This past weekend I tried to expose some embryos. I couldn’t even get to the embryos. My left fingers cramped up from holding the seeds while I chipped at the outer coat with a clipper. The finger pain made me give up.
Question: for many of the seeds I chipped the seam that runs around the outer shell. Will this step alone improve germination? This much I can do. I understand the testa has anti-germination properties but if I make it easier for the embryo to push a root out through the outer seed layer, will that help?
[quote=“cathymess”]I am going to experiment with a few batches of seed:
open up seed coat seam using clippers, this doesn’t take too much work
then soak seed in giberillic acid to see if it gets in under the outer coat, and counters the anti-germination chemical in the testa.
Any germination better than my usual 20% would be welcome!
Cathy
Central NJ zone 7a[/quote]
Cathy,
I’d suggest you use gibberellic acid only on seeds you don’t care about–just to find out what it does, if you wish. Except in extraordinarily dilute solution, it can be toxic. Twenty percent germination is better than zero percent. If you’re going to be opening the seeds with clippers, you might discover that a lot of them have grubs in them or that the embryos are dead for some other reason. Some years ago, maybe ten or more, John Sheldon conducted an experiment. He was dissatisfied with his 15% germination rate, and decided to look inside the seeds. More than half the seeds had embryos that were dead of unknown reasons or of grubs. Maybe you have such a problem, and by protecting the developing hips you will get fewer grubs and a higher percentage of germination.
" Straw cellulose-decomposing microbes and Sporotrichum Thermophile agent can break seed dormancy of the specie R.brunonii. at a significant level with the maximum germination rate of 13.3%. Humus soil plus activated carbon is most suitable for seed germination of Rosa brunonii with germination rate of 76.7%"
H Kuska comment: Activated carbon is probably used to remove the germinating inhibiting chemicals. This would be safer than your suggestion to use gibberellic acid because as Peter has stated that could be counter productive (my understanding is that the concentration of gibberellic acid is critical).
I recommend organic enzyme household drain cleaners to break down the seed seam.
Use of Household Enzymes to Improve Germination
One often reads in the rose hybridizing literature that the tough seed coat of the rose seed is probably weakened in Nature by the passage though the digestive system of an animal or bird when the hip is eaten. This can now be simulated by soaking the seeds in common household enzymes. That this effect does work has been determined by a published scientific experiment which is supported by my own experiment. Recently another paper has been published in a reviewed scientific journal that found that the enzyme treatment works on other seeds.
Soak the seeds (or, if the blender was used, seeds and remaining pulp) for two days in a enzyme drain cleaner solution prepared by adding about 1 tablespoon of enzyme to 150 ml (about a half cup or 5 oz) of water. The enzyme drain cleaner should be one that states on the label that it will dissolve paper or includes cellulase as one of the ingredients. From my having poor germination from seeds that were treated with a liquid enzyme drain cleaner product that contained something that turned the solution blue, I recommend solid products that do not have a color additive. After the enzyme soak, rinse the seeds using a small mesh wire kitchen strainer. The rinse is important as longer contact with the cellulase containing enzymes may kill the seed or result in the seed being put into secondary dormancy if the enzyme drain cleaner starts reacting with your germination media and produces heat (this is another reason I prefer sand as my germination media, sand is inert).
I think Cathy wrote about calcium nitrate, but Peter replied about gibberellic acid . In either case, soaking for a period such as overnight is not the same as putting it into the stratification medium. This year I’m trying vacuum infiltration, overnight soaking, or no treatment, all followed by nitrate in the stratification medium. So far I know that vacuum infiltration does not kill all the seeds, but it will take some months to know if it is better or worse than overnight soaking or just going direct to the stratification. In principle the vacuum infiltration ought to speed up the task of getting the nitrate to the seed. I don’t think that it exactly neutralizes the growth inhibitors, but it may counteract them by stimulating some particular metabolic pathways- who knows what those might be.
Vacuum infiltration is a lot easier than trimming the achenes with tools if you want to do hundreds. Now I have to design a simple vacuum machine for regular home use. I need to see if you can by an attachment for a garden hose, maybe a spray or fertilizer applicator would serve the purpose.
Peter quote: “I’d suggest you use gibberellic acid only on seeds you don’t care about–just to find out what it does, if you wish. Except in extraordinarily dilute solution, it can be toxic. Twenty percent germination is better than zero percent. If you’re going to be opening the seeds with clippers, you might discover that a lot of them have grubs in them or that the embryos are dead for some other reason. Some years ago, maybe ten or more, John Sheldon conducted an experiment. He was dissatisfied with his 15% germination rate, and decided to look inside the seeds. More than half the seeds had embryos that were dead of unknown reasons or of grubs. Maybe you have such a problem, and by protecting the developing hips you will get fewer grubs and a higher percentage of germination.”
Peter, my original post mentioned gibberellic acid. But I couldn’t find it among my supplies. So I replaced the words with calcium nitrate in my original post. My quickie online research seemed to indicate that calcium nitrate might improve germination. I soaked a few test batches of seed in Calcium Nitrate overnight after clipping a hole into the outer seam, and will plant them today.
[quote=“cathymess”]Peter quote: “I’d suggest you use gibberellic acid only on seeds you don’t care about–just to find out what it does, if you wish.”
Peter, my original post mentioned gibberellic acid. But I couldn’t find it among my supplies. So I replaced the words with calcium nitrate in my original post. My quickie online research seemed to indicate that calcium nitrate might improve germination. I soaked a few test batches of seed in Calcium Nitrate overnight after clipping a hole into the outer seam, and will plant them today.
Cathy
Central NJ, zone 7a[/quote]
The mystery is solved. You edited your original post after I’d responded to it, making my response look a bit strange. But there are stranger things in this world.
Larry Davis’s research has shown that calcium nitrate in the strength he has recommended generally improves germination, so if the seeds are viable you should get some improvement in results.
[quote=“Larry Davis”] I don’t think that it exactly neutralizes the growth inhibitors, but it may counteract them by stimulating some particular metabolic pathways- who knows what those might be.
[/quote]
Larry, can I soak the entire seeds in calcium nitrate WITHOUT clipping a hole into the outer coat? Or does the outer coat still need to be opened up for the CaNitrate to work?
I don’t know if a simple overnight soak for uncut seeds does anything. I always have nitrate in the stratification medium. But i am testing this year to see if soaking first is better. Also as I mentioned above somewhere, I am trying vacuum infiltration. That takes advantage of the stomates in the pericarp to draw out some air.then when the vacuum in released, liquid floods back in to wet the seed inside. All I know so far is that this trick doesn’t kill all the seeds. Whether it helps will take a couple more months to determine.
I don’t do enough seeds to get results having any statistical meaning, but I had wondered about experimenting with stratification with Ca(NO3)2-soaked paper towels for several weeks, then rinsing and putting into charcoal medium to finish. (Joan Monteith once mailed me some seeds (Mr. Nash x Rugelda) that she had, on a whim, placed into charcoal. Our assumption was that they would be slow to germinate, but some were sprouting by the time I received them, and I speculate that the charcoal might have accelerated their rate of germination. I don’t recall, but I think she said they had only stratified for few weeks beforehand.)
If you decide to nick a LOT of seeds, I wonder if it might be worth investing in a rotary tool (Dremel-type), many brands of which can be had for under $20. Grinding permits you to see the gradual appearance of layers as you cut into the material.
That is a good idea, Philip. I have a Dremel tool with attachments, However, with 2 chips from a clipper I can make a hole in the outer coat seam. If that is enough, then I may not need to remove the entire outer coat.
I will try the Dremel next January, and see how it compares to the clippers.
Probably not warranted then. I do use such for larger xeric seed – A lot of these seeds have hard, waxy coats, and for things like Mexican “Buckeye”, or Texas “Mountain Laurel”, a grinder could be very helpful. Penetrating the coating at one point is all that is really needed for such. (Not sure if it’s smart for me to make seed dust from these toxic seeds, however…)
That reminds me of my laziest germination method (that has worked). Put seeds (in any condition, really, they don’t even have to be cleaned well) into an at least equal amount of worm castings. Get thoroughly wet, and leave that way for 1-2 days. Add at least 4 times as much relatively inert media – good potting soil, vermiculite, whatever – as you did worm castings, dampen if needed, mix, stratify as desired.
The benefits of this method were:
No need to weigh out and mix 25 mg of nitrates (or whatever) for a small batch of seeds, or even to have a scale
No need to clean seeds well, the microcritters will do it
No need to enzyme treat, live media will break down cellulose too
No mold or mildew problems, live media defends its own turf
Requires no precision about anything, no sterilization of anything, and uses only a couple of very common materials
Since they’re sprouting in loose media, no picking tiny roots out of paper towels, etc.
Disadvantages:
Nitrate levels may not be ideal
Microcritters may also gobble a few embryos
Cathy,
I have used the CaNitrate for I believe this is the fourth yr-since 2011. I have never even considered filing or clipping or cutting seeds. I place them in a baggie with vermiculite wetted to what I feel is the correct moisture amount and then place them in the fridge for about 7-9 weeks. And then right on schedule the seeds start germinating and I plant them in their little styrofoam cups with the end game measuring about 35% germination-however some are at 0% and a few are at 80 to 90 %. I have found a couple that germinate better the second yr., and I do not discard my last yrs seeds until the season of sprouting is completed this yr. I do have a few that do not get planted because a few randomly sprout through out the yr and I only check regularly during Jan through May-maybe once in June, but those have such a late start that the downy mildew that hits then would probably wipe them out first. Downy mildew has lessened since I have used soil Mycorrhizae and humic acids on all the potting soil. I cannot imagine that the time spent on clipping and filing seeds yields much return for time spent if all else is handled adequately and routinely.
I have never clipped a seed, or sanded it, or filed it, for germination purposes. AS Jackie says, the overall % germ varies by CV. I averaged around 80 % for R canina last year which is pretty good for that species. things with Bulls Eye in the mix were the poorest performers. Members of the Knockout family rarely exceed 50 %, for OP seeds, though in crosses with Rainbow KO pollen I often get a lot better than that.
Having nitrate in the stratification medium is the key, for me. AS I said, I’m going to see if overnight soaking with nitrate solution first helps. In principle it should, by getting nitrate into the seeds quickly.
BTW, I don’t weigh nitrate per batch of seeds. I make a gallon at a time in distilled water, which you can buy locally. Keep the solution dark and cold until use or you may get algae growing in the jug. It’s cheap enough that any left over after fall can be used to water plants. If diluted 1:1 it is equal to a standard fertilizer solution (Hoagland’s formula) that is intended to be used about once a week on rapidly growing plants. Generally I weigh out some vermiculite and add 2x that weight of nitrate solution then mix it up. Half a pound of vermiculite (~ 240 grams) plus a pint of water mixes well in a gallon ziploc bag. Keep that in the fridge and use 1 oz (weight) per batch of seeds up to 100 or so, in a zip sandwich bag. You have enough for two dozen bags at that rate.
In nature, hips are either swallowed by critters or hang on the bush until they ferment. The consequences are similar. Swallowed hips and achenes are exposed to acid in the stomach, then to ammonia as they pass through the intestines, and finally to oxygen when they “deposited”. If the hips are left to ferment, sugars are converted to alcohols and then to acids. Azobacteria in the soil also feed on sugar, absorb atmospheric nitrogen and excrete the excess as ammonia. Oxygen reaches the seeds as the mess dries.
Stratification doe not require the physical exposure of an embryo by clipping, sanding, scarifying or removing the pericarp because the pericarps will easily absorb water and oxygen.
Husk the seeds from the hip soon after harvest. Clean them to remove the pulp and debris. Soak them in clean, ice cold water (or nitrate solution) in the fridge for three days. Shake them dry in a strainer leaving a bit of water clinging to them. Seal them in a thin polyethylene baggie layered one seed deep (not balled up). Refrigerate them at the coldest setting for as many months as you can being sure that the bags are exposed to air (do not stack the baggies on top of each other). Germinate them by raising their temperature gradually to 48 degrees F/ 9 degrees C. Hold them at that temperature until you run out of patience then rinse (literally) and repeat.
If a seed fails to germinate under these conditions it had no embryo; the embryo was dead, diseased or genetically impaired; the stratification protocol was not followed rigorously; or there was more abscissic acid precursor (carotene) in the testa than the embryo could metabolize before it (or your patience) expired.
The latter cause is the reason that scarification is useless. Unless the testa is removed the embryo won’t germinate until it can outrun the abscissic acid that the testa throws at it which has nothing to do with the pericarp.
I have read of cases (can’t recall the source just now) of embryos that were too weak to push through. Cracking the achene would give them a fighting chance of escaping and growing on.
Oh, and there it is in Reychler’s report: “This experiment gives ground to the opinion I so often expressed: that with many seeds, those of orchids included, the difficulty of germination resides in the weakness of the germ that must pierce the enveloping membrane.”
