Arbuscular Mycorrhizal Symbiosis in Temperate Grassland Forage Species of Argentina

Abstract

Grasslands are the sources of many agronomic productions, livestock systems, and environmental issues with positive and recognized impacts on water quality and biodiversity. Arbuscular mycorrhizal (AM) fungi are one of the most common root-associated soil biota, which influence plant productivity. In this sense, AM fungi are of high value for the functioning and sustainability of grasslands. Soil characteristics, plant species, and climate factors are known to influence AM fungal communities in temperate grassland ecosystems of South America. Thus, the uses of these environments for raising livestock as well as the addition of fertilizers to increase the forage resource are agronomic practices which modify not only the plant communities but also the AM fungal communities and then the benefits of this fungal group on plant development could decrease. On the other hand, phosphorus (P) fertilization is necessary to obtain maximum forage yield in most P-deficient grassland soils. However, when P availability in the soil increases due to the fertilization, both AM root colonization and mycorrhizal response decrease in several plant species, even if AM fungi can still be actively contributing to plant P uptake. Compared with agricultural crops, little is known about the effect of grazing/defoliation or P fertilization on the symbiosis between forage species and AM fungal communities from grassland soils of Argentina. Specially, this chapter discusses the ecological role of AM symbiosis on the functioning of temperate grasslands of Argentina as valuable information to promote better management of forage land sustainably while increasing forage production and preserve the beneficial effects of AM communities in these ecosystems. We focus mainly on the effects of grazing/defoliation and P fertilization on the mycorrhizal status and AM benefits on forage species growing on grassland soils of the Argentine Flooding Pampa.