Re: TGZ formula/Malmgrens medium

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Abgeschickt von Anders Johnsen am 08 August, 2000 um 10:55:42

Antwort auf: TGZ formula von Victor Tanneur am 15 April, 2000 um 10:47:35:

For my orchids, I use Malmgrens modified medium. Malmgren has shown this medium to superior to TGZ-N .It has been developed by Malmgren (1993) for asymbiotic seed germination and culture of North American and European hardy orchid species, but it also works well with tropical species. The medium does not contain inorganic nitrogen since Malmgren has shown that this is toxic to seedlings possibly because of low levels of nitrate reductase in the embryos. The original reference (Malmgren 1993, Svensk Botanisk Tidskrift , v87, p221-234) is in Sweedish, (which is very close to Danish but impossible to read for non-Scandinavians) but it has an abstract and figure texts in English.

Malmgrens modified medium contains per litre:
sucrose 15 g
Agar 7-8 g
MgSO4 75 mg
Ca3((PO4)2 75 mg
KH2PO4 75
FeS04 10
Vamin (amino acid mixture) 1g
pineapple juice 25 ml
activated carbon 0,5 g
pH 5.6
For slipper orchids, include 5 mg kinetin.

I use a further modification of Malmgrens medium which gives even better growth of embryos and seedlings

sucrose 15 g
MgSO4*7H2O 155 mg
CaCl2 90 mg
Na2HPO4 80 mg
KH2PO4 75 mg
FeSO4*7H20 18 mg
Peptone or tryptone 4g
agar 6g
trace element solution 1 ml
pineapple juice 25 ml
pH 5.6

I use a general plant trace element solution (without iron), but it is probably not really necessary since pineapple, agar and peptone also contains trace elements.
For slipper orchids, add one 5x5x5 mm cube of raw potato per 5 ml of medium (a source of cytokinin and other growth promotors). The easiest is to add the cubes directly to the flasks before autoclavation. For hardy slipper orchids: Keep the seeds in the refridgerator at 5 degrees C for at least 12 weeks.

I have had good results with Cypripedium, Dactylorhiza, Orchis, Epipactis (green pod), and Paphiopedilum (subtropical)