Research must use a systems agronomy approach if management of the arbuscular mycorrhizal symbiosis is to contribute to sustainable intensification

Ryan, Megan H.; Graham, James H.; Morton, Joseph B.; Kirkegaard, John A.

doi:10.1111/nph.15600

Cited by 16 publications

(15 citation statements)

References 19 publications

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“…In absence of in situ studies on the functioning of AMF communities in agroecosystems, we can at present only speculate about the functional implications that loss of AMF taxa due to intensive agricultural land use may have (Ryan and Graham, 2018;Rillig et al, 2019;Ryan et al, 2019). Gigasporaceae, such as Scutellospora spp., are reported to be particularly important for plant mineral nutrient uptake (Maherali and Klironomos, 2007), while AMF richness and diversity are known to promote the productivity of grasslands through increased soil resource use by functional niche differentiation (van der Heijden et al, 1998;Wang et al, 2019).…”

Section: Possible Trait-and Life History-related Explanations For Shimentioning

confidence: 98%

Forage Rotations Conserve Diversity of Arbuscular Mycorrhizal Fungi and Soil Fertility

2020

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In the Mediterranean, long-term impact of typical land uses on soil fertility have not been quantified yet on replicated mixed crop-livestock farms and considering the variability of soil texture. Here, we report the effects, after 15 years of practice, of two legumewinter cereal rotations, olive orchards and vineyards on microbiological and chemical indicators of soil fertility and the communities of arbuscular mycorrhizal fungi (AMF). We compare the changes among these four agricultural land-use types to woodland reference sites. Root colonization by AMF of English ryegrass (Lolium perenne L.), a grass that occurred under all land use types, was only half as heavy in biannual berseem clover (Trifolium alexandrinum L.)-winter cereal rotations than in 4-year alfalfa (Medicago sativa L.)-winter cereal rotations. In olive (Olea europaea L.) orchards and vineyards (Vitis vinifera L.), where weeds are controlled by frequent surface tillage, the AMF root colonization of ryegrass was again much lower than in the legume-cereal rotations and at the woodland reference sites. All the microbial parameters and soil organic carbon correlated most strongly with differences in occurrence and relative abundance (β-diversity) of AMF genera in soil. The soil pH and mineral nutrients in soil strongly correlated with differences in AMF root colonization and AMF genus richness (α-diversity) in soil. Diversity of AMF was much less affected by soil texture than land use, while the opposite was true for microbial and chemical soil fertility indicators. Land uses that guaranteed a continuous ground cover of herbaceous plants and that involved only infrequent tillage, such as multiyear alfalfa-winter cereal rotation, allowed members of the AMF genus Scutellospora to persist and remain abundant. On the contrary, under land uses accompanied by frequent tillage and hence discontinuous presence of herbaceous plants, such as tilled olive orchard and vineyard, members of the genus Funneliformis dominated. These results suggest that multiyear alfalfa-winter cereal rotation with active plant growth throughout the year is the least detrimental agricultural land use in soil carbon and AMF abundance and diversity, relative to the woodland reference.

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Section: Possible Trait-and Life History-related Explanations For Shimentioning

confidence: 98%

Forage Rotations Conserve Diversity of Arbuscular Mycorrhizal Fungi and Soil Fertility

2020

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“…In no cases were there correlations between the nutrients transferred (data not shown). (Cotton, 2018;Rillig et al, 2019;Ryan & Graham, 2018;Ryan, Graham, Morton, & Kirkegaard, 2019).…”

Section: Carbon-for-nutrient Transfer Between Wheat and Amfmentioning

confidence: 99%

Carbon for nutrient exchange between arbuscular mycorrhizal fungi and wheat varies according to cultivar and changes in atmospheric carbon dioxide concentration

Thirkell

Pastok

Field

2019

Global Change Biology

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Arbuscular mycorrhizal fungi (AMF) form symbioses with most crops, potentially improving their nutrient assimilation and growth. The effects of cultivar and atmospheric CO2 concentration ([CO2]) on wheat–AMF carbon‐for‐nutrient exchange remain critical knowledge gaps in the exploitation of AMF for future sustainable agricultural practices within the context of global climate change. We used stable and radioisotope tracers (15N, 33P, 14C) to quantify AMF‐mediated nutrient uptake and fungal acquisition of plant carbon in three wheat (Triticum aestivum L.) cultivars. We grew plants under current ambient (440 ppm) and projected future atmospheric CO2 concentrations (800 ppm). We found significant 15N transfer from fungus to plant in all cultivars, and cultivar‐specific differences in total N content. There was a trend for reduced N uptake under elevated atmospheric [CO2]. Similarly, 33P uptake via AMF was affected by cultivar and atmospheric [CO2]. Total P uptake varied significantly among wheat cultivars and was greater at the future than current atmospheric [CO2]. We found limited evidence of cultivar or atmospheric [CO2] effects on plant‐fixed carbon transfer to the mycorrhizal fungi. Our results suggest that AMF will continue to provide a route for nutrient uptake by wheat in the future, despite predicted rises in atmospheric [CO2]. Consideration should therefore be paid to cultivar‐specific AMF receptivity and function in the development of climate smart germplasm for the future.

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“…At present, although mycorrhizae efficacy is controversial (Hart et al 2018;Ryan and Graham 2018;Rillig et al 2019;Ryan et al 2019), most authors agree on the need for new methods to disentangle the impact of arbuscular mycorrhizal fungi in the field. Rillig et al (2016) advocate to produce easyto-use tools for on-site mycorrhizal abundance and diversity monitoring, plant breeding programs prioritizing plant mycorrhizal responsiveness, and mycoengineering (promotion of mycorrhizal strains with desirable traits) while Ryan and Graham (2018) emphasize the need for comprehensive agronomic approaches.…”

Section: Resultsmentioning

confidence: 99%

“…Whilst enhancing colonization by indigenous arbuscular mycorrhizal fungi seems to be a promising alternative practice (Pellegrino et al 2011), yield benefits provided by such a crop management are controversial. Some authors argue that the literature presents an overoptimistic vision of the impacts of arbuscular mycorrhizal fungi on yields (Ryan and Graham 2018;Ryan et al 2019). Others reply that limiting the analysis to yields is restrictive in view of the many services that arbuscular mycorrhizal fungi can provide to contribute to the sustainability of agrosystems (Rillig et al 2018).…”

Section: Introductionmentioning

confidence: 99%

Codesigning biodiversity-based agrosystems promotes alternatives to mycorrhizal inoculants

Chave

Angeon²,

Paut

et al. 2019

Agron. Sustain. Dev.

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Facing the challenge of the ecological transition of agriculture, biodiversity opens new avenues to enhance ecological interactions and reduce chemical input dependency. Designing biodiversity-based agrosystems requires an agroecological approach that combines key principles: exploring a wide range of concepts and solutions, adopting systemic reasoning, implementing a sitespecific approach, developing an action-oriented process, and maintaining a continuous improvement dynamic. This type of approach has never been developed to harness mycorrhizal fungi, which are key components of soil biodiversity, because their beneficial action on crops depends on complex and underexploited ecological interactions. At present, mycorrhizae are mainly used through industrial inoculants that fit within the productionist paradigm. To shift toward agroecological approaches, we implemented a methodological framework conceived to better address the design of mycorrhiza-friendly cropping systems by sharing knowledge with farmers in four different study areas (Provence, French Guiana, Guadeloupe, and Martinique). This framework includes participative workshops, a board game, and prospective exercises to collect farmers' proposals and the factors that prevent from implementing mycorrhiza-friendly cropping systems. We showed that 90% of the farmers proposed alternatives to industrial inoculants, 50% of them adopted systemic reasoning by combining these alternative proposals. Most farmers understood that they were all potential "mycorrhizae producers". We showed, for the first time through on-farm experiments that valorization of indigenous mycorrhizal fungi strains using a donor plant is an effective practice to increase root colonization before planting (up to a frequency of 95% and an intensity of 32%). Considering the increasing supply of mycorrhizal inoculants and despite the uncertainty of related knowledge, we codesigned innovative practices. Learning communities (technical advisors, high school teachers, etc.) assumed responsibility for continuous improvement in knowledge and practices. Finally, beyond the issue of mycorrhizae, we showed that an agroecological approach could bring stakeholders one step further into the design of biodiversity-based agrosystems.

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Research must use a systems agronomy approach if management of the arbuscular mycorrhizal symbiosis is to contribute to sustainable intensification

Cited by 16 publications

References 19 publications

Forage Rotations Conserve Diversity of Arbuscular Mycorrhizal Fungi and Soil Fertility

Forage Rotations Conserve Diversity of Arbuscular Mycorrhizal Fungi and Soil Fertility

Carbon for nutrient exchange between arbuscular mycorrhizal fungi and wheat varies according to cultivar and changes in atmospheric carbon dioxide concentration

Codesigning biodiversity-based agrosystems promotes alternatives to mycorrhizal inoculants

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