Frost resistant varieties

[marches]

What specifically frost resistant varieties of potato exist and how well do they withstand it?
How common is frost resistance in hybrid potatoes.

[DarJones]

It is better to ask what species of potato are most frost resistant. High altitude varieties such as are grown in the Lake Titicaca area would be prime candidates.

Look for the species with "T" to the left. Bulbocastanum would be a good start.
es.wikipedia.org/wiki/Anexo:Especies_de_Solanum

[Tom Wagner]

High altitude varieties such as are grown in the Lake Titicaca area would be prime candidates.

We don't as a rule grow frost resistant potatoes and I suspect Lake Titicaca would have some prime candidates for selection work.

Lake Titicaca elevation 12,507 feet. Interesting reading about raised field platforms planted in potatoes alongside water-filled canals so that during a night of light frost the potatoes are where the temps are a bit higher.

The functions of q’ochas include improved microclimate: The humid depressions improve the climate conditions for
crops and reduce the risk of frost damage

Solanum tuberosum damaged at 30 F
Solanum andigena damaged at 28 F
Solanum ajanhuiri and curtilobum damaged at 23 to 26 F
Soalnum juzepczukii damaged at 23 F

The problem with some of the best frost resistance is bitterness due to high glyboalkaloids. The first three are OK generally but the last two ...nope.

I grow lots of possible candidates for improved tolerance to frost and I bet lots of the andigena material I have is a source for improved tolerance at they are bred into the conventional tuberosum lines. Rob Wagner is helping out crossing acuale and ajanhuiri lines this year.

I have lots of anecdotal evidence based on personal observation,or random investigations rather than systematic scientific evaluation for many years. In Bakerfield, CA much of my observation was on fall planted potatoes Aug to November. Late varieties with pedgirees fro Peru faired very well for improved canopy protection...sometimes the resistance was only partial but allowed the tubers to finish off nicely into December.

Locally, I work more toward freeze resistance of the tubers. Over wintering potatoes sure helps identify good lines. Frost resistance may be that the tubers recover from frost around the tubers or that they set deeply.

[marches]

Jul 16, 2014 21:51:38 GMT -8 Tom Wagner said:

I work more toward freeze resistance of the tubers. Over wintering potatoes sure helps identify good lines. Frost resistance may be that the tubers recover from frost around the tubers or that they set deeply.

You mean so they can be left in the ground over winter? Wouldn't they go woody or mushy?

[DarJones]

Marches, that is the purpose of the selection work. He is targeting varieties that stay firm and normal/edible over winter.

[atash]

>>How common is frost resistance in hybrid potatoes.<<

It is extremely rare outside of the tropical Andes where potatoes are native. It's the exception to the rule even in the Andes. I am suspicious that it doesn't occur at all in the ancestral species, and that all frost-resistance in potatoes is the result of hybridization with other species. You can't help but notice that frost-resistant potatoes often seem to have fertility problems.

The tropical Andes have surprisingly stable climates even at very high elevations. As a result, species can live perilously close to their limits. I would guess that S. stenotomum naturally occurs below frost level, and/or “hides” in protected pockets. I have seen that phenomenon in other species from that part of the world that occur at high elevations but have little or no frost tolerance.

Tom mentioned microclimates on the altiplano. I have seen photos of Passiflora pennatistipula flourishing on an island on Lake Titicaca against the wall of a house. That species has almost no frost tolerance.

Alaska Frostless tolerates just a few degrees. It has some S. acaule in its background. S. acaule tolerates quite severe radiation frosts without any need to harden off.

S. acaule is not easy to use. It's listed as a “tetraploid” but more likely it's an “amphiploid” with chromosomes from two different species. They are not a perfect double, and won't align with the chromosomes of tetraploid domesticated potatoes.

It's possible to work around that obstacle, and it's been done. You're apt to end up at weird 'ploidy levels, which is a problem with Alaska Frostless.

Other species are probably easier to work with than S. acaule. The x ajanhuiri is half S. megistacrolobum, and two cultivars of it are already non-bitter. And it does not require short days. It's not very fertile at all, so large numbers of manual pollinations are needed to get just a few seeds. I have exactly 3 plants that are half x ajanhuiri, and half 'Magic Dragons', which are mostly S. stenotomum.

S. paucissectum might be a good species to use for frost-resistance.

You also have to breed out the bitterness again, and any day-length sensitivities. That said, it can be done, and essentially has been done. From time to time Tom runs into frost-resistant cultivars, including his own that serendipitously end up with some thanks to their exotic pedigrees.

>>Marches, that is the purpose of the selection work. He is targeting varieties that stay firm and normal/edible over winter.<<

Marches, there are two different issues: frost-resistance in the “vines”, and frost-resistance in the tubers. Frost-resistant vines do not necessarily imply frost-resistant tubers, which is probably what you are thinking. But some potatoes give you both.

Imagine a potato that is significantly more frost-resistant than a rutabaga! They already exist. The bad news is that they also have day-length problems: they wont start making tubers until around the autumnal equinox. There had to be a catch! But all of these problems can be worked around.

It's almost surprising nobody bothered to on any significant basis up to now. You'd think they would be a hot item in places like Estonia and Finland.

Even as they are usually not frost-tolerant, potatoes saved millions of lives in Europe during Solar minima of the past, when cereal crops lodged horribly in cold, wet weather, but tough, tolerant potatoes made a summer crop.

Summer frosts have gotten rare since 1850 except at high elevations or latitudes, but we will probably start seeing them again with the next solar minimum.

I'll post some photos later.

[DarJones]

Here is a link to a reasonably current listing of wild species of potato along with some good descriptive and geographic information.

www.vcru.wisc.edu/spo~onerlab/pdf/Potato%20Atlas%20Final.pdf

There are times when I want to kick proboards in the backside. The problem is the word "spo.on" which proboards insists on re-translating into "thingy". blatherskites!

Please copy and paste the above link into your browser and remove the ~ that I deliberately placed into the link so proboards won't garble it.

[Tom Wagner]

Thanks, Atash/Rob, for that update.

Darrel, I couldn't load the link to the pdf file but this might help...entering this into the search bar

www.vcru.wisc.edu potato species atlas of wild potatoes

143 pages and lots of info
www.vcru.wisc.edu/sthingyerlab/pdf/Potato%20Atlas%20Final.pdf still does not work for me.

[atash]

Here's a list of species evaluated for frost-tolerance:

diva-gis.org/docs/Frost.pdf

Pages 3 and 4. The right-most column gives "percent non-damaged tissue after two frosts at –2C and one at –5◦C in Sturgeon Bay, Wisconsin, USA in 1992". You want that number to be as close to 100 as possible!

They're arranged in series. Ideally you would want to pick candidates that are in the same series as the domesticated potato, but notice that most of those have low frost tolerance percentages! That might be why domesticated potatoes don't like frost.

Paucissectum = 92; it's a deep-tropical species from northwestern Peru and southern Ecuador but at high elevations. It's a diploid. I have seed for it somewhere, that I'd like to start next year. Acaule = 100; it's a cosmopolitan high-elevation species growing right up to the permanent snowfields.

Demissum scores a respectable 92%; that's hardier than I expected. It's native Mexico to Guatamala at 2100 to 3700 meters asl, and is notable for being native to the homeland of late blight! It's been used for increasing disease resistance, but it could contribute hardiness too. You have to cross it to a diploid to get a tetraploid; it's hexaploid. Probably an amphiploid of 3 different species. Tom, we should have that one. Can you get it?

S. megistacrolobum (spelling is wrong in the linked-to white paper!) is another high-elevation species from southern Peru and Bolivia; it intersects the higher end of the altiplano and spontaneously crossed to S. stenotomum in the farmers' fields to produce S. x ajanhuiri. It scores a respectable 83%.

When you cross species, you get reduced fertility (maybe none if too far apart!) due to chromosomes that don't align perfectly--they can't because one species has genes the other one doesn't! You also get a phenomenon called "linkage drag" when unwanted traits are encoded on the same chromosome as traits you do want.

I think the biggest two obstacles are day-length sensitivity whereby you don't get tubers until after the autumnal equinox if indeed they make it that long without going senescent (currently fighting that...), and unwieldy 'ploidy levels on some of these.

[DarJones]

Work I've read in the past on high ploidy levels such as pentaploid and hexaploid showed that crossing to a diploid usually results in issues with pachytene pairing of the chromosomes. In other words, they don't pair up so the cellular machinery that duplicates chromosomes can do its thing. If you want to dig into this, look up "allosyndetic pairing".

[atash]

Thanks, snickeringbear.

[atash]

This is one of the 3 seedlings that is

(x ajanhuiri 'Sisu') x 'Magic Dragons'

The Magic Dragons pollen-parent was a white-fleshed, purple-flowered variety.

The seedlings little resemble either parent. Two of them have hybrid vigor and/or their chromosomes spontaneously doubled, so they are larger, coarser-leaved plants than either parent. They lack the dark, almost black stems of x ajanhuiri, and the "sooty" leaves. I took photos of both big ones but they are both very similar.

The third seedling looks somewhat like 'Magic Dragons'.

That "x" in "x ajanhuiri" means it's a hybrid. It's a spontaneous hybrid of S. stenotomum x S. megistacrolobum. The frost tolerance is from the wild, male parent.

So these hybrids are 1/4 the wild, frost-tolerant grandpa. I don't necessarily have all of the genes that are associated with frost-tolerance--in fact, probably not, with only 3 samples. I wanted to cross them back to the x ajanhuiri to collect more genes, but I dunno if any of them are going to bloom this year, or if they do, if they'll bloom in time to make seed. I do see buds on a few of the plants. Most of them promptly started going into early senescence, a frustrating bad habit of this variety. Tom says that low productivity is a reason that this variety is not grown more in its native areas, and I bet the problem is its strongly determinate habit, and susceptibility to early senescence. Probably also due to lack of vigor due to virus buildup over the centuries, since they don't tissue-culture it or raise them from seeds.

But it's not a total wasted year, as I am crossing two of the seedlings to each other, to increase the number of seedlings to work with, and also to create recombinations. That is, assuming that the pollinations take. I see one berry rapidly developing so I suspect I have at least a few. I don't think I'll get a huge number as I did not have enough blossoms open simultaneously to get all of them. More buds are on the way. I'm just glad it's not semi-sterile like its mother is. I only bothered to go one direction because S. x ajanhuiri produces so little pollen, most of it probably not even viable. I was worried, because so many potatoes carry male sterility in the cytoplasm. Not this one. The partial sterility could be due to one or more of:

• interspecies cross
• virus buildup

[Tom Wagner]

Atash/Rob, I haven't been by your place for a while so I sure appreciated seeing a photo of that hybrid. Hopefully, the frost tolerance of the Magic Dragons series may manifest itself in the hybrid...maybe even some synergistic influences. Hope the yield is super!

BTW, the plant looks tetraploid.

[atash]

I too suspected it was probably tetraploid, and I'll bet the other one is too.

I sent you a photo of #3 for your opinion. Depending on which way it went that will impact my plans.

[Tom Wagner]

i.imgur.com/LSwyLlY.jpg

tetra