Mycorrhizal fungi in relation to control of tobacco stunt disease with soil fumigants

Modjo, Hakam S.; Hendrix, James W.; Nesmith, William C.

doi:10.1016/0038-0717(87)90011-3

Cited by 27 publications

(11 citation statements)

References 10 publications

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“…Mycorrhizal effects on plants growing in nonsterilized soil must be considered from the standpoint of the mycorrhizal fungal community, not just of individuals from the community, for pure cultures of Glomales fungi do not occur in nature. In agricultural or unmanaged habitats, over a dozen species are usually found (Schenck and Kinloch 1980;Rich and Schenk 1981;Hetrick and Bloom 1983;Hendrix 1984, 1986;Modjo et al 1987). At the site of the study reported here, An et al (1990a) described propagules of 13 species in limited samplings, some occurring consistently and at high population densities, others occurring patchily.…”

Section: Introductionmentioning

confidence: 82%

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The influence of crop rotation and soil fumigation on a mycorrhizal fungal community associated with soybean

Hendrix

Hershman

et al. 1993

Mycorrhiza

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Abstract. Population densities of mycorrhizal fungal propagules in a western Kentucky field highly productive for soybean were measured by bioassay throughout a soybean production season. The primary experimental variables were crop rotation (soybeans in 1985, then 2 years in corn, milo, rescue, or soybean, then soybean in 1988 on all plots when populations of propagules were determined) and soil fumigation with 67% methyl bromide/33% chloropicrin. Of the 20 species in three genera found, Glomus predominated both in terms of number of species and population densities. Most species of Glomus occurred at higher population densities in rotated plots than in continuous soybean plots. In continuous soybean plots, species of Gigaspora made up a much higher proportion of the mycorrhizal fungal community than in rotated crops. Species richness and diversity were lower, and dominance and equitability higher, in nonfumigated continuous soybean plots than in rotated plots early in the season, but the differences were not present at the end of the season. Soil fumigation killed most propagules in the upper 15 cm of soil, but after production of a crop of soybeans, populations of total propagules and most Glomus spp. recovered to prefumigation densities. However, Gigaspora margarita and Gigaspora gigantea did not recover similarly. Fumigation reduced species richness and diversity and increased dominance, but the effects were ameliorated by the end of the season. Colonization of roots was low during vegetative growth but increased rapidly after the onset of soybean reproduction. There was no evidence for mutualism during the early half of the season, perhaps due to high soil P and low dependency of soybean. Fumigation increased soybean yields. A stable mycorrhizal fungal community appeared to become established with continuous soybean production, and both crop rotation and soil fumigation disrupted the community.Correspondence to: J. W. Hendrix

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Section: Introductionmentioning

confidence: 82%

“…Because soil fumigants are lethal to mycorrhizal fungi (Menge et al 1978(Menge et al , 1982Hendrix 1984, 1986;Modjo et al 1987), soil fumigation was employed as a control treatment which disrupts the community of mycorrhizal fungi. The results reported are primarily from the final year of a 3-year experiment.…”

Section: Introductionmentioning

confidence: 99%

The influence of crop rotation and soil fumigation on a mycorrhizal fungal community associated with soybean

Hendrix

Hershman

et al. 1993

Mycorrhiza

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“…An extreme example of a mycorrhizal fungal association that decreases plant performance is observed in an intensively managed agricultural system in Kentucky, USA . A series of field and glasshouse studies has shown that colonization of tobacco by an endemic isolate of Glomus macrocarpum significantly reduces root length, aboveground biomass, and fiowering (Modjo & Hendrix 1986;Jones & Hendrix, 1987;Modjo, Hendrix & Nesmith, 1987;Hendrix, Jones & Nesmith, 1992). Although this isolate of G. macrocarpum is strongly parasitic (pathogenic) on tobacco in field soils with extremely high P, it does not appear to have parasitic effects on other crops.…”

Section: (3) Genotypic Factorsmentioning

confidence: 99%

Functioning of mycorrhizal associations along the mutualism–parasitism continuum*

1997

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3 SUMMARYA great diversity of plants and fungi engage in mycorrhizal associations. In natural habitats, and in an ecologically meaningful time span, these associations have evolved to improve the fitness of both plant and fungal symbionts. In systems managed by humans, mycorrhizal associations often improve plant productivity, but this is not always the case. Mycorrhizal fungi might be considered to be parasitic on plants when net cost of the symbiosis exceeds net benefits. Parasitism can be developmentally induced, environmentally induced, or possibly genotypically induced. Morphological, phenological, and physiological characteristics of the symbionts influence the functioning of mycorrhizas at an individual scale. Biotic and abiotic factors at the rhizosphere, community, and ecosystem scales further mediate mycorrhizal functioning. Despite the complexity of mycorrhizal associations, it might be possible to construct predictive models of mycorrhizal functioning. These models will need to incorporate variables and parameters that account for differences in plant responses to, and control of, mycorrhizal fungi, and differences in fungal effects on, and responses to, the plant. Developing and testing quantitative models of mycorrhizal functioning in the real world requires creative experimental manipulations and measurements. This work will be facilitated by recent advances in molecular and biochemical techniques. A greater understanding of how mycorrhizas function in complex natural systems is a prerequisite to managing them in agriculture, forestry, and restoration.

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“…Although these symbioses are cited in textbooks as clear examples of mutualism and plants often benefit from the association, the interaction might better be viewed as exhibiting a continuum of outcomes as the fungi can sometimes be of little net benefit to host plants or even function as a net parasitism. Different variables control whether a symbiosis between a mycorrhizal plant and fungus will develop as a mutualism or parasitism, including host plant characteristics, fungal characteristics, soil biotic and abiotic conditions, and experimental procedures (Modjo et al. 1987; Johnson et al.…”

Section: Introductionmentioning

confidence: 99%

A meta‐analysis of context‐dependency in plant response to inoculation with mycorrhizal fungi

Hoeksema¹,

Chaudhary²,

Gehring³

et al. 2010

Ecology Letters

952

817

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Mycorrhizal fungi influence plant growth, local biodiversity and ecosystem function. Effects of the symbiosis on plants span the continuum from mutualism to parasitism. We sought to understand this variation in symbiotic function using meta-analysis with information theory-based model selection to assess the relative importance of factors in five categories: (1) identity of the host plant and its functional characteristics, (2) identity and type of mycorrhizal fungi (arbuscular mycorrhizal vs. ectomycorrhizal), (3) soil fertility, (4) biotic complexity of the soil and (5) experimental location (laboratory vs. field). Across most subsets of the data, host plant functional group and N-fertilization were surprisingly much more important in predicting plant responses to mycorrhizal inoculation (Ôplant responseÕ) than other factors. Non-N-fixing forbs and woody plants and C 4 grasses responded more positively to mycorrhizal inoculation than plants with N-fixing bacterial symbionts and C 3 grasses. In laboratory studies of the arbuscular mycorrhizal symbiosis, plant response was more positive when the soil community was more complex. Univariate analyses supported the hypothesis that plant response is most positive when plants are P-limited rather than N-limited. These results emphasize that mycorrhizal function depends on both abiotic and biotic context, and have implications for plant community theory and restoration ecology.

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Mycorrhizal fungi in relation to control of tobacco stunt disease with soil fumigants

Cited by 27 publications

References 10 publications

The influence of crop rotation and soil fumigation on a mycorrhizal fungal community associated with soybean

The influence of crop rotation and soil fumigation on a mycorrhizal fungal community associated with soybean

Functioning of mycorrhizal associations along the mutualism–parasitism continuum*

A meta‐analysis of context‐dependency in plant response to inoculation with mycorrhizal fungi

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