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Re: Re: HYB: Removing germ. inhibs. pt 2


Linda,

Thanks, I have two bee pods on NORTHWARD HO that will be harvested in
about a month from now.   These seeds are going to get the Sulfuric acid
treatment.  I'll report back in about 2 months with the results of the
experiment.  

This year was the worst ever for germination so the possibility of this
working would be fantabulous ;-)

Thanks again for doing this research.
Chris
Lafontaine, Quebec Canada

Linda Mann wrote:
> 
> Chris said:
> <Caution against any mustard  compounds.>
> 
> Fortunately, BAM is British <anti> Lewisite.  It was developed as a
> treatment for mustard agent exposure, so isn't a mustard agent itself.
> 
> & added:
> <I'd be interested in the Sulfuric acid data>
> 
> To back up a little - bearded iris seeds have two (at least?) types of
> germination inhibitors.  One is in the seed coat, the other is
> embryonic.
> 
> Soaking in aerated or frequently changed water or removing the seedcoat
> removes the inhibitors in the seed coat, but chilling is required to
> remove/break embryo dormancy (also known as physiological dormancy, I
> think I read..)
> 
> Lots of different things have been used to speed up removing seed coat
> dormancy, including various mechanical (scarification) and
> thermal/chemical methods, including sulfuric acid soak to remove part of
> the seed coat.
> 
> Removing the seed coat or removing the inhibitors in the seed coat
> doesn't affect embryo dormancy, which is most easily removed by chilling
> in moist, aerobic conditions (i.e., damp but not soggy paper towel
> burrito rolls in the fridge for 3 months).
> 
> =====According to some information I read yesterday, there is something
> called heat-induced thermodormancy (defined a little differently in
> different sources I looked at) in which seed ripening at high
> temperatures or exposed to high temperatures can enter deeper embryo
> dormancy that requires longer chilling than they would otherwise.  High
> temperatures cited were 30 to 40oC (where's my calculator - I think
> that's in the 90s?).=====
> 
> The following are treatments that are known to shorten the duration of
> or eliminate <embryo dormancy> (i.e., eliminate need for chilling) in
> various plant species.   Sometimes, these treatments apparently improve
> uniformity of germination.  Some of these are discussed in Vallette's
> book & I will post details later.
> 
> 1) Gibberellin - Gibberellic acid (GA) promotes germination in many
> seeds.     Seed may be soaked with concentration of 100 to 1,000 ppm for
> 24 hours.  I think I've seen some kind of GA (rooting hormone?) for sale
> at WalMart.
> More details from another website (lecture notes, I think..): soak seeds
> overnight in100-500 ppm GA3 (better if buffered),  K-salt formulation,
> which has excellent solubility.  Pro-Gib is a commercial product that is
> sometimes used.  GA can cause seedling elongation in some species.
> 
> 2) Cytokinins - Natural growth hormones stimulate the germination of
> many kinds of seed by acting at the molecular level on biological
> processes. According to what I found on the web, "synthetic cytokinins
> are available from tissue culture supply houses,  but since they must be
> kept at a low temperature to prevent
> decomposition, they are not available in garden supply centers. Soaking
> for three minutes in kinetin at concentration of 100 ppm has been
> recommended.  Another website recommended soaking seeds in 100 mg/l (100
> ppm) Cytokinins ( Kinetin, BAP, Zeatin).  (This has been shown to
> overcome high-temperature dormancy in lettuce seeds, for what that's
> worth)
> 
> 3) Ethylene -     This gas occurs naturally in plants and has a number
> of biological
> effects, including the stimulation of seed germination. According to one
> website, one of the chemicals available to gardener to generate ethylene
> is Ethephon & another website mentioned Ethrel. Ripening fruits also
> generate ethylene, but I don't know what concentrations are supposed to
> be helpful in germinating seeds.
> 
> =====The same web site said that since gibberellins, cytokinins and
> ethylene are the three dominant components in initiating germination,
> they work best when applied together.
> 
> 4) Potassium Nitrate - Many freshly harvested dormant seeds supposedly
> germinate better if soaked in a 0.2% potassium nitrate solution.
> Somebody asked before what concentration of nitrate was recommended, &
> for how long, but  I couldn't find any details before - here it is!
> Seeds should be soaked for no more than 24 hours and then rinsed well.
> 
> Those are the generalities - on to details, starting with sulfuric acid,
> since you asked.
> 
> --
> Linda Mann east Tennessee USA zone 7/8
> East Tennessee Iris Society <http://www.korrnet.org/etis>
> American Iris Society web site <http://www.irises.org>
> talk archives: <http://www.hort.net/lists/iris-talk/>
> photos archives: <http://www.hort.net/lists/iris-photos/>
> online R&I <http://www.irisregister.com>
> 
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