Author Topic: Homestead Potato Breeding and Selection  (Read 3299 times)

Oxbow Farm

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Re: Homestead Potato Breeding and Selection
« Reply #45 on: 2018-12-05, 11:06:02 AM »
Gilbert, you might consider trying some Cimatli potatoes from Cultivariable.  They might be more adapted to such a dryland system than tuberosum. 

https://www.cultivariable.com/product/potato/potato-wild-relatives/cimatli-5-tubers/

nathanp

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Re: Homestead Potato Breeding and Selection
« Reply #46 on: 2018-12-05, 04:31:18 PM »
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?

I am curious, are you sure that they are selfed and not open pollinated?  If there are other potatoes (diploids or tetraploids), it is possible there was cross made unless there is a significant isolation distance or complete lack of overlap in flower timing. 

There are quite a few self compatible diploids, but not much is documented, other than those with the Sli gene.  The Sli gene is being used in commercial breeding to develop highly inbred diploid varieties, in particular varieties that do not suffer as much inbreeding suppression.  I've grown a few with the Sli gene and made crosses using varieties with it.  But I have also found other diploids that I suspect may be self compatible just based on large numbers of berries compared to neighboring plants.  Either the Sli gene is more common that generally supposed, or there could be other genes in play doing the same thing.

nathanp

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Re: Homestead Potato Breeding and Selection
« Reply #47 on: 2018-12-05, 04:36:20 PM »

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.

I find this is actually counterproductive unless it is a variety that spreads widely.  Gaps between rows of potatoes tends to actually dry the soil out.  Having full foliage cover conserves water similarly to mulching.  The best yielding potatoes, in my experience, tend to be the ones that quickly provide full foliage cover of the soil first. 

Doro

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Re: Homestead Potato Breeding and Selection
« Reply #48 on: 2018-12-06, 03:10:16 AM »
Nathan, I am pretty sure they are. After reading about them being self compatible in a potato database I got curious and put a bag over some flower clusters to keep pollinators out. They were still setting fruit readily. Despite being a bad berry year. It was very interesting to watch them keep most of their fruit while other varieties aborted a lot of berries because of heat and dry conditions. I'd say they are very fertile.

nathanp

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Re: Homestead Potato Breeding and Selection
« Reply #49 on: 2019-11-02, 07:39:11 AM »
This white paper has some information that looks particularly useful with selection of TPS seedings for earliness/lateness in their seedling year.  I plan to pay attention to this next year.

https://link.springer.com/article/10.1007%2FBF02365785?fbclid=IwAR2Kry5nAiKZmGnFvpnjr_vsCaPdwBmegXR4ih_O9p1GJXKzOCO6f8d-wRA

Andrew Barney

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Re: Homestead Potato Breeding and Selection
« Reply #50 on: 2019-11-02, 08:03:29 AM »
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.

Up to this point I have not done much with potatoes, but I'd like to. After reading your post I have a few thoughts.

1. Im not sure breeding for very abundant fruit set will have plants that have good edible root yields. I think there is some degree of mutual exclusivity,  but not completley. I think there may be a "sweet spot" where you get decent tuber yields and some,  but perhaps not a lot of berry set. The plant only has limited resources after all. I would think a plant would tend to want to do one or the other but not both unless very carefully selected to do so. But even then you wouldn't get maximum yield potential for both traits at the same time. Only in the middle for both if your lucky.

Similar to trying to breed for perennial grasses or corn. They may have perrennial traits, but that probably means you take a hit on yearly yield or they become biannual. But is probably hard to get both in one plant.

2. Im wondering if self incompatible genes like Joseph's tomato project Is the way to go. Heterosis or Hybrid Vigour seems to be a major benefit for potato growing,  so that seems very logical to me. I guess that means Diploids despite the tubers being smaller and that they grow slower.

But smaller potatoes is not necessarily a bad thing.  Tiny foods are becoming popular at whole foods and sprouts like stores. There is a niche market.

3. I'm still attracted to diploids despite it being the harder way to go. One just probably needs to go for it anyway and try to avoid self compatibility genes.
« Last Edit: 2019-11-02, 08:08:47 AM by Andrew Barney »