Vesicular-arbuscular Mycorrhizal Inoculation of Hawaiian Plants: A Conservation Technique for Endangered Tropical Species

Forty species of plants (including 28 species endemic to the Hawaiian Islands) were evaluated in the greenhouse for their response to inoculation with the vesicular-arbuscular mycorrhizal fungus Glomus intraradices Schenck & Smith. Seedlings, cuttings, and established plants were inoculated. Several kinds of growth media were used. Increased growth and survival most frequently occurred when plants were grown in a gravel or fine sand medium that included calcined clay (up to 50% by volume) or sphagnum peat (up to 20%). Significant increases in height, weight, leaf number and size, and survival were noted in 10 of 14 species of seedlings grown in media in which peat content was 20% or less. Mycorrhizae were only rarely present in the noninoculated plants except for plants grown from cuttings. The latter routinely formed mycorrhizae in the absence of added inoculum. Addition of mycorrhizal fungi to potting mixes appears to have value as a conservation technique for some plants that are difficult to propagate

Mycorrhizal Status of Gunnera petaloidea in Hawai'i

Eight collections of the endemic Hawaiian angiosperm Gunnera petaloidea ssp. kauaiensis were examined for mycorrhizae. Soil-inhabiting roots of all specimens possessed extensive vesicular-arbuscular mycorrhizae 01AM). Aerial roots lacked mycorrhizae. Soil from the root zones of the plants contained propagules of VAM fungi, and spores of two species of VAM fungi were found in the soil. The discovery of mycorrhizae in Gunnera adds another symbiont to the Gunnera-Nostoc symbiosis