Author Topic: Homestead Potato Breeding and Selection  (Read 808 times)

Oxbow Farm

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Re: Homestead Potato Breeding and Selection
« Reply #30 on: 2018-11-15, 01:31:20 PM »
So it seems like I can never find a seedling that is 100% what I am looking for. 

This seedling yielded just about the maximum possible yield a potato is capable of, at 13 lbs of tubers.  I wonder if I'll ever see single plant yields like this ever again, this year was such a bizarre weather year with almost an extra month and a half of growing season when you add the early start and super late end.  Plus colossal rain from July till winter. 


They did have a bit of hollow heart, and many of the tubers were on the small side.

I cooked them up and they were extremely floury, the flesh texture was just exactly what I love.  I had steamed the split half tubers in the picture till they were fork tender, and the skin peeled away from the flesh, so I had tried the flesh separately.  When I tasted the skin it was EXTREMELY BITTER.  The bitterness lingered in the back of my mouth and throat for several minutes after eating the skin from one of the half tubers.  Several hours later and my stomach does not feel any discomfort, but the initial bitterness was so intense that I am pretty sure that this potato has unsafe levels of glycoalkaloids. 

In the Cultivariable podcast with Tom Wagner, https://www.cultivariable.com/tom-wagner-of-tater-mater-seeds/ Tom talked about liking to use Lenape (B5141-6) as a parent variety, even though it had been found to have excessive glyco levels.  So I'm wondering about the wisdom of saving this one as a parent for high yield and flouriness, despite the bitterness.  I don't have any idea how one goes about testing for glycoalkaloid levels  other than tasting the spuds.  I've never had a seedling that I found offputtingly bitter before this. 

bill

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Re: Homestead Potato Breeding and Selection
« Reply #31 on: 2018-11-15, 06:44:28 PM »
Adults can usually handle quite a bit of glycoalkaloid without getting sick, but if you can taste bitterness, the level is outside the safe zone.  If it rises to burning/tingling, then you are probably above 100mg/100g, which starts to get dangerous.  There's no reason you can't keep breeding with it though - most of the progeny will probably have much lower levels, even if they are just self progeny.

Doro

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Re: Homestead Potato Breeding and Selection
« Reply #32 on: 2018-11-16, 06:03:55 AM »
I have not bred with bitter ones, so I don't know.
The few bitter TPS plants that I had so far were undesirable in more traits and they just became compost right away.
I'm just a flyweight of kids size, but did not feel sick after taste testing them either. Just had one bite though, it's such a nasty surprise.

nathanp

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Re: Homestead Potato Breeding and Selection
« Reply #33 on: 2018-11-28, 05:37:01 PM »
I would like to derail this topic a bit and insert some of my reflections on potato breeding.  I would be interested in hearing thoughts from others on these ideas.  If this is best left as a new topic, I can repost this separately from this one.

When I first set out to work with potatoes several years ago, I had been heavily influenced with the desire to build a potato landrace, in the more modern sense, meaning heavily diverse, abundantly fruitful, and adapted to my local climate.  Ideally, that would have been productive TPS seedlings that resulted in production in the seedling year.  I have come to realize that most of these goals are largely not possible without heavy selection (but of what?), and not just relying on the selection of what produces fruit(berries) in my climate.  The landrace philosophy is greatly attractive to me, and constant, recurring selection towards what grows well for me, in my area, makes a great deal of logical sense.  I have move towards doing that largely with all other crops I grow.  That includes tomatoes (though I do still track pedigree and F# with dehybridized plants and lines), beans, squashes of all types, greens of all types, etc.  Just not potatoes.

What I have found in relying chiefly on selection by berry production is that the results skew heavily towards potatoes that produce berries, but often lack yields I am happy with. Largely, this is anecdotal and reflects my thinking as I do not have hard evidence and numbers on this, yet it seems more true the longer I work at this.  Likewise, relying on production of tubers from TPS seedlings provides subpar yields that at best in the seedling year, would be difficult to rely on if food production was necessary. 

I have corresponded with others who have also made attempts to save TPS seed from a large diverse crop of potatoes, only to be disappointed with the results of a high percentage of the TPS seedlings.  I suspect this is evidence that selection of parents is the most important factor in potato breeding.  I strongly suspect that there is a regression to the mean with selection for berry or TPS production both for volume from varieties, or of volume saved from many varieties accumulated, that brings average yields down if I am not carefully selecting for parentage and making intentional crosses, rather than just relying on open pollination. This practice seems to prove counterproductive to the end goal of producing valuable and useful TPS plants to be regrown in future years.

Being more careful to make crosses, and forcing hybridization seems to produce much higher yields in the offspring.  Using varieties that produce high volumes of berries that are often selfed, rarely produce offspring that are high yielding for tubers.  In fact, these varieties often seem to only produce middling results as parent unless I am using their pollen to pollenate other varieties. 

I can modify my goals or plans to be far more selective with which potatoes I allow to be parents of TPS I grow out.  But this seems to be in some contradiction of principle with the theory that abundantly fruitful potato plants should eventually lead to producing high yields.  I will point out that I do think these goals are not easily aligned, and possibly cannot be aligned.

There is a case to be made for wanting potatoes that are all of hybrid offspring (and yes I know in theory even selfed potatoes are hybrids of a sort, but all are not equal).  This makes a good deal of sense, assuming it is a case of hybrid vigor.  A minority of selfed plants might also produce equally, but the percentage of good yielding seedings from selfed TPS is much lower.  Plants that produce a high percentage of selfed berries tend to produce low percentages of good yielding potatoes, and low percentages of seed that is open pollinated.

What I am moving towards is using only specific, proven varieties to pollinate other varieties.  The longer I have been growing out TPS, the more I find I am selecting not for production in their seedling year predominantly, but production when grown from tubers in their 2nd year. It is becoming increasingly important to me to identify which varieties are of highest value in using as parents in crosses, and less about just wanting a larger diversity of plants that are open pollinated or selfed, or produce high volumes of berries or TPS. I do want both, but intentional focus on parentage seems to be of higher value in breeding, than just broadly growing out TPS from a diverse mixture.  Paying attention to varieties and record keeping with notes is becoming more valuable with potatoes than with any other crops I have set my hand to grown.  A modern landrace of potato plants then, really, is built from varieties that have proven themselves primarily by yield and success in a local climate, and can be used as parents.  That is not easily done without some semblance of tracking parentage and a track record that crosses multiple years and multiple generations of plants.

Some of this should be a bit obvious upon reflection, but it is not the direction I thought I was headed in when I began this journey with TPS. 

Selection then, might be most usefully done with regard for proven parentage of useful tubers of acceptable yield, with those potato varieties becoming central to a breeding program. 

Introduction of new varieties is done not just for the purpose of having a wide genetic base, and hoping for mass open pollination with other varieties. It is instead with the goal of identifying which varieties will be most useful as parents in future cross pollination.

My landrace, therefore, has become merely a genetic pool of plants that I have deemed to be useful, productive parents.  Not really a landrace at all.  This is very different from what I seen with other crops I have grown. 
« Last Edit: 2018-12-16, 03:17:02 PM by nathanp »

bill

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Re: Homestead Potato Breeding and Selection
« Reply #34 on: 2018-11-29, 12:51:08 AM »
My experiences are similar to yours, Nathan.  Making modern landraces out of clonally propagated polyploids is a tall order.  Odds of success would go up in diploids, since they will hold onto recessives longer.  Self-incompatibility will help as well in maintaining the population over generations.  But it is always going to be easier to propagate rare and superior genotypes clonally than to try to fix them for sexual reproduction.

I haven't found much conflict between yield and berry set in late varieties, but in early varieties, they are just about inversely proportional.

Doro

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Re: Homestead Potato Breeding and Selection
« Reply #35 on: 2018-11-29, 08:46:44 AM »
Even though I love the idea of modern landrace breeding I don't apply it to potatoes. The main reason is that our European pollinators are not interested into potato flowers at all. On a row of a male sterile variety, grown between fertile varieties, I might find a single berry on 20 plants. Which in turn means that basicly all volunteer berries on high fertile varieties are selfed. After just a few generations things would run into inbreeding depressions by default.
The other reason is that the interest in starting from seeds (anything really, even tomatoes) is basicly nonexistant in my neck of the woods. People don't want to start seeds indoors and care for seedling plants for 6 weeks. Which has to be done for tps in our climate or you won't harvest more than micro tubers.
In my breeding I'm just looking for good tubers to propagate and eventually share them with interested gardeners. Being in Europe I can't really sell or even give away 'unrecognized varieties' for food anyways. However I can share food crops for experimental, educational or ornamental purpose lol yeah, the idiocy of modern day regulations. Potatoes used to be a huge part of our foodculture, but they are disappearing from our plates. All food has to be a certified variety, but those all look and taste the same and almost all are 'all purpose' i.e. usable for most things, but not really good for anything. It's not surprising that people stopped eating or growing those incrediby boring round clumps of uniform and tasteless things advertised as potatoes.
My simple motivation in breeding potatoes is to bring back some diversity and flavour, at least into home gardens. It's the last place in Europe where food diversity can thrive until laws are changed.
But I'm rambling and drifting away from topic here, sorry.

However that's why most of my crosses are deliberate crosspollinations. I'm trying to match varieties that compliment each other in disease resistance (scab mostly), food quality and unique colour or shape. For me good berry setting ability and selfing ability mainly plays the practical role in regards of 'it needs to be fertile to breed with it' and when it selfs there are no sterility issues in the next generation.
Since I can't produce more than we eat at home, I have to plan carefully what cross is promising enough to make and grow.
I just sow a few seeds from selfed volunteer berries. If I sow them it's just to get an idea of the traits hidden in a certain variety. The offspring can produce decent or not. I guess the underlying issue here is inbreeding depression. Older heirloom varieties, which were probably selfing for some generations already, are not going to have much high yielding offspring when selfed, but might be great for crossbreeding because of other traits and hybrid vigour kicking in. When growing selfed TPS from modern varieties with documented pedigree of a varied parentage, the harvest is usually quite good. I avoid going into a selfed second generation, just occasionally grow them when I know more about their parentage and can guess that inbreeding depression won't set in already.
However I'm interested in finding out how fast inbreeding actually affects potatoes and will probably inbreed a line on purpose. This year I grew a selfed F1 from a variety called Heiderot, which has 4 different grandparent varieties. The F1 had good yields on average (when I exclude the ones being too late for my short season). I plan to grow a F2 next year and don't expect yields to drop just yet. But I have a feeling that inbreeding depression will show up within roughly 5 generations already. Will see.

Oxbow Farm

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Re: Homestead Potato Breeding and Selection
« Reply #36 on: 2018-12-04, 07:33:32 AM »
I have never been particularly interested in landrace plant breeding for most crops.  I also do not think that potatoes are particularly well suited to landrace techniques, at least under my conditions.  It seems like the only way to do that effectively is to use diploids, given their combination of pollen fertility with self incompatibility.  With pollen fertile tetraploids, I find that plants that produce huge crops of berries are almost certainly self pollinating to a huge extent.  I do think I have relatively high levels of crossing in my potato plantings, since I see the bees working the flowers actively, and I know most of the stuff I grow is pollen fertile. 

This year I collected approximately 13 ounces of bulk TPS from my potatoes.  Over 50% of that was from one variety that produced 7.5 ounces of seed (that I managed to harvest).  I was very happy to collect so much seed, and I happily was able to sell some wholesale and donate a large amount to the Kenosha potato project. 

For my own TPS grow-outs though, I am more interested in the tiny batches of seed I collected from other potatoes with much more sparse fruiting.  It seems much more likely to me that these indicate successfull crosses, and are likely to produce a variety of offspring to select from. 

I remember a few years ago on HG Joseph was advocating breeding for an "abundantly fruitfull" potato landrace, which would produce high yields of tubers and large amounts of seed.  It isn't clear to me that that is a feasible goal, at least under North American conditions.  I do think it is important to focus on male fertile lines as much as possible.

For my own projects, I don't know if I will begin doing careful planned crosses though.  It is very difficult for me to commit that kind of time to hand pollinating at that time of year.  In general hand pollinating is not a breeding technique I'm particularly interested in, simply due to lack of time. 

What IS fairly easy for me to do is grow out large numbers of seedlings, and to evaluate them over a number of years.  I've been really grateful to have access to Nathan's extra TPS crosses, as they have been very fun to grow out.

One area I would like to explore more is to better understand the difference in behavior of TPS seedlings from the seedling year to the first and second tuber years.  I would like to get much better at evaluating seedlings for their potential.  I have found that the results from the seedling year don't necessarily translate to the tuber grown years, and I want to understand better what changes can be predicted.  If that makes sense. 

reed

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Re: Homestead Potato Breeding and Selection
« Reply #37 on: 2018-12-04, 08:40:59 AM »
I think what I'v settled into with my sweet potatoes is saving superior plants as clones and growing them along with new sprouts and new varieties each year. My storage capacity is limited so I'm going to have to set a limit of around ten or so to keep for cloning and replace as better ones show up. Extra seeds go into the archived grex.

I know they are very different things but might something like that work with potatoes as well?

Joseph Lofthouse

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Re: Homestead Potato Breeding and Selection
« Reply #38 on: 2018-12-04, 09:45:16 AM »
Tim: Wonderful on producing so much TPS!

When I was originally advocating for "abundantly fruiting" potatoes, that might have meant 20 berries per plant. Wow, we have advanced a long way in a decade!!! I'm reading reports recently about hundreds of berries per plant. I think that today I would advocate for growing varieties which are "reliably fruiting".

My polyploid plant breeding projects are primarily dealing with varieties that are cloned. So once a suitable clone is identified, then it is cloned year after year.  Predicting outcomes of manual crosses is much more difficult with the polyploids.

My experience with potatoes, is that 2nd year tubers tend to do worse than the first year plants, and a few do much better.


Gilbert Fritz

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Re: Homestead Potato Breeding and Selection
« Reply #39 on: 2018-12-04, 04:03:33 PM »
I thought that potatoes were strongly outcrossing; is this not the case?

From the Cultivariable site:

Quote
The potato of commerce is tetraploid, bearing four copies of each chromosome, resulting in a sort of built-in hybrid vigor that typically allows them to grow larger and yield more than diploids.  Potatoes are outbreeders and experience inbreeding depression.  As a result, they do not grow true from seed.  Every potato plant grown from TPS is genetically different.

How do they become selfed and inbred if they are outbreeding?

My interest in TPS is different now from a few years ago. A few years ago, I was very interested in breeding a "tower potato." I now think this may be impossible, and besides, I'm not sure if it is desirable.

I'm now more interested in the fact that the native climate of some potato species and varieties is rather like the high desert climate of Colorado, and that potatoes can be dry farmed. I'm also attracted by the ability to avoid purchase of certified seed and the trouble of overwintering large amounts of seed potatoes; planting an expensive seed potato in a marginal dry-field where yield will be low doesn't seem like the brightest idea. 

I'd like to grow TPS in a garden plot to form micro-tubers, which could be tasted to eliminate bitter ones, before planting out on a dry field for production the next year.

If I only harvested TPS from clones in their second (or third) year after evaluating yield, would I avoid the problems discussed above?

Oxbow Farm

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Re: Homestead Potato Breeding and Selection
« Reply #40 on: 2018-12-04, 04:55:42 PM »

How do they become selfed and inbred if they are outbreeding?



Diploid potatoes have a strong self incompatibility mechanism, but it is not functional in tetraploids for some reason involving the doubled genome.  So it is easy for a pollen fertile tetraploid to produce a lot of self pollinated seeds since the pollen is released in immediate proximity to the stigma in Solanum flowers.

nathanp

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Re: Homestead Potato Breeding and Selection
« Reply #41 on: 2018-12-04, 09:35:38 PM »
Quote from: Joseph Lofthouse
Tim: Wonderful on producing so much TPS! I think that today I would advocate for growing varieties which are "reliably fruiting".

I think that this is an apt way to put it, and a very realistic goal.  I am certainly content with ones that behave like this.  Tim certainly has had a few that are abundantly fruitful.  I've had one or two, but have found that they mostly produced high volumes of selfed TPS.

Quote from: Oxbow Farm
For my own TPS grow-outs though, I am more interested in the tiny batches of seed I collected from other potatoes with much more sparse fruiting.  It seems much more likely to me that these indicate successful crosses, and are likely to produce a variety of offspring to select from.

This is what I aim to do when I an unable to make specific crosses take.  It's a much better likelihood of being crossed, resulting in seedlings with highbred vigor instead of selfed.  This year, for example, I did not have any successful hand pollinations. 

Quote from: Gilbert Fritz
I'm now more interested in the fact that the native climate of some potato species and varieties is rather like the high desert climate of Colorado, and that potatoes can be dry farmed.

If by dry farming, you mean no irrigation, then I dry farm everything I grow.  I only water at time of transplanting seedlings.  That will limit yields with many crops, however, including potatoes.  Potatoes mostly like regular watering.

Quote
I'm also attracted by the ability to avoid purchase of certified seed and the trouble of overwintering large amounts of seed potatoes; planting an expensive seed potato in a marginal dry-field where yield will be low doesn't seem like the brightest idea.

I'd like to grow TPS in a garden plot to form micro-tubers, which could be tasted to eliminate bitter ones, before planting out on a dry field for production the next year.

This is fairly realistic, but it's still a bit of guesswork to determine which ones to save for seed tubers and which ones to drop.  As for bitter tubers, unless you are working with wild species, you won't run across many.  I think based on what I've grown the past few years, the percentage of truly bitter and inedible ones must be in the ballpark of 1 out of every 500 or so.

Quote
If I only harvested TPS from clones in their second (or third) year after evaluating yield, would I avoid the problems discussed above?
Somewhat yes and somewhat no.  The no first.  There are too many genes involved with tetraploids and if you want to stabilize a trait by inbreeding (like tomatoes), you probably would need something over 20 generations for clones that have rather uniform genetics.  Widely divergent segregating potatoes could take many more generations.  But you would hit inbreeding suppression long before then.  Researchers currently are trying to stabilize highly inbred diploid populations, which can be stabilized more similarly to tomatoes in 7-8 generations (both diploids).  The trick for them is to find ones that do not suffer inbreeding suppression, if possible. 

I think the value of selecting TPS from clones that are proven for several years in your climate is that they are proven in your climate, especially if they produce berries.  I have zero interest in potatoes if they do not produce berries.  The could be the world's best yielding potato, but that does nothing for me if they cannot be a parent.  If I have two consecutive years with no berries, that is one I will drop.  TPS from those that are proven in your climate are probably more likely to produce desirable TPS plants, rather than ones that struggle in your climate and growing conditions.  That is exactly what I would advocate, that one of the best things you can do is select tubers to be good parents to breed with.  And then, one way or another, using crossed TPS from them, rather than selfed TPS. 

Doro

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Re: Homestead Potato Breeding and Selection
« Reply #42 on: 2018-12-05, 01:47:20 AM »
The self incompatibility mechanism in diploids is missing in some commercial diploids. I grew Mayan Gold and Inca Bella, they both set fruit when selfed.
Which makes me wonder, if they are easily making selfed fruit, how many more diploids do? Is the mechanism really present in most diploids or is it just some? Which ones?

rowan

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Re: Homestead Potato Breeding and Selection
« Reply #43 on: 2018-12-05, 01:55:20 AM »
I have one diploid that is self compatible, but I haven't grown seeds form it yet to see if it shows much inbreeding depression. I will be saving seeds of it this season.
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Gilbert Fritz

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Re: Homestead Potato Breeding and Selection
« Reply #44 on: 2018-12-05, 08:46:49 AM »
Quote
If by dry farming, you mean no irrigation, then I dry farm everything I grow.  I only water at time of transplanting seedlings.  That will limit yields with many crops, however, including potatoes.  Potatoes mostly like regular watering.

And I'm in a much more arid location. But, this guy is growing dry-farmed (no irrigation) potatoes and other vegetables on 12 inches of rain. On the other hand, he has a somewhat cooler climate than I do. http://bobquinnorganicfarmer.com/dry-land-vegetables/

I'd guess that a targeted breeding program would end up with potatoes that ran roots much further from the center of the plant to capitalize on the wide spacing of dryland farmed plants.