In situ preservation of potatoes

[Tom Wagner]

Amphigories and Gobbledygook

Prefacing the illogical is the only way I can introduce this topic.  Food Storage may seems to be the sub forum to post this topic

The phenomenon of leaving something exactly in place where it occurs and not moving it to some special medium is a biological definition of in situ!

Often, I leave potatoes in the ground where they were grown and this is an "On Site" conservation term and is significant when one leaves the potatoes to suffer the winter's ravages such as freeze damage. Many varieties fail simply because the tubers are set too close to the surface and freeze quickly when the frost level goes down to 3 to 4 inches.  This past winter with no snow cover and temperatures in December down around 10 degrees F. shot the freezing line down to about 10 inches.

You are probably asking at this point why I would leave potatoes in the ground un-harvested all winter. Simple…I plant too many potato varieties in too many places with too little time to travel and harvest in time and a lack of storage facilities to place the potatoes.  But then again, I stress the need for sustainability practices and the need for survival crops and the breeding therein.

In-situ conservation, protecting a plant species (Solanum) in its agricultural habitat; for the conservation of genetic resources applied to conservation of agricultural biodiversity in agro-ecosystems by this farmer; is especially an unconventional farming practice.
One benefit to in-situ conservation (wintering over) is that it maintains surviving and recovering populations in the surrounding where they have developed their distinctive properties (freezing resistance). Another is that this strategy helps ensure the ongoing processes of evolution and adaptation within their environments. As a accidental or planned event, ex-situ conservation may be used on some or all of the population, forcing a screening of tuber lines that set deep enough to escape freeze damage.
The population size must be sufficient to enable the necessary genetic diversity to survive within the population, so that it has a good chance of continuing to adapt and evolve over time. Such methodologies link the positive output of scientific research with this farmer’s experience and field work. The accessions of a variety stored at a germplasm bank and those of the same varieties in multiple crosses and multiplied by this farmer are jointly tested in the field. I get knowledge about the production characteristics of the surviving varieties and the best tested accessions are crossed / mixed and multiplied under replicable situations. Thus, this farmer’s efforts are enabled to grow improved selections of his own varieties. This technique of conservation of agricultural biodiversity is perhaps more successful in marginal areas, where commercial varieties are not expedient, due to climate, soil fertility, and economy of scale restraints. 

I do a lot of crazy things like planting potato seedlings from TPS out to the field around July 1st.  I did not get to dig these out due to wet weather and being gone during the best two months to dig them.  Only one family out of many seedlings survived this test with the freezing going down 10 inches. Two plants had one tuber each out of the F-2 population of my Primo Russet.  Primo Russet is a cross of Primo and A81286-1.  Primo was one of  recombinant seedlings out of Argentina’s Primicia Inta, an X and Y virus resistant clone that traces a pedigree back to Feldeslohn and a numbered Argentine clone.  A81286-1 is a rare breed of russet, one that has high culinary qualities in every cooking method known.  It has some high vitamin C from its grandfather ….Butte.
In the normal transplanting time in May, another seedling clones that has A81286-1 as a double g. grandparent survived the freeze as well.


Big vines with deep roots and stolon initiation at deep levels that grew downwards seemed to survive best.  Two hybrids, both with Awol Dude as a male parent also did well.  The similarity didn’t stop there, the maternal lines---India 1038 and India 1035---both lines that do well in the Philippines for example---have some Late Blight tolerance and the health of the dead vines indicated that the L.B. resistance from Awol Dude carried thru as well.

One of the prettier clones that had nearly every tuber survive the freeze under its hill was a recombinant of my Boy Pig X Red Thumb hybrid called Pigs Knuckles.  It has long, nearly fingerling red tubers with yellow eyes and fairly deep red flesh.  I will certainly expand this clone and will use it in breeding a lot this coming summer. I am thinking of naming it Knuckle Down, an obvious pun on the ancestry and its ability to grow down below the frost line.

I dug hundreds and hundreds of clones and fortunately I have a sample of every type of potato I need for further breeding, whites, russets, yellows, red with yellow flesh, red with white flesh, purples with white flesh and blues with blue flesh. It appears that only 5 % of the seedling clones produced tubers that resisted the freeze.

Tom Wagner BTW, Atash knows something of this project....

[opsec]

I'm definiteley interested in the decendents of the freeze survivors.

[Dame]

This may be of interest.

Before we got chickens, potato peelings and other kitchen scrap was dumped in a loose heap in the garden and worked in the following spring.  I would not really call it a compost heap as it was spread thinly over a larger area.  Every year after the garden was up, I would find random potatoes. 

The first year I unearthed these potato plants to find what they were and would find they had started from some piece of potato peel with an eye in it.  Winter temps here are very cold (-40F) and prolonged (at least 3 weeks with these cold temps).  And having been put on the surface during the winter, the plants were exposed to repeated freezing and thawing prior to being worked into the ground.

We generally ate these first because of their random and usually inconvenient placement.  I suspect they were either Norland or Netted Gems.

[Atash Hagmahani]

Tom Wagner BTW, Atash knows something of this project....

It was a "sobering" experience. Perhaps a "reality check"?

I tend to think of potatoes as being easy to harvest, relative to the amount of food you get. This was a "search and rescue" mission. It wouldn't have been much payoff relative to the amount of work, if it wouldn't have been for rescuing F2 generation seedlings that are starting to segregate out characteristics that Tom is trying to combine in specific patterns.

The humbling part was that digging potatoes in heavy, mucky, clay-rich soil (I had no idea anybody actually grew potatoes in such heavy soil; no wonder they plant so late) is a lot more work than it is in my light sandy loam that is really easy to dig. In other words, my imagination of what it must be like to dig potatoes when one's life depends on it, was overly optimistic due to an unrealistic idea of what typical field conditions might be like.

We were both tired by mid-day. I had expected to put in a full day's work, but I think we were wise to call it a day early. Tom did most of the heavy digging--he attacks the clumps from the side from where we've already dug out a trench, and lifts them straight up, without any leverage. I am not used to that strenuous of labor, and kept digging from the top so that I could leverage them out.

The vast majority of the potatoes were dead and rotting. What we lost in salable material, I suppose we gained in extreme stress-testing of Tom's potatoes. All of the survivors we found were seedlings; all of his existing lines seemed to be total losses. That raises an interesting question regarding what the difference was. Although none of the survivors was on or near the surface, they often were no deeper than other potatoes that were killed. Furthermore, some varieties seemed to produce more survivors than others; some varieties were total losses, and some produced multiple survivors.

I would not put much faith in a single test on a single generation. I bet it is not so much frost-resistance as ability to recover from damaged tissues (versus rot). If something like this were done a few more times, I would bet you'd find more and more survivors in successive generations.

The farm is in the Skagit Valley, near the river. It's in the upper valley, where the mountains are close at hand. Very picturesque. Being a notorious shutter-bug I had to snap a few pix. I'll post them later this evening.

[Atash Hagmahani]

Story time.

This is what we found when we got to the potato harvest-party:



Note the clods of clay. It's probably hard to tell, but they are fairly wet. I don't know how cold it got out there, but temperatures vary over surprisingly short distances in this part of the world, and Seattle is normally significantly warmer than the hinterlands, due to both geography and the heat-island effect. We got down to about 19F, with NO SNOW COVER, and about a week of freezing temperatures. I would imagine that out there, it probably got down to single digits.

It was cold enough, for long enough, that the ground froze, which is not typical of here. Wet soils and heavy soils are particularly deadly to plants when they freeze. The same cold that killed the potatoes was so severe, even most (not all) of the Kale was killed! It wasn't necessarily cold per se that did it, but more likely the fact that the ground froze, and a lot of plants dehydrated to death in the cold dry wind.

Here's Tom hard at work with the search-and-rescue operations. Typically we would dig up the ground around the base of the remains of the plant, and then sift through the clods of dirt with our hands. In Tom's case, bare hands. I had gloves on.



This is what we were after:



The two on the left are alive. The other two are not just dead but squishy rotten.

To fully appreciate this, you have to realize that the live ones were massively outnumbered by dead ones, and typically were no deeper than others that died. It is possible that the Kale growing in the same field protected some tubers but not others. I tend to suspect it was a threshold issue: some tubers were just ever-so-slightly on one side of the killing threshold, and recovered.

These are the foothills of the Cascades:



This is a narrow glacial valley with hills like this one to the north and the south quite close at hand; it feels very "enclosed". I would estimate around 800 or so feet above the valley floor, but I don't know how high the valley was. It seemed like we didn't go up very much. The other end of the valley is barely above sea level, and the river is tidal at that point.

It's quite picturesque. It might have been worth a panoramic shot, except we weren't really there to take pictures all day.  I shot some video though that we might post later.

The white stuff dusting the top of the hill is snow. I don't think it was all that cold up there; it just takes a while for the all the snow to melt. That was the shady side of the hill for that matter, though there were bits of snow even on the south-facing slopes near the tops of the hills on the other side. Down in the fields it was fairly mild, around the upper-40s F I think.

[Tom Wagner]

Iron Mountain just to the south of the field is a little over 4100 feet, but the river valley where we were is only 140 ft above sea level.  The peak of Iron Mt. is about 3-4 miles away.This field is about 40 south of the B.C. border with Washington state.

I have more to say about the freeze resistance of the tubers, but will wait til I have more time.  Thanks for sharing Atash.  Funny how two people can write about the same subject, yet the imagery is so strikingly different.

[The Future]

Atash what is the woody looking material in the photo of Tom digging?

[Atash Hagmahani]

Atash what is the woody looking material in the photo of Tom digging?

It's not woody; it's just potato-"vines" that have been bleached down to their cellulose fibers.

I have more to say about the freeze resistance of the tubers, but will wait til I have more time.  Thanks for sharing Atash.  Funny how two people can write about the same subject, yet the imagery is so strikingly different.

Take it easy on me, Chief, I'm not a botanist and have very little understanding of biochemistry. 

What I do know is about the functioning of anti-frost mechanisms on a very gross scale of things. You've seen my garden full of oddly exotic plants. How is it for example that a Banana--namely Musa basjoo--can survive in the decidedly non-tropical climate of Seattle?

What tends to kill plant tissues in cold weather is the formation of ice crystals in their cells, that destroy delicate cellular substructures.

The solution to frost is generally to keep those ice crystals from forming. The mechanisms include

* higher starch and sugar concentrations, that lower the freezing point of the cellular fluid
* specific proteins that inhibit the ice crystals from finding a nucleus to form around
* removal of water from the cells. This is how it is possible for tropical plant seeds to survive freezing! But non-seed tissues of coldhardy plants can generally do it to a certain degree--that's one of several reasons why coldhardy plants often wilt in cold weather (the other being that their roots can't supply water anyway when the ground is frozen...).

Interestingly, the ability to regulate water in plant tissues explains why the most cold-resistant Eucalyptus grown here in the Northwest are NOT the ones from the highest, coldest elevations in Australia and Tasmania, but oddly, from wetlands.

Eucalyptus neglecta is one of the most cold-resistant Eucalyptus grown here--it essentially never freezes back, even though its broad leaves which are prone to collecting snow that can damage the branches from too much weight, are poorly-adapted to snowy climates. Its native climate isn't snowy--it comes from only a few thousand feet elevation, a bit frosty but not prone to heavy snow. It can tolerate cold because it regulates the amount of moisture in its tissues, which it has to do, because its habitat is the banks of a single river.

On the other side of the coin, most cacti can tolerate frost in habitat, but not in maritime climates, where winter rains saturate their tissues and make them vulnerable to frost (the exceptions are mostly those species with so much  hardiness to spare that it doesn't matter too much, and even they need good drainage).

The easiest frost-resistance mechanism to develop is probably to have higher concentration of starch and sugar.

One more factor partially related to frost-tolerance:

the temperature range at which biochemical processes are optimized can make the difference between life and death. I do not know a lot about the underlying biochemistry, but I do know that some plants grow best at relatively high temperatures (corn and amaranth, that do C4 metabolism), and some plants are adapted to grow at low temperatures. There are something like 3 or 4 bands of temperature ranges, that different plants tend to fall into.

One thing that can happen, is if a plant's active temperature range is too high compared to the ambient temperature, even if temperatures are above freezing, it can die from lack of enough activity to fend off pathogens active at much lower temperatures.

There are undoubtedly more mechanisms I am not aware of.

[Tom Wagner]

The relationship between seasonal changes in anti-oxidant system and freezing tolerance in potato tubers left in rows in the field.

Why does that sound like a professional topic? 
and what relationship should we, as food storage freaks, consider the anti-oxidants to be a partner in preparing for the future...Probalby none, but Oh, Well!!!

Sorry for my short message...I am down at my daughter's place...we are consoling her since her brother in law was involved in an accident with a train in Riverside.