Burgeff's N3f Medium

Dissolve 1 and 2 separately in 500 ml of water each. Mix together and add the following:

Here the citric acid and phosphate solution acts as an effective buffer. This medium is specially recommended for germinating Paphiopedilum seeds.

A great deal of research has been done on improving these media by supplementing with virous carbohydrates, organic nitrogen sources such as amino acids , nucleic acids and growth promoting substances . The most popular among these are the extracts of various fruits , like pineapple , banana, tomato , coconut water etc. Of these babana has consistently given beneficial results . It was Graeffringer (1950) who first reported on the advantages of using powdered banana as a nutrient for the germination of orchid seeds. Withner (1953 )also reported that 40 gm per litre of mashed banana in Knudson 'C' medium Burgeff N3f is excellent for Paphiopedilum seeds.

Lawrence and Arditti (1964) reported that Knudson 'C' medium with the addition of niacin , adenine , ribose, banana mash, tomato juice , coconut milk and contents of a vitamin capsule , is ideal for the healthy growth of the seedlings. Arditti (1968) conducted extensive researches on the beneficial effects of banana mash on seedling growth . He suspected this effect to be due to the " synergistic interaction " of various factors like the buffering effect of banana homogenate which helps to maintain an optimum pH, the chelating of iron thus making it available to seedlings , presence of mineral nutrients which promote growth and the presence of substances fo a cytokinin nature, which are similar to those found in coconut endosperm and which enhance growth rate , or auxins or gibberellin , all of which were found to be present in banana mash.

Hoyt (1960) suggests addition of 15 % pineapple juice substituted for water in Chang's formula for prompt germination and healthy growth of seedlings . The same was also recommended by Hamilton (1965) along with 2-3 mgms of Indole-butyric acid to a litre of the medium .

Rev. Masao Yamada of Hawaii is of opinion that coconut water is a great stimulant to the growth of seedlings. Water taken from coconuts at the green tender age is the best.

Beneficial effects of coconut milk on Vanilla and Cypripedium were reported by Hegarty (1955) and on Dendrobium by Ito (1960).

Kotomori and Murashige (1965) found that even though the coconut water added to Vacin and Went medium stimulated seedling growth , they did not hasten germination of seeds.

Thomale (1954) observed that a combination of glucose and fructose is necessary for the germination of Paphiopedilum seeds . Honey contains equal proportion of these two sugars and is hence ideal for use in culture media . In addition it also contains Vitamin B2 and nicotinic acid.

Mariat (1952) in Cattleya and Withner (1953) in Paphiopedilum observed that peptones accelerated growth of seedlings. Tsukamoto , Kano and Katsuura (1963) recommend addition of bacto-tryptone at 2 gm per litre of the medium for increased stem and root growth . According to Burgeff (1964) orchid fungal extracts , alcoholic yeast extracts etc. are especially beneficial to genera like Vanda and Phalaenopsis . Griffith and Link (1957) reported that cotton seed meal and fish emulsion hasten growth of seedlings in culture .