Fungal inoculants in the field: Is the reward greater than the risk?

Hart, Miranda M.; Antunes, Pedro M.; Chaudhary, V. Bala; Abbott, Lynette K.

doi:10.1111/1365-2435.12976

Cited by 200 publications

(189 citation statements)

References 93 publications

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“…Use of indigenous inoculant would mitigate bulk and expense, and avoid questions about the desirability of exotic inoculants (Hart et al, 2018). Several field studies demonstrate that indigenous AMF, produced on-farm with mycotrophic hosts, may be an economical and sustainable practice.…”

Section: Augmentation With Indigenous Amf May Benefit Cropsmentioning

confidence: 99%

Little evidence that farmers should consider abundance or diversity of arbuscular mycorrhizal fungi when managing crops

2018

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Contents Summary 1092 I. Introduction 1093 II. Investigating activity of AMF in agroecosystems 1093 III. Crop benefit from AMF: agronomic and mycorrhizal literature differ 1094 IV. Flawed methodology leads to benefits of mycorrhizas being overstated 1094 V. Rigorous methodology suggests low colonisation by AMF can sometimes reduce crop yield 1095 VI. Predicting when mycorrhizas matter for crop yield 1096 VII. Crop genotype 1099 VIII. Fungal genotype 1100 IX. Complex interactions between the mycorrhizal fungal and soil microbial communities 1102 X. Phosphorus-efficient agroecosystems 1102 XI. Conclusions 1103 Acknowledgements 1104 References 1104 SUMMARY: Arbuscular mycorrhizal fungi (AMF) are ubiquitous in agroecosystems and often stated to be critical for crop yield and agroecosystem sustainability. However, should farmers modify management to enhance the abundance and diversity of AMF? We address this question with a focus on field experiments that manipulated colonisation by indigenous AMF and report crop yield, or investigated community structure and diversity of AMF. We find that the literature presents an overly optimistic view of the importance of AMF in crop yield due, in part, to flawed methodology in field experiments. A small body of rigorous research only sometimes reports a positive impact of high colonisation on crop yield, even under phosphorus limitation. We suggest that studies vary due to the interaction of environment and genotype (crop and mycorrhizal fungal). We also find that the literature can be overly pessimistic about the impact of some common agricultural practices on mycorrhizal fungal communities and that interactions between AMF and soil microbes are complex and poorly understood. We provide a template for future field experiments and a list of research priorities, including phosphorus-efficient agroecosystems. However, we conclude that management of AMF by farmers will not be warranted until benefits are demonstrated at the field scale under prescribed agronomic management.

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Section: Augmentation With Indigenous Amf May Benefit Cropsmentioning

confidence: 99%

Little evidence that farmers should consider abundance or diversity of arbuscular mycorrhizal fungi when managing crops

2018

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“…Recent evidence suggests that inoculation with whole soil transfers results in greater mycorrhizal colonization and plant growth compared with commercially produced inocula (Rowe et al ; Maltz & Tresder ). The long‐term consequences of applying commercially produced inocula are often poorly understood, yet can have far reaching impacts, including the potential suppression of native microbes in field settings (Schwartz et al ; Mummey et al ) or the alternation of ecosystem function (Hart et al ). Additionally, arbuscular mycorrhizal fungi (AMF) derived from commercial inocula may not always improve plant growth, as certain AMF may be less efficient at improving plant growth and performance than others (Johnson et al ; Klironomos ; Faye et al ).…”

Section: Introductionmentioning

confidence: 99%

Microbial inoculation influences arbuscular mycorrhizal fungi community structure and nutrient dynamics in temperate tree restoration

Lance

Burke

Hausman

et al. 2019

Restoration Ecology

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Soil microbial communities have a profound influence on soil chemical processes and subsequently influence tree nutrition and growth. This study examined how the addition of a commercial inoculum or forest‐collected soils influenced nitrogen (N) and phosphorus (P) dynamics, soil microbial community structure, and growth in Liriodendron tulipifera and Prunus serotina tree saplings. Inoculation method was an important determinant of arbuscular mycorrhizal fungi (AMF) community structure in both species and altered soil N dynamics in Prunus and soil P dynamics in Liriodendron. Prunus saplings receiving whole forest soil transfers had a higher rhizosphere soil carbon/nitrogen ratio and ammonia content at the end of the first growing season when compared to unmanipulated control saplings. Inoculation with whole forest soil transfers resulted in increased inorganic phosphorus in Liriodendron rhizosphere soils. The number of AMF terminal restriction fragments was significantly greater in rhizosphere soils of Liriodendron saplings inoculated with whole forest soil transfers and Prunus saplings receiving either inoculum source than control saplings. Forest soil inoculation also increased AMF colonization and suppressed stem elongation in Liriodendron after 16 months; conversely, Prunus AMF colonization was unchanged and stem elongation was significantly greater when saplings were inoculated with whole forest soil transfers. Longer term monitoring of tree response to inoculation will be essential to assess whether early costs of AMF colonization may provide long‐term benefits. This study provides insight into how practitioners can use microbial inoculation to alter AMF community structure and functioning, subsequently influencing tree growth and nutrient cycling during the restoration of degraded lands.

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“…Knowledge regarding AM fungal dispersal 55 mechanisms aids in the further incorporation of filamentous fungi into classic movement 56 ecology models (Bielčik et al, 2019). Furthermore, an improved understanding of AM fungal 57 dispersal, and how it may vary among species, improves our ability to manage mycorrhizal 58 symbioses in both natural and managed ecosystems (Hart et al, 2018). For example, efforts to 59 restore native mycorrhizal populations in anthropogenically disturbed soils could theoretically 60 focus on species with limited dispersal capabilities, but such efforts require species-specific 61 data on AM fungal dispersal to inform predictions.…”

mentioning

confidence: 99%

Trait-based aerial dispersal of arbuscular mycorrhizal fungi

Chaudhary

Nolimal

Sosa‐Hernández

et al. 2020

Preprint

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44 45 are important determinants of AM fungal community structure, but stochastic processes like 53 dispersal can also influence AM fungal community structure and biogeographic patterns 54 (Chaudhary et al., 2008; Nielsen et al., 2016). Knowledge regarding AM fungal dispersal 55 mechanisms aids in the further incorporation of filamentous fungi into classic movement 56 ecology models (Bielčik et al., 2019). Furthermore, an improved understanding of AM fungal 57 dispersal, and how it may vary among species, improves our ability to manage mycorrhizal 58 symbioses in both natural and managed ecosystems (Hart et al., 2018). For example, efforts to 59 restore native mycorrhizal populations in anthropogenically disturbed soils could theoretically 60 focus on species with limited dispersal capabilities, but such efforts require species-specific 61 data on AM fungal dispersal to inform predictions. 62 Trait-based approaches are increasingly being utilized in ecology to shift from 63 descriptive to predictive work (Messier et al., 2010). Spores, the primary reproductive 64 propagule for AM fungi, differ among species with respect to a suite of quantifiable 65 morphological traits (e.g. intrinsic properties) that likely influence movement and dispersal 66 capabilities. Arbuscular mycorrhizas notoriously form the largest single-cell fungal spores on 67 Earth, with some species measuring larger than 1 mm in diameter and visible to the naked eye 68 (Nicolson & Schenck, 1979). However, different species form spores up to two orders of 69 magnitude smaller and, for a comparatively species-poor group, interspecific variation in AM 70 fungal spore size is considerable (Aguilar-Trigueros et al., 2018). Because spore size, to an 71 extent, can be proportional to aerial dispersal predictors such as settling velocity (Kauserud et 72 al., 2008; Norros et al., 2014), it could be a useful trait for making predictions regarding AM 73 fungal dispersal. Other spore traits, such as surface ornamentation or color may also influence 74 AM fungal aerial dispersal; species-specific pits or projections in spore surfaces could affect 75 fluid drag (Roper et al., 2008) and differences in the degree of spore melanization could be 76 linked to stress tolerances such as UV radiation during aerial movement (Deveautour et al., 77 2019). Patterns in fungal traits observed in aerially dispersed AM fungi have the potential to 78 bring increased insight into predictions regarding which species or groups of species are more 79 likely to disperse by wind or long distances. 80 128 symbioses can vary as fungal communities shift, studying AM fungal dispersal in cities has 129implications for efforts to improve urban sustainability (Chaudhary et al., 2019). We also 130 compare the measured traits of aerial spores to known traits for all described AM fungi present 131 in the FUN FUN fungal functional trait database (Zanne et al., 2019). We predict that aerial AM 132 fungal spores will possess traits more conducive to wind dispersal such as a sm...

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Fungal inoculants in the field: Is the reward greater than the risk?

Cited by 200 publications

References 93 publications

Little evidence that farmers should consider abundance or diversity of arbuscular mycorrhizal fungi when managing crops

Little evidence that farmers should consider abundance or diversity of arbuscular mycorrhizal fungi when managing crops

Microbial inoculation influences arbuscular mycorrhizal fungi community structure and nutrient dynamics in temperate tree restoration

Trait-based aerial dispersal of arbuscular mycorrhizal fungi

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