Gigaspora gigantea: Observations on Spore Germination of a VA-Mycorrhizal Fungus

SUMMARYSpore germination of a vesicular-arbuscular mycorrhizal fungus in the absence of a host plant was investigated. Spores of Gigaspora gigantea were tested for the ability to germinate under laboratory conditions approximating field conditions. No differences were noted between germination of surface-sterilized or nonsurface-sterilized spores collected throughout the year and incubated at several temperatures on 2% agar and sterile or nonsterile dune sand. Spore germination was unaffected by phosphorus concentrations of up to 500 ppm. Spores extracted from the dune sand without washing or seiving germinated as well as those recovered by conventional methods. Germination rates were not improved by cold storage. Water potentials of -10 bars or glucose in the medium slowed the germination rate and the growth of germ tubes. The implications of these results are discussed.