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

[Chris Morrison]

And this is how my 282 seeds are starting life, inside, in a conservatory, for now, first popped up today - see NZ thread.

[Mikkel ImGrimm]

This is my sweetpotato patch.  These are 2 year old seedlings from reed`s seeds.

all flowering plants from last year had no roots and no seeds in the end. I hope there will be flowers this year.

[reed]

Season here will be done pretty soon. I always look forward to that cause I get to find out what kind of roots the new plants have.

Seed production is a little disappointing this year in a way. I already probably have the most seeds ever and a lot more maturing now but the most ever is likely because I have way more plants than ever.  I think seeds per plant is less than I've seen before. I attribute that to neglect of watering during the terrible dry heat of June and July. Lots of days they were badly wilted by end of day. They are very tolerant of that though and I had lots of other stuff going on so I didn't worry over it.

They are also extremely crowded, I think maybe some less vigorous ones might have been even more stunted by competition. They each have their own pot but some could have been robbed of light because of the crowding.

The one I am considering kind of special because of it's extremely compact growth and extremely fat trunk is a little disappointing in that it has only made a few seeds. Those with fat trunks and bushy habit seem often to also have the clump root trait I like and I can tell from the base of this ones trunk that it's roots will be orange. I favor that for personal preferences. I'm learning to use the others colored ones in satisfying ways but traditionally sweet and orange is what I think of when I think of sweet potatoes. Even though it hasn't been a good seeder if it has nice roots I'll probably clone this one next year.

Someone gave me some this spring that were distributed at a food bank. Very spherical shaped, orange through and through and sweet. I had never seen any like them, only one sprouted slips and they have grown well but no flowers, o'well.

I have some this year with very, very, large vines. I don't especially like that and have half halfheartedly selected against it but these have bloomed a lot. I've been keeping their seeds separate from the overall mix but I'm sure that trait has been widely distributed in this years seed crop. 

I think if I ever really, really want to focus only on the specific traits that instead of starting new seeds each year I could just clone my favorites for a season or two and start again with mostly just those seeds. I have done that already to some degree but also always started new ones. Anyway now that giant vine pollen is everywhere. Then again it came pretty much from nowhere in the first place so maybe it doesn't really matter.

I'm not complaining because in truth it actually makes it more fun but as far as reliably predicting phenotype based on that of the mother isn't working out all all. It's clear that they just flat don't care what I think about it. Still I believe that repeatedly cloning particular ones to back cross the next year has to have some effect. Maybe it just takes a little longer, few more years maybe? decades??

Another interesting little thing is as I clean up other parts of the garden getting ready for winter I'm finding little sweet potato volunteers all over the place. Seeds can apparently lay dormant in the ground for years. 

Overall I think the project "turning sweet potatoes into a seed grown annual" is pretty much done. So now on to turning them into a seed grown annual with some degree of predictability of phenotype. I'd say at this point an accuracy in that predictability is maybe 25%, so I'll shoot on improving it to 50%

Still even though specific phenotype can't be predicted the project is somewhat complete in another way too. That being that if I plant say 100 seeds I can conservatively get 50 plants and even though I can't exactly quantify that right now some number of them will produce large storage roots that will keep without any special conditions all the way till the next harvest. And a stockpile of seeds will store and stay viable for many years, probably decades if frozen.


ImGrimmer, I'm sorry you didn't get any new seeds and sorry I didn't get any more sent off to you. Will see about remedying that before next season.

[Johann Kuntz]

Regarding the discussion mid-thread about crossing I. batatas with one of the two more cold hardy diploid species:

In theory, if one of these crosses were to be successful the result would likely be (possibly) fertile tetraploids which could be further crossed and selected amongst each other, but not back to either parent species as back crossing would theoretically result in primarily sterile triploid or pentaploid progeny depending which parent was used for the back cross. 

[reed]

Regarding the discussion mid-thread about crossing I. batatas with one of the two more cold hardy diploid species:

In theory, if one of these crosses were to be successful the result would likely be (possibly) fertile tetraploids which could be further crossed and selected amongst each other, but not back to either parent species as back crossing would theoretically result in primarily sterile triploid or pentaploid progeny depending which parent was used for the back cross.

Interesting, and I hope to find out. I now have 11 good looking seeds that (I hope) are crosses between batatas and pandurata. I say I hope because I can't tell by looking, they look just like regular batatas seeds. I was careful in doing the crossing, covering the crossed flower with tea bags and all but the bees are very active on sweet potato flowers. Also I'm sure the batatas plant that made most of them is self compatible. I know it is commonly thought batatas isn't self compatible but in my plants it often is. The first seeds I ever found were from a selfed plant.

In my research I found that pandurata also isn't supposed to be self compatible but most of my seeds are collected from a single isolated plant that I found along the road a few miles away. The near 100% of seed producing flowers can't be explained by pollination from another more distant plant and their flowers are very distinct. If there was another one anywhere nearby I think I would have found it. The pollen in my attempted cross came from that plant and it's offspring now growing by my mailbox.

Now if these seeds sprout and grow next year, and if they truly are crossed it should show up as phenotype differences.

[reed]

Spent the last couple of days cutting back the sweet potatoes so it's easier to find the seeds. I remove all the big leaves especially if they are a little yellowed and also cut off most al of the stems that don't have capsules developing. Always find lots of seeds when I do this and also it makes it so I can tell the plants apart.

Got a new Bushy Bloomer this year, actually three or four of them. The old original Bushy Bloomer didn't make a good storage roots nor did a lot of it's immediate descendants. I think based on the look of their primary trunk that these may be better in that department.

This year after trimming and identifying individual plants I tagged those that are good seeders, about 30 or so got tags. When I dump the pots the whole plant mostly stays intact so this year when I do that I can better match those with good roots to those that are good seeders. Assuming I have a good number of them, minimum of ten, I'm thinking that next year I will mostly just grow clones of them and archive most of my seeds.
I think if I get 10 and i think I will,  that meet the criteria of nice seeds and roots and grow say five clones each next year that should help "distill" those traits into a new more elite line of seeds. Also I can start trialing for other traits like flavor and texture.

I already know culinary traits also vary widely from delightful to awful. I probed around and found some small side roots and they range from a purple skinned, orange fleshed one that is yummy, yummy even without curing to an all white one that is like chewing on a rope. Also an all purple one that tastes like nothing at all. As a rule those with orange or yellow flesh meet my personal tastes best but the purple/white ones are growing on me as a replacement for Irish potatoes. Generally I think sweet potatoes are good no matter what, those that are really bad for one reason or another represent at most 10% of the total.

A couple of my favorite Bushy Bloomers have a lot of seed developing right now. They were a little late getting going good cause they were actually almost discarded early on just because I ran out of pots but they kept going and recovering repeatedly from rabbit attack so I finally found them some. If weather turns cold I'll just clip off the stems with developing seeds and bring them inside, I've done that before and it works pretty good. Most of those flowers in the last photo have been pollinated but do not have time to mature before frost. At this stage if I brought them in they would probably abort but if they have at least another week outside then most will finish up inside.

It didn't work out this year with the seed company on a partnership to market seeds but that is still on the table so if it works out I may send 1/2 or more of my seeds to them.

[reed]

It might not be to early to go ahead and start selecting for culinary quality in my sweet potatoes this year. Here are some small ones I pulled out from the edges of the pots, leaving the main plant and hopefully larger roots to finish making more seeds.

The white/purple one is very crunchy and not sweet, I think it would be good in beef stew or fried with onions or garlic. When it was first cut the white part was snowy white but by time I found the camera it had changed. Don't know how that would effect flavor, might if using it in a dish want to get it cooking immediately. I have lots that are good that way though so no need to worry over this one too much.

The orange one is Ok, probably would benefit from an actual curing period. Again noting of real note but it is a good seeder. Here is where I might start selecting. I expect that other good seeders will be at least as good for seeds but better for culinary, so this one might not make the cut.

The yellowish on on the right is yum, yum, yum even with out curing. It is only moderate for seeds, say in the neighborhood of 6 out of 10 but it is wonderful, hard to imagine I'll find one better  but can always hope. Of all those I've seen over the years if I was to select one to scale up and keep for clonal propagation this one might be it.

Wonderful, wonderful variety in sweet potatoes, that for sure!

[Richard Watson]

If the yellow is yum yum yum but only produces small amounts of seed, does that matter really, does it need to grow lots of seed? as long as you get enough for the following season and some stored as backup. Then maybe one year you might get one clone from this line that shows greater seed production.

[reed]

If the yellow is yum yum yum but only produces small amounts of seed, does that matter really, does it need to grow lots of seed? as long as you get enough for the following season and some stored as backup. Then maybe one year you might get one clone from this line that shows greater seed production.

All makes good sense, problem is I can't seem to make up my mind about it all. I was never even all that interested in Sweet Potatoes. Back when I first discovered a few seeds I offered to give them away on the HG forum but no takers. Now they largely dominate my gardening and there are tons of different experiments and selection paths I can think of. If I devoted my whole garden to them it wouldn't be enough. Once I got hooked the whole idea was just more seeds, I never really expected it to work.

I have decided for sure that I will start very few if any new seeds next year. Instead I'm going to clone some of the best from this year and let them cross with each other. I'm going to try to limit that to the ten best but there are lots of other things I haven't paid much attention too yet. Do they keep good all winter? Do they easily sprout slips the next spring? Not all do.  Do they get something called internal cork in storage? I don't know what internal cork is but it's something the professors at University of North Carolina screen for.

So looks like I have about 30 that meet the very seedy criteria and maybe 15 more that are moderately seedy. the rest make some seeds and a few have none.  When I harvest this years roots I hope to have at least 20 that also have nice sized roots. I'd kind of like to start with just the 10 best next year so I guess I'll tag and save them all and wait till spring to make the final selection after they have stored all winter. That yellow one for sure will be in the 10, unless it fails storage for some reason or I guess if I find better ones. It might also be one I clone lots of for food rather than experimentation. I also need to learn more and pay better attention to properly curing them cause I guess it effects storage.

There are still lots of seed maturing out there and weather is turning quite chilly. I reckon I'll soon be clipping stems to bring in to finish and go ahead and harvest the roots. 

[whwoz]

Wonderful, wonderful variety in sweet potatoes, that for sure!

Reed could the variety in sweet potato that you are finding be somewhat self-defeating in your aim to turn them into a seed grown annual?  Just musing here, but if you cannot limit the variation within a given batch of seed for a seed company to sell, how would you describe it?  Ok to say parent was light yellow with purple skin for example,  but what if the seeds give range to the sort of variety you show above?   Lots of people expect to get 10 identical plants out of 10 seeds.

On the other hand,  if you labelled as landrace rather than variety....

Love following your progress and hoping to start getting seed this year.

[Richard Watson]

Reed could the variety in sweet potato that you are finding be somewhat self-defeating in your aim to turn them into a seed grown annual?  Just musing here, but if you cannot limit the variation within a given batch of seed for a seed company to sell, how would you describe it?  Ok to say parent was light yellow with purple skin for example,  but what if the seeds give range to the sort of variety you show above?   Lots of people expect to get 10 identical plants out of 10 seeds.

On the other hand,  if you labelled as landrace rather than variety....

Love following your progress and hoping to start getting seed this year.

It seems that many gardeners are not always into identical plants when buying seed. On our Sentinels website the #1 best seller for two of our growers is TPS, when it was first put up we never thought we would sell much at all and yet here we are selling more of that than say carrots, parsnips etc etc, variation in type sells well, I'm even been selling a first year grex beetroot cross, even that is a good seller.

[Chris Morrison]

Camote seed sprouting hack?. I was sick of waiting, so bunged a few in the hot water cupboard. Bingo, up they come. They appear not to enjoy diurnal temp fluctuations , must water each day but.Comments?

[Mikkel ImGrimm]

@reed this is the 2nd year for the seedlings I got from you. It seems there will be no flowers again.
Last year half of the seedlings flowered very late without setting seeds but made no tubers at all. So I lost them.
All non flowering plants made tubers. These ones I still have.

[reed]

Whwoz, I don't know what to expect as far as how people might receive them but for me I'm happy with the variety. My thoughts is it's a positive but I know a lot of people do want uniformity. It's an issue with my talks with the seed company too. Not that we are arguing about it they just don't understand that they are not just another "heirloom" tomato, there isn't a romantic story of how aunt Poly smuggled them out of Poland in her petticoat.

My sales pitch might be if you buy these seeds... I recommend you use conscientious germination techniques to insure high germination, unlike the willy nilly way I do it. If (no guarantees) you are successful you should get some percent of plants (as yet unknown) producing nice sized roots in 100 days or less from germination even in areas less than perfect for sweet potatoes.  If you are successful (no guarantees) you will have options:
1 - just save any you really like as clones and make slips of you own brand new kind each year and keep your seeds (they store for 20 years or more, I'm told) to start over if you ever lose or eat all your stored roots
2 - use your seeds to continue breeding and selecting for a variety that even more meets your personal idea of a perfect variety.

So my job now is to continue breeding and selecting with the goal of increasing the chances that say, out of any 25 seeds those options would indeed come available.  And there in lies my problem. I need to know specifically what percent of  seeds will sprout, out of those, what percent will produce good roots and seeds.

I can't do that all by my self, I need a partner who can scale it up, grow hundreds instead of dozens of plants in more controlled conditions and who has the infrastructure to market the results. And who understands their investment is not greater than mine and nor should be their return. I may have found that partner but COVID nearly shut down their operations this spring and it slowed mine too. The owner also isn't much on electronic communication so except for one phone call with him my contact has been with staff and I don't want to deal with staff cause they can't make real decisions and agreements.

Chris, I'd say if you find something that works go for it. I lucked into enough seeds to afford to be sloppy and since I'm all about easy I have mostly taken that route and just accepted the high failure rate. It seems to be working though, this year I got a nice germ rate sowing directly in the ground.

ImGrimmer, too late now I reckon but you can keep those that don't make storage roots alive as houseplants but I'll be sending you some more seeds to get you back on track.

[Mikkel ImGrimm]

Thanks @reed ! What I wanted to say but forgot to was that maybe climate is playing a role in Ipomoea batatas flowering. If your improved flowering plants refuse to flower here. there must be other factors e.g. the climate.