The follow-up.
Download the full text at the site below to see my enzyme experiment
https://www.researchgate.net/publication/282330944_Improvement_of_Rose_Germination_with_Household_Enzymes
Here’s one from today that I’ve been waiting on to harvest.
(OTB x 11Z29) x “Fire 'n Spice”. This breaks down to (Outa the Blue x (Prairie Joy × Knock Out)) x (unknown × Belle Poitevine). Some good genes here in this one too.
“Fire 'n Spice” is completely disease free here in BS central. I’m finding that there is some fertility using its pollen.
All that is left to harvest are OP seeds.
Thanks, RBaxter.
Thanks, Henry.
Rob, I had Fire 'n Spice for a while. Couldn’t get anything from it, I think, and I no longer have it. I can’t remember if I ever planted it outside to see how it performed in this climate.
So, about the enzyme thing. Hmm. Henry’s research seems to imply significant improvement over tap water. Is this cold stratification thing all about weakening the pericarp? I remember when I misguidedly soaked my seeds in straight and strong bleach solutions. I’m sure I killed many seeds, but there was one rose whose seeds responded very well to that near-toxic treatment…they were big seeds. I haven’t found out yet if that rose’s seeds will germinate as well under conventional stratification.
Hi Joe. Just saw that I hadn’t responded to your message. I’m looking forward to seeing what I get out of Gaye Hammond. I’m hoping that yellow and resistance will be carried forward.
I received pollen from Morden Blush x Hazeldean so I don’t know what it looks like.
I share your concrens about resistance of Campfire so I’m trying to match up with other hardy and resistant cv. I agree with you that something hardy should come from my Canadian Shield x Campfire. Showy would be cool.
I had not seen the article on this page before now, but the timing is interesting. Last month I came across a recently expired bottle of Sporacidin which is a mix of enzymes – I believe, amylase, protease, and lipase – and I wondered if it might be something to try in solution to soften the sutures on some seeds. I decided that the results, inevitably, would be akin to Joe’s bleach experiment, and would probably kill the embryos since I had no idea as to what kind of concentration (I assume very weak) nor timeline I should aim for. But now ya got me thinking there might be more validity to that crazy idea… I suppose it would have to be a soak and then a very thorough rinse prior to germinating – I am quite sure any remaining enzyme would do-in an emerging radicle, should such emerge… Henry, do you think there is potential merit to such, or would I just be killing seeds?
philip, I would first try on some non important seeds. However, the drain cleaner method has been demonstrated to work so you might want to compare the two methods to see which is better.
I doubt that amylase would have any effect on anything because there is no free starch in the achene outer coat. It is all pectins of one sort or another at the suture. that requires a pectinase such as the drisilase mixture contains. Lipase would not likely get into the actual seed coat. I have no idea how long it might survive in the environment of stratification. The protease is hard to predict. It may be a very general one. Ordinary laundry detergents have had these enzymes added for quite a few years. The surfactant in the sporicidin is the most likely damaging material in the whole pot. The on-line materials data sheets (MDS) don’t really tell what it is. Very likely something quite cheap and very harsh such as sodium lauryl sulfate
It’ my personal belief that very few rose achenes are limited by the physical encasement. It is much more likely to be something like abscisic acid (ABA) keeping the embryo dormant to prevent swelling which would pop the achene open. that’s why Don has success with taking the outer layer off. The hydraulic pressure of water entry into the seed is very powerful. Maybe you’ve seen pictures of weeds pushing up through asphalt or mushrooms lifting concrete.
I have found that soaking achenes in plain water for a couple of days - ‘imbibing’ - is enough to completely hydrate the embryos in all cases.
As Larry points out, hydrostatic pressure is a powerful force but apparently not enough to split open achenes. The reason for this is that the achene forms around a fully hydrated embryo so that the embryo occupies a volume that accommodates it. Imbibing fresh achenes does not further increase their volume unless germination initiates, which can’t happen until the ABA is gone. Embryos in achenes that are dried after harvest shrink a lot and simply expand to their original volume when rehydrated.
My personal opinion is that the key to initiating germination is removing ABA and providing aqueous oxygen. You do that by removing the testae or by flushing the ABA away as fast as it forms in the testae (which stores the precursor to ABA, not ABA itself, and generates ABA at a steady state enzymatically). If you are not going to extract the embryos and remove the testae then flushing the achenes with ice cold water on a continuous basis is the next best course. ABA is water soluble while the ABA precursor is not so you have to keep up with removing the ABA over time.
Sorry i wasn’t clear enough. I didn’t mean that simple hydration (imbibition) would split achenes, but the swelling that results from the uptake of water during the initiation of germination. That is when the cotyledons begin to enlarge so that they can open out, turn green and begin photosynthesis. A quick cheap way to watch this process is with sunflower seeds. I germinate a lot of them to use in a teaching lab. The root emerges without opening the achene larger than the size to let a root out. Only when the stem pushes above ground and the cotyledons begin to swell does the achene pop. Sometimes it splits all the way but mostly the cotyledons slip out one side and then expand. For a few % the achene doesn’t fall all he way off and the true leaves force their way out. (These are hybrids grown for oil so maybe not exactly what would happen with a wild one.) Still germination and emergence in vermiculite is better than 90%.
The observation that calcium nitrate speeds germination shows clearly that stuff gets in through the suture, or perhaps directly through the stomates in an achene. Also kar1 in solution stimulates germination in at least a couple rose species (by no means all). so it’s not just nitrate that can get in. I found that vacuum infiltration of water or nitrate was of absolutely no benefit in speeding germination. Just a day or 2 in water is as good, or stratifying in moist vermiculite.
I struggle with what I consider to be low germination percentages. I haven’t kept good enough records to give you exact numbers, or maybe I could but I’m too lazy to go back and do the detective work. But I’d guess 15%.
Every year I try some crazy new thing wholesale. There are just so many different factors. For example, after shelling the achenes and before stratifying I would usually place the achenes of each cross (I call them “seeds”) in a cheap ziploc sandwich bag. When I completed all my shelling, which might take place over a month span, I would do whatever for stratifying. Therefore the crosses with a ton of seed might remain moist in the bag but those with fewer seeds would dry out. I’m thinking that, based on stuff I’ve read mostly here, it’s probably better to never allow your seeds to dry out because that might initiate a deeper dormancy. Then again I had some seeds from a friend in a desk drawer dry in a baggie for 8 months before sowing and they germinated as well or better than mine.
Last year I attempted the extended warm stratification thing, and also leaching under running water as Don describes. In order to solve the problem of leaching a large number of crosses at the same time, I sealed each cross’s seeds into nylon mesh teabags with a laser-printed tag inside.
I would have done the same nylon mesh bag thing this year but when I got started I thought perhaps it would be beneficial to never allow the seeds to dry out. It wasn’t practical to print my laser tags one at a time and do it as I went, so I started putting a couple of spoonfuls of moistened activated carbon into each bag. Too much to fit into a tea bag so now I can’t really do the teabag thing.
I had ordered the activated carbon because I had the following plan, based on Don’s wisdom. I would set up a pail of water with an aquarium bubbler and activated carbon as a filter and immerse the seeds in that for…how long? two weeks? until germination? …and at what temperature? If I was bubbling it for oxygen could/should it be at room temperature? (based on Don’s statement that cold water holds more oxygen and that warm water can drown seeds of oxygen quickly).
It’s all moot now because I screwed up the mesh bag plan. Also, I guess I don’t want germination now anyways. I just want a higher percentage germ in the spring. Plus I really need to sow the seeds before many of them germinate because I have so many crosses that it would be a nightmare keeping them straight if I can’t transplant all the seedlings of a particular cross at the same time. January is the best time to sow the seeds, for me, because I have time them. If I wait until closer to spring I’m possibly too busy.
But maybe in the future if I can do the mesh baggie thing I can wait until a little closer to spring, then do a two week cold bubbler immersion with activated charcoal, and then sow. Are some of my seeds rotting when they’re in germination mix during the cold stratification period?
Too many questions, too many variables. Maybe too many answers, too, but I’m glad to hear any you might have.
‘Germination percentage’ is a terrible metric when it is defined as the number of achenes from a hip that germinate. It ignores two not so obvious facts.
Many achenes have no embryos. Often times most achenes have no embryos. Sometimes no achenes have embryos. The float/sink screening method whereby freshly harvested achenes are soaked overnight in cold water and floaters are discarded is 98.5% effective in eliminating achenes with no embryos. It is not 100% effective.
Many embryos are infected with pathogens before they are harvested which is to say the pathogen is intrinsic to the achene. Sometimes I can tell the radical is infected such that the pathogen appears to have entered through the funiculus but most of the time the pathogen breaks out all over the embryo. I highly recommend the use of systemic pesticides to prevent such infection.
If you screen your achenes for floaters and have been rigorous in your pesticide regimen then germination percentage is a more accurate metric and higher in value than it would otherwise be.
cold bubbler immersion with activated charc
It’s really easy to overthink the stratification process. Nature does it with snow. I don’t stratify my seeds but if I did I would consider laying them out in polyester mesh bags with no media under a pile of snow all winter making sure the snow stays piled on them until spring thaw. Temperature control is a problem in Frigidsota for which I have no advice.
Thanks, Don. I appreciate your advice and insight.
I agree that outdoor stratification would be ideal except for the whole -30F thing we get here. The natural leaching in a more temperate climate would be a big advantage. Mice would be a risk factor.f
I notice you avoid saying fungi and fungicide but I assume you primarily are concerned with fungal infections. Systemic insecticides would probably not be a bad idea, either. Those little grubs that look like seeds and bore into the hip are probably spreading fungal infections as they go and perhaps killing seeds directly.
Joe, I did avoid specifying which diseases I have seen on account of I have no idea except, sure, fungii are a significant factor but so are bacteria. Some embryos get coated in slime, some go pink like serratia marcescens, some get fur coats, some disintegrate into fluid. It’s downright discouraging. I speculate that bacteria are post-mortem most of the time but I’m not a pathologist. If you can concoct a defence against bacteria I’m all in favor.
Purists will say that diseases weed out the weak and good riddance. There is a lot to be said for that but when you are trying to fix a physical trait like a blotch or architecture or pigment or pricklessness or pickle warts you can work on health and vigor later in the process especially when you are resource constrained.
This paper may be of interest to those interested in germination:
http://hortsci.ashspublications.org/content/25/7/786.full.pdf+html
These are the papers that have cited the above paper:
https://scholar.google.com/scholar?cites=1675964414649156554&as_sdt=5,36&sciodt=0,36&hl=en
This paper may also be of interest to those interested in germination:
http://journal.ashspublications.org/content/120/6/953.full.pdf
These are the papers that have cited the above paper:
https://scholar.google.com/scholar?cites=10410405389063093468&as_sdt=5,36&sciodt=0,36&hl=en
Here is the download PDF link for:
Title: “Breaking seed dormancy in oil rose (Rosa damascena Mill.) by microbial inoculation”
https://www.ajol.info/index.php/ajb/article/download/92310/81761
Thanks so much for these papers, Henry. Very good information. Well written and detailed, but accessible to the non-scientist like me.
(Note to clickers: those are download links. After you’ve clicked seventeen times and it doesn’t open a new tab check your browser’s download folder to find seventeen copies of the article.)