Banana, coconut, tomato...WHY

[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)

[SteveT]

Not a silly question at all. The pH is corrected to about 5.6 or so regardless.