Forced Germination - preparing onco seed

[PeterT]

FORCED GERMINATION
I started soaking onco seeds on boxing day and cutting them the day after, about a third have started to germinate in the warm without even being chilled, I took some pictures of the procedure. The seeds were soaked for 24 + hours with some detergent and chlorine (very dilute).
Then I wiped the sink with bleach and put some chlorine solution in it. I work in a baisin in the sink. It has water and a 'milton' sterilising tablet in it, also a razor blade. Each lot of seed is put in the basin with it's lable, and I scrape the cover off the pointed end of the seeds where the aril sits, then I cut off the tip of the seed to open the hole where the embryo emerges from. The cut seeds are put in bags with perlite and a little water,  in the warm for a week then in the fridge for a month unless they already start to germinate. I decided I had not cut enough off this seed and cut a second slice which is visible on the blade. The hole in the slice is shows quite well.

[PeterT]

A better picture of the second slice off a seed. sometimes it is difficult to decide how much to cut.
and a picture of the seeds in their bag after cutting.

[Regelian]

Peter,

great series of fotos.  You've really captured the procedure. (mind you, I use a scalpel knife, double edge razors are not only more difficult and dangerous, but almost impossible to find these days!) The shot with the little hole into the endosperm is absolutely spot on.  I always try to get this 'look', as I find less doesn't seem to trigger germination in many species, although AB hybrids appear to be less fussy.

I'm amazed you had such fast germination on some.  What seed germinated so quickly?  I've just started soaking my seed yesterday.  Today and tomorrow I'll be doing some slicing and dicing.  Getting just the right amount off the seed has proved important for me.

This is such an exciting event, getting these seeds to spring into life, don't you find.  Off course, there is a bit more to get the flower.

Jamie

[Tom Waters]

Excellent photos, Peter--a very nice resource for those wanting to learn this procedure. Where will you be growing the germinated seedlings?

[BULBISSIME]

Super Peter 
Thank's for sharing this technical pictures, always better than a long text 
we're waiting now for the babies... and the flowers 

[Maggi Young]

Folks, I've split this most interesting thread off to make it stand out.

 See also here : http://www.srgc.net/forum/index.php?topic=847.0

[PeterT]

Once one knows a trick and can do it it becomes easy though of course things can go wrong!
Tom I shall grow the seedlings in my kitchen for the first few months. It gets no direct sun  and is quite a cold room. The problem with oncos is how to create good growing conditions for mature plants- I desperately need more space for frames next winter!- any one with space I can use locally??
 The seedlings are extra delicate produced this way, I shall post some pictures of the procedure I use for dealing with them.
Thankyou for the compliments Jamie, Fred, Tom, - Maggie I thought people might be interested in seeing this 'reliable' method of germinating onco seed. I have germinated them tradditionally and it can be done that way.
I think over 50% have started germinating before cold treatment, I feel this is exceptional, I would have expected about 10%. Possiably it's due to not keeping the hot water tank hot all the time -so the temperature has fluctuated. about 2% have developed mould and been discarded, taking pictures probably cost in hygene, so did running out of boiled water for the perlite and hunger.
The species I am germinating include acutiloba forms, paradoxa forms, barnumae forms, ibericas, meda, gatesii and some more southern species too.
I have also cut a few Juno seeds as an experiment and some pogons( junonia and trojana), one lot of trojana has started so far.
 There is no pattern by type of onco as to which species have germinated quickley. nor is there a pattern according to the age of the seed. Some I sowed 5 years ago, and after no germination for three years I gave up and sived the seed out of the compost. It has sat on a table for two years and has now started to germinate. some is this seasons seeds. I have not kept any of it in the refridgerator.
Jaimie, if you don't cut enough off the seed the wound heals over and the scab prevents germination, the scab can be cut off to allow the process to work. I have done so successfully.
Every seed is different and one has to use instinct on how much to cut, but I agree with Jamie that I like to see the hole in the centre of the cut.

[JohnLonsdale]

The small white dot you refer to as "the little hole into the endosperm" is actually the embryo.  You need to be careful not to slice off too much of the embryo or you will negatively affect root formation and also risk expelling the embryo.  The increased hydrostatic pressure exerted inside the fully hydrated seed will push it out like a pencil lead.

Best,

John

[Hans A.]

Fantastic pics Peter!
Thanks for showing the procedure!
Just to keep in mind - there is another very interesting thread about germination Iris where among many other grower Rafa and John show superb pictures about forced germination: http://www.srgc.org.uk/smf/index.php?topic=847.0

[LucS]

Peter if I understand you well, you cut of the aril plus a small amount of the seedbody itself ?

[PeterT]

Thankyou Hans, you are very kind. Amoung these seeds are the kirkwoodii that you gave me at the species group day two years ago. I shall go back to read the other thread properly.
John,  I had a suspicion that was the case but I make no claim to be a botanist. I'm pleased to learn though. I'm just a gardener who likes the difficult plant as well as the easy ones. I did not know you were on the forum, and pleased to meet you again.
I have just read your post from a little over a year ago and I would concur that the mouldy seeds are in the wettest bags, I have just been adding dry perlite to them. Your article ( in the aril soc journal?) a couple of years ago was very interesting- how have the plants matured? Had I known of your posts I would have modified my techniqe a little as your suggestions are very helpful.

Luc, the aril and seed coat is an obstacle which I scrape off before cutting a slice off the seed.

 In the post I refer to, John suggests the seed coat is a source of (?fungal) infection. The surface of the seed is removed over the tip of the embryo, about the thickness of a piece of paper. too much will kill the embryo as John points out, too little and the wound heals -preventing germination as Jamie mentioned.
I am amazed that now the majority of seeds have started without chilling. 3 years ago when I last did this most of them needed a few weeks in the fridge. I hope it is not because I cut too much? The first seeds look as if they will be ready for pots by the end of the week

[PeterT]

It is interesting to see how much of this information and more that Rafa, Hans, Fred, John and John have provided in the other thread, of which I knew nothing. In 2007 I achieved 180 plants with forced germination on about 200 aril (mostly hybred) seeds. Some are still here but I had more than I knew what to do with!
The ones I am growing this time are mostly species though there are a few of Pat's hybreds, Harold Mathes's, Laurence Ransom's and Sharron McAllisters.
I am working hard on providing space so that these ones are not neglected!
 
One of the less promising looking bags is Iris gatesii x afghanica has any one grown this before? It sounds an amazing combination!

[PeterT]

Some pictures of seedlings this evening, I have been lining them up in perlite. Ideally they would be in individual pots but space is at a premium, I am going to give them a little bottom heat and put a little phostrogen in the water. In the one picture of 5 barnumae seeds two have gone mouldy. Several bags that were too damp had most or all seeds rot. I shall definately err on the dry side next time. Also I think the most damaging thing is contact with condensation in the bags so I shall probably bag the seeds sown in pots next time as John suggested

[PeterT]

a few more pictures including the placing of the seedlings

[Hans A.]

Thanks for your superb pictures, Peter! After seeing your results I think I will try forced germination again.