Arbuscular mycorrhizal fungi (AMF) root colonization% and spores density
The root system of each plant was separated from the shoot, and dry weights were determined after the preparations were dried for 36 hrs at 70°C. The presence of an AMF infection was determined visually by clearing washed roots in 10% KOH and staining the preparation with 0.05% (vol/vol) trypan blue in lactophenol as described by Phillips and Hayman, (1970). The stained roots placed on the glass slides for microscopic observations under 200×magnifications (Leica DM550Q, USA). The calculation of AMF colonization was estimated for each sample by examination about one hundred pieces of roots (1cm long), and the AMF spores densities were calculated according to Schenck, (1982).