I am thinking about experimenting with sulfuric acid treatment of Cornus mas seeds.
I have never done this with any seed before. Does it remove the need for both scarification AND stratification or is that seed dependent?
From what I have read Cornus mas seeds need about five months warm stratification followed by three months cold. Supposedly the five-month warm stratification allows for microorganisms to degrade the surface of the seed making it penetrable to water. The acid is supposed to replace this part of the procedure (if I understand it correctly). Would I then just cold stratify the seeds or is that still necessary?
It does not eliminate stratification requirements to any seeds. At least cold stratification. I never heard of a seed needing warm stratification. In the case of Rubus seeds if you didnāt use acid, it will sprout in 2 years. But it may only need 5 months, getting 5 months the first season would be hard, so it usually sprouts the 2nd year.
Rubus is tough as the seeds also need light to sprout so cannot be buried.
Also I have grown Cornus mas seedlings and they need 6 years to fruit on average, a minimum. I have a couple seedlings that may take 8 years? Three did fruit in 4 years, the rest out of 14 of them fruited in 6 years, except for two. Fruiting is sparse the first few years.
The two unfruited trees are now 7 tears old. Hopefully next year.
The acid could help with scarification but it wonāt reduce the need for stratification. What concentration of Sulfuric acid are you thinking about using? Concentrated sulfuric acid would destroy the seeds. Youāre going to need to use a diluted acid. I have worked with concentrated sulfuric acid and itās not something you want to handle without PPE and reviewing the SDS.
Several suggestions:
I would join the Facebook group for Cornelian Cherries (cornus mas). People there are starting cornus mas from seeds for rootstock or breeding.
Why are you starting cornus mas from seeds? If your wanting rootstock or just to make a hedge for decorative use this is a reasonable approach. If your growing it for fruit you really need grafted trees. It really takes too long to grow them from seeds and the fruit quality isnāt as good as you get from grafted trees. I planted grafted trees and it took 4 yrs to get a small crop of fruit.
I have āPlant Propagationā by Alan Toogood. For cornus mas propagation it recommends:
Store fruit in warm water for several days and remove seeds.
Then store cleaned seeds in moist sand for 60 days in a refrigerator.
Then sow into containers and germinate at 60-70F.
If germination fails chill again for two months and try to germinate again or leave outside over the Winter and germinate in the Spring.
That looks like good info. Cornus mas though is a lot different than the other dogwoods.
Here I stratify seeds in an unheated garage over winter. Works well and I can keep moist and no soil in the fridge! My only beef with the article is lack of info on sulfuric acid concentration. I also have Gibberellic acid but I use it for other reasons (larger grapes, more fruit on tomatoes).
I have found with stone fruit if you put the seed in moist paper towel for a month in the fridge the shell becomes brittle and is easy to break. The seed is re wrapped in moist paper towel and kept moist in the fridge till it germinates, than is placed in soil.
So your unheated garage would be your cold stratification? And thatās all you do to the seeds? Or are they in your garage long enough to experience a swing in temperatures (60s trough 30s)?
Iām trying to grow a bunch of rootstock for future grafting but thanks to the Facebook group listed above I now know of a nursery that sells rootstock. Given that I now have seeds I may pursue both options.
From a couple of different sources I have found online it seems like warm stratification and scarification are the same thing or rather they perform the same function. They both allow for the impermeable seed coat to be degraded and warm stratification was probably in practice long before someone tried dropping seeds in acid to see what happened. When scarification became more common the term stratification became universally understood as cold stratification. Probably.
Yeah it gets down to 25. Really you need chill hours, so anything under 40 counts.
It is warm at first till winter hits, and then warmer in the spring. I usually put them outside on my porch (overhead protection) in March. So once they can germinate from warmer temps, they are outside.
I agree, I never heard of it, but that is my ignorance. I have now thanks for posting about this.
Yes, I never knew of warm, just assumed cold. I know better now.
Oh I use battery acid btw as it is sold at any auto parts store. It is only 30% and safer to work with. Leave in 3 times longer than you would in 95% sulfuric acid.
@Drew51
For cold stratification , I was taught ā¦
,itās time below 45deg F.
But above 32deg F .
Below 32 the clock stops.
And can damage some seed to freeze when wet.
( pawpaw for example.)
Others not so much
I found this at a local Walmart. Is it suitable for scarification? (and also for acidifying soil?). I have a load of different Rubus seeds in my freezer from several species (curtesy of GRIN), and I have a poor track record trying to germinate Rubus seeds in prior occasions, so I really donāt wanna mess it up. Lots of rare species, and I need āem for my breeding project.
If suitable, how would I use it? Iām actually rather scared.
Sulfuric acid can be handled safely with care, but it does have its dangers. Wear old clothes, good eye protection, some hand/wrist covering that lets you use your fingers, and great ventilation. Have some sodium carbonate, borax, or even baking soda handy to help neutralize any spills right away.
I donāt know anything about using it to treat seeds -how strong, how long, etc. But Iāve handled strong sulfuric, hydrochloric, and nitric acids in bulk without any lasting harm. Just remember that the fumes can damage eyes, mouth and nasal areas fairly quickly.
As for acidulating soil I think thatās been discussed here in the past, and I think the uptake is that since sulfuric acid has no buffering capacity itās not well suited to most plans.
Yes you can use it for water. I not familiar with that product. I use battery acid and any auto store should have it. I found 20 minutes in 30% sulfuric acid was enough to scarify raspberry seed.
I know soaking seeds in battery acid sounds terrible,
But for some seeds with a ā hard seed coat ā this is very effective.
I soaked some ( several pounds of ) black locust
( known to have a hard seed coat ) seeds in battery acid for 1/2 hour , rinsed very well ,soaked in water over night .sprinkled with baking soda to make them safe to handle .,they swelled up with water very nicely.
Spread them around fence rows , hedge rows, field edges ,etc. ~ 30 yrs ago. Sprouted in days .
I have hundreds of nice locust trees now .!
Untreated seed would not swell up with water .
I have read way way too many scarification papers. Rubus is my focus and they have built in mechanisms to keep them from germinating (or else they would suffocate themselves). Very hard seed coats that need acid or mechanical means to break through. (birds or other critters that eat the seedsā¦and venture far away from the main plant and seeds remain in stomach acid for several hours)
After reading these studies i found that there were 3 methods that i felt comfortable doing. Hot water, bleach, and hydrogen peroxide. I wanted to bypass using acid. I bypassed the hot water due to the soak being longer at 24 hrs.
Bleach- 4 hrs
Hydrogen Peroxide- 4 hrs.
Both worked nearly 100 percent in my 77 cell trays of blackberries.
This was of course factoring in the warm stratification and cold moist stratification.
There is also the mechanical means by etching which i did not use.
For now i feel safest and comfortable with hydrogen peroxideā¦ it also seems to be favorable in other hard seed coat things like watermelon etc. Timing also seems to be of importance in soak. Less than 4 hrs results in less germination, longer than 6 hrs also results in less germination. I only relied on papers written by others to settle on my 4 hr soak time.
Perhaps there are other seeds with harder seed coats that warrant sulfuric acidā¦ im not sure. But for Rubusā¦ 4 hrs of bleach or hydrogen peroxide seem to be just right.
I also experimented with peach pits, beach plums, hazelnuts, cornelian and nanking cherries this past year. Soaking each in H2O2 for 4 hrs then refrigerating in a damp coffee filter in a ziplock bag for 3 months. When i inspected each had began sprouting in the fridge. Im new to all of these so perhaps they all do this.
Thatās good to know. As it is a safer option, at least the H2O2. Iām a retired Medical Technologist, so handling acid is not a big deal. Handling the HIV virus, etc. was, which I had to do. So itās not a big deal for me.
Bleach is just as dangerous as battery acid, so not sure why that would seem safer? It is not. I myself avoid working with bleach because of the toxic fumes.
Peach pits donāt need scarification. I canāt speak for the other seeds.
