Field management of VA mycorrhizal fungi

Abstract

The potential for management of VA mycorrhizal fungi at a particular site depends on the factors that limit plant growth and the extent and timing of mycorrhiza formation. We are attempting to develop a procedure for predicting those sites where the benefits from the mycorrhizas are less than optimal. This involves gaining an understanding of the relationships between plant growth and soil and fungus parameters, predicting mycorrhiza formation using a bioassay, and subsequently quantifying the benefits that could result from management of the fungi. With existing knowledge it is not possible to (i) identify sites used for broadscale agriculture where the symbiosis is operating suboptimally, (ii) quantify the benefits that would result from increasing the rate and extent of colonization of roots by effective fungi, and (iii) identify the most cost-effective method for managing the fungi either by choice of agricultural practice or by inoculation with selected fungi. Our attempt to overcome these limitations has led to the identification of specific areas where further research is necessary. These include studies of the factors that affect the formation and functioning of mycorrhizas in field soils, the relationship between mycorrhiza development in the field and plant growth for soils that differ in their phosphate adsorbing capacity, and the ecology of the fungi in field soils.