ABSTRACT
Mycorrhizae are a mutual symbiotic link between the plant root and a fungus that colonizes the cortical tissue of the roots during active plant growth periods. Both the host plant and the fungus have the potential to benefit. Mycorrhizae are ubiquitous throughout the world in terrestrial ecosystems. The purpose of this study is to evaluate the association of arbuscular mycorrhizal fungi in cotton crops with AM fungal population density in rhizosphere soils, investigate the qualitative composition of AM fungal species and the percentage of root colonization. The results showed that the number of AM fungal propagules collected from different locations in cotton crops ranged from 235 to 1580 spores per 100 g of soil. Due to the widespread nature of AM fungi, they occurred in almost all soil samples, but the number and type of spores and sporocarps varied. In total, 41 AM fungal species belonging to the genera Glomus, Acaulospora and Scutellospora were isolated. Glomus was found to be predominantly followed by Scutellospora in cotton soils in the rhizosphere. The distribution of spores, density and composition of AM fungi are observed to be influenced by environmental and physicochemical factors. The AM spore number, root colonization percentage and distribution vary depending on the seasonal fluctuations in moisture, temperature, pH and soil mineral nutrient status such as OC, P2O5, K2O, Zn, Cu, Fe, Mn, etc. The obtained data shows that nitrogen-deficient soils had more AM fungal propagules. The soils with a high concentration of phosphorus and potassium had the least AM fungal spores. Depleted zinc, copper and manganese levels have also been positive for more fungal occurrence and distribution. The presence of high iron levels in the soil, however, encourages more AM spores and a percentage of root colonisation.