We conducted a field experiment for investigation of arbuscular mycorrhizal (AM) colonization of roots and extramatrical hyphae growth for prairie dock (Silphium terebenthinaceum), wild quinine (Parthenium integrifolium) and smooth blue aster (Aster laevis), all prairie plant species in the family Asteraceae, but with different root architectures. We expected extent of AM colonization of roots and extramatrical hyphal biomass to vary inversely with degree of fine root proliferation among the three species. Soil samples and fungal in-growth bags (buried for one year) were collected near three-year-old individuals of each species in the field. Live roots were separated from soil, and total root length was determined for each root sample. Root samples then were stained and mounted on microscope slides for determination of root length colonized by AM. Extramatrical hyphae were extracted from fungal ingrowth bags, freeze-dried, and weighed.

Results/Conclusions

Silphium, with the lowest degree of fine root proliferation, had the highest root lengths colonized by AM/cm³ soil; and Aster, with the highest degree of fine root proliferation, had the lowest root lengths colonized/cm³ soil (mean ± S.E. = 5.56 ± 0.70 cm/cm³, 10.41 ± 2.77 cm/cm³ and 16.11 ± 2.28 cm/cm³ for Aster, Parthenium and Silphium, respectively). Extramatrical hyphal biomass also was highest for Silphium and lowest for Aster (mean ± S.E. = 21.7 ± 7.9 μg/cm³, 33.1 ± 9.0 μg/cm³ and 55.2 ± 10.9 μg/cm³ for Aster, Parthenium and Silphium, respectively). Results from this study will be an important step toward improving results and predictability of prairie restoration efforts.