The present manual is of immense importance for the researchers,teachers and scholars in the field of biological sciences.It will also prove of great importance to the industrialists for developing an effective mycorrhizal cultures on commercial scale.The mycorrhizal fungi are playing a multipurpose role in the crop improvement programmes by improving the plant health through the acquisition of many micro and macro nutrients.The use efficiency of different nutrient elements is also enhanced by AM fungi. Mycorrhizae provide protection to the plant roots against many soil borne diseases.Regarding the plant water relations,these organisms play a pivotal role in controlling the release of water by the plants during drought conditions.Soil physical properties like granulation and aeration are also improved by these fungi. The author is highly thankful to the scientific staff of Department of Agricultural Microbiology,TNAU,Coimbatore for their generous help in providing the material for the present work.