MYCELIAL GROWTH OF PRE-GERMINATED SPORES OF THE ENDOMYCORRHIZAL FUNGUS GIGASPORA-GIGANTEA IN LIQUID-MEDIUM SUPPLEMENTED WITH NITROGENOUS ORGANIC-COMPOUNDS

The effects of 14 nitrogenous compounds on mycelial growth of G. gigan tea spores were evaluated in a liquid medium. Spores were pre-germinat ed in water-agar and transferred to glass tubes with nutrient liquid m edium containing one of the following compounds: glycine, histidine, l eucine, lysine, phenylalanine, asparagine, arginine, cysteine, methion ine, cystine, proline, aspartic acid, glutamic acid and peptone. Each compound was added individually to the nutrient basic medium at three different concentrations. Tubes with spores were incubated at 25-28-de grees-C for 15 days when mycelial growth was evaluated by grid interse ction method. The amino acids histidine, cysteine and leucine and pept one stimulated fungal growth, while phenylalanine and methionine showe d significant growth inhibition. Growth enhancements were linear for h istidine, and square-root model for leucine, cystine and peptone. Meth ionine showed linear inhibition, while phenylalanine exhibited quadrat ic response. All the other compounds tested showed no significant effe ct on mycelial growth.