Species and distribution of Vesicular arbuscular mycorrhizal fungi in various soils and their effects on the growth of corn

Ten soil samples were collected from each of Dry dipterocarp forest, Dry evergreen forest and agricultural field. Spores of V-A mycorrhiza fungi were counted according to the modified new plate method of Smith and Skipper (1979). Result showed that in Dry dipterocarp forest, number of spores from upper soil, at the depth 0-15 cm., were 160-325 per gram of soil; and that from lower soil, at the depth 15-30 cm., were 84-218 per gram of soil. In dry evergreen forest, number of spores in the upper and lower soils were 57-371 and 44-174 per gram of soil, respectively. In agricultural field, number of spores in the upper and lower soils were 29-158 and 26-108 per gram of soil, respectively. Fourteen types of V-A mycorrhizal spores were found in dry evergreen forest soil and 12 types of spores in dry dipterocarp forest soil. An unreported species of V-A mycorrhizal fungi (VAM no. 1) with black spores was found to be the dominant type in both forests. The minor groups of spores of the two forests were not of the same types. Studies were also made on propagation of V-A mycorrhizal fungi by pot culture method. All types of the spores found were inoculated to the host plants. Only ten types of the spores were reproduced: Acaulospora spinus, Acaulospora scrobiculata, Gigaspora gigantea, Gigaspora margarita, Gigaspora heterogama, Glomos monosporus and four unreported species of the genus Entrophosphora sp. no. 1, no. 2, no. 3 and Gigaspora sp. no. 1. Comparative study on the effect of four species of V-A mycorrhizal fungi namely, Acaulospora spinusa, Giagaspora gigantea, Giagaspora margarita and Entrophosphora sp. no. 1, on the growth of corn was conducted. A completely randomized design was used. Inoculation with Acaulospora spinusa and inoculation with all of the four species gave the largest, significant increase in growth of corn plants. Inoculation with Gigaspora gigantea and Gigaspora margarita produced significant increase over the control