Effect of tree-enset-coffee based agro-forestry practices on arbuscular mycorrhizal fungi (AMF) species diversity and spore density

A study on arbuscular mycorrhizal fungal (AMF) spore abundance and species composition was undertaken along different tree-enset-coffee based agroforestry practices in Sidama administrative region of Southern Ethiopia. Soil samples were collected from 36 sampling points for each tree-enset-coffee combinations within the nine sampling sites. The soil samples were processed for soil physicochemical properties; AMF spore abundance, AMF species composition and soil trap cultures. In tree-enset-coffee based agro-forestry practices there was significant (P < 0.05) effects on AMF spore abundance among different combinations. However, land uses with Millettia ferruginea and Erythrina brucei had higher spore numbers than land use types with Cordia africana as a shade tree. AMF species also seemed to show preference for specific tree-crop combination. Percentage root colonization of five months old Sorghum bicolor grown as a trap plant in field soils collected along the tree-crop combinations from the experimental sites showed significantly different (P < 0.05) root colonization. There was a positive correlation (r = 0.458, P = 0.016) between root colonization and spore abundance at the 0.05 level (2-tailed). A total of 28 AMF morphotypes from eight genera were isolated. Species diversity also responded differently to different tree-crop combinations, in tree-enset-coffee based agroforestry practices for all experimental sites. The response of AMF species to different tree-crop combinations therefore indicates the importance of selection of specific species of trees for better management of small holder at low external input agroforestry practices.