Factors controlling the distribution of vesicular-arbuscular mycorrhizal fungi in relation to soil pH.
The aim of this study was to identify the particular soil properties which caused distinct populations of VA mycorrhizal fungi to occur at 2 adjacent sites in a semi-arid, Mediterranean environment in Western Australia. When inoculated into the soil in which they did not occur naturally, the fungi infected fewer roots and produced fewer spores than in their soil of origin. Fewer spores of the dominant fungi (Site I: Acaulospora laevis, Site II: Glomus spp. (WUM 2 and 3)) germinated, and they produced shorter germ tubes than in their soil of origin. From 2 subsequent experiments studying the effect of adjusting the pH of either the soil or an extracted soil solution used as germinating media, it was concluded that soil pH is likely to be important in limiting the distribution of A. laevis and Glomus sp.