This year I unintentionally treated my seeds differently before planting. Usually, right after the seeds are extracted from the hips, I put them in damp paper towels and store them in ziplock bags in the refrigerator for 6 to 8 weeks.
This year, after the seeds were extracted, I was delayed in getting them into paper towels, although they had been stored in the refrigerator, until their last 1 to 2 weeks in the refrigerator. I was a bit concerned about how well they would germinate since I had stored seeds “dry” in the refrigerator in the past, and got very little germination. I was happy to see though, that germination seems about the same as it has always been, except that it was about 2 weeks slower than usual.
Because the seeds were in the paper towels for a shorter period of time, it was way easier to get them out of the paper towels. Some lots of seeds seem to “digest” the paper towels during cold storage so that it is a real mess getting them out of the paper towels. Next year I will try to experiment with putting a small amount of water in the ziplock bags, without the paper towels to see whether germination continues to be good.
I’ve found that some lots of seeds seem to eat holes in the paper towel too… so I switched to moist perlite in a ziplock bag and after stratification I just spread the lot on the seed bed and cover with a little extra perlite.
Some lots of seeds seem to “digest” the paper towels during cold storage
I have had this happen too. It has to be due to cellulase, as there are few other things in the world that can disolve paper and the would all kill seeds. The question is where it comes from.
When it happened this year I examined my seeds closely for visible signs of fungus, which would be an obvious source, but found none. I can’t help wondering whether certain seeds harbor native cellulases as a natural means for breaking down the pericarps.
I would worry about putting seeds + water unbuffered by any medium in a bag. Either they drown under water, or potentially dry out if water leaks through pinholes or poor zip. I have had both happen. I’d put something in there somewhere, like a rolled up, sort of wet, paper towel.
If I ever finish my review of germination it will discuss the use of cellulases to open pericarps. There are some publications on driselase, a complex mix with some in it. I think Henry Kuska has also tried proteinases. No surprise if there is some cellulase coming off the roots as they elongate. There are a lot of exo enzymes around a plant root, in the slime of the root cap especially.
My observation is that seeds kept at 100 % humidity at 4 C germinate well, even if they are not in contact with the peat medium in the bag. Sometimes I forget or am too lazy to mix seeds and medium thoroughly, but they still germinate. So that shoots a hole in the notion that you have to wash out the hormones or have them bind to the peat or other medium to get germination. (Although there are papers suggesting both these things do have an effect). It seems more likely it is (or can be) a totally internal process, if you’ve cleaned off all of the flesh of the hep.
For a long time, I have thought that rose seed germination inhibitors (which are probably either in the seed coats or in the hip pulp) undergo degradation and become germination promotors. This may occur through the action of various fungi on the rose seed coat/hip pulp.
In other threads, the range of fungi seen on paper towels has been discussed. It is amazing that some paper towels, when the seeds are removed, look like that have been pelleted with shot.
Larry, I understand your concern about too much water trapped along with the seeds. I am thinking about a scant amount - just to produce moisture. Perhap using a small slice of a sponge would provide moisture without drowning the seeds… There definitely has to be something better and faster than fighting the paper towels. It is very time consuming to wrap up the seeds when putting them in the refrigerator and then unwrapping them before planting.
that shoots a hole in the notion that you have to wash out the hormones or have them bind to the peat or other medium to get germination.
I have thought that rose seed germination inhibitors (which are probably either in the seed coats or in the hip pulp) undergo degradation and become germination promotors.
I think you are both correct. Germination seems to be an enzymatic balancing act.
Enzymes in the testa are optimal at warmer temperatures and produce abscissic acid (ABA) from precurrsors (carotenoids) in the outer layer of the testa, which leach into the embryo to maintain dormancy. Enzymes in the embryo that are optimal at lower temperatures metabolize the ABA. If the temperature stays cold for a long enough period of time the ABA degradation process in in the embryo outpaces the production process in the testa, the ABA level drops below a critical threshold and the embryo germinates.
If things warm up before that happens, abscissic acid builds up again bringing about secondary dormancy.
If the seed survives long enough it can eventually exhaust the supply of ABA precursor and the embryo can germinate regardless of temperature. From what I have seen, though, that’s a big IF.
The outer layer of the testa is the storage place for the ABA precursor and the inner layer of the testa is where it is metabolized to produce ABA. The pericarp neither stores nor produces ABA or the carotenoid precursor.
ABA doesn’t actually exist except at the boundary between the testa and the embryo at the moment it is produced. The carotenoid precursors are insolulable in water so they cannot leach away. Since the outer later of the testa is loaded with carotenoids it is water-repellant which prevents or at least retards leaching of ABA.
The enzymatic processes involved require moisture to proceed. If the seed drys out both processes come to a halt. They resume when the seed rehydrates.
Over the years I have adapted my process to limit some of these problems, including the degraded paper towel issue and limiting the amount of fungal growth in the bag. I simply refrigerate the hips, whole, in the bags until about two weeks before I plan to sow the seeds. I used to remove the seeds from hips in November and I found that at planting time, I had a mess of mold in the bag mixed with digested paper towel. It was a mess to handle. Not only that but this usually precipitated a fair percentage of seeds germinating WAY before I wanted to sow them. I am one of those who believes that it is better to germinate the seeds in the medium they are intended to grow in rather than allowing germination in the bags followed by transplanting to soil. When I had to do that, I lost a lot of these soft seedlings to disease or shock.
So now, the bagged hips remain in the fridge intact until about the second week of February and I start to clean them at that point. (I just started a few days ago) This way I can be sure that none will germinate before I sow the flats in late February, and I won’t have a baggie full of mess to deal with at sowing time. I have found no adverse effects on germination rates by delaying removal of seeds from the flesh of the hips. I make the same number of pollinations each year (about 6000) and I end up with the same number of seedlings (between 4000 and 6000) which I consider to be my capacity under my current conditions.
One last note: I have found that the majority of molds that occur in the baggies DO enhance germination, probably by digesting the outer achene layer(s) and/or breaking down inhibitor chemistry. I did a test one year where I separated a batch of seeds into two lots: one that was allowed to go moldy and one that was kept mold free by use of dilute H2O2. The moldy group germinated about 50% better than the H2O2 group. However, I also found that while the white and blue/green molds were beneficial to germination, there were sometimes slimy growths in reddish/beige colors that apparently were capable of killing most or all of the seeds of that lot. Fortunately these were rare, but I saw this happen several times. (It is possible these were bacterial and not fungal infections, I’m not sure.)
Paul, on your website you said you felt the perlite seems to offer some kind of mechanical barrier to the development of moulds around the top of developing seedlings. This is one reason I switched to using perlite in the ziplock bags instead of either papaer towel or peat. Peter Beales recommends using vermiculite with the seeds on his website too ( Search results for: 'articles hybridising breeding_roses_hybridising' | Peter Beales Roses - the World Leaders in Shrub, Climbing, Rambling and Standard Classic Roses ). The perlite still develops mould and will go brown over time (almost like diatomaceous algae than mould) but nothing like that which develops when using paper towel and the seeds stay uniformly moist without being wet. The seeds still developed mould on them but this mould was restricted to the surface of the seeds and the scarifying effect of the perlite rubbing against the seed coat when I inspected the seeds for germinants, I feel, helped keep this to a minimum. Last season was the first time I used perlite and got extremely good germination from my rugosa hybrids (Frau Dagmar OP seeds) but very poor germination from my species seeds, which I feel was more due to my inexperience than the perlite.
I think you may have misunderstood my recommendation: I use only paper towels in the baggies, but when I sow my seeds in flats, that is when I put a 1/4" layer of fine grade Perlite over the seeds, as the final covering. This layer of Perlite has been nearly 100% effective in eliminating Damping Off disease among my seedlings, to the point that I no longer use any fungicides or H2O2 to control the disease.
I do not make any effort to prevent mold formation on the seeds when they are in cold storage, except as described above in which case I leave the seeds in the hips until 2 or 3 weeks before sowing. This dramatically shortens the amount of time that molds can develop and makes handling the seeds at sowing time a lot cleaner and easier.
No… I knew what you meant… I just thought it sounded good for stratifying too as I had a bag of perlite here I could play with It worked really well so now I do it often
I have just spent hours cleaning seeds from hips as I am leaving for 6 wks next Sunday.
It gives you time to think of better ways to do things. So I thought an update after 2 years would be a good idea.
For my part I now collect all hips that discolour and those with black stems before actual harvest and I store them in sealed zip lok bags (with a little water to produce visible condensation)in the fridge.(some of them have been there for over 3 mths and have started to rot.)
I add the rest at harvest and store them in the hips until cleaning.
I use a pair of old curved bladed secateurs to open the hip and to extract the seeds. I drop the seeds into a plastic double kitchen strainer and when all are in, I grind them around the strainer with my knuckles to clean them and remove the debris.(It works very well). Then I tip the seeds back into the bag they came from and add 1ml. water per 50 seeds.
I hope this will cause condensation in the bags as it did with the hips.
I see in Pauls post above that he was leaving them in the hips almost to sowing and I wonder if there has been any updates.
I think they would be much safer in the hips while I am away but I was rushing to get things done so I did not think untill too late.
I especially like the idea that Paul had mentioned about leaving whole hips in the cold store until a couple of weeks prior to sowing time.
Taking that idea one step further…I wonder if anyone has just left the seeds chilled in their unopened hips, and then sown them directly from hip to sowing media, hence bypassing the baggy step altogether… lazy I know, but I wonder if this might work ok???
In answer to George, yes, no, maybe. I did a little unintentional experiment like you suggest last fall with a rose that I can only call Founder’s Hill Pink at the moment. It is a pink small shrub/floribunda used as landscaping at an apartment complex. It sets a phenomenal abundance of hips by OP. I harvested a lot when ripe. Some I kept in hips until late Jan. Then separated out and put in moist peat. Some I kept at R.T., others cold. My amazement- germination happened at R.T. to several %, in few weeks. Not in cold of course in same time. Now we’re playing out the rest of the story over 6 mo or so to see which way gives better total germ %. The R.T. germ stopped after month or so, then those went into cold. SO was the cold storage of hips equivalent to cold storage of separated achenes? Would this work with other CV? Will the net result be better? Stay tuned.
I did that George, and so far it sucks. 18 seedlings out of 12 trays. Seven and a half weeks in the greenhouse so far and just now getting two-three germinations per day. 56F in the greenhouse this morning and now over 80F. There are 25 seedlings growing in last years 10 trays and a new one just popped up yesterday. Next year the seeded trays are going in a refrigerater about late Dec. I did the baggie thing last year without anything but seeds and some pulp and they did great. So what if a hundred or so germinated seeds became broken(first time clumsy), it was a lot better than this year. Sooner or later all of these seedlings end up outside and later seems better around here after the waves of bugs and disease have passed. The growth seemed about the same.
One of the top UK breeders has mentioned elsewhere that the single most important factor in the successful germination of rose seed, is actually application of bottom heat to the sown seed!.
I read this about six months ago somewhere on the net. Since this information is coming directly from someone involved in the commercial side of the rose breeding industry, I believe it is significant, and looks to be a very key “ingredient” that may have been overlooked.
On this forum, it is interesting and significant that Micahel G recently also noted a similar observation, which is corroborative evidence, not that I ever doubted the original comments of this very well known UK breeder.
I noticed that there are “rotten” hips that vary from soft mush to dry brown and hard. They are very easy to clean & end up as dark “weathered” seeds by comparison with the fresh white seeds from “sound” hips that have to be forced out.
If they are as fertile as “normal” seeds it would make life very simple to leave the hips until ready to sow, then extract and sow at a convenient time, avoiding all the risks of stratification with seeds in all sorts of mediums to acheive the same result
Is there any information on the germination of seeds from these rotten hips?
Do the moist rotten ones end up as dry hard hips or just become more mushy over time.
I am speaking of hips that are rotten when taken out of bags to clean the seeds. They may have been stored in the fridge up to 3mths
Since I collected seeds as they discoloured as well as when they ripened I dont know precice history but the state of the hip is obvious when cleaning.
As an afterthought, the “dry rot” is a lot better to handle then the wet mushy stuff, it may be worth leaving the hips to dry to a certan level before putting them in the moist storage bag atmosphere(I often have this happen when hips are left in the collection boxes for a few days). These dry hips are great to handle, once opened the seeds can be rolled out with thumb pressure and virtually clean as you go.
The rotten ones just become more rotten. The dried hips develop from gathering green and trying to ripen in a sun room and after time in a baggie with water become soft. It’s a fast way to find seeds if any but the last time I’ll try it. Some good ripe hips stored in a baggie in the frig. for six months also rot, up to 50 percent each baggie. The black seeds didn’t look good to me and I was over two weeks late starting so even when thinking of a comparison run didn’t take the time.
George, tried bottom heat on two trays last year for a few weeks and nothing happend. Also tried seeds in a glass of water at room temp. this year on leftover seeds and finally discarded.
Also had some dry seeds in the frig. for nine months and they where the first to germinate and continue to germinate but only about 10%. There where some fresh seeds sown and some lots are starting to germinate but the temps. are about the same as a frig. almost 60F at 11am.
With everything different than last year Mycorrhizal Fungi was added to all the trays. With a maybe five or six month growing season timing counts for a lot and living in a rain forest doesn’t always suit me.
It worked really well so now I do it often