The Influence of Phosphate and Other Nutrients on the Development of Vesicular-arbuscular Mycorrhiza in Culture

SUMMARY: Vesicular-arbuscular mycorrhiza were established in Trifolium parviflorum in culture by inoculation with Endogone spores. In a medium containing 265 mg. phosphorus (P)/l., as CaHPO4 and K2HPO4, infection occurred only when the medium lacked nitrogen (N). In a medium containing only 100 mg. P/l., infection occurred readily in the presence of 0·5 g. KNO3/l. Calcium monohydrogen phosphate, Ca phytate, Na phytate, Fe phytate, phytin, lecithin and DNA were adequate sources of phosphate for both plant and fungus. Ca phytate and DNA greatly stimulated fungal growth, and DNA also stimulated spore formation, in the agar medium. With Na in the medium infections in the root were sparse. Inositol may serve as a carbon source for Endogone. Mycorrhizal infection occurred with either FeCl3 or Fe-EDTA in the medium; when so little iron was present that plants grew poorly, there was also little mycorrhizal infection.