Diversity of arbuscular mycorrhizal fungi in horticultural production systems of southern Chile

Abstract

The diversity of arbuscular mycorrhizal (AM) fungi in six Capsicum annuum or Lycopersicum esculentum L. horticultural production systems of small farmers, and of two wheat agrosystems was comparatively investigated in Southern Chile (La Araucanía). Soils in this region are mostly originated by volcanic ashes which are characterized by high organic matter content and high P-fixing capacity. Arbuscular mycorrhizal fungal symbioses are playing a key role for P uptake by horticultural crops grown there. The objective of this study was to determine AM fungal communities in cropping systems and to identify soil factors affecting their frequency and diversity. Of the totally 32 AM fungal species identified, 5 to 21 AM fungi species were found in horticultural locations and 8 to 11 AM fungi species in conventional tillage (CT) and no-tillage (NT) agroecosystems. No relationships on AM fungal diversity with soil factors were found. In wheat based agrosystems fungal diversity was somewhat lower under CT than NT whereas no such relationships between diversity and intensity of land use could be generated from horticultural systems. It is concluded that it will be advisable for farmers to inoculate their horticultural crops with selected mycorrhizal inoculants during the nursery stage, as it cannot be predicted from the soil conditions whether the native AM fungal community is sufficient to sustain a stable horticultural production in the region.