NUTRITIONAL CONDITIONS REQUIRED FOR THE NON‐SYMBIOTIC CULTURE OF AN ACHLOROPHYLLOUS ORCHID GALEOLA SEP TEN TRIO N ALIS

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Abstract
Summary: Galeola septentrionalis Reichb. f. grew and developed roots and leaves on the agar medium containing commonly used nutrients in the absence of its symbiotic partner when kept in appropriate atmospheric conditions.Glucose, glycerol, fructose, inositol, mannitol, mannose, ribose, sorbitol and xylose were utilized as carbon sources, arabinose, rhamnose and sorbose were not and galactose inhibited growth. Mixture of two monosaccharides in some combinations showed no synergistic effect though they had an additive effect.An amino acid mixture and urea were good nitrogen sources, but allantoin, ammonium salt and nitrate were poor ones. Nitrite and uric acid inhibited growth.Several vitamins did not affect growth when added to or deleted from the culture medium singly or in combinations.Auxins improved growth immediately after germination and cytokinins showed no effect at this phase. The growth and development following this phase, however, were promoted by addition of cytokinins and not by auxins. Cytokinins given during this later phase induced rhizogenic growth at concentrations lower than 10−7 M and induced caulogenic growth at concentrations higher than 10−6 M. Gibberellin at concentrations higher than 3 × 10−7 M retarded growth. G. septentrionalis is considered to be a prototrophic heterotroph and its mycorrhizal fungus may act by supplying commonly known nutrients to this achlorophyllous orchid.