The Mycorrhizal Fungus<i>Glomus macrocarpum</i>as a Cause of Tobacco Stunt Disease

Modjo, Hakam S.; Hendrix, James W.

doi:10.1094/phyto-76-688

Cited by 95 publications

(53 citation statements)

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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%

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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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Section: (3) Genotypic Factorsmentioning

confidence: 99%

“…Koide, 1985 ;Fitter, 1991;Modjo & Hendrix, 1986;Bougher, Grove & Malajczuk, 1990; see also references in Smith & Smith, 1996). Does this suggest that mycorrhizal fungi are sometimes parasitic on plants ?…”

Section: Introductionmentioning

confidence: 99%

Functioning of mycorrhizal associations along the mutualism–parasitism continuum*

1997

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“…This slight loss in yield was unrelated to P insufficiency, and appeared to be due to a poorly symbiotic AM isolate. Narrowing of mycorrhizal communities, evident after longterm monoculture, may directly contribute to reductions in crop yield (Modjo and Hendrix 1986;Johnson and Pfleger 1992;Johnson 1993). The possibility that this mechanism is in action in the northern Queensland cane industry has been raised (Magarey 1996).…”

Section: Introductionmentioning

confidence: 99%

Growth responses of sugarcane to mycorrhizal spore density and phosphorus rate

Kelly

Edwards

Thompson³

et al. 2005

Aust. J. Agric. Res.

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Abstract. Arbuscular mycorrhizal (AM) fungi, commonly found in long-term cane-growing fields in northern Queensland, are linked with both negative and positive growth responses by sugarcane (Saccharum spp.), depending on P supply. A glasshouse trial was established to examine whether AM density might also have an important influence on these growth responses. Mycorrhizal spores (Glomus clarum), isolated from a long-term cane block in northern Queensland, were introduced into a pasteurised low-P cane soil at 5 densities (0, 0.06, 0.25, 1, 4 spores/g soil) and with 4 P treatments (0, 8.2, 25, and 47 mg/kg). At 83 days after planting, sugarcane tops responded positively to P fertilizer, although responses attributable to spore density were rarely observed. In one case, addition of 4 spores/g led to a 53% yield response over those without AM at 8 mg P/kg, or a relative benefit of 17 mg P/kg. Root colonisation was reduced for plants with nil or 74 mg P/kg. For those without AM, P concentration in the topmost visible dewlap (TVD) leaf increased significantly with fertiliser P (0.07 v. 0.15%). However, P concentration increased further with the presence of AM spores. Irrespective of AM, the critical P concentration in the TVD leaf was 0.18%. This study confirms earlier reports that sugarcane is poorly responsive to AM. Spore density, up to 4 spores/g soil, appears unable to influence this responsiveness, either positively or negatively. Attempts to gain P benefits by increasing AM density through rotation seem unlikely to lead to yield increases by sugarcane. Conversely, sugarcane grown in fields with high spore densities and high plant-available P, such as long-term cane-growing soils, is unlikely to suffer a yield reduction from mycorrhizal fungi.

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“…Las micorrizas poseen características tanto químicas como físicas y a su vez biológicas que determinan la fertilización y conservación de los agro sistemas, la actividad de estos microorganismos influyen en la cinética que se lleva a cabo en los suelos cultivados como no cultivado tales como: la mineralización e inmovilización de nutrientes y su participación activa en el ciclo de los nutrientes del suelo (Modjo et al, 2006).…”

Section: Introductionunclassified

Efectos De La Fertilización Nitrogenada Y Fosfatada Sobre Poblaciones De Micorrizas Asociadas Al Cultivo De Cacao

Coello

Navarrete

Arteaga

et al. 2017

ESJ

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Cocoa is one of the most significant assets in the ecuadorian agricultural structure, which also provides a good source of income for thousands of farmworker families. However, fertilization research works in cocoa cultivation have been relatively scarce. Decades of global research have shown that mycorrhizal fungi determine the fertilization and conservation of agrosystems. Fertilization is considered to be among the cultural and agricultural practices affecting mycorrhizas, which diminishes or prevents the fungal colonization. The objectives of research works were the following: the characterization of mycorrhiza species associated with cocoa, to determine the effects of nitrogen and phosphate fertilization in plant population and to identify the critical dose affecting the fungus development. A factorial design was used (AxBxC), with two (2) application systems, four (4) doses of nitrogen fertilizer, and two (2) doses of phosphate fertilizer with three repetitions. The turkey's test was used to evaluate means with confidence interval of 95%. The evaluated variables were: diameter and length of cocoa pods, number of cocoa pods per tree, index of cocoa beans and almond yield per hectare, as well as, mycorrhizal spore counting, percentage of mycorrhizal fungi colonization, visual density of endophyte, and characterization of mycorrhiza species. The results concluded that the application of 100 Kg/ha N + 70 kg/ha P in the system below the soil surface, achieved yield increments

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The Mycorrhizal FungusGlomus macrocarpumas a Cause of Tobacco Stunt Disease

Cited by 95 publications

References 0 publications

Functioning of mycorrhizal associations along the mutualism–parasitism continuum*

Functioning of mycorrhizal associations along the mutualism–parasitism continuum*

Growth responses of sugarcane to mycorrhizal spore density and phosphorus rate

Efectos De La Fertilización Nitrogenada Y Fosfatada Sobre Poblaciones De Micorrizas Asociadas Al Cultivo De Cacao

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