Very Easy Sterilisation Method - My Seedlings

[Orchid Whisperer]

The Cattleya alliance seeds (Cattlianthe Golden Wax) that I posted about earlier were sewn later, September 4, I think, but 4 of 6 flasks remain uncontaminated & germinated well (3 to 3.5 hours with the bleach fumes). The protocorms are now developing little leaf points.

I also tried 3 flasks of the same seeds using conventional sterilization and sewing methods, 2 failed quickly, the third germinated, but later developed contamination. Roby's method works much better , IMO.

[Silje]

I've done some more flasks with seeds that I can afford to lose with this method and I struggle to keep them sterile. :/ Argh!

But I struggle equally much trying produce sterile flasks in my home-made glove box as well.

How strong is the bleach solution you're using? I'm consciously using really small glasses nowadays to make sure that the seeds and the growth medium is exposed to the fumes, but within a week there has been contamination.

I'm just playing around with NOID phal seeds and other home-grown pods so it's not as if I'm losing precious plants here, and it is meant as trial and error tests.

During the weekend I opted for pre-sterilizing the seeds before I put them into the flasks, by rinsing them in bleach solution as described by Lincoln Orchid Society.

They still look clean, but it's only been a couple of days and way to early to tell yet.

Hmmm... I'm a bit at a loss as to what to change next if they also mold up...

[Orchid Whisperer]

Silje, the bleach I used is a generic type from one of our chain discount stores (Walmart). Their standard bleach is 6.0% sodium hypochlorite, the one I used is advertised as "33% more concentrated", so that would make it 8.0% sodium hypochlorite.

Although I have had good success with using this bleach for this type of disinfection (I leave exposed to the fumes for about 3 to 3.5 hours) for the first few months, I have noted that mold has suddenly developed in some of my flasks 3 to 4 months later. The seeds have developed into small seedlings with tiny leaves but no roots. I tried re-plating some onto fresh agar, followed with more bleach fume exposure, but this killed the tiny seedlings. Others I have experimentally transferred into jars with heat-sterilized moist sphagnum, and these remain alive, but still no roots yet. I have a few that are a bit older (bigger leaves, still no roots) that I may try experimentally growing on beds of live moss in glass jars, sort of like tiny terrariums.

I have one flask/jar that remains contamination-free. I will keep that jar going as long as I can, hopefully until I get some roots growing.

[Silje]

Something worth trying for your tiny seedlings living is sterilized sphag is perlite, also boiled and heat sterilized. Keeps moist, but not soggy and personally I find that it remains algae free and fresh longer, but that's just personal preferences.

Talking about bigger seedlings, I've been puzzling how on earth to do the re-plating and manage to produce clean flasks in that process. Like you say, the bleach will kill the seedlings... hmmm...this obviously still needs some fine-tuning.

I do like the idea, because working in a home-made glove box is frustrating, I think, but I'm leaning towards trying to find a friendly lab where I might be allowed to use a proper laminar flow cabinet for this kind of work.

[Fairorchids]

If you have localized infection in a flask, get hold of a magnifying glass. Take the flask outside on a sunny day, and use the magnifying glass to concentrate the sunlight on the infection.

This burns away the infected area, but leaves the rest of the flask intact.

[Orchid Whisperer]

Thanks Silje, I will see if I can find some perlite locally. It might be easier to find once spring returns here. I have also considered using sterilized coarse sand or fine charcoal.

The original experiment, to try to grow seeds using this fume method, seems to be spawning numerous side-experiments. Necessity is truly the mother of invention!

---------- Post added at 10:53 AM ---------- Previous post was at 10:48 AM ----------

Originally Posted by Fairorchids

If you have localized infection in a flask, get hold of a magnifying glass. Take the flask outside on a sunny day, and use the magnifying glass to concentrate the sunlight on the infection.

This burns away the infected area, but leaves the rest of the flask intact.

Fairorchids, have you done this successfully? I would have thought this would be difficult through the side of a flask, but I would like to hear how this worked out for you.

[Fairorchids]

My dad had an orchid nursery (in Denmark, 1950-1977). He flasked in the kitchen, and used the magnifying glass successfully (on glass flasks). Not sure whether it will work on plastic flasks, but it should.

[OCRC_Dir_China]

For the cellophane, we use to just cut a tear off sandwich bag and cut down one side. Then hold one side of the bag in your fist with about 1/8 to 1/4 inch sticking out, then just cut it off. When you open it will look like a hole in a square parachute. I use 10% bleach and distilled water solution with a drop of any liquid dishwashing soap and wet the sandwich bag to kill any bacteria, which might be on it.
One major thing though is using fresh house hold bleach and quality bleach. Not all bleaches are equal in their strength, and any liquid bleach can lose it strength, different countries have different standards for bleach so lab results can vary dramatically.

[plumania]

Originally Posted by Fairorchids

My dad had an orchid nursery (in Denmark, 1950-1977). He flasked in the kitchen, and used the magnifying glass successfully (on glass flasks). Not sure whether it will work on plastic flasks, but it should.

Sunlight through magnifying glass might actually burn and poke a hole in the plastic flask. We used to poke holes in plastic and burn small piece of paper during science experiments at home with help of magnifying glass.

[orchiddream]

can I do this with replating as my seeds arnt growing and lots of condensation in jars, they are approx. 1mm and I did them in November.