effect of soil physical and chemical properties on common bean root colonization, spore number and infection potential of arbuscular mycorrhizae

in order to investigate the physical and chemical properties of some iranian soils under common bean cultivation, forty-one soil samples were collected from azna, zanjan, aligoudarz and khomein regions. root colonization percentage, spore number and infection potentional of arbuscular mycorrhizal fungi in soils were evaluated after sorghum cultivation. the results showed that the soils had a wide range of physical and chemical properties. soils 3 and 13 (sampled from khomein and azena) had the highest number of spores (55) and infection potential (138 infectant) per 20 g of soil respectively. the highest percentage of root colonization by arbuscular mycorrhizal fungi was observed in the soil no. 38 (prepared from zanjan) with 38% root colonization. this study revealed that the soil ec, calcium carbonate, organic matter and dtpa-extractable zinc content had positive and significant correlation with the number of spores, infection potential and root colonization percentage. whereas, there was negative and significant correlation between the amount of phosphorus and three parameters mentioned above.