I did a germination test for seed that have very hard and impermeable seed coats, so an inability to germinate. I made a mechanical scarification and chemical scarification, to try to turn impermeable to permeable seed coat. When I did the mechanical scarification, I damaged the cotyledons, or embryo, and chemical scarification with sulfuric acid and oxygenated water, some seeds germinated, but after a while the root has stopped growing.
I agree with Rajaram, sulphuric acid is a good method (and definitely less time consuming than sand paper), but timing requires optimization - from my experience with some species it's enough to use H2SO4 for as short as 1 min in order to break the seed coat and avoid damaging the seeds at the same time. Also - I know, it may seem trivial - rinsing with sterile distilled water numerously (5 times is a minimum) is essential after the sulphuric acid treatment.
15 years ago my Japanese colleagues were making mechanical scarification after freezing seeds in liquid nitrogen. Seeds inside the coat were hard as stone, and coats were fragile
Sorry, it was a commercial KnowHow. Applied by several seeds companies.
I've had rather good experiences with mechanical scarification up to now. Used sandpaper on seeds of 1-2mm size with an impermeable seed coat...kept checking under the microscope after a little bit of "sandpapering" so that I would not overdo it and damage the seedling. One does not need to uncover the seedling entirely...when it's enough to allow water to soak through, the seedling should be able to do the rest itself.
Ad Alex' comment and your question about freezing duration: given the extremely low temperature the seeds are frozen at when using liquid nitrogen I would assume that duration shouldn't matter that much. If you give it a try, please let us know how it went.
Cheers
I did the mechanical scarification with sandpaper and my seeds are small its took me a lot of time for scarifiers, I will tray freezing seeds.
Dear Massakib Bekkaye ·
You need to standardize the duration of H2SO4 treatment. My seeds got damaged at 30 mins of treatment. I got good seed germination in 10 mins treatment. After that I used to soak it in sterile d.water for half hour and then I have inoculated into M.S Medium.
I agree with Rajaram, sulphuric acid is a good method (and definitely less time consuming than sand paper), but timing requires optimization - from my experience with some species it's enough to use H2SO4 for as short as 1 min in order to break the seed coat and avoid damaging the seeds at the same time. Also - I know, it may seem trivial - rinsing with sterile distilled water numerously (5 times is a minimum) is essential after the sulphuric acid treatment.
i think seed germination is dependent to its seed characteristic (include its coat), sometimes its need particular heat or cold temperatures, or even acid solution, try to freeze or give acid solution, or both, but i think using acid solution like H2SO4 are more common for many seed to initiate the germination but i think you need to set the concentration of its acidity, or contact time to get desired result ,,keep trying :D
Hi, Massakib, which seeds have you used? What is the seeds size? i agree with Joanna, H2SO4 treatment must be quite short, but this alos depedent from seeds size. For some seeds 2-3 minutes will be wnough, but for some you need much longer treatment. Have you netrilize H2SO4 ? Have you perform cold tretament after soaking?
Good luck!
I did treatment with acid H2SO4 at different times, 1 min, 5 min 10 min etc.. and before the treatment I put the seeds in the freezer at a temperature -4 °
Small seeds are damaged even in the treatment of a minute
large and medium-sized seeds, some seeds have germinated, but the roots stopped growing.
In an endozoochory study in which we simulated different steps of digestion by ruminants and horses, we generally found higher germination percentages and rates for impermeable seeds when using chemicals. In our case we used HCl and the combination of HCl and pepsin (simulating stomach fluids). We put the seeds in an HCl solution with pH 3.5 during 15 minutes and rinsed them afterwards with destilled water.
@ Tanja Milotice: ok thank you , I will try it , but just a question: you said that you put the seeds in an HCl solution during 15 min , what about the combination of HCl and pepsin ? you mean I have to do a treatment with HCl followed by treatment with a combination of HCL + Pepsin?
Hi Massakib,
Do you know which species the seeds belong to?
Another method for rendering an impermeable seed coat permeable is thermal scarification. You could try immersing your seeds in boiling water (100 °C) for various durations, ranging from few seconds up to 1 min maximum and then sow them directly in petri dishes. I'd suggest you give it a try! Cheers :-)
One thing you cold also try that can be less detrimental than sulfuric acid is a heat shock treatment. Just drop your seeds in boiling water for a minute or so and then transfer them to cold water. That might also require some adjustments but it should work. The heat shock will then produce cracks in the seed coat allowing the seeds to imbibe and germinate up to satisfactory rates. If your seeds are big enough and you decide to scarify them manually with sand paper try to avoid the hilum region. Cheers
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