Banana, coconut, tomato...WHY

[Brian Monk]

Something I don't quite understand is the reason for these complex organic additives in tissue culture media. What is their function? Do they simply provide complex sugars? Growth modulators? Do they inhibit bacterial or fungal growth? And have any other than these 4 been used for orchid TC?

Brian Monk, DVM
Ft.Lauderdale, FL

[amyarquiza]

Surprised that one has answered your post.

These are all organic substances that provide sugars, growth regulators, vitamins, nutrients etc. Though not consistent in analysis has been very useful in the culture of many orchids. You can look at the book by Arditti (Microprogatation of Orchids) it has portions on the basic analysis of some of these.

Just consider what human and animals get from eating these stuff! Though plants have a different set of essential requirements, there are some similarities.

Amy

[amyarquiza]

Well the literature is rich in these...others have tried using orange juice, grape juice etc etc. Different varietes of banana and a lot more.

Substances like peptone were somehow deveped from the same concept.
And now there is already coconut water in concentrated form.

Amy

[Piper]

Ok! I'll be spreading peanut butter on my leaves this afternoon...doubles as sun block.

Julie

[Diane]

And a quick snack if you get hungry! (ants may be an unpleasant side effect)

[Piper]

Added protein!

Julie

[Hoa Tony Nguyen]

In making these media, people must use di-ionized distilled water (ddH2O) and this water is too pure and many things (microorganisms, plant tissue cultures) will grow poorly with this water. Even though the Knudson formulation has most of the marco and micro nutrients for plant growth, often it is not quite enough. Over the years, people have discovered that adding certain natural extracts (potato puree, tomato puree, fruit juices and especially coconut juice), the plantlets grow much better. Most of these "additives" must also be sterilized so I think their potency is disputable. However, in the case of cococut juice, I believe it is supposed to be added as fresh, un-autoclaved liquid, and that is the reason I believe it is a good supplement. It appears that there are natural plant growth hormones and other beneficial substances in coconut juice that help with the orchid seed germination and the meristem cloning process (like some compounds prevent the blackening of the tissue due to oxidation of phenolic compounds = cell death).
Cheers.

[amyarquiza]

Here's what I can get from the net from a site that's dependable.

Analysis of coconut water from USDA

http://www.nutritiondata.com/facts-B00001-01c20oF.html

Though this may be from a more mature coconut water... the substance not included in this analysis I believe which are impt in tc are the cytokinins which are important for growth and development. notice the abundance of vitamins and amino acid.

I have used coconut water in several thousands of liter of culture media and it really works well. Though there are some which we dont add or reduce the rate in order to reduce shoot proliferation.

We usually use if freshly harvested at a young stage and usually at a desired ph esp for meristem culture!

Use of ddH20 depends on the type of water in the lab's area of source. We usually make use of dH20 but we have been successful in using rain and tap water in some cases (our area has very clean water, but we often dH20).

We are talking about in vitro culture here!!!

Amy

[SteveT]

Something I don't quite understand is the reason for these complex organic additives in tissue culture media. What is their function? Do they simply provide complex sugars? Growth modulators? Do they inhibit bacterial or fungal growth? And have any other than these 4 been used for orchid TC?

Why didn't anyone actually answer the question? Okay, amateur hour is over.

Banana, coconut water, and tomato pulp are endosperm. This is food for the developing seed. Many orchids seeds are thought to contain no endosperm, for which the reliance on mycorhizzae comes from. This is unproven.

Banana has the added benefit of ethylene production, which can induce germination and maturation. However, it can also cause cell death. Ethylene reacts differently and unpredictably in all plants, so you take a WAG everytime you use it, unless you have venting caps on your flasks.

The use of most of these is voodoo, but not taboo, and thus hoodoo. I typically don't use any of these hormones in germination media, but I do for cloning and occaisonally reflasking media.

Coconut water is not only an endosperm, but it also contains plant growth regulating hormones. There is a balance of cytokinins and auxins in coconut water. You take your chances when using them. And the greener the coconut, the higher the activity levels of the hormones.

Tomato? You got me, endosperm and the phytochem lycopene, which may inadvertantly dye the plants. I don't know what else is in tomatos.

[bench72]

interesting stuff Steve...

another thing with the tomatoes... i thought they were very acidic? (was told not to put those in the worm compost for that reason), so wouldn't that be bad, aren't we trying to get a fairly neutral pH?

(sorry if the above is dopey wannabee-scientific questions)