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

[reed]

Many people familiar with the HG forum are already familiar with this project so rather than start all over I thought I would just give a run down of how it stands now. My eventual goal is to release and sell true seed producing sweet potatoes as breeding material under the OSSI pledge. I just need to produce sufficient quantities, develop a good naming convention for the different lines and find out, in the event I want to release some as clones, what legal hoops I'll need to jump through to send them through the mail.

Anyway, five years after discovering my first true sweet potato seed  I have a total of 8 of my own seed grown clones that meet my criteria of short season production (100 days or less) of both food quality roots and seeds. I recently became aware that there is also more interest in lines developed more for greens over roots than I realized. That might greatly increase those I keep as clones. Up till now I have been mostly discarding those that only produce foliage, even if they did make seeds.

As it stands now along with those 8 seedy clones and a few other, non-rooting ones and after finding a pack I had forgotten about I have approximately 2500 seeds. Half or more of those are buried deep in the ground in well sealed stainless steel canisters.

I'm interested also in developing lines that are easy to grow and tolerant of poor conditions or neglect so I take no special actions to insure germination. I start them in cool conditions on a drafty window sill on a cheap heat and without any artificial lighting. Germination in successive generations under these conditions has increased from about 5% within a week to about 20%. Germination in an outside cold frame of just a few seeds in that time was 2%. Germination by folks I'v shared seeds with using much more controlled conditions was reported much higher, in the neighborhood of 90%.

My friend Richard in New Zealand had germination of 20% or higher, I think using a technique similar to mine and some of his plants are currently blooming. The climate there is not especially friendly to sweet potatoes so I'm watching his reports closely and keeping fingers crossed he gets good roots and seeds.

I hope in 2019 to get reports from New York and Germany. Other locations where they have been trialed include;

Sweden - no real report on germination or success
 
North Carolina - poor germination using techniques similar to mine, good root production on those that did grow, no seeds. No seeds was due to poor observation and repeated destruction of the vines by rabbits and deer. (*interesting, you can still get a harvest even if vines are seriously damaged)

Minnesota - no report, I think he may not have planted them yet.

Texas - excellent germination direct seeding in mid May, excellent root production, few seeds. I don't know a reason for the poor seed production there.

California - excellent germination, excellent seed production but most with poor stringy roots. I imagine by selection, crossing to new varieties and mutation the stringy root problem can soon be solved. 

Utah, Ah, Ha, this is the most exciting. This farmer and you know who you are Joseph Lofthouse did cheat some by tightly controlling germination conditions and got very good results. Still in a high desert with cold nights and a frost free season of less than 100 days managing to harvest food sized roots AND seeds FROM seed is pretty exciting.

I'm thinking for this year I will focus on continuing to push the extreme of germination under poor conditions (for sweet potatoes) even farther and plant about 500 seeds in the unheated cold frame. Select from them the first 20 or so that sprout and discard the rest. I'll also maybe keep some of the later sprouting volunteers which I expect because of my poor seed collection practice last year. I may not start any inside this year.

I'm also going to grow more individual plants of my saved clones instead of just one or two to increase the number of harvested roots from them. Those 8 all make good roots and seeds so I hope to cross them with several new commercial clones I'll get from Sandhill Preservation and elsewhere.

I want to up my seed production to 5000 this year. It's an ambitious goal not because it will be that hard to get the plants to do it, just have to have enough of them. It's ambitious because they are not exactly what you could call determinate. They just keep making seeds, you can't just harvest them all at once like you might with dry beans, there are only at most 4 in each capsule instead of hundreds like in a tomato. You have to spend an hour or more every single day looking for and collecting the seeds and there is a narrow window before they shatter. O'well, somebody's gotta do it I reckon.

[nathanp]

How many seedlings do you figure it took growing out to get to the 8 clones you have that produce well for you?  I'm curious about percentages of seedlings that germinated.

[reed]

How many seedlings do you figure it took growing out to get to the 8 clones you have that produce well for you?  I'm curious about percentages of seedlings that germinated.

My poor record keeping is biting me in the rear again but I'd guess very roughly, it took 150 germinated seeds to find the eight clones I'm keeping. That's over the life of the project but the % of good ones is increasing. I think I had just one of my own seed grown clones in 2016, two in 2017 and then it jumped to eight this past year. The first one has been dropped because the next two were both better. I still have those two and six new ones from 2018.

The six from 2018 came from about 40 germinated seeds. So I guess about 15%, that's way up from prior years.

To release seeds for sale and or pledge I want to be confident that a minimum of 10% of seeds will produce a good plant, I think I'm already there but I need to be able to document and describe them more accurately, so better record keeping from now on, is definitely called for.

[reed]

Past seasons I'v grown my sweet potatoes in a combination of large tubs, smaller pots, and in the ground. This year I am transitioning  to growing exclusively in small 3 - 5 gallon pots. This will keep initial growth high enough off the ground to be safe from the rabbits that always seem to break into the garden at lest once in awhile. Growing in the small pots allows me to easily harvest just by dumping them out and also very importantly to easily select for the "clump root" trait that I like. Clump Root varieties make all their big storage roots in a nice clump directly under the main plant stem which again makes harvest much easier even if grown directly in the ground.

I'v found that they grow and produce very well in pots much smaller than I used think they would as long as all the drain holes of the pot are buried in the ground to prevent drying out from the bottom. It's important not to disturb the pots once planted so the long feeder  roots can exit the holes and travel as they will in the ground beneath. Some plants I'v seen will develop storage roots off of those feeder roots in the ground.  Plants that do that as well as plants that don't make storage roots at all will be easily identified and eliminated as clones.

I can also identify root size and shape properties this way. Shorter, fatter storage roots form perfectly in the pots where as long thinner ones hit the bottom of the pot and end up crooked. Giant "clunker" roots can push themselves up out of the pot.  I'm looking for plants that make a nice clump of roots the size of large baking potatoes and since I already have some that meet that description I think by saving only them as clones and recrossing them for seed each season I can increase that trait. 

I don't want at his point to discard very much genetic diversity so I'll still keep seeds from any plant that produces them well. As far as diversity goes however I think it might take a long time to actually genetically depress a variety, they are just too diverse to start with with many phenyotypes that don't resemble any of the original parents showing up in successive generations and in all sorts of combinations.

I'm also going to trellis the vines this year and even trim bushy plants to just a few stems. This will help in three ways I think. One to add still more protection from rabbits, two, to prevent vines from flopping on and rooting to the ground, which I think can cause small storage roots to form, taking away form the main ones under the main stem. Last and most important to make it easier for me to do my seed inspections. if I don't have to stoop over so much or dig around in thick bushy foliage it will help a lot to prevent losing seeds to shattering because I didn't find them in time.

[Richard Watson]

Growing in pots would mean warmer soil = better growth, only that the need to stop them from drying out. This maybe a good way for me to grow in my changeable climate (62F today, near 100F next week), so wouls i be right in that the bottom of the pot needs to be just below ground? would have to go too deep.

[reed]

I don't think the pots have be buried very deep, just as long as the side drain holes are covered good. I have some pots that only have bottom drain, I like them better.

[Richard Watson]

That's all ive got in the large pots are bottom draining, I'll play around next summer with them

[reed]

I don't think the pots have to be very large. I just use ones I collect up from the curb where people set them out for garbage. like I said, 3 to 5 gallon range. I'm not going to use my big cattle feed or half barrel tubs this year. There is no need to give the plant what it needs nutrient or water wise inside the pot, they get that from the feeder roots in the ground.

This year I'm gonna make mounds about 12 meters long, similar to If I was gonna plant in the ground but instead I'll set the in the pots making sure the drains are well buried and heavily mulch around and between. Then a trellis of fence wire across the top. They don't really climb like a bean but it is easy to stick the vines through and then back through the other side as the grow. Seed collection should be much easier than how I'v done it in the past.

[Richard Watson]

The pots that I have are about that size.

[reed]

Was just short of 70 F here yesterday after a few days with lows below 0 F. Houseplant sweet potatoes got to spend the afternoon outside in the full sun. Gave them a nice drink of pond water with a little bird poo from under the feeder and washed the indoor dust off their leaves with a spray bottle. They were looking a little poorly from the cold windowsill and lack of light but starting to get new shoots now that days are getting longer so I clipped off a lot of old leaves. They seemed to enjoy their outing and spa treatment and looked very happy this morning. I'm in hopes the rough conditions on the window sill, going back and forth from the heat of afternoon sun + nearby wood stove to cold drafts at night might spark some mutation.

Also took a peek at the roots being saved for slips, all look great save one that is pretty badly withered up. So bad at one end I couldn't read what I had written on it. First though to go ahead and try to sprout it but decided if it has tendency for spoiling before spring I don't want it anyway so I pitched it in the compost. 

[Richard Watson]

A question, I'm sure I understand this right but if a flower has failed to be pollinated the flower and base drops off straight away? most of mine are still on a week later is a good sigh??

[reed]

A question, I'm sure I understand this right but if a flower has failed to be pollinated the flower and base drops off straight away? most of mine are still on a week later is a good sigh??

Yep, that's about right, they drop off pretty much immediately if not pollinated. Sometimes the individual stem is still there, sometimes it drops off too. But if the base of the flower is still there then a seed capsule is developing. I never tracked it for sure but seems like it takes em a good bit to mature, a couple weeks or more.

I'm undecided on how to go on with mine. I want to trial a lot of seed in the cold frame outside to select for those that easily sprout like that but I also want to get some new commercial clones and try to up the genetic diversity. I can make more than enough to plant a large patch from my saved roots and clones and most all of them are good seeders so I'm thinking now I might just use them with some new purchased ones for the new diversity and save the cold frame trials for the next year. 

[Richard Watson]

That's great, that means ive got seed developing on two plants.

[reed]

I think I'v decided on my sweet potato plans for this year. I'm seeing lots of new kinds coming from apparent genetic segregation and even some mutation but still all of mine are descended from those same original parents and I already have a good backup supply of those genes in my stored seeds.  I also have my saved roots and clones that grew from them in the last couple seasons. I kind of hate the idea of not starting any from seed this year but I don't think I will, or at least not many if I do.

Instead I'm gonna get as many new kinds as I can and grow them together with my cloned seedy varieties and see if I can get new genes into my mix. I'll grow several each of my own, especially my favorite seedy, clump root types and at the same time maybe produce enough of their roots to possibly share some as OSSI clones. That however is an issue I'll have to look into as I don't even know what is needed or how much it would cost to legally be able to ship sweet potatoes or slips, one of those bridges to be crossed when I get there I reckon.

I'll do mass poly-cross this year and keep track of seeds by who the mother was just like the university breeders do. I'll do that for any seeds from new varieties and I should probably also give more official and permanent names to my own varieties so I can track them the same way.

I'll be set back a year on finding new seed sprouted varieties that meet my favored phenotypes but that's OK as I already have several that are petty darned good for growth habit, production, flavor and seediness. I'm gonna go all out, well as far out as I can, on buying new ones and I want it to be the last time I shell out money to buy slips, it's just way too expensive. Insane for folks who always grow sweet potatoes to buy them every year but to each his own I suppose.

I'v got about ten, new to me, varieties picked out and if I get seed from half of them I will be happy. I should be able to get lots from my own too along the way, I'm shooting for a number in the thousands from them. All in all sweet potatoes is probably take a big chunk of my gardening effort this year.

[reed]

Reed, getting back to edible ornamentals--

What about breeding some sweet potatoes selected for both beauty and flavor of foliage? Maybe it would be happy houseplants in winter that you could snack upon. Then it gets used to make starts that are set out in spring and grown for greens.

In tropical areas sweet potatoes are a favorite crop to interplant with corn. I suspect they wouldnt get enough sun interplanted with corn in temperate areas. But maybe they would. or maybe they would if they were mostly producing leaves rather than roots. Might be worthwhile deliberately selecting under shady conditions. Lots of urbanites have gardens than are mostly shaded because of other houses and trees.

I have some pretty close to that growing on the window sill right now. Can't do much snacking on them cause conditions in my house are pretty poor for sweet potatoes or any tropical houseplant. Just keeping them alive has been the goal but I do notice some stay happier looking through the cold dark days of winter than others. They are all perking up now that it is warmer and have been outside on days over 60, even those that looked bad are growing nicely now. It works out pretty good cause you end up with bare stem with new growth on the tips which allows allows for rooting new plants that have not been in contact with soil. A couple have tried to bloom intermittently, in a warmer brighter house they might bloom all winter.

I'm not sure but sweet potatoes may like it in some shade. Especially those with dark purple leaves often wilt pretty dramatically in hot afternoon sun. I finally figured out that just cause they like it hot doesn't necessarily mean they like full sun. It probably depends on where you live. In a cooler place full sun, in a hotter place some afternoon shade might be better.  In my experience so far I haven't seen it make a dramatic difference in production or in blooming. I'm moving mine this year to the end of the garden where it goes in shade about 4 PM or so.

I'm finding that other than being slightly less cold tolerant than tomatoes, sweet potatoes are very adaptable and sturdy plants. I have a lot of them and I've had to discard a lot that might have been great ones to go on with for ornamental or eatable leaves cause I just don't have room to keep them all so I have mostly focused on my primary goal of a line that reliably produces good food from seed. 

It happened a little by accident but I do kinda now have two basic kinds. Seed production ability is still the most important so when I originally kept those that did that but that did not make big roots the only way to do it was as houseplants. So now I have the rooters + seeders saved  mostly just as roots and the non-rooters saved as plants.

Some of those sprouted from seed more than a year ago and have been cloned since, so some of last year's new ones for example were descended from them. I'm adding new purchased clones into the mix this year and am going to try to focus on getting their genes into my grex so won't be starting as many seeds this year.

So this year:
I want to mix in as much new material as possible from several new commercial clones.
Produce as many seeds as possible from my old lines, hopefully in the thousands.
Establish better naming conventions and keep better records.

In future I want to divide the lines into the root group. Defined as reliably producing big roots (from seed).
And the ornamental / eatable group, defined as having beautiful eatable foliage and lots of flowers.

The two lines will eventually have to be maintained separately because some of the ornamental / eatable group while having what I call the super bloomer trait, make very few seeds and no large roots. I can't assume that because they don't make seeds that they don't make pollen so they will have to be kept separate so as not to degrade the big root quality of the other group.

I want any particular seed from the root group to have a 50% or higher chance of making big roots. I'm estimating that chance now from any of my seeds, at 10% but think that's low. Another thing I want to keep better track of moving forward. Actually I can do that this year with what seeds I do start. I'll accurately record % germ under my conditions and the % of those that make big roots. Of course both numbers might be different if more controlled germination practices were used but I want lines that don't need tight germination conditions.