Vesicular-arbuscular mycorrhizae and cultural stresses

This chapter reviews the responses of vesicular-arbuscular (VA) mycorrhizae to cultural practices, and outlines research and levels of understanding necessary before mycorrhizae can be managed as components of sustainable agroecosystems. It considers how cropping sequence, plant breeding, pesticides, tillage, fertilizer, and VA mycorrhizal (VAM) inoculation effect VA mycorrhizae in agroecosystems. When considering cultural stresses on VA mycorrhizae, assessing the species composition of VAM fungal communities may sometimes be more important than assessing levels of root colonization or spore densities. Studies show that the degree to which cultivars are colonized by, and benefit from, mycorrhizae is a heritable trait selectable through plant breeding. Application rate is important in determining the effects a pesticide will have on VAM fungi. The organic matter in soils and fertilizer carriers may mediate mycorrhizal responses. There has never been a study comparing species composition of VAM fungal communities across a range of soil disturbance levels while all other factors remained constant.