00531nas a2200133 4500008004100000245009600041210006900137300001100206490000700217100001700224700002000241700001500261856012100276 1989 eng d00aSuppression of vesicular-arbuscular mycorrhizal fungus spore germination by nonsterile soil0 aSuppression of vesiculararbuscular mycorrhizal fungus spore germ a18 -230 v671 aWilson, G.T.1 aHetrick, B.A.D.1 aKitt, D.G. uhttp://knz.lternet.edu/content/suppression-vesicular-arbuscular-mycorrhizal-fungus-spore-germination-nonsterile-soil02115nas a2200157 4500008004100000245011400041210006900155300001300224490000700237520151900244100002001763700001701783700001501800700001701815856012501832 1988 eng d00aEffects of soil microorganisms on mycorrhizal contribution to growth of big bluestem grass in nonsterile soil0 aEffects of soil microorganisms on mycorrhizal contribution to gr a501 -5070 v203 a

Plant dry weight and mycorrhizal root colonization of big bluestem (Andropogon gerardii Vitman) inoculated with Glomus etunicatum Becker and Gerd. were suppressed if non-sterile prairie soil sievings were added to pasteurized soil. Addition of prairie soil microorganisms, isolated onto peptone yeast extract, King's B, or starch casein agar media, to pasteurized soil also reduced dry weight and mycorrhizal root colonization of big bluesteam inoculated with G. etunicatum. In contrast, addition of non- sterile soil sievings or filtrate or organisms isolated onto potato dextrose or pseudomonas isolation agar to pasteurized soil improved growth of non-mycorrhizal big bluestem. These effects of soil microorganisms on plant growth were further quantified by comparing 32P uptake by fungicide treated and untreated mycorrhizal plants and by non-mycorrhizal plants in pasteurized and non-sterile soil. Mycorrhizal plants grown in pasteurized soil absorbed approximately 10 times more 32P than mycorrhizal plants grown in non-sterile soil. Application of propiconazole (Tilt) or fenarimol (Rubigan), fungicides which inhibit non-sterile soil, respectively. Thus, more 32P is absorbed in pasteurized than in non-sterile soil, probably because soil microorganisms limit mycorrhizal activity in non-sterile soil. Assessments of mycorrhizal contribution to plant growth conducted in sterilized soil may significantly overestimate the effects of VAM fungi because other soil microorganisms are not considered

1 aHetrick, B.A.D.1 aWilson, G.T.1 aKitt, D.G.1 aSchwab, A.P. uhttp://knz.lternet.edu/content/effects-soil-microorganisms-mycorrhizal-contribution-growth-big-bluestem-grass-nonsterile01692nas a2200157 4500008004100000245010000041210006900141300001500210490000700225520110000232653002201332100002001354700001501374700001701389856012801406 1988 eng d00aMycorrhizal dependence and growth habit of warm-season and cool-season tallgrass prairie plants0 aMycorrhizal dependence and growth habit of warmseason and coolse a1376 -13800 v663 a

Warm-season (C4) and cool-season (C3) mycorrhizal grasses were 63-215 and 0.12-4.1 times larger in dry weight than non-inoculated controls, respectively. Nonmycorrhizal warm-season plants did not grow and frequently died, while cool-season plants grew moderately well in the absense of mycorrhizal symbiosis. Like warm-season grasses, tallgrass prairie forbs were highly dependent on mycorrhizal symbiosis, even though they are not known to employ the C4 photosynthetic pathway. Thus, phenology may be more critical than photosynthetic pathway in determining mycorrhizal dependence. Warm-season grasses and forbs had coarser, less frequently branched root systems than cool-season grasses, supporting the hypothesis that mycorrhizal dependence is related to root morphology. Cool-season grasses may have developed more fibrous root systems because mycorrhizal nutrient uptake was not effective in the colder temperature environment in which they evolved. In contrast, warm-season plants and dependence on mycorrhizal fungi may have coevolved, because both symbionts are of tropical origin

10atallgrass prairie1 aHetrick, B.A.D.1 aKitt, D.G.1 aWilson, G.T. uhttp://knz.lternet.edu/content/mycorrhizal-dependence-and-growth-habit-warm-season-and-cool-season-tallgrass-prairie-plants03487nas a2200157 4500008004100000245012000041210006900161300001100230490000800241520289500249100002003144700001703164700001703181700001503198856011603213 1988 eng d00aPhysical and topological assessment of vesicular-arbuscular mycorrhizal fungus on root architecture of big bluestem0 aPhysical and topological assessment of vesiculararbuscular mycor a85 -960 v1103 a

The influence of vesicular-arbuscular (VA) mycorrhizal fungus, phosphorus (P) fertilization, and soil microorganisms on growth and root architecture of big bluestem (Andropogon gerardii Vitman) was investigated. In pasteurized soil, mycorrhizal inoculation significantly improved plant growth and increased root length and the number and the diameter of the primary, secondary and tertiary roots. These differences between mycorrhizal and non-mycorrhizal plants diminished with added P. In pasteurized soil amended with non-sterile soil sievate, differences between mycorrhizal and non-mycorrhizal plants were still obvious, but in may treatments these plants grew more poorly (had less dry weight, root length, number or diameter) than their counterparts in unamended pasteurized soil. Growth in non-sterile soil was also suppressed, and mycorrhizal responses were not detected since all of the plants in non-sterile soil became mycorrhizal whether or not they were inoculated. Two analyses of calculated parameters which describe root- system architecture were conducted. The first, specific root length (SRL), revealed that mycorrhizal symbiosis dramatically alters root morphology in soils of low fertility. These changes were similar to the changes evoked by added P. The second, path length (Pe) revealed that mycorrhizal fungi (and to some degree other soil microbes) significantly alter root architecture by reducing the relative amount of root branching. Apparently, mycorrhizal plants develop a more elongate, exploratory growth pattern which permits the fungal hyphae to extract nutrients from a larger volume of soil. In contract roots of non-mycorrhizal plants maintain a more highly branched pattern of root growth, and the roots themselves play a more critical role in the direct extraction of nutrients from the soil. These differences in root topology were not directly associated with the concentration of exogenous P, but instead appeared to be controlled by the mycorrhizal fungi themselves. Thus, while internal P content of plants mediates the establishment of the mycorrhizal symbiosis, the fungi can alter the root architecture of the plant to a form which best accommodates the symbiosis under the prevailing fertility and rhizosphere conditions in the soil. By altering root-system architecture in this manner, the mycorrhizal fungi can control, at least to some degree, the dependence of the host on the symbiosis. Thus, the topology of the root system is contingent upon the microflora in the rhizosphere. The topological analysis revealed differences in root architecture not detected by any of the other measures of root morphology. These differences suggest that mycorrhizal fungi affect root architecture and plant growth in ways not directly associated with phosphorus uptake. Key words: path length, phosphorus, root morphology, specific root length

1 aHetrick, B.A.D.1 aLeslie, J.F.1 aWilson, G.T.1 aKitt, D.G. uhttp://knz.lternet.edu/content/physical-and-topological-assessment-vesicular-arbuscular-mycorrhizal-fungus-root01963nas a2200145 4500008004100000245012100041210006900162300001300231490000800244520138500252100001501637700002001652700001701672856012801689 1988 eng d00aRelationships of soil fertility to suppression of the growth response of mycorrhizal big bluestem in nonsterile soil0 aRelationships of soil fertility to suppression of the growth res a473 -4820 v1093 a

When growth of vesicular-arbuscular (VA) mycorrhizal and non-mycorrhizal big bluestem was evaluated in 15 soils, three different growth response groups were evident. Group one, which included the prairie soils, displayed high mycorrhizal dependency as well as significant suppression of plant growth in non- sterile soil. Group two showed no mycorrhizal dependency; however, plant growth was suppressed in non- sterile soil. The last group exhibited no mycorrhizal dependency or suppression in non-sterile soil. Mycorrhizal dependency of big bluestem was not highly correlated with any individual soil parameter; however, concentrations of soil K, Ca, Cu, and Fe were used to successfully classify "high" and "low" mycorrhizal dependency. Suppression of plant growth in non-sterile soil was also related to soil fertility. The magnitude of non-sterile suppression was described by equations using soil Na, Zn, Mn, organic matter, Mg, and NH4. The mechanism of this suppression is still unclear; however, the nutrients which predict suppression may be related to the development of mycorrhizal symbiosis or in demand by plants and other microbes, while those nutrients which predict mycorrhizal dependency may be related to those supplied to the plant by the symbiosis. Key words: Glomus etunicatum, mycorrhial ependency, vesicular-arbuscular mycorrhizas

1 aKitt, D.G.1 aHetrick, B.A.D.1 aWilson, G.T. uhttp://knz.lternet.edu/content/relationships-soil-fertility-suppression-growth-response-mycorrhizal-big-bluestem-nonsterile01541nas a2200145 4500008004100000245008200041210006900123300001300192490000700205520102700212100001701239700002001256700001501276856010401291 1988 eng d00aSuppression of mycorrhizal growth response of big bluestem by nonsterile soil0 aSuppression of mycorrhizal growth response of big bluestem by no a338 -3430 v803 a

Inoculum potential of Glomus mosseae and Glomus etunicatum was reduced significantly in pasteurized soil amended with a sieved suspension from non-sterile soil. Regardless of mycorrhizal fungus inoculum dosage, dry weight and root colonization of plants grown in pasteurized soil with non-sterile soil seievings never equalled those of plants grown in pasteurized alone. However, plants exposed to non-sterile soil were more colonized and grew faster than plants in pasteurized soil alone. Only after 13 wk were plants in pasteurized soil significantly more colonized, and after 16 wk larger in dry weight than their counterparts in non-sterile soil or pasteurized soil with sievings. Apparently, loss of inoculum potential alone cannot fully explain the suppression of plant growth observed in non-sterile soil. The suppressive effects of non-sterile soil may be best related to microbial mediation of nutrient availability in soil. Key words: inoculum potential, Glomus etunicatum, Glomus mosseae, inoculum dosage

1 aWilson, G.T.1 aDaniels, B.A.H.1 aKitt, D.G. uhttp://knz.lternet.edu/content/suppression-mycorrhizal-growth-response-big-bluestem-nonsterile-soil01650nas a2200145 4500008004100000245008000041210006900121300001300190490000700203520113600210100001501346700002101361700001701382856010501399 1987 eng d00aSporulation of two vesicular-abuscular mycorrhizal fungi in nonsterile soil0 aSporulation of two vesicularabuscular mycorrhizal fungi in nonst a896 -8990 v793 a

Spore numbers and species diversity of vesicular-arbuscular mycorrhizal (VAM) fungi from agricultural soils may be significantly lower than those observed in native soils (Hetrick and Bloom, 1983). In a survey of corn fields from four locations throughout a growing season, one soil (Scandia, Kansas) contained primarily Gigaspora spp. at all sample dates (G. rosea was present on two of the sample dates) while the others contained primarily or exclusively Glomus spp., including G. etunicatum (Hetrick et al., 1984). The present study was initiated to determine whether the Scandia soil favored sporulation of Gifasopra spp. and conversely whether a soil containing predominantly Glomus spp. would preferentially stimulate Glomus spp. sporulation. Because nonsterile soil has been shown to suppress mycorrhizal growth response and root colonization (Hetrick et al., 1986), the effect of nonsterile versus sterilized soil and interspecific competition on sporulation was also studied to determine whether these factors influenced species dominance and might also explain the low spore numbers observed in agricultural soils

1 aKitt, D.G.1 aHeterick, B.A.D.1 aWilson, G.T. uhttp://knz.lternet.edu/content/sporulation-two-vesicular-abuscular-mycorrhizal-fungi-nonsterile-soil