Breeding Sweet Potatoes (turning them into a seed grown annual)

[whwoz]

Nice video Reed.  I find it useful to help sorting out ideas to write them down while thinking about them, even if I then don't go back to those notes

[reed]

Still assessing it all in effort to make a plan for next year but here are a couple more little videos about this year's harvest.

[Kadence Luneman]

Watched your videos earlier. My mind has been turning over the bit about (from memory) your experience has been that if you grow a sweet potato plant from seed it's likely to produce some amount of seed. If you keep a sweet potato of the plant to grow clones next year, the clones are less likely to produce seed, and maybe even to flower. If you save a clone of that plant to grow out the following year, etc into future years, then the ability for it to produce seed, or even be able to make flowers gets much less likely each time.

That is quite interesting! Is it possible that the sweet potato clones are losing the ability because those genes are inserted a different way in the tuber/root than into the seed? Or could it be like a "use it or lose it" trait, where the moment it doesn't get used the genes go dormant...? Very curious!

[reed]

Watched your videos earlier. My mind has been turning over the bit about (from memory) your experience has been that if you grow a sweet potato plant from seed it's likely to produce some amount of seed. If you keep a sweet potato of the plant to grow clones next year, the clones are less likely to produce seed, and maybe even to flower. If you save a clone of that plant to grow out the following year, etc into future years, then the ability for it to produce seed, or even be able to make flowers gets much less likely each time.

I can't say that for sure but there does seem to be a hint of something like that going on. A lot more time and experiments would been needed to see if it is really so, or not. It does appear that in general, first year seedlings and clones for the first two or three years make the most seeds but the older generations don't completely stop. Exceptions like the number seven plant contradict that though.

There is also the compatible issue, maybe a very seedy plant, one year is because it was a close neighbor of a highly compatible partner but another year the same clone by chance is only close to less a less compatible one. Just too many variables to identify to make any statement for sure. 

[UnicornEmily]

I think I've read somewhere (Cultivariable?) that potatoes tend to gradually accumulate viruses throughout their lifetimes, and the longer they live (in other words, the more years they are cloned), the more their productivity and fertility tend to decrease.

Maybe a lot of root crops might be the same way?  Like sweet potatoes?  The hypothesis could be tested by taking some sweet potatoes that used to be able to make seeds and stopped being able to, and tissue culturing them to remove any viruses, and seeing what the resulting clones do.  My suspicion is that, because that works for potatoes, it may work for other root crops, too.

[reed]

I certainly don't really know but I don't think it is really the same. Potatoes and sweet potatoes are commonly associated but they are very different things. The word potato is in their name and the part generally eaten grows in the ground but that's about the limit of the similarity. It's a little like saying that what applies to peaches applies to cucumbers because they are both juicy inside.

[Paul Anguiano]

In garlic, there seems to be some epigenetics involved in diminished seed set, with fertility rapidly recovered to some extent in few generations.  Most garlic lines just hadn't been reproduced by seed until very recently.

Potatoes definitely acquire viruses over time, but they also suffer from being grown outside of their original short-day and restricted temperature conditions, which means reproduction in our gardens has to be bred into them (and largely has, though large operations are busy inserting male sterility into everything to ease their cross-breeding).  But given their strong day-length sensitivity, there's no reason to expect potatoes to be equally fertile at all latitudes. And that's before we mix in all of the various species that have been bred into modern potatoes, and varying levels of ploidy, allele, and cytoplasmic compatibility.  I suspect that some species and landraces (like Ozette) have similar issues as garlic, though.

I've also heard the same claim made for potatoes (without much data) that I've heard for sweet potatoes, that first year seedlings produce seed differently than overwintered tubers.  There is certainly precedence in many other plants for diminished fruit production with age.

I don't see a lot of concern about virus accumulation in ipomoea in the scientific literature, but they also don't view fertility as a problem.  Most sweet potato lines are easily induced to produce seed under controlled conditions, so I think the problem we have with reproducing them is that the conditions are not the same as those in our gardens (though the above problems might apply more with older heirloom varieties).  I've spoken with some southern growers who claim that most of their varieties of sweet potato go to seed every year.  Some of them view this as a negative, believing (without providing data that I've seen) that this diminishes tuber production.  I suspect there is at least some selection bias going on among farmers to grow varieties that don't flower in production, and to save tubers which haven't flowered.  Seed production in their fields could be a real quality control problem if they come up with subsequent plantings, so I suspect it is a highly undesirable trait, selected against in breeding programs, much like the biennial seed production we've induced in so many other crops.

All of which is to say that I suspect Mark's program is exactly right, selecting for varieties that are prolific in tuber production while still being fecund in his growing conditions.  This will line up all of the variables in his favor, genetically and epigenetically, and either leave behind viruses that inhibit this, or breed fertile tolerance to endemic diseases in his soil and companion plants.  Honestly, I don't think there's any way around this--if you want to make a particular line of sweet potatoes more likely to produce seed, you're going to have to find a way to get seeds from it and start a selection program (even if it's just a survivability/fecundity screen).

[reed]

Day length sensitivity comes up in discussion of sweet potatoes sometimes. I was convinced that they are not day length sensitive, and I know for sure that mine are not because I've had them bloom after the first set of true leaves. I've also seen some examples, including in videos of them blooming and even volunteers sprouting down south.

A friend in South Carolina grows one released by a university in Louisiana and it blooms for him a lot, but not until late in the season, but does not make seeds, I don't remember its name right off. He sent me some roots, and the clones indeed bloomed but just a very few and very late. There was no time for seeds with its genetics, even if it happened to pollinate mine to mature. I wanted it to cross with mine because it had the nice clump root trait that I like, and I figured it might have other genetics that a university can test for, but I can't, so I tried again with some purchased slips. Same thing happened.

I saw a video from a woman, I think she was in Tennessee and she was showing how she hoes and hills her corn. In the process she was chopping out lots of sweet potato seedlings. She didn't mention the seedlings, I don't think she knew what they were or didn't care. Maybe she thought they were some other Ipomoea like bindweed or morning glories, but they most certainly were sweet potatoes. By the size of the corn, the seedlings had sprouted pretty late but apparently a lot of seeds had been lost on the ground the year before. The plants they came had to have been either self-compatible or she had more than one variety growing together and both had to have bloomed early enough for the seeds to mature, and they had to have been cross-compatible.  I know for sure that not all plants capable of producing seed are compatible with all others that are.  Identifying which particular one(s) is/are compatible with which other(s) is way beyond my ability. I have to be careful not to get too carried away with culling so as not to lose that apparent balance in mine.  Anyway, I tried twice to contact that woman to find out what varieties she grew but she never responded.

I imagine that if those varieties have genetics applicable to my project, I already have them anyway because I've grown pretty much all of the varieties common down south except for Georgia Jet because it came up in my research as having several traits that I don't want in mine. I don't know if it is self-compatible, but Georgia Jet does make seeds because the folks in Canada who worked on breeding sweet potatoes, even before I did, mentioned using it. I don't know what happened to that project, but I think, similarly to the universities, they were just looking for another new clone. If they were looking for a line nicely adapted to Canada, I think they gave up too soon. I don't think anything but continued selection through sexual reproduction could do that, and it might take decades.

I eat the last of or outright discard good new clones all the time. For my goal they have to make nice roots and seeds, and they have to do it fast. I have a half a dozen or so other traits I consider important, if not critical. Almost all of my more recent generation seed will yield some of those traits and I'm not so picky that one has to have all of them but just two or three isn't enough to warrant cloning.  I can't yet afford to discard outright any that don't have the whole collection. I can't guess how much longer that will take.

Finding all of the traits in the same plant is still pretty rare but percentages are improving. Those are the ones that I clone for crossing with each other and with new seedlings in separate semi-isolated plots. All traits seem to be quantitative, controlled by a group of genes, Mendel's pea experiments just don't apply. If I say a plant has green leaves, it's because I don't know how to describe dozens of different shades of green. The only things that seem to have just a little bit of variation is the color and size of the flowers. 

My rambling about other stuff aside, my previous belief that sweet potatoes are not day-length sensitive may be wrong. Most of what I've seen from down south, even when I've sent my seeds and clones to people there, looks like they are day-length sensitive, when I know, or though I knew that they are not. I think I figured that something like day-length sensitivity was such a fundamental thing to a species that it wasn't variable but maybe not. I'm thinking now that it is. 

Or maybe there is some other environmental issue between here and there that I haven't identified.  One time I sent slips to a friend in Texas and they didn't bloom until October when I was collecting seeds from the same clones in July. Does anyone have a guess about why that could happen? 

[reed]

Sweet potato season will be starting soon. I've been thinking about making a video about it and I will I guess pretty soon but I have been a bit lazy about it so for now just a written update.

My two favorite ornamental plants that I have referred to as Miss Bloom and Likes to Climb have done very well over winter. Always before I kept them as potted plants in the unheated room upstairs where they lived but just barely. This winter I just kept them as cuttings in pint jars of water in the south facing windows downstairs and they have done really well. Not nearly as much issue with spider mites overall and the lady bugs helped out with that too.

All through my work, along with selecting for sexual reproduction of superior lines, I've also worked to see just what a plant really needs to live and produce. For over winter storage, all a sweet potato needs at the beginning of the growing season is to not be dead. It doesn't matter how bad it looks when the longer days and warmer temps arrive, if the plant has life, it will soon be growing again. Doesn't matter at all to me what the "best" way to do it might be. I don't know how many plants I have, some died early on because the stems were not long enough and they didn't make it down to the water. I'm guessing I have about ten nice plants each of the two ornamentals and they have started growing nicely so each can easily make three or four new cuttings. Lots more than that actually if I keep letting them regrow after trimming and there is lots of time before they need to go out. They were just in the jars of water and fed once in a while with the stuff I squeeze out of my aquarium filter. This method was lots easier and more productive than keeping them as potted plants.

On the culinary side I'd have to go look to see how many I have, but again I'm getting pretty lazy. I remember I have plants #s 10 and 11. They are both very nice bushy, seedy plants with orange/orange nicely sweet roots that grow in the clump habit that I like. I also have plant # 7 which is similar except it has white/orange roots and is very, very seedy. All together I guess I have eight to ten culinary roots saved to grow this year. One is a 2025 volunteer with white/yellowish roots that I think I might like but need to grow more of it to see for sure. It's roots boarder on what I call clunkers, meaning they get bigger than I like. I prefer clusters of roots around six to eight ounces over a few much larger ones. I grow most of mine in pots, so it isn't an issue to just dump them out but if the really big ones were grown in the ground, it would be hard to harvest without damaging them. Also, if you have a three-pound sweet potato you can cut off a piece to eat and the rest will still keep for later, I would just rather have six 1/2-pound sweet potatoes. 

I had mentioned in one of my videos that selecting for the traits I like I might also be selecting for the same boring heart shaped leaf. There is nothing wrong with that, I reckon, I just like a little more variety and the 2025 volunteer I mentioned has a thin finger shaped leaf so I'm going to turn it loose in the culinary patch.

I only have the two ornamentals but last year three or four great ornamentals volunteered but I did not keep them. Now that I know how easy it can really be to keep them, I'm going to save more of them from now on.

I've said before that I might not start any new seeds, but I always do, plus I always find volunteers. Volunteers are decreasing a little though because I'm keeping the garden more heavily mulched most of the time and that seem to prevent them from having a chance. I have the same issue with my marigolds, dill, radishes, mustard and so on but that's a different problem that needs addressed overall.

So, I probably will start some new seeds, but I think I'll open the vault, put in most of the newer seeds and get out some of the much older ones. They have lower probability of having all the preferred traits of course, but they also have a bit more diversity of phenotype and I think it might be fun to explore that more, now that I have little better handle on what I'm doing. Even back in the beginning, more than ten years ago some really nice ones showed up but I didn't keep them more than a year or two for backcrossing. To prevent contaminating the current project I'll keep sprouted from old seeds isolated from the rest. I did keep a small area around last year's patch mostly mulch free so should also have some volunteers.

[Tim DH]

Hi Reed,
   Forgive me, but I'm a little confused. ...
   The title of this thread mentions 'turning them into a seed grown annual', but you don't appear to be planning any ''seed to harvest'' this year?
   Have the goal posts moved since you first embarked on your project?

Tim DH

[reed]

O' no, the ultimate goal of seed to harvest and more seed in 100 days or less is already accomplished. They really are already a seed grown annual. It's just that there are still lots of unanswered answered questions and lots of different side avenues that might be explored.

I want to get to where I feel comfortable releasing them too, for money. I'm thinking now the best way to do that might be by clones that I know have all the desired traits instead of seeds that only might have them. That way I can be sure the buyer gets a plant that will make nice roots and seeds. Even that though has a problem because I grow in polyculture and still in most cases I don't know for sure which plants are self-compatible and which are not, nor which particular plant is compatible with which other particular plant(s). I need to know those things so that so a person could buy either a known self-compatible plant or a collection of two or more cross-compatible plants. Because collecting sweet potato seeds in quantity is such a pain in the rear, I'm not sure selling seeds is worth the effort from a financial standpoint and selling plants has regulatory issues that I'm not sure I can afford to navigate.

What I would really like is to pass a few thousand seeds and clones of the best plants to someone who can scale this project up and market it widely. That way people who were interested in a little food security could just grow clones like normally done and at the same time squirrel away the seeds. That way a total crop failure in one year isn't the end of the world, just get out your seeds and start over. Or if they wanted to keep breeding new ones. Maybe someday 100% of new plants would have all of the desired traits instead of just 25% or so.

Somebody needs to grow, track and document hundreds of plants and I just can't do that. I want to just keep a few for myself and ride off into the sunset.

[Cathy A]

...your experience has been that if you grow a sweet potato plant from seed it's likely to produce some amount of seed. If you keep a sweet potato of the plant to grow clones next year, the clones are less likely to produce seed, and maybe even to flower. If you save a clone of that plant to grow out the following year, etc into future years, then the ability for it to produce seed, or even be able to make flowers gets much less likely each time.

Kelly Winterton observed this exact behavior when breeding potato onions. He eventually concluded that it was important to grow a certain amount from seed each year in order to preserve the seed-producing trait. Unfortunately that means it's difficult to preserve a particular strain of potato onion, which is generally done by cloning.

It's interesting to see the same behavior reported for sweet potatoes.

[reed]

I put my sweet potatoes in for clones today. I have nine plants in the culinary line and two ornamentals. The culinary are a mix of mostly planted on purpose and volunteers. Three of them #s 7, 10 and 11 are three or more years old, some are just newly sprouted last year. I've changed up how I'm starting them this year with each in its individual pot, so they don't get so tangled together.

The ornamentals, Miss Bloom and Likes to Climb are started from clippings kept in the window over winter. They look kind of rough but will perk up soon.



I've been wanting to sell some of my sweet potatoes for a long time and I'm thinking I may offer some on eBay or maybe Permies but I don't think I'll offer seeds, rather clones. I've done a lot with them, but they are still pretty screwy, and I think a buyer might get a better deal with clones of proven seed producing plants than with seeds. Uless someone bought a lot of seeds the chances of failing in the first year are too high for my comfort level, considering how much I will likely ask for them. All nine of the roots I'm cloning make seeds, nice roots and have all or most of my other preferred traits like clump root, bushy habit and so on. I of course still cannot guarantee success but if a person buys a collection of say five or more clones (from different roots) the chances of getting more seeds and roots to eat, on 100 days or less are very high.

I have all the sweet potatoes and sweet potato seeds I will ever need and will keep playing with them myself for the most part I'm considering the culinary side of this project near completion. The culinary line is what I'm considering selling perhaps under OSSI, perhaps not. I need to get in contact with my advisor with OSSI and get their input first.

While I won't stop working with the culinary, maybe introducing a new one now and then, I'm turning my attention to the ornamental line. Lots of ornamental sweet potatoes are already on the market but mine, I believe are superior for a number of reasons, one being they bloom, a lot. Miss Bloom for example is quite unique in that the abundant flowers are held above the foliage rather than buried in it like most strong blooming plants.

My abuse of the ornamental plants, keeping them in water on a cold windowsill, allowing the spider mites to chew on them and they still survive shows that they, with just a bit of attention could be fantastic and edible house plants. Pretty plant, pretty flowers and greens, year-round anywhere with a sunny warm window. So many great ones show up and I just discard them. I think it would be more fun to turn most of my breeding attention to them. I've observed often times that people will often pay more for flowers than food, so perhaps considerably more profitable and less restricted too. If I'm able to get through the OSSI pledge process it will just be for the culinary.

[Kadence Luneman]

Very exciting!

[Wyatt]

Selling through eBay, Permies, or elsewhere, would be grand. You will have a buyer with me at least, for both clones and seeds. A mix of clones for "guaranteed" success and a bunch of seeds to see what takes or not would be interesting. Sweet potato has a special place in my heart, just hard to grow as far north as I am! Having them as an annual would be a big win in my book and something to share with those around me. Thank you for all your hard work, please keep us updated with your plans!