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

Ha. This is an easy one.

Banana and Coconut are providers of endosperm. Coconut water is also rich in cytokinins. Tomatos? Dunno, but it has lots of chemicals. Maybe when they are green and unripe they are endosperms.

Ha. This is an easy one.

Banana and Coconut are providers of endosperm. Coconut water is also rich in cytokinins. Tomatos? Dunno, but it has lots of chemicals. Maybe when they are green and unripe they are endosperms.


What do you mean by endosperms ?

Chun

Endosperm - a complex organic containing mostly carbohdrates, used by seedlings for growth efore they are capable of producing their own food via normal photosyntetic pathways.

By cytokinins, I imagine you mean cytokines, which are horone-like intracellular chemical signals that tell plant cells what to do, what to produce, how to grow, etc. Specific examles are auxins, which may diect root growth or stem extension.

Any idea which ones work best?? What about ading exogenous plant growth regulators to the media directly?

Brian

No. Cytokinins and Auxins are two types of Plant Growth Regulator hormones. Cytokinins enhance shoot growths and internode elongation, whereas auxins induce root formation, off the top of my head.

Cytokinins examples:
Kinetin
Zeatin
meta-topolin

Auxins:
Indolic acids
Naphthelenic acids
Chlorophenoxy acids
Benzoic acids
Picolinic acids

Some are more active than others. Zeatin is about 10,000 times as active as Kinetin, if i remember correctly.

There are many ideas about which work best. But It depends on what you are trying to do. If you are looking to germinate, many people use no hormones at all. Others do with varying success. The ingredients and amounts of chemicals in media are closely guarded secrets among orchid flaskers.