Taxonomy and Ecology Of Inland Sand Dune ... - Mycorrhizae

21dune plants, the development of externalmycelium, and propagule density. Thereare no comprehensive studies ofmycorrhizal relationship in inland sanddunes.III. PLANT NUTRIENTS AND VAMFUNGAL DEPENDENCYVAM fungi offer significant benefits totheir host when compared tononmycorrhizal host plants grown innatural soil. Safir (1987) characterizedplants as independent (e.g., species ofthe Brassicaceae), facultativelydependent (e.g., seral species), orobligately dependent (e.g., tropical foresttrees) on VAM fungi for mineralnutrient uptake. VAM fungi provideplants with phosphorus that enablesmycorrhizal plants to grow better thannonmycorrhizal plants when thiselement is limiting (Mosse, 1972;Williams et al., 1974; Roncadori andPokory, 1982; Pleachett et al., 1983;Koske and Polson, 1984; Backhaus etal., 1986). Yield or biomass often isincreased when plants form VAM fungalassociations (Bolgiano et al., 1983;Singh and Singh, 1986).VAM fungi improve growth in bothnitrogen-fixing and non-nitrogen fixingplants. Singh and Singh (1986)inoculated lentil plants with Glomusfasciculatum and found that lentilshowed mycorrhizal dependency forphosphorus uptake. Glomusfasciculatum increased Rhizobiumnodulation, nitrogen fixation, lentilgrowth, and lentil yield. Citrus alsoappears to have a high level ofmycorrhizal dependency, especiallywhen rock phosphate is used as thephosphorus source. Mycorrhizal citrusplants show much better growth thannonmycorrhizal citrus plants (Grahamand Timmer, 1984).