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Author Topic: PEG6000 and germination  (Read 1074 times)

P. Kohn

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PEG6000 and germination
« on: December 22, 2019, 04:44:17 PM »
The Jelitto catalogue recommends the use of PEG6000 for certain categories of seed. Amongst those we are sowing this year, it is recommended for Iris setosa ssp canadensis.  Past experience is that Irises are always slow to germinate and ofter eventually often germinate at unlikely (and unhelpful!) times of the year. Weare going to give this a try but wonder if anyone has experience of this technique. A quick trawl of the internet reveals that PEG6000 is more often used to mimic drought stress and is associated with inhibition of germination so we are intrigued to know how this is meant to promote germination in this case. Jelitto talks about it acting as a 'softening agent'.

First trial is with 20% w/v soaking for 1 hour as this is mentioned in one quoted paper (Jelitto has no information about solution strength and only a vague recommendation of 'several hours')

Jeffnz

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Re: PEG6000 and germination
« Reply #1 on: December 22, 2019, 07:16:23 PM »
We use PEG 6000 as a wetting agent (surfactant) in paint manufacture, the possible role is to soften the seed coating and allow water to pass through.
Best wishers to all for 2020.

Gabriela

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Re: PEG6000 and germination
« Reply #2 on: December 24, 2019, 05:29:31 PM »
I feel the need to point here that: substances used in the creation of PEGS (polyethylene glycols) are strong pollutants!!!
Why use them to treat seeds when it is not really necessary?

More than this Iris hookeri - the accepted name for I. setosa ssp. canadensis, germinates very well after +/- 3 months of cold-moist stratification.
Gabriela
Ontario, zone 5
http://botanicallyinclined.org/

P. Kohn

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Re: PEG6000 and germination
« Reply #3 on: December 25, 2019, 08:34:31 AM »
Sounds like the Jelitto advice is unnecessary. Our standard procedure should have been fine. Our experience with Irises is that they almost always take a long, but rather random time to germinate. The possibility seemed to be that this was a function of the hard seat coat and we wondered whether this might also apply to Aconitum.

What is involved in PEG manufacture that you feel is so polluting ?  Can you suggest other less damaging alternatives ?

Gabriela

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Re: PEG6000 and germination
« Reply #4 on: December 26, 2019, 06:51:42 PM »
Although various PEGs have large scale applications, with many very useful, one can guess just from its name PEG= polyethylene glycol, about its manufacturing.
Polyethylene = plastic and that's exactly what PEGs are, a mixture of different petroleum based compounds.

I already mentioned well known options in the Aconitum thread and will add more.

Seeds treatments are useful only when applied in correlation with the type of seedcoat and dormancy.
For seeds with underdeveloped embryos, trying to soften the seed coat has no purpose, because until the embryo grows, no germination can occur anyway.
Gabriela
Ontario, zone 5
http://botanicallyinclined.org/

Jeffnz

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Re: PEG6000 and germination
« Reply #5 on: December 26, 2019, 09:19:51 PM »
Gabriela
While I share your concern about plastic and the environmental consequences associated disposal of solid plastics the term polyethylene is generic term to define a specific polymer chain. The use of micro sized plastic beads has a greater environmental consequence for marine life but media focus has always been on solid plastics as these are so much easier to present to a public audience. Should we return to non plastic packaging, yes where ever possible. Plastics are relatively cheap to manufacture and provide a light weight  packaging option, sadly we have evolved into a throw away society, we are definitely at the dawn of a new environmental age which will see consumers needing to make choices around packaging type. Consumer driven change  is the only way to effect change.
Polyethylene plastic has a long standing use as piping, the product is stable and does not undergo breakdown by microorganisms. Some may argue that this is a negative as the product is non bio degradable, the opposing view is that the fact that this is the case then the product is sustainable,
PEG is not a solid plastic, in fact all PEG's are water soluble and some grades are used for medical purposes with no established mammalian toxicity.

 

P. Kohn

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Re: PEG6000 and germination
« Reply #6 on: December 27, 2019, 08:56:34 AM »
Thank you for clarifying this. I agree with the general principle of letting natural germination occur at its own pace wherever possible but long experience also highlights those genera and species where nature is not very successful under our conditions and where experiments seem justified if there are no serious environmental down sides which seems to be the case here.

 


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