Pardon me if this has already been posted.
I’m afraid much of the protein analysis in this study is above my pay grade, but it did help me better understand the concept of primary and secondary dormancy, vis a vis stratification temperatures.
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Thanks for sharing, another pertinent European cold germination research paper for my interest.
Noted their stated belief that commercial not keen on long duration stratifying and cycling germination research.
Still need to link their tests, noted biochemical signatures, and observation’s for interpreting my test results this year. Mine are complicated by scores of crosses that may, or may not be viable.
Key results trip for me is no visible above ground germination after first warm stratification at 15C for 28 days, after ~ 110 days at below zero C.
But germination after 9 days following 2nd cold stratification for 18 days at marginally above + C.
That real observation in my mind over now three natural and artificial stratification tests and observations of garden seedlings appearance from wild seeds at “0C” for months, puts the kibosh on “cold” ruins hardy to bone hardy seeds as a PoBS.
Kind of wonder whether it had already started for some in 1st warming cycle for this year’s crosses, and then arrested in second chilling, or still going, then to break away in second warming - never know. For me only “green” counts.
Paper seems to say no, but need re-read it for improved comprehension.
I had never heard of second dormancy but now just assume it means in nature a germination process is stop by nature until conditions improve - aka temp…
Yesterday yet another Nordic gallica - Explorer germination 16 days after start of second warming period - that cross tray left out, at now 20C. Other 60 non-germinated trays in for third 2- week cold cycle at marginally plus C.
Going to fun sorting qualitative critical path theories for this year’s coming seed harvest.
I do like this quote below from the paper. This simple qualitative discussion puts it in a nutshell for stratification vs. germination behaviour - excluding incompatible crosses. Maybe obvious, but mostly after the fact, in that by stumbling around (testing documented and natural hypothesis) I found by trial and error something that works with low efficiency so far “(e.g. prob was too high temperatures for too long)” … now maybe found too low of a temperature for too long.
What fun as winter activity in the “land of the ice and snow … From the midnight sun where the hot springs flow …” (J. Page et al).
Seed dormancy is an evolutionary, environmentally imprinted adaptive trait that prevents germination under unfavourable temperature conditions. If seeds able to germinate lose this ability due to stressful environmental conditions (e.g., too high temperatures), secondary dormancy is established [2]. Such seeds revert to dormancy and overlap until the following spring or longer, which is a beneficial process from a biological standpoint (seed banks) but undesirable from an economic one, e.g., in a nursery. For their germination,repeated stratification is needed, but this does not guarantee eventual success.
[2] Hilhorst, H.W.M. The regulation of secondary dormancy. The membrane hypothesis revisite. Seed Sci. Res.1998, 8, 77–90.
If you have trouble in work flow path - as I did in details of their practical experimental seed treatment time line - download the power point diagram in the index of supplementary data.
The methodology time line path diagram clears everything up for me. The difference in germination rates is pretty stark and dramatic as in table 1.
My germination rates are equivalent to germination rate (at 20C) after “combinational”, cold and then “secondary” dormancy experimental time line results (at 20C).
Make your own conclusions … maybe too soon out of in the 1st cold stratification at marginally below zero as in pulling too soon out of fridge. Or was fighting secondary.
I never did their formal pre-treatment to break combinational dormancy, except in the short lag time from seed harvest to dropping in fridge to the first marginally below zero stratification. Seeds at ambient during this time.
Great food for thought for next harvest.
Again thanks for paper
Addendum:
Got interested in the combinational dormancy treatment, or step 1. Never recognized it before.
A rose friend sent a paper of a Felicitas Svejda on her experiments on various seed coating treatments using chemical, mechanical, thermal and “no intervention” as they apply to improving germination.
A 1968 HortScience paper vol 3.
Effect of temperature and Seed Coat Treatment on the Germination of Rose Seeds
Quote
“In general, after-ripening treatment of 60 days at 20C, followed by 90 days at 3C promotes germination adequately in the seeds of rose species with which we are concerned in our breeding program” (Explorer Roses).
As l read after-ripening treatment basically meant damp rest at ambient by putting in moist peat moss for the 60 days before stratification. I assume this approach softens seed covering.
This step f1st major change being done next year.
What l did in past was add pearlite and seeds with ambient water addition tcondensation / mist on bag after pearlite pore absorption - never waited “days”, maybe 24 hours at tops- never thought of softening benefit vs triggering dormancy. Figured ice damage seed covering.
For late mature hips could apply change also if beat first hard freeze.
Also likely try +0C to limit to two variable change - soak and thermal level during.
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On April 5/6, after 3rd chill period ended, followed by ~11 days at 20C for 3rd warm period, my first R. laxa tetraploid version parent germinated. Young diploid didn’t bloom this last year.
And my Nordic gallica masked singing star x Ross Rambler #1 germinated.
Ahhh visions of a Bentley GT W12 in driveway in few years if color and hardiness transfers from parents to cross … but be too old to drive a 12 cylinder and live it. 
Total warm Siberian, and icy Bermuda chill time for 3 cycles between October and April was
~ 138 days (+/- 2 days) at - 4C (primary) and +4C for secondary and tertiary re-chill tests.
Total of 3 warm cycle days, - 30 days +/- 2 days (15-20C).
Plus side… by temperature cycling as Roseus suggested, managed to germinate some crosses and all OPs of target bone hardy species used by Prairie pioneer hybridizers and an Explorer / Schowalter rose with a gallica …
… grew much older during the process wait time vs giving up and tossing after first warm cycle where germination was zero.
Second chill and warm cycle gave “adequate” results to recycle again after rush of germinations ended.
Plus side now have a loose time vs type baseline experience to compare against using Svejda pretreatment method next year for hardy species and their crosses use.
Total germination score … not worth mentioning 
…
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4th cycle germination starting results after ~ 3 weeks at ~4C and a week at 18-19C.
Germination of my OPs of Nuits de Young (Laffy 1845). A color source is the reason the semi - tender in garden. Great dense bloom last summer. Makes me wonder if my Mossman and NdY are compatible.
Btw there is no logic l can crack as to why a tender rose sprouted after 4 cycles. I just now assume no seedling will be delivered before its time. Works for me like checking the post.
Good thing too that it germinated as source NdY plant shredded by winter but regenerating.
Update ahaha
In additions to NdY, 48 hrs later … 9 seedlings in one go of Schoener’s Nutkana x (Prairie Peace - Hazeldean mix pollen).
My cup runeth over in round 4. These one should be rock hardy.
Hope it crossed, with pink yellow (or apricot blend) fully double and tall tall tall and mildly prickly results … if big lucky.
And even technically more important may have finally found a hardy non- rugosa seed parent ( in zone 4A CDN) that might cross with others … this alone is a exciting reconn survey result for me from self effort.
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Wow, congrats on the sudden burst of germinations from such neat parentage! Those combinations do sound exciting. The closest I’ve been able to come to growing either Prairie Peace or Hazeldean is Musician. If the cross that produced Musician could result in an apricot color, and considering the coloring of Soleil d’Or wth its parentage, then there’s a decent chance that you could see that sort of color range in your seedlings, too.
Mossman should be compatible with Nuits de Young if it’s fertile; it had an old moss rose as a pollen parent itself.
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Yes very excited about finally getting …
- a rock hardy cross - cross still a maybe classification - that may involve a hexaploid x tetra or triploid if my homework data correct.
1a) with apparently Paul Neyron ??? grafted gene’s transfusion??? as a parent of Schonoer’s
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germinating a hardy cross in copious numbers potential (relative … to 75 seeds collected)
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Potential for interesting color mix -,see Musician photo below of bloom last year when reacting badly to transplanting in shade - SdO shading totally believable. Like a painter’s background wash before the real color is applied.
I have not tried my The Musician yet, it was moved the year to less crowded patch in shade of perennials that combined to de- stabilize the color of the bloom - also led to cantankerous spring results - as in starting over this year. Its hardy just bad reaction to transplanting and in shade.
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I haven’t had a chance to do anything with Musician yet either (mostly because it is just getting going after poking along its first summer, and will probably produce its first blooms next spring). It’s neat that even with that parentage it appears to have well-developed (and hopefully fertile) pollen, from the image that someone helpfully posted to HMF! It looks pretty nice in your photo, even if the color is dialed back a bit.
I almost forgot this, but as luck would have it, I’ve had both Schoener’s Nutkana and Prairie Peace on a custom root order since last year. They should arrive this fall. It will be interesting to see how Prairie Peace does here–there aren’t a lot of reports from climates like mine. Schoener’s Nutkana sounds like it has a large number of good qualities, both as a parent and as a garden rose.
I think there is a learning or something in cycle 4 (Oct22 to end of May - used 4 cycles of stratifications) besides don’t give up - not sure what it is.
But cyclical stratifications going to be used with #1 cycle long and heavy (-0C) at front after 30 days pre-treatment in moist ambient as per Sved of explorers way.
Now more real hardy crossings showing up today … only about 50 more crosses need to show life.
Feeling a lot better with hardy crosses finally germinating after years of dud tries.
Today
The two below today with usual caveat of a “maybe” on a successful cross.
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Tove Jansson (Finn) x R. xanthina nornalis
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R. nutkana (species ver.) x Prairie Peace (CDN)