HCL vs. H2SO4 acids for seed treatment

[gtarman]

Hey guys.

So I've discovered from this study that pre-treating Passiflora edulis seed by soaking in 98% sulfuric acid for 5 minutes resulted in a 94% germination rate, as opposed to the control untreated germination rate of only 20%.

After having tried to grow banana passionfruit (P. mollisima) again several times last year and experiencing zero germination after 2 months I'm determined to give nature a helping hand this time as I can't babysit/water seeds for that long.

Only thing is I've also discovered that sulfuric acid is very difficult to come by in oz, whereas hydrochloric acid can be bought cheaply by the litre at Bunnings.

I'm just not really much of a chemistry person so I was wondering what strength and soaking time I should use the HCL to try and emulate the above conditions with the sulfuric acid approximately. I'm aware that they're not equivalent, but I'm just trying to get an idea, because these seeds are sort of dear as far as seeds go.

What do you guys reckon would be the way to go?

[FragmentedSanity]

Sulfuric can be had easily enough. Mitre 10 carries it as drain cleaner (at least all the ones ive seen do). MO flo. From memory its pretty concerntrated wouldnt be regent grade, but should do the trick.

As for the question as to whether HCL would work, i have no idea, but if H2SO4 dosent kill the seeds id be tempted to try.... mind you ive seen a vid where germination was increased by almost as much by just taking the seed from a ripe fruit and washing/rubbing off the pulp then drying it out prior to sowing, so i might be tempted to just try that and avoid the chems.

Im currently having some success taking clones from cuttings of my passionfruit vines... they are just starting to form roots after a couple of weeks. The mint i put in next to it 3 days ago already has nice roots. But if you can find a vine you like i reckon clones are the way to go!

Edit: had a quick skim of the paper. Shows 86% by soaking in 10% sugar water for a couple of weeks and 76% if you just chuck it in water for 7 days. I like the idea if sugar water, but 5 minutes sure is quicker with the sulfuric.

I wonder if soaking in diluted seaweed sokution for a while days might work well and promote healthier plants.

Edited November 26, 2015 by FragmentedSanity

[gtarman]

Yeah I saw the bit about fermentation, so that might be the way to go. Not quite as badass or quic as an acid bath though lol. I just want to be an evil scientist

[ace1928]

The issue I could possibly see from HCl would be residual chlorine. Some seeds have issues with that while others don't.
With how cheap it is from bunnings I reckon it would be worth a try.
The pH should still scarify the crap out of the seed but it doesn't have dehydrating properties like sulfuric does (if that is even necessary).

You should totally try a 5 minute soak in concentrated HCl and let us know what happens. I'm pretty interested in increasing passionfruit germ rate. Have had similar success to you gtarman

[Sallubrious]

You can use food grade H2O2 (30%) to scarify seeds too. It's wicked shit so you'll need to take all the safety precautions like you would with acid.

H2O2 won't leave any residues that won't wash off easily.

[gtarman]

Also I'm kinda curious...why is it illegal/hard to buy sulfuric acid but not HCL?

[Sallubrious]

I should mention that most of stuff you'll find on the web involves 3% or 6% H2O2 for long soaks - sometimes hours.

If you use 30% you only need to do it for a few seconds or minutes at the most. After the intial 20-30 seconds you add more water to dilute it down to 3 or 6 % and then let it soak for a few hours. It also disinfects the seeds.

I've never tried it with Passiflora but it has worked on well on Acacias.

[Sallubrious]

I don't know about the issue with sulphuric acid gtarman, it was commonly used in batteries and for some types soldering flux but I haven't seen it for ages.

I have to admit I only just read that paper you linked a few minutes ago and it was a quick skim at that. I saw that the fermentation process specified a 10% sucrose solution but the details of the culture used for fermentation were non existent ( unless I've missed something, I am on 6th drink)

Maybe it was a wild fermented lactobacillus ferment with the organisms coming natural environment ie an open fermentation. It wouldn't hurt to add a starter culture to the sucrose solution to kickstart the process. A few possibilities come to mind - normal bakers yeast, brewers/distillers yeast or you could even try a kefir or kombucha culture.

If I was doing it, I'd probably opt for something simpler. Get some citric acid - you can buy it a supermarket in the baking section near the flour and baking shit and mix it to saturation point. Test it with litmus papers if you are that way inclined and whack the seeds in seeds in and soak. If you have enough seed, do several test groups and soak them for different amounts of time - 1 hour, 2 hours, 3 hours and 4 hours.

Citirc acid in powder form will only cost you a few bucks and it might come in handy for other experiments.

It's not going to have the same Pka of sulphuric acid but there would probably be some median between the energy and the time constant that will arrive at the same point.

Edited November 27, 2015 by Sally

[FragmentedSanity]

http://www.ebay.com.au/itm/mo-flow-moflow-momar-sulfuric-acid-liquid-drain-solvent-acid-x-1L-/191253218475?hash=item2c879484ab:m:mIhCN-UTbtP3MKD_GaI4qdA

Thats the product i mentioned. Pick up only in sydney, but clearly not that hard to find.

Like i said its been at most every mitre 10 store ive walked through the plumbing section of.

You can buy battery acid from auto stores, but they usually want you to buy a battery too.

You could make it yourself with a bit of effort if you are really worried about buying it, but as far as im aware its not illegal.

[vitex]

As I understand it acid treatment is just one way of scarifying seed. If its a hard-coated seed sulphuric acid works well - I've used it for thousands of seeds myself. If you want to avoid acid, you can sandpaper the seeds (put in a tin with sandpaper and shake). you can tell if you've broken the seed coat by soaking in water - the seeds swell up (imbibe). if they don't swell, rinse and repeat Even a nail file will break the seed coat enough