Tropentag, September 19 - 21, 2012 in Göttingen "Resilience of agricultural systems against crises"

Organic Management Practices Enhance AM Biodiversity in Tropical Agricultural Soils

¹Teri University, Centre for Mycorrhizal Reserach, Biotechnology and Bioresources Division, India
²The Energy and Resources Institute, Centre for Mycorrhizal Reserach, Biotechnology and Bioresources Division, India

Abstract

Arbuscular mycorrhizal fungi (AMF) have been recognised as an important component of organic agriculture. Modern agricultural practices, such as chemical fertilisation, pest control, continuous monoculture and tillage impact AMF and plant interactions. With a view to study the impact of these practices, investigation was undertaken to compare the AMF diversity in the trap cultures raised from conventially managed as well as organically managed fields. Spores of AMF were collected from trap cultures of both fields (northern India) and based on their morphology were grouped into morphotypes. Partial sequence analysis of rDNA from single spore of each morphotype was undertaken using either a small-subunit internal transcribed spacer (SSU-ITS) or a large subunit (LSU) region and fatty acid methyl ester profiles (FAME) of similar morphotypes were compared. Organic sites contributed the 18 AM species belonging to Genera Rhizophagus and Funneliformis and 7 AM fungi of Acaulospora, Gigaspora and Scutellospora. In contrast, conventional sites selectively favour only smaller size AM species belonging to genera Rhizophagus and Funneliformis species. We observed that organically managed farmland contributed the largest number of AMF species richness and colonisation potential, which suggests that factors contributing to the diversity of AMF are indeed complex: for example, chemically managed farmland not only causes loss of fungal biodiversity but also selectively favours smaller spores (Rhizophagus sp.), thereby affecting ecosystem functioning adversely. The present study showed that both abundance and diversity of AMF is favoured by low-input agriculture incorporating planting on raised beds (RB) and organic practices such as zero tillage that do not disturb the physical properties of the soil.

Keywords: Arbuscular mycorrhizal fungi, fatty acid methyl ester profiles, large subunit, raised beds, ribosomal DNA

Contact Address: Sanjeev Kumar, Teri University, Centre for Mycorrhizal Reserach, Biotechnology and Bioresources Division, TERI, Darbari Seth Block, Sixth floor, I.H.C, Lodhi Road, 110003 New Delhi, India, e-mail: sanjeev.kumarteri.res.in