OK, just what kind and concentration of acid is to be used for treating seeds of Opuntia, Echinocactus poly. parryi, and xeranthemoides, and Pediocactus simpsonii? Also seeking soak time. Thanks in advance
Ed J
the CACTOMAN
Acid for Seed Treatment
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esp_imaging
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Re: Acid for Seed Treatment
Which Opuntia(s)?
Not sure if there is much reliable info on acid enhanced germination for them, certainly not applicable to the whole genus.
Lots of people find them easy to germinate, if a bit erratic. I got good germination with O. imbricata with no special treatment this year within about 3-4 weeks, even though this species has a reputation for being tough to germinate.
I'd be tempted to sow a batch of the Opuntias and see how you get on. If there is OK germination, sow the rest, if not experiment with acid / chipping / stratification / wet-dry cycling or whatever you fancy or research suggests may be useful
Not sure if there is much reliable info on acid enhanced germination for them, certainly not applicable to the whole genus.
Lots of people find them easy to germinate, if a bit erratic. I got good germination with O. imbricata with no special treatment this year within about 3-4 weeks, even though this species has a reputation for being tough to germinate.
I'd be tempted to sow a batch of the Opuntias and see how you get on. If there is OK germination, sow the rest, if not experiment with acid / chipping / stratification / wet-dry cycling or whatever you fancy or research suggests may be useful
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esp_imaging
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Re: Acid for Seed Treatment
This paper seems to suggest 90min in conc. sulphuric acid for O tomentosa.
The introduction discusses reasearch suggesting different approachs for a few different Opuntias.
https://opuntiads.com/records/Germinati ... entosa.pdf
The introduction discusses reasearch suggesting different approachs for a few different Opuntias.
https://opuntiads.com/records/Germinati ... entosa.pdf
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greenknight
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Re: Acid for Seed Treatment
Fungal inoculation is another option, research has shown a number of fungi can enhance germination of Opuntias by weakening the seed coat. At least one of these, Trichoderma harzianum, is widely available as an innoculent, used to enhance growth and prevent disease. See: https://www.researchgate.net/publicatio ... ral_Mexico
Spence 
Re: Acid for Seed Treatment
As opposed to the aforementioned 90 minutes for O. tomentosa, This Paper on O. ficus-indica found a short 5 minute soak to be best, increasing 40 day germination rate to 11 times that of untreated seed. Interestingly, they found that germinating the seed in 1/3 to full strength household strength hydrogen peroxide after sulfuric acid scarification increased germination rates even more.
Hydrogen peroxide alone, without sulfuric acid pre-treatment was half as effective as sulfuric acid alone and 1/3 as effective as both. So if your not comfortable working with concentrated sulfuric acid then using hydrogen peroxide would be a next-best.
Right now I'm testing the combination treatment on O. engelmanii and O. macrorhiza, but I just started a few days ago so no results yet.
Hydrogen peroxide alone, without sulfuric acid pre-treatment was half as effective as sulfuric acid alone and 1/3 as effective as both. So if your not comfortable working with concentrated sulfuric acid then using hydrogen peroxide would be a next-best.
Right now I'm testing the combination treatment on O. engelmanii and O. macrorhiza, but I just started a few days ago so no results yet.