Dm. Sylvia et al., EVALUATION OF VESICULAR-ARBUSCULAR MYCORRHIZAL FUNGI IN DIVERSE PLANTS AND SOILS, Soil biology & biochemistry, 25(6), 1993, pp. 705-713
A regional study was made to identify vesicular-arbuscular mycorrhizal
(VAM) fungi effective in promoting plant growth in diverse plant and
soil systems. Eight cooperators in six states of the eastern United St
ates evaluated six VAM fungal isolates on soybean (Glycine max L. Merr
.) and sorghum (Sorghum bicolor L. Moench) in a shared soil and in at
least one regional soil from each location. Plants were grown with hig
h VAM inoculum densities (minimum of 20 VAM propagules ml-1) for 42-57
days in pasturized soils in greenhouses or growth chambers. Shoot and
root dry masses, total and colonized root lengths and shoot-P concent
rations were determined at harvest. Under the experimental conditions
tested, the VAM fungal isolate was more important than the soil or hos
t plant in determining effectiveness. In the shared soil, inoculation
with two isolates of Glomus (GE329 and GENPI) resulted in the greatest
shoot masses for soybeans, while the same two isolates and GE312 prov
ided maximum response in sorghum. In the regional soils, GE329 and GEN
PI had the widest range of growth promotion with both soybean and sorg
hum; however, for both plant species the mycorrhizal response was grea
test in soils with less than 10 mg extractable P kg-1. For soybeans, c
olonized root length was not related to VAM growth response. For sorgh
um, there was a positive correlation between colonized root length and
plant growth response. We conclude that VAM isolates exist which are
effective in promoting plant growth over a range of edaphic and host c
onditions.