The Effects of Soil Texture on Extraction of Vesicular-Arbuscular Mycorrhizal Fungal Spores from Arid Sites

Extraction methods for vesicular-arbuscular mycorrhizal fungal spores were compared using soils from arid habitats. The methods were wet-sieving and decanting, flotation-adhesion, two density gradient centrifugation techniques and differential water/sucrose centrifugation. In clay soils, all methods except differential water/sucrose centrifugation were statistically similar. Differential water/sucrose centrifugation extracted 185% more spores than the other methods. When comparing methods using soils of differing textures, the efficiency of extraction of Gigaspora spores was similar, but more Glomus spores were extracted with differential centrifugation. Exposure to a 2 m solution dehydrated 52% of exposed spores in 24 h. Following immersion of those spores in distilled water, 98% were hydrated after 24 h. The concentration of sucrose used in the differential centrifugation method appeared to cause little permanent damage to spores. We conclude that several methods should be compared initially when spores are extracted from new habitats to ascertain the optimum technique for the given soils.