DIVERSTY AND ABUNDANCE OF ARBUSCULAR MYCORRHIZAL FUNGI ACROSS DIFFERENT LAND USE TYPES IN A HUMID LOW LAND AREA OF ETHIOPIA

Abstract

The aim of this work was to study the effect of different land use types on arbuscular mycorrhizal (AM) fungal populations in soil and trap cultures from Showa robit, Ethiopia. Seven land use types were selected. There were low-input arable systems, either having a mixture of crops (Arable1) or monocropped with sorghum (Arable2) or maize (Arable3). Arable4 was relatively a high-input system with monocropped sorghum. A fruit cropping area (FC) managed with composts and plant residues, a natural forest (NF) and an acacia plantation (AP) were also studied. AMF spore abundance, species richness, diversity indices and mycorrhizal inoculum potential (MIP) were studied. In field soil, significantly higher spore numbers were recorded from FC, Arable1 and Arable3 (5.8-6.1 spores g-1 soil) than in Arable4, NF and AP (2.8-3.9 spores g-1 soil).  In trap cultures, AP, FC, and Arable2 had the highest spore numbers (9.8-11.1 g-1 soil) and Arable4 and NF the lowest (2.5-3.8 g-1 soil). Slightly different MIP patterns also occurred with Arable1 (53.7%) and FC (52.6%), having significantly higher hyphal colonization, 53.7% and 52.6%, respectively,  compared to the other land use types that fell within percentage colonization of 19.9-25.8 %. A total of 42 and 33 morphospecies of AMF were identified in field soil and trap culture soil, respectively. Trap culturing increased spore numbers but caused a loss of AMF species richness. Higher species richness was obtained in FC and Arable1 compared with the other systems. Claroideoglomus and Funneliformis were the dominant genera in all land use types in both trap culture and field soil. The results clearly imply that organic management and diversification of crops enhances AMF diversity of low-input agricultural systems.