The importance of mycorrhiza for the improvement of plant growth is increasingly being realised in Agriculture and Forestry and several mycorrhizal fungi have been commercially recognised for the purpose. The aim of this book is to describe the various techniques used to study the mycorrhizal biology. Problems with preparing such a book are many. Mainly mailing of manuscripts to and from authors resulted in irregular and final editing. Every effort was made not to change the peer review original manuscript to ensure accuracy. Our sole aims is to communicate to the greatest extent possible a current world need in mycorrhizal research. Plant productivity is regulated by microbial associations established in the plant root systems. The interactions of microorganisms and plant roots are especially important in providing nutritional requirements of the plant and the associated microorganisms. Plant growth and development are controlled largely by the soil environment in the root region -rhizosphere. This is a very complex environment in which the effects of the plant on soil microorganisms and the effects of microorganisms on the plant are interacting, interdependent and highly complex. Plant root exudates and breakdown products feed the microbes and the microbe in tum often benefit the plant. Mycorrhizal fungi are important tools for increasing growth, development and yield of economically important plants, they play important role of biofertilizer which can help establish plants in nutrient deficient soils, particularly phosphorus deficient soils, arid, semi-arid and waste lands.