Quantification of External Hyphae of Vesicular-arbuscular Mycorrhizal Fungi

This chapter presents current knowledge on the function and distribution of the external hyphae of vesicular-arbuscular mycorrhizal fungi; and describes techniques for quantifying vesicular- arbuscular mycorrhizal hyphae in soil. It is demonstrated that external hyphae of vesicular-arbuscular mycorrhizal fungi take up phosphorus from the soil and translocate it some distance to the plant. In addition, it is reviewed that the water relations of vesicular-arbuscular mycorrhizal plants and concluded that most changes attributed to vesicular-arbuscular mycorrhizal fungi were secondary responses due to improved plant nutrition. Indeed, improved nutrient and water uptake by vesicular-arbuscular mycorrhizal plants are closely related phenomena because nutrients are available to the plant only in the soil solution. Under conditions of water stress movement of nutrients in the root zone is restricted, limiting uptake of poorly-mobile ions. The chapter further describes the methods of quantification, such as indirect methods for total hyphae. Moreover, there is completely satisfactory method to quantify external hyphae of vesicular-arbuscular mycorrhizal fungi in soil.