A few of last year’s diploids have popped up from left over tubers I’m guessing. The bed now has teraploids in it. Do I want these mixing? Not sure. Would crosses between diploid and tetraploid be triploid? Seems likely unless there is some miraculous chromosome doubling! What would this mean? A triploid seed might grow but I don’t imagine it would be fertile. If not, it would be a dead end as far as breeding goes.
Any ideas good people?
Mark R
Is there any way, without a laboratory, to know which is which? Or do you just have to keep track of how they were labeled when you got them?
I “think” mismatch in ploidy levels is ONE of the issues with compatibility in my sweet potatoes, but I can’t see it so all I can do is favor seed from those more prone to making seeds. Some make a couple of dozen, some make hundreds, some make none. With sweet potatoes those that do make nice storage roots do it from seed, “in one season”, so it’s easy to find the plants that do both. Since the nice roots and the seediness are easy to see I can just favor them for the next generation and don’t have to actually know the genetic details. The ability to make roots, and seeds or either one isn’t necessarily passed to the next generation but over the years the incidence of that has increased.
Unfortunately, that kind of selection by simple observation apparently can’t be done with potatoes. The only example of potatoes I’ve ever heard of that comes close to making something worth eating, from seed, is in the video of
Julia D’s garden.
Emily S
That’s an interesting question. If someone else did a similar experiment with sweet potato breeding and started with different cultivars, might they end up with a different ploidy in the majority of their population, meaning that some things that are seedy for you would not be for them, and vice versa?
I guess the only way to know for sure would be if someone did it, and you and they traded clones with each other that flowered a lot and didn’t produce seeds, to see if they did better in the other person’s population.
Christopher W
You might want to take a read through this: Potato Ploidy and Endosperm Balance Number - Cultivariable
Ray S
Between Mark’s very sensible, observational approach and the article recommended by Christopher (see both above) I’ve decided to leave the diploids and tetraploids together. A cross is unlikely but should one occur the seed would in all likelihood be sterile. But should such a seed grow and should the resultant plant produce viable seed (again, very unlikely) then yippeee, I have something worth pursuing.
Julia D
For now I also am allowing the diploids and tetraploids to all grow together and I don’t worry about it. That’s how my colorful seed grex is too. I think the main reason I will eventually shift to separating them is because most diploids have almost no dormancy. Does this mean the original growers of diploids grew them continuously? But the Andes region does have a long dry season so that doesn’t make sense to me. Or did they grow them every year from seed?
Ray S
Something I’ve wondered myself. Last season I left diploid tubers in the ground and also put some in the cold store (a heavily insulated room in the shed). Both sprouted in spring. I don’t know what this means as far as dormancy goes.
Mark R
@Julia D “DID they grow them every year from seed?” yes, that is THE, or rather A question, interesting but also somewhat irrelevant.
I certainly have no clue, so to me the REAL question is: CAN they be grown every year from seed??? It may always be difficult in my climate but some in your garden looked to me to be close to making a good harvest from seed.
Might you just do what I have done with my sweet potatoes? Forget color, flavor, ploidy levels and everything else for now and simply plant seeds only from those that make the largest tubers and seeds.
Give me seeds that can actually produce potatoes, in one season (from seed), and you’ll get all the sweet potatoes you could ever want. 
Julia D
That is a generous offer but do I want sweet potatoes ? 
Ok just kidding, of course I do. … The harvest of 2020 when Joseph was there was amazing. And my first from TPS. Yields per plant were often better than the tuber grown plants. Then… this past year it was not so good. I had a big project, started with about 900 seedlings transplanted. The plants started flowering and fruiting waayyy earlier, while they were pretty small. That sounds like drought or nutritional stress, but water wasn’t an issue, and it was the same even in rows that had more compost added. I think it was because it was an especially foggy summer, they weren’t getting enough sunlight and thought it was fall and started flowering/making tubers and berries before the plants were big enough. And then they stopped vegging because they were in reproductive mode so plants stayed smallish. And then because of fog the blight was worse than normal, and most plants died… the problem with this theory is that lack of sunlight shouldn’t have affected all of them in the same way. My yields were more like what people talk about-- low yields of small tubers. I think probably half a pound to a pound each, even from seeds whose parents had produced 11 pounds per plant. So… long story short, I need more years of doing this. But your suggestion on selecting for any plants that produce a good yield in the first year is a good idea. I didn’t do that this past year, because high yielders were always white, and calories from white potatoes are cheap and abundant, and I figured I’d rather have lower yields from purple and pink potatoes. But next year I will segregate the high yielders group from the mixed dark colors group, and look for a potato for you so I can get all the sweet potatoes I ever want…
@julia.dakin
You say in the post a bit higher that the Andes has a dry season. I’m reading a book about the history of the potato. It says the Andes is a 4000 km long mountain range. In the tropical part of the Andes there is great variation in microclimates.
In a day’s walking one could go from temperate valleys to cold dry 4000 m high Altiplano or one could descent into the tropical areas of the plains.
They grew potatoes all over. Proof of gathering wild potatoes dates back 13 thousand years. In Peru gardeners have been landracing potatoes for 8 thousand years in all of the differing microclimates.
The wild ancestors sport fiddly tubers. They grow in dry deserts at the ocean up to the valleys of the Andes between 2500 and 3200 meters.
Solanum acaule apparently is frostresistant, others flourish in humid tropical climates bordering the Amazon, like Solanum urubambae and Solanum yungasense.
These have not been cultivated. 8 have been.
I could go on and on, but i might repeat long known facts. It’s a jaw dropping read to me. I could start a thread instead of poluting this one. Or maybe not.
The history and science of domesticated and wild potatoes and tomatoes is dizzying and interesting lol
As to the original post, I think the ploidy of potatoes is a lab level thing. Diploids tend to be smaller but I haven’t seen if that’s definitive or not.
I think there are some rules they follow but ploidy won’t cross naturally, it requires lab equipment and culturing the early failing fruit/seed?? Anyhow… certain ploidy are odd so when they split you end up with mostly the ploidy you expect, and some random “oops” where the halves didn’t rejoin correctly so they spit out an even. I wanna say it’s for 5x ploidy but it’s been a minute since I read over all that. Check the Cultivariable info pages.
I’m going to be growing a bunch of potatoes from TPS but don’t have experience yet. Excited to see how it goes.
That is fascinating, thanks for sharing. Potato diversity is even more incredible than I thought, what is the book? Does it talk about people growing from true seed every year?
Hi Julia. It’s a book mainly about recepies by top-cooks and thé hundred somewhat most used varieties, done by Lyndsay and Patrick Mikanowski i happened to stumble upon.
Lyndsay is ethnologist and sociologist and landscapearchitect who has done an extensive study on how thé potato came to Europe.
Thé Spanish colonialists brought it to Europe and used it to féed their army in thé war thé Catholic. south waged on thé Protestant north. For twohundred years thé scientific community obeyed the secrecy and selfcensured all publications. While using the Peruvians as slaves to mine the silver used to finance this holy war.
It focusses on these three subjects and speaks of the incredible variety and power house and game changer the potato is. The other eight potato family membres are briefly mentioned. We use only one.
It’s tomato degeneration all over. They have a similar book about tomatoes.
It does speak of growing potatoes in a good way, respect for soil life is essential but of seed potatoes and not of planting from seed and making it’s own varieties.
Of interest is the CIP, the international centre for potztoe in Peru which has great funding and keeps thousands of varieties and does great work preserving and researching and supporting farmers and the like. They’re totally worth checking out, because otherwise you and Joseph will have to go to the Andes on a mission of obtaining all differing potato varieties adapted to the cold/ heat / drought and tropical humidity!
It would be awesome if we could get germplasm from the CIP. I thought that Peru had a ban on exporting potatoes to North America, but I can’t find anything about that on the internet now.
Going back to comments made in December… There are two major groups of diploid potatoes. Low dormancy diploids (once classified as Solanum phureja) were grown in lower, warmer, eastern Andean valleys where potatoes could be grown year round. They were selected from high dormancy diploids (once classified as Solanum stenotomum and S. goniocalyx) a more primitive group of highland diploids that have dormancy and are normally grown at higher elevations. And, to close out the diploids, there is also S. ajanhuiri, a natural hybrid between high dormancy diploids and the wild species S. boliviense, which is frost resistant and grown up to the limits of cultivation.
There is little concern about crossing between diploids and tetraploids. It happens, but it is a fairly low probability event and, beside that, it is usually desirable. There are lots of interesting traits in diploids and they aren’t so easy to move into tetraploids, so it is a happy day when it works.
There is no indication the prehistoric Andean farmers grew potatoes from seed. Most likely, seedlings came up among the crop and, if they either looked good or were indistinguishable from the variety, they were kept. This is the definition of a traditional potato landrace: a phenotypically (mostly) uniform type, often including more than one genotype. Of course, there are some interesting indications that the Incas had some pretty advanced agriculture, so they certainly knew how the process works. Were there Inca potato breeders? It is fun to think so. Sadly, we will probably never know.
The main reason you can’t import from CIP is phytosanitary restrictions. Everything must go through quarantine, there are only a few slots each year, and they are prioritized for professionals. Peru also has laws that restrict the distribution of some of their signature native varieties and crops. That said, the US potato genebank has so much Andean potato germplasm that you couldn’t work through all of it in a lifetime, so there is little need to resort to CIP.
Being in Australia, access to germplasm is pretty limited. My interest in true seed stems from a concern about increasing disease burden when growing the same clone year on year. I’m not even sure that this concern is justified. Perhaps all I need to do is grow a number of different clones so that should one do poorly for whatever reason one season I might still get something to eat.
It is a legitimate concern. Varieties eventually become so burdened with viruses that they no longer yield well and they will never be free of the viruses without laboratory work. Before the introduction of certified seed systems, the standard practice was to constantly introduce new seed grown varieties and abandon older clones. There are others producing true seed in Australia from locally available varieties, so you should be able to manage that if you start acquiring different varieties and your climate is favorable enough.
I live less than 30 km (a little under 19 miles) from a seed potato growing region so the climate suits potatoes quite well. As luck would have it, two of the clones I grew this season both produced lots of berries which appear to have seeds. I’ll test their viability once I’ve harvested and processed said berries. I’ll also plant these two clones next to each other next season in the hope of them crossing.
Hi William, lovely to see you hear on this forum!
How do you reckon this went for the ‘prehistoric Andean farmers’? Do you think that (presumably rather tiny?) trickle of volunteer TPS potatoes was enough to balance against the disease buildup in the clonal populations?
And if so, do you reckon that, once our landraces have been established through starting with hybrid swarms of TPS and letting them adapt for a few years, we ought to follow in their footsteps and go clonal, whilst allowing those volunteers (whether ‘allowing’ means consciously or through not even noticing them!)? Also presumably they didn’t rotate crops, just planted in the same field each year? Or at least more than 1 year at a time, otherwise can’t have surviving volunteers, right? So non-rotation would seem important.
If you have anything to say about their methods or non-use of tillage and cover crops or polyculture for potatoes I’d sure be interested too
I think we have a pretty good idea of how things worked for prehistoric Andean farmers, since subsistence growers in the Andes still grow the same way, with only small changes like the introduction of fertilizer. The first thing to understand is that their yields were/are low. Less than half of what would be a normal yield today and often more like a third. They grew/grow a lot of varieties and exchange them a lot, even over long distances. That said, there are a lot of natural barriers to the structure of the Andes that introduce some isolation between communities. That means that not only human trade, but pests and diseases can’t move as efficiently between different regions, which meant that they didn’t have to fight everything at once. If you live in the USA or Europe, in mostly flat country connected by fast travel and common markets, you are always going to be close to someone who is growing potatoes that have all the common diseases. So, the only way we manage high yields over time is constantly displacing infected varieties with clean.
Their varieties were landraces, but the major feature of these landraces was probably varying viral load more than varying genetics. The genetics certainly varied, but Andean potatoes are self-compatible, so would be mostly self-pollinated. So you can imagine an Andean potato landrace as mostly a complex of selfed generations containing the same base genetics, with younger members having lower viral load. They would grow these varieties until their performance became too poor for their standards and then trade for new varieties with a similar phenotype. In some cases, they may have even been trading to recover the same lineage grown in another area with lesser viral assault. Over time, many of them likely also became unproductive because you do run into inbreeding depression as you continue through several generations of self pollination. There was undoubtedly outcrossing with other groups and feral or wild potatoes but, even in small fields, that happens mostly around the fringes. The vast majority of volunteer types will be selfed. So, they have a complex system for recognizing and mitigating the problems inherent to clones, just as we do.
Most of the time, they rotate out of potatoes, but not necessarily after one crop. As I understand it, they tend to fallow fields, grow a few crops of potatoes, then often a few rounds with other crops, and then back to fallowing. The fallowing times tend to be long. Highland potato agriculture was not that different than how everyone else does it, other than that they did the work by hand. The field was tilled with hand tools and potatoes were grown in ridges. They still do the same today, but with more modern tools when they can afford it.
Interestingly it seems the part I highlighted also very much applies to traditional rice cultivation in Laos, from what I have read. And according to the paper ‘Participatory varietal selection: Lessons learned from the Lao upland programme’ “Between 1992 and 2000 more than 13,000 traditional
rice samples (representing over 3000 different
varieties) were collected from Laos.”, and according to the FAO (Food and Agriculture Organization of the United Nations) there are “more than 14,000 varieties of rice in Lao PDR”. Who knows which is right but there are certainly many!
So I guess this would make their method less good for us now, due to their’s being almost entirely clonal-based? Such that… we should be consciously using TPS, which of course in this group we are. Great!
So I guess variation must have been very slow, since there would be a very low percentage of plants from seeds, plus a very low rate of crossing, so for example if it was a 1% rate of ‘volunteers’ and a 1% rate of outcrossing, that’s a 0.01% rate of outcrossed plants. But, suppose there’s only a 20% chance that the plant it outcrosses with is not a fellow clone, then that’s just a 0.002% rate of plants that have crossed with non-clones.
That really makes me wonder if there were traders breeding from seeds. Because people just trying to swap their tired out sick landraces with each other sounds like a rapidly catastrophic situation. Another solution I can imagine is maybe if on those fallow fields you mentioned, they found volunteers that were particularly nice, which maybe any outcrossed volunteer, maybe first or second year ones, could be, if their clones were suffering so badly. And if such occurrences happened frequently enough then perhaps that could be a sustainable source of new varieties?
Do you have a sense of, in our day and age, a kind of ideal balance between clones and seed, whether that be:
a) How many years to do clones for before doing a TPS year, or perhaps
b) What proportion of TPS vs. clones to do each year?
The second option is my idea as a kind of simulation of the volunteer proportion in the traditional context, but doing it consciously could mitigate against
I am guessing that once a landrace is made such that the bubbling genetics are well established to the local situation (after however many years that takes), toning down the TPS plant numbers and toning up the clones, would result in a higher harvest. And having plants with not excessive seed production (like we want for mass TPS production) would also mean higher tuber production, so for acclimatised landraces we might benefit from selecting for merely ‘reasonable’ seed production rather than excessive. So I guess I am curious as to where that balance between TPS and clones might lie, for a kind of optimal, long term level of genetic variation.
Maybe one could even plant rows to help keep track. For example 4 rows, a row of TPS plants, then year 1 clones, year 2 clones, and year 3 clones. Then eat up all the year 3 clones so you only clone up to that many times, for example. Or however many years one might want to. I wonder if anyone does something like that? Though also just mixing them all and introducing a percentage of TPS plants each year would also clean them all out eventually.
Thanks for the info on their cultivation methods!
I think you have reached the mostly inevitable conclusions. Most people will be better off growing a relatively small amount of TPS every year or two, selecting the best from that batch, and beginning to grow them with the rest of their clones. Each year, you eliminate old clones that are no longer performing and introduce new ones to take their places. How long the cycles are depends on how high the disease pressure is. Some people will be lucky in their location and climate and will be able to go many years. People close to commercial potato cultivation and population centers will mostly have to cycle pretty fast - maybe every three years on average. Culling arbitrarily old clones as you suggest would probably be more effective, but the trade off is that you might be able to grow good clones much longer if you wait for production to drop.
It has not been my experience that even heavy seed production competes with tuber production in a significant way. I’m sure there is some yield advantage in varieties that don’t waste energy on sexual reproduction, but it is not enough that it would be the first or even the tenth thing that I would focus on.
It is interesting to speculate on exactly how they produced and maintained such an abundance of varieties in the Andes but, unfortunately, there are no real answers. It might have happened gradually over a long period of time, with each of the many thousands of valleys producing its own varieties (this is probably the leading view). On the other hand, it might have happened relatively quickly if they were doing intentional breeding at some point. What we see today might be very similar to a system extending back in time 10,000 years, or it might be the degenerated remains of an explosion in potato varieties produced by the potato breeders of a centrally planned empire.
@Justin Even at slow rate of crossing crosses in big populations are inevitable. Mutations also happen in every plant during their life and in big populations beneficial mutations will build up. For example modern corn has only 5 genes differentiate it from teosinte, one got rid of the hard shell, one made more rows per cob and one less tillers. Can’t remember the rest. It all happend relatively fast from teosinte to something that is indistinguisable from modern corn. I think it was as little as few hundred years. It was in some corn history/breeding youtube video by some university. With potatoes, there must have been just so large amount of possibilities for crosses and mutations to happen, that it wasn’t that rare even. Wouldn’t also discount the possibility that some people knew more about plant breeding than we might give credit to. I mean, at lowest it could be just to know to plant two different varieties together. But it might happen also just by change if someone likes to eat many different varieties. By the way, if you want, you can take “virtual tour” with google maps around lake titicaca. Quite a lot of potatoes being grown there as well some other crops that I didn’t quite recognize. Possibly ulluco, but not sure if that’s grown as high up. Also some potato plant are slightly atypical with leaf shape to what is normally grown here and quite few seemed to have blue/purple flowers.
This talks about the five genes: Evolution of Corn
Thanks for all that William.
Oh that’s very good news, and rather surprising!
Interesting about the corn!