Survey of Arbuscular Mycorrhizal Fungi symbiosis with cotton root in north khorasan province

To investigation existence of arbuscular mycorrhizal fungi symbiosis with cotton root, determination of root colonization percent and characterization of spore situation, 22 soil and root samples gathered from cotton fields of different areas in north Khorasan province. After root staining and extraction of spores from soil, root colonization and spore population determined, also effect of soil pH on these factors was evaluated. Results showed that all samples have arbuscular mycorrhizal symbiosis. About indices related to colonization, average of mycorrhizal frequency (%F) in different areas was between 95 to 100 percent. Average of mycorrhizal intensity index (%M) in Sankhast and Ashkhaneh areas with 59.8 and 31.9 was maximum and minimum respectively. about spore population density index maximum and minimum was in Esfarayen and Ashkhaneh with 212.9 and 137.2 spores per 35g/dried soil respectively. Correlation of measured indices with pH showed that correlation of spore population density with pH was significant (α = 0.05) and this correlation was positive.