as it is much less bothered by squash pests than the pepo. The first photo is of the potential species cross. The second is of the argyrosperma female parent, and the third is of the pollen source, my hulless pepo.
I'm pretty convinced it's a successful species cross, as the leaf outline of the crossed plant looks more like the pepo pollen parent. I will try backcrossing to a silver seed argyro, as well as selfing it.
I planted two plants of the possible argyrosperma X pepo cross out into my garden on May 10. They are growing vigorously, and had a number of female flowers develop, and then after a week a few male flowers. Since both parents were genetically diverse (the argyrosperma was a cross between Tennessee Sweet Potato and Mexican Wild Green, and the pepo was from an open pollinated population from crosses I did ~20 years ago, with naked "hulless" seeds), it's not surprising the fruits of the two plants look different. It's interesting that both have an elongated shape, which none of the parents did. On the argyrosperma side, Mexican Wild Green was a flattened round shape and Tennessee Sweet Potato is pear shaped, has a short neck. On the pepo side they are pumpkin shaped, of varying sizes. The north plant fruit has the coloring of Tennessee Sweet Potato, while the south plant coloring looks more like my hulless pepos, and more like Mexican Wild Green. I'll put in photos of two hulless pepo fruits so you can see the variation and similarity.
The argyroXpepoNorth fruit came from the first flower to develop, and was pollinated with pepo pollen from 5 different plants. The south plant fruit came from a later flower, and there were male argryoXpepo flowers available. I tried something different for it's pollination. You know how there are three lobes of seeds in the mature squash fruit. There are three lobes on the stigma in the female squash flower. I put pollen from the north argyroXpepo on one lobe, from the south argyroXpepo (selfing) on the second lobe, and hulless pepo pollen on the third lobe. My thought is the diverse pollen might help ensure the fruit develops, but I might also be able to to tell which lobe is from which cross in the final fruit. I would expect the lobe with the hulless pepo pollen would be more likely to have some hulless seeds, or if vice versa the pepo pollen doesn't produce filled seeds there will be a lobe with no good seeds.
I'm waiting now for my straight argyrosperma plants to have male flowers so I could try backcrossing that way too.
An interesting idea, to pollinate the three lobes of the stigma with different pollen, I'll be interested to hear how that goes.
Tim DH