Cold hardiness of seeds as a predictor of cold hardiness

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donaldvancouver
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Cold hardiness of seeds as a predictor of cold hardiness

Post: # 66659Post donaldvancouver
Sat Dec 16, 2017 8:09 pm

Hi-
Does anybody know of studies that investigate the cold tolerance of seeds as a way of predicting cold hardiness of adult roses?

I'm interested in breeding cold hardy roses, but I live in zone 8. So I'm looking for ways of evaluating seedlings for cold hardiness. If I froze seeds at, say, -35C, would that select for cold-hardy roses? Northern rose breeders report that seeds of roses like Prairie Peace can withstand a winter outdoors at -40 and still be viable. Has anybody investigated this systematically? I have done some online searching but I know some of you are more adept at searching journals than I.

Thanks

d
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Larry Davis
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Re: Cold hardiness of seeds as a predictor of cold hardiness

Post: # 66660Post Larry Davis
Sat Dec 16, 2017 10:22 pm

I cannot recall ever reading a systematic study paper. I know that when I froze some rose hips quickly in a -20 freezer, there was no germination of the separated achenes later. this was with a Buck hybrid (Country Dancer?). ON the other hand I've had decent success with overwintered hips of several CV though most from places that don't get really cold like here where 0 F is usually the lower limit this century. One exception, which I wrote about in the newsletter was hips retrieved in summer north of Gardner MT. Still not -40 F winter though.

My prediction based on the work of Rajashakar at K-State Horticulture is that there can be supercooling to a rather low temp but perhaps not below for most CV. Probably adaptation to low temps helps improve tolerance to freezing in rose as it does in many species.

If I were doing a study I would collect hips very late autumn and through winter where I live, then stratify and count germination rate for the next year with added nitrate. then warm up for a month, return to cooler and watch another year. In a study not published, I've found that R canina that has fully matured on the bush may have an obligate need for a cold/warm/cold cycle to get maximum germination. Without nitrate, no germination either year 1 or 2. Even with nitrate, the exact time of harvest affects total germination and rate, a lot.

donaldvancouver
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Re: Cold hardiness of seeds as a predictor of cold hardiness

Post: # 66661Post donaldvancouver
Sat Dec 16, 2017 11:05 pm

Thanks Larry-

I would like to collect seeds at 120 days maturity as usual, and stratify one group in the fridge as a control, and freeze another group for say 10 days at -25 or -30 C. I would do this with a few cultivars with known differences in cold hardiness, say a R. rugosa, a Kordesii, and some tender types. I would like to see if I can correlate the germination rates of the frozen seeds with their known cold hardiness. If so, I can use seed freezing as a quick method for selecting cold-hardy offspring of my crosses, without having to find trial gardens in cold places for 2-3 years.

I just need to get my hands on a good lab freezer.

d
Zone 8, with warm dry summers, cool wet winters. Southern Gulf Islands, BC

Johannes pl

Re: Cold hardiness of seeds as a predictor of cold hardiness

Post: # 66662Post Johannes pl
Sun Dec 17, 2017 4:39 am

I find decication of seeds = resistance to low temperatures.

david zlesak
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Re: Cold hardiness of seeds as a predictor of cold hardiness

Post: # 66663Post david zlesak
Sun Dec 17, 2017 9:22 am

This is a great line of research to pursue. Years ago Dr. Leo Dionne on our RHA newsletters (a researcher from Canada that worked with potatoes and other crops during his career and got into roses more in his retirement) had this to say from his general experience. He found that generally with the wild and hardier rose hybrids he was working with that as he would try to gather seeds later in the winter or spring and try to germinate them that if the canes the hips were on were killed by the cold the seeds generally were too and if the stems were alive, the seeds still generally had viability.

That's a good point Johannes about drying adding to ability to survive cold better. From my understanding how much water is in cells, where it is distributed in cells, and what is dissolved or not in it impacts freeze injury and how low of temps can be tolerated.

pgeurts
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Re: Cold hardiness of seeds as a predictor of cold hardiness

Post: # 66664Post pgeurts
Sun Dec 17, 2017 9:34 am

Donald,
I haven’t heard of any studies testing if the cold tolerance of mature plants is also expressed in the seeds. But I have read of people collecting seeds in the middle of winter that had success in germinating the seeds. This would make sense from a survival point of view that seeds left on the plant over winter would be viable in the spring. My feeling is that the cells of a cold hardy plant will protect themselves from severe cold no matter what stage of live they are at, because they are genetically programmed to do that.

I froze some seeds several years ago, not to test for cold hardiness, but to test if freezing was a good way to delay germination of the seeds. I collected seeds from three different varieties, one was an R.blanda x R.rugosa hybrid and another was a second generation r.arkansana hybrid. Those two had cold hardy species in their background and I expected them to survive and germinate. I dried the seeds first and then froze them at 0F for two months. I then warm stratified them for one month before cold stratification. I stopped the test after two months cold stratification because I was moving and had to concentrate on that. There was some germination of the third variety and I believe there would have been more germination if I had continued the test. I didn’t save those seedlings so I’m not able to observe how cold hardy those plants are.
Paul Geurts
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donaldvancouver
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Re: Cold hardiness of seeds as a predictor of cold hardiness

Post: # 66665Post donaldvancouver
Sun Dec 17, 2017 12:14 pm

Thanks very much Johannes, David and Paul. I think I will pursue this next year.

I collected some single-flowered rugosa seeds in Alaska one year, dried them completely and threw them in the freezer at normal household freezer temps (around -10 to -15C, I think.) They started germinating as soon as I re-hydrated them at room temperature, and had one of the highest germination rates I've seen.

d
Zone 8, with warm dry summers, cool wet winters. Southern Gulf Islands, BC

doug wild
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Re: Cold hardiness of seeds as a predictor of cold hardiness

Post: # 66666Post doug wild
Sun Dec 17, 2017 1:16 pm

Donald...Is it possible for a breeder in a warm climate to breed roses for cold temperature hardiness? I think David Austin accomplished that with Wild Edric.
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Hansa (left) Wild Edric (right)

donaldvancouver
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Re: Cold hardiness of seeds as a predictor of cold hardiness

Post: # 66667Post donaldvancouver
Sun Dec 17, 2017 1:28 pm

Doug- Sure it is- Wild Edric is a great example.

The problem with doing so in a warm climate is identifying which of the F1s are cold hardy.

Felicitas Svejda was able to demonstrate that hardy x hardy = hardy. That's simple. Where it gets interesting is when you cross hardy with tender. She found that the offsprings' hardiness was distributed on a kind of a bell curve- a few were fully hardy; most were half-hardy; a few were tender. So in my program, I'm crossing hardy with tender (because I can), and I need a way to select for cold-hardy F1s.
Zone 8, with warm dry summers, cool wet winters. Southern Gulf Islands, BC

pgeurts
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Re: Cold hardiness of seeds as a predictor of cold hardiness

Post: # 66668Post pgeurts
Sun Dec 17, 2017 2:48 pm

Donald,
I remember you mentioning the good results you had with your frozen seeds before I tried my test. It gave me hope to get as good of results from my seeds, but that wasn't to be.

You mention freezing the seeds at -35C, where most home freezers are at around -20C. Do you have a place to store the seeds at -35C? Would you be able to send your plants to friends or other members in zones 3 or 4 to test their hardiness?
Paul Geurts
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donaldvancouver
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Re: Cold hardiness of seeds as a predictor of cold hardiness

Post: # 66669Post donaldvancouver
Sun Dec 17, 2017 3:21 pm

Paul- I would need a laboratory freezer—one that lets you determine the desired temperature. I'm hoping I might be able to find a local university who might let me have a bit of space.

I do plan to trial my roses in gardens across the country, using an informal network of friends and interested people. I have started this already. The challenge is in doing the first triage; I can't really see myself sending hundreds of seedlings around the country. But if I can do the first rounds of selection here at home (for health, hardiness, vigour, beauty), I can send the most promising ones for trial.

If my freezer idea doesn't work, I may just rent a plot up in Prince George or somewhere in zone 3, once I get enough seedlings to make it worthwhile.

d
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Larry Davis
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Re: Cold hardiness of seeds as a predictor of cold hardiness

Post: # 66672Post Larry Davis
Sun Dec 17, 2017 8:30 pm

Actually the freezers in most labs are either regular -20 C or a full -70. Only horticulture depts or places that do freeze tolerance tests on insects or animals have ones that span the range.

Several folks have mentioned a very important point. Dry the seeds first. Then cool them slowly. In most instances when hips remain on bushes over winter they get pretty dry, at least in a climate like mine, cold but no snow. Even with snow, the vapor pressure of water is so low that the ice sublimes out of things giving freezer burn. I would put my seeds or room dried hips, in a very think styro box made for shipping on dry ice. Then put that in the freezer. It will freeze but maybe over 2-3 days, especially if you put in a few (unfrozen) ice paks. On thawing, leve all in the box at room temp until it melts. That way you have a more natural freeze-thaw cycle.

Until 10 min ago I had totally forgotten to mention that some years back I collected a bunch of rugosa hips up in Lincoln NE in mid-April. totally desiccated, repeatedly frozen and thawed. But I got pretty good germination, as I described somewhere in a RHA newsletter maybe 3 years ago. A couple weeks ago I found more of those seed sitting on a shelf where they had been for years. I started stratification that day. So by fall we'll see if rugosa can handle overwintering, and then dry storage for years. My bet is yes, some will be viable.

donaldvancouver
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Re: Cold hardiness of seeds as a predictor of cold hardiness

Post: # 66673Post donaldvancouver
Sun Dec 17, 2017 8:45 pm

Larry- thanks very much for the advice. Hmm, -70 is a bit too cold, even for acicularis crosses :)

It will be interesting to see if your rugosas germinate.

This winter I'm trying an all-natural stratification: I have my seeds planted in trays of potting soil already, and they're sitting outdoors with good drainage in the rain and frost. The winter temps here range between about -4C to 6C, rising and falling all winter. We'll see how that shakes 'em up.

d
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Larry Davis
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Re: Cold hardiness of seeds as a predictor of cold hardiness

Post: # 66674Post Larry Davis
Sun Dec 17, 2017 9:28 pm

Curious about my own results I went back and checked. The Lincoln rugosas stratified immediately (April 16 2012) gave about 35 % germ within a year +, while those held until Dec gave the same (though actually I ran out of patience and warmed the seedpackets after 11 mo and counted final sprouts a week later). However a batch started the following Nov 20, gave 50 % germination over the next year.

With the CV Chuckles I got 50 % germination on hips harvested in March, while those help in refrig until next DEc gave only 30 %. So maybe the warm dry is actually favorable for some types.

Karl K
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Re: Cold hardiness of seeds as a predictor of cold hardiness

Post: # 66679Post Karl K
Mon Dec 18, 2017 9:50 am

donaldvancouver wrote:Felicitas Svejda was able to demonstrate that hardy x hardy = hardy.
However, Erlanson (1934) wrote, "Seedlings of R. blanda from northern Michigan segregated into tender and hardy individuals at Ann Arbor, 300 miles south of their natural habitat."
bulbnrose.x10.mx/Roses/breeding/Erlanson/ErlansonRevision1934.pdf

Karl K
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Re: Cold hardiness of seeds as a predictor of cold hardiness

Post: # 66680Post Karl K
Mon Dec 18, 2017 10:10 am

donaldvancouver wrote:Does anybody know of studies that investigate the cold tolerance of seeds as a way of predicting cold hardiness of adult roses?
Natural selection operates on all phases of an organism's life-cycle.

If the hips of a very hardy rose normally hang on the branches during the coldest winters, we may expect natural selection to favor the offspring of specimens that bear very cold-resistant achenes.

On the other hand, where the hips are generally consumed by grouse (or whatever), the achenes will usually spend the winter under a layer of insulating snow. They will not get so cold, or so dry, as those that hang out in the frigid winter air.

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