Native Arbuscular Mycorrhizal Research Articles

Tracking arbuscular mycorrhizal fungi to their source: active inoculation and passive dispersal differentially affect community assembly in urban soils.

Communities of arbuscular mycorrhizal (AM) fungi assemble passively over time via biotic and abiotic mechanisms. In degraded soils, AM fungal communities can assemble actively when humans manage mycorrhizas for ecosystem restoration. We investigated mechanisms of urban AM fungal community assembly in a 2-yr green roof experiment. We compared AM fungal communities in inoculated and uninoculated trays to samples from two potential sources: the inoculum and air. Active inoculation stimulated more distinct and diverse AM fungal communities, an effect that intensified over time. In the treatment trays, 45% of AM fungal taxa were detected in the inoculum, 2% were detected in aerial samples, 23% were detected in both inoculum and air, and 30% were not detected in either source. Passive dispersal of AM fungi likely resulted in the successful establishment of a small number of species, but active inoculation with native AM fungal species resulted in an immediate shift to a diverse and unique fungal community. When urban soils are constructed or modified by human activity, this is an opportunity for intervention with AM fungi that will persist and add diversity to that system.

Arbuscular mycorrhizal fungi with contrasting life-history strategies differently affect health-promoting compounds in field-grown tomato by changing arbuscule occurrence and mycorrhizal assemblages in roots

Contrasting life-history characteristics of arbuscular mycorrhizal (AM) fungal families may have important implications for mycorrhizal functioning. Nevertheless, the effect of inoculation with AM fungi having different life-history strategies on the quality parameters of tomato fruits was not investigated. In this study, fruit and sauce quality of two tomato varieties were evaluated in field conditions after inoculation with four AM fungal species belonging to Glomeraceae and Gigasporaceae. The functional relationship between AM fungal traits (i.e., root colonization structures, community diversity) and fruit quality parameters was analyzed. AM fungal inoculation increased total phenols (TPC) and lycopene concentration in fruits of both varieties (47% and 247%, respectively) and antioxidant activity in var. Rio Grande (85%). Gigasporaceae were more effective in increasing TPC and antioxidant activity compared to Glomeraceae in var. Rio Grande. Gigaspora gigantea outperformed Scutellospora pellucida in var. Pisanello for TPC, antioxidant activity, and lycopene. Inoculated strains of G. gigantea, S. pellucida, Funneliformis mosseae, and Sclerocystis sinuosa were molecularly retrieved within tomato roots. In both varieties, a functional relationship between occurrence of arbuscules in roots and fruit quality was found. In var. Rio Grande, the abundance of some native AM fungal taxa shaped the pattern of fruit quality parameters. Gigasporaceae might be of great relevance for the synthesis of health-promoting compounds in tomato and should be included in biostimulant programmes targeting the production of high-quality vegetables.

Crop Productivity Boosters: Native Mycorrhizal Fungi from an Old-Growth Grassland Benefits Tomato (Solanum lycopersicum) and Pepper (Capsicum annuum) Varieties in Organically Farmed Soils.

This paper investigates the response of five tomato and five pepper varieties to native arbuscular mycorrhizal (AM) fungal inoculation in an organic farming system. The field experiment was conducted across a growing season at a working organic farm in Lawrence, KS, USA. The researchers hypothesized that native AM fungi inoculation would improve crop biomass production for both crop species, but that the magnitude of response would depend on crop cultivar. The results showed that both crops were significantly positively affected by inoculation. AM fungal inoculation consistently improved total pepper biomass throughout the experiment (range of +2% to +8% depending on the harvest date), with a +3.7% improvement at the final harvest for inoculated plants. An interaction between pepper variety and inoculation treatment was sometimes observed, indicating that some pepper varieties were more responsive to AM fungi than others. Beginning at the first harvest, tomatoes showed a consistent positive response to AM fungal inoculation among varieties. Across the experiment, AM fungi-inoculated tomatoes had +10% greater fruit biomass, which was driven by a +20% increase in fruit number. The study highlights the potential benefits of using native AM fungi as a soil amendment in organic farmed soils to improve pepper and tomato productivity.

Native Microbes Amplify Native Seedling Establishment and Diversity While Inhibiting a Non-Native Grass.

Although several studies have shown increased native plant establishment with native microbe soil amendments, few studies have investigated how microbes can alter seedling recruitment and establishment in the presence of a non-native competitor. In this study, the effect of microbial communities on seedling biomass and diversity was assessed by seeding pots with both native prairie seeds and a non-native grass that commonly invades US grassland restorations, Setaria faberi. Soil in the pots was inoculated with whole soil collections from ex-arable land, late successional arbuscular mycorrhizal (AM) fungi isolated from a nearby tallgrass prairie, with both prairie AM fungi and ex-arable whole soil, or with a sterile soil (control). We hypothesized (1) late successional plants would benefit from native AM fungi, (2) that non-native plants would outcompete native plants in ex-arable soils, and (3) early successional plants would be unresponsive to microbes. Overall, native plant abundance, late successional plant abundance, and total diversity were greatest in the native AM fungi+ ex-arable soil treatment. These increases led to decreased abundance of the non-native grass S. faberi. These results highlight the importance of late successional native microbes on native seed establishment and demonstrate that microbes can be harnessed to improve both plant community diversity and resistance to invasion during the nascent stages of restoration.

Assessment of the Effects of Selected AM Strain on the Growth and Yield of Brinjal

Arbuscular mycorrhizal (AM) fungi can increase plant uptake of nutrients especially relatively immobile elements such as P, Zn and Cu and consequently, improve plant growth and yield. The study was conducted to identify native AM strains, multiply and test their effects in reduction of P fertilizer brinjal production. Rhizosphere soils and roots of and brinjal were collected from each of four AEZs, viz. AEZ-9 (RARS, Jamalpur), AEZ-11 (RARS, Jashore), AEZ-25 (ARS, Bogura) and AEZ-28 (BARI, Joydebpur) in 2014-2015. Characterization and identification of arbuscular mycorrhizal strains was studied in the microbiology laboratory of Bangladesh Agricultural Research Institute (BARI). Nine AM strains were identified in brinjal Glomus geosporum, G. mosseae, G. fasciculatum, Acaulospora dilatata, A. mellea, A. morrowiae, Entrophospora infrequens, Sclerocystis coremioides and Gigaspora margarita were identified in brinjal. The collected mycorrhizal strains were maintained with trap crop sorghum under net house condition in 2014-2015 onwards. The best performing AM strain (Glomus mosseae) was selected from pot experiments at greenhouse of BARI. The sandy clay loam soil was used as the potting media. Nine each AM strains each from brinjal were tested with corresponding crops. Randomized Complete Block Design (RCBD) was followed with four replications. Dry matter yield (both root and shoot), some vegetative parameter, % root colonization and number of spores were observed. Finally the efficiency of the selected mycorrhiza. Glomus mosseae was tested under field condition during 2016-2017 and 2017-2018. Factorial RCBD was followed for field experiments with eight treatments and four replications. Selected soil-based AM inoculum (Glomus mosseae) those preserved in sorghum culture were used in seedbed of respective crops. Many morphological parameters and yield attributes were found as highest from 75% P. The highest crop yield was found from 75% P+AM, which was statistically similar to 100% P-AM indicating the possibility of saving 25% P in these three crops in AEZ 28 of Bangladesh. It was observed that Glomus mosseae could save 25% P in brinjal cultivation.

Synergistic enhancement of the phytostabilization of a semiarid mine tailing by a combination of organic amendment and native microorganisms (Funneliformis mosseae and Bacillus cereus)

The goal of this work was to evaluate the effects of fermented sugar beet residue and inoculation with a native arbuscular mycorrhizal (AM) fungus, Funneliformis mosseae (Nicol. and Gerd.) Gerd. and Trappe, or a native bacterium, Bacillus cereus Frankland & Frankland, alone or in combination, on the establishment of Lygeum spartum L. seedlings grown in a mine tailing under semiarid conditions. We conducted a field study to analyse root and shoot dry biomass, shoot nutrient contents, mycorrhization, plant nitrate reductase (NR) and acid phosphomonoesterase activities, soil enzyme activities and aggregate stability. Ten months after field transplanting, it was found that the three experimental factors had interacted synergistically with regard to shoot and root biomass, with increases of about 410% and 370%, respectively relative to plants in the untreated soil. The treatment combining all three factors increased the root content of all heavy metals, and the levels of nitrogen (N), phosphorus, potassium and NR activity in shoot tissues, whereas it decreased root acid phosphomonoesterase activity. Soil dehydrogenase, protease and β-glucosidase activities, total N content and aggregate stability were increased by the combined treatment. In conclusion, the combination of the organic amendment, the native AM fungus and the native bacterium can be regarded as a suitable tool for phytostabilization with L. spartum due to its ability to enhance the tolerance of plants to heavy metals, improve the plant nutritional status and increase the soil microbial function related to the C cycling.

Interaction of rhizobia with native AM fungi shaped biochar effect on soybean growth

While biochar amendment is widely recommended as an excellent agricultural management practice, the biochar effect on the productivity of legume crops with symbiotic microorganisms has been poorly elucidated. Hence, a pot experiment was conducted by growing soybean with or without commercial rhizobia inoculation in an arbuscular mycorrhizal (AM) fungi rich sandy soil amended with wheat straw biochar produced respectively at 350 °C, 450 °C, and 550 °C. We tested the effect of biochar on soybean–rhizobia symbiosis and its impact on plant growth, leaf gas exchange and mycorrhizal colonisation. In brief, rhizobia inoculation, without biochar, increased net photosynthetic rate by 81% and plant total biomass by 44% compared to no inoculation (the control). Without inoculation, amendment of low-temperature biochar (350 ºC) resulted in higher (by 51%) plant biomass than high-temperature (550 °C) biochar. With rhizobia inoculation, low-temperature biochar decreased plant biomass by 9.3% compared to high-temperature biochar. Further, soybean with rhizobia under high-temperature biochar decreased plant biomass by 17% compared to rhizobia inoculation only but increased by 19% compared to the control. Soybean leaf gas exchange capacity and root morphological traits were consistent with plant biomass but symbiotic activity showed small differences among all the treatments. Overall, N-fixing rhizobia could alter the biochar effect on soybean in soil rich in indigenous AM fungi, depending on the pyrolysis temperature of the biochar used. Low-temperature biochar stimulated soybean growth greater than high-temperature biochar, while rhizobia shifted biochar’s positive effect. • Pyrolysis temperature shaped biochar effect on soybean growth with and without rhizobia inoculation in a sandy soil. • Soybean growth without rhizobia inoculation is promoted rather by biochar-350 °C than by biochar-550 °C. • A tradeoff on soybean plant growth between biochar and rhizobia inoculation. • Soil inorganic N correlated with root morphology while leaf gas exchange responded to soil NO 3 - .

ARBUSCULAR MYCORRHIZAL FUNGI INOCULATION PROMOTES GROWTH OF VEGETATION IN REFUSE DUMP SOILS OF OPEN CAST MINE FIELD

Removal of soil from natural forest during open cast mining operation leads to severe disturbances not only to the local ecosystem also to livability of people. Reforestation is becoming a challenging task in post-open cast mine land as trees struggle to survive in refuse mine dump soils. Use of Arbuscular Mycorrhizal (AM) fungi can increase vegetation growth in disturbed soils. A study was conducted at refuse dump soils of Ballari, India. The objective was to investigate the effect of AM fungi in vegetation growth in the refuse dump soils. Twenty species were selected based on their ecological values viz., medicinal properties, firewood, fruits and shelter for birds etc. The saplings were inoculated with native AM fungi and maintained under nursery conditions for twelve months. The seedlings were observed for their growth characters by measuring height and collar diameter at regular intervals of every 3rd, 6th and 12th month. AM inoculated seedlings showed a greater increase in height than the control or non-inoculated seedlings. The increase in growth was three times in Syzygiumcumini, Thespesiapopulnea, Grevillearobusta and Holoptelaintegrifolia and two times in Mangiferaindica, Cordiaoblique, Tectonagrandis, Swieteniamahogany, Azadirachtaindica, Ficusbenghalensis, Ficusreligiosa and Phyllanthusemblica. Enhancement of collar diameter was three times in Thespesia populnea, A. indica, Ficus benghalensis, Ficus religiosa, Syzygiumcumini, Holoptela integrifolia and Grevillea robusta. The observation on establishment and survival rate of transplanted species like Tamarindus indica, Butea monosperma, Phyllanthus emblica and Cordia obliquato the main field was better when compared to other species. The study thus indicates the need and beneficial effect of AM fungi as growth promoters for tree species in refuse dump soils of opencast coal mine land.

Manipulating plant microbiomes in the field: Native mycorrhizae advance plant succession and improve native plant restoration

Abstract The plant microbiome is critical to plant health and is degraded with anthropogenic disturbance. However, the value of re‐establishing the native microbiome is rarely considered in ecological restoration. Arbuscular mycorrhizal (AM) fungi are particularly important microbiome components, as they associate with most plants, and later successional grassland plants are strongly responsive to native AM fungi. With five separate sites across the United States, we inoculated mid‐ and late successional plant seedlings with one of three types of native microbiome amendments: (a) whole rhizosphere soil collected from local old‐growth, undisturbed grassland communities in Illinois, Kansas or Oklahoma, (b) laboratory cultured AM fungi from these same old‐growth grassland sites or (c) no microbiome amendment. We also seeded each restoration with a diverse native seed mixture. Plant establishment and growth was followed for three growing seasons. The reintroduction of soil microbiome from native ecosystems improved restoration establishment. Including only native arbuscular mycorrhizal fungal communities produced similar improvements in plant establishment as what was found with whole soil microbiome amendment. These findings were robust across plant functional groups. Inoculated plants (amended with either AM fungi or whole soil) also grew more leaves and were generally taller during the three growing seasons. Synthesis and applications. Our research shows that mycorrhizal fungi can accelerate plant succession and that the reintroduction of both whole soil and laboratory cultivated native mycorrhizal fungi can be used as tools to improve native plant restoration following anthropogenic disturbance.

Mycorrhizal types influence island biogeography of plants

Plant colonization of islands may be limited by the availability of symbionts, particularly arbuscular mycorrhizal (AM) fungi, which have limited dispersal ability compared to ectomycorrhizal and ericoid (EEM) as well as orchid mycorrhizal (ORC) fungi. We tested for such differential island colonization within contemporary angiosperm floras worldwide. We found evidence that AM plants experience a stronger mycorrhizal filter than other mycorrhizal or non-mycorrhizal (NM) plant species, with decreased proportions of native AM plant species on islands relative to mainlands. This effect intensified with island isolation, particularly for non-endemic plant species. The proportion of endemic AM plant species increased with island isolation, consistent with diversification filling niches left open by the mycorrhizal filter. We further found evidence of humans overcoming the initial mycorrhizal filter. Naturalized floras showed higher proportions of AM plant species than native floras, a pattern that increased with increasing isolation and land-use intensity. This work provides evidence that mycorrhizal fungal symbionts shape plant colonization of islands and subsequent diversification.

A habitat analog approach establishes native plant communities on green roofs

AbstractNovel habitats can support biodiversity by amending what has been lost through urban development. However, the effects of fragmentation, disturbance, and altered availability of resources in cities can prevent many local plant species from establishing and persisting. Novel habitats like green roofs could be colonized by native plants if species could overcome particularly harsh environmental conditions. To do so, green roofs could be designed using a habitat analog approach wherein natural habitats with similar abiotic characteristics inform the potential species pool. In this study, we tested the efficacy of using a habitat analog approach to establish native plant communities on green roofs. We surveyed vegetation in 18 dry prairies of three subtypes (gravel hill, dolomite, and sand) and planted replicates of two communities (sand prairie and rock prairie, which combined gravel hill and dolomite) on green roofs to determine which prairie was the most suitable analog. We investigated the effect of three environmental variables on plant establishment, survival, and growth: soil continuity (continuous soil vs. isolated trays), planting method (seeds vs. pre‐grown seedlings), and the addition of native arbuscular mycorrhizal (AM) fungi. We determined the most suitable habitat analog and measured the effect of the environmental variables by conducting vegetation surveys in the experimental roof plots for three years. The experimental rock prairie communities more closely resembled the target than did the sand prairies, supporting the hypothesis that shared soil properties are important for establishing analogous plant communities in novel habitats. At the community level, survival and growth were higher in continuous soil, highlighting the importance of belowground components of constructed habitats. We found no effect of planting method or addition of native AM fungi on plant survival or growth. Overall, our results support using a habitat analog approach to select native species that support biodiversity in constructed novel habitats like green roofs.

Mycorrhizal inoculation increases fruit production without disturbance of native arbuscular mycorrhizal community in jujube tree orchards (Senegal)

Arbuscular mycorrhizal (AM) fungi constitute promising biofertilizers for the deployment of a sustainable agriculture. However, the evaluation of mycorrhizal benefits in the field is poorly documented, notably in fruit tree orchards, and concerns exclusively growth performance and nutrition. Here, we evaluated the persistence of beneficial effects of AM fungal inoculation on two jujube (Ziziphus mauritiana Lam.) cultivars (Tasset and Gola) inoculated in nursery conditions and subsequently transferred in the field until fruit production. The growth-promoting effects on jujube observed in nursery was still maintained 18 months after planting, with significant higher rates of survival and an increase of fruit production for inoculated jujube cultivars. Nevertheless, AM-mediated responses were dependent on cultivar. No major disturbance of native AM fungal community was associated with AM fungal inoculation but a stimulation of AM fungal colonization is probable. The use of mycorrhizal inoculation with the R. irregularis IR27 strain hold promise for the development of efficient jujube orchards under semi-arid conditions.

Divergent root P uptake strategies of three temperate grassland forage species

Temperate grasslands are affected by nutrient deficiency and this deficiency is one of the main limiting factors for forage production, such as the grasslands of the Salado River Basin (Argentina), which exhibit low-P availability for plant growth. Alternatives to increase forage production include the selection of plant species adapted to grow under P deficiency, P fertilization, and arbuscular mycorrhizal (AM) fungi. In a pot experiment, we investigated the effect of low and high-P doses and AM fungi on the development of three forage species. The interaction of P addition and AM fungi increased L. tenuis (legume) biomass production and improve P nutrition, even with high-P dose, because of its higher P requirement to grow and lower ability for P uptake than grasses. High-P increased the biomass of S. arundinaceus (C3 grass) and P. coloratum (C4 grass), and AM fungi did not directly impact on plant growth of grasses, but did impact on P nutrition at either level of P fertilization. The specific P uptake of non-fertilized L. tenuis plants increased 97% due to AM inoculation and was the highest value among the three non-fertilized species. Furthermore, the specific P uptake of non-fertilized grasses was similar, despite the C metabolic pathway and AM fungi, but the specific root length was 70.88% lower for P. coloratum than for S. arundinaceus. Thus, the main strategy of L. tenuis was AM association, whereas that of S. arundinaceus was the highest ability of the root system to explore the soil. In P. coloratum, the strategy could not be explained by changes in specific root length or AM association. Our results would be an advantageous first step to promote better management of forage land sustainably while increasing forage production and preserve the beneficial effects of native AM communities in the Salado River Basin.

Genotypic variation in response and dependency of Cajanus cajan (L.) Millsp., on arbuscular mycorrhizal fungi in a tropical Alfisol

Plant genotypes significantly differ in their growth characteristics and dependence on arbuscular mycorrhizal (AM) fungi for maximum growth and productivity at a given soil fertility level. Therefore, we examined the mycorrhizal dependency and response of seven pigeon pea (Cajanus cajan) genotypes (BRG–1, BRG–2, BRG–3, BRG–4, BRG–5, TRG–7 and Vamban–3) on native AM fungi. Plants of pigeon pea genotypes were grown in the presence and absence of native AM fungi for 45 days. At harvest, plant growth characteristics, root architecture, nodulation, AM fungal colonization, and plant nutrients were measured and nutrient uptake, nutrient use efficiencies and mycorrhizal dependency were calculated. The plant growth, root architecture, nodulation, and nutrient characteristics varied significantly among pigeon pea genotypes and were positively (except nutrient usage) influenced by AM fungi. The mycorrhizal dependency significantly varied among pigeon pea genotypes and ranged from 30.54% to 65.02%. The genotypes BRG–3 and BRG–4 were highly mycorrhizal dependent and accumulated maximum biomass under mycorrhizal conditions. Our results show that AM fungi in addition to improving plant growth and nutrient uptake can also modify the proportional allocation of biomass to shoot and root, root architecture, and nutrient use among pigeon pea genotypes.

Abiotic and biotic context dependency of perennial crop yield.

Perennial crops in agricultural systems can increase sustainability and the magnitude of ecosystem services, but yield may depend upon biotic context, including soil mutualists, pathogens and cropping diversity. These biotic factors themselves may interact with abiotic factors such as drought. We tested whether perennial crop yield depended on soil microbes, water availability and crop diversity by testing monocultures and mixtures of three perennial crop species: a novel perennial grain (intermediate wheatgrass—Thinopyrum intermedium-- that produces the perennial grain Kernza®), a potential perennial oilseed crop (Silphium intregrifolium), and alfalfa (Medicago sativa). Perennial crop performance depended upon both water regime and the presence of living soil, most likely the arbuscular mycorrhizal (AM) fungi in the whole soil inoculum from a long term perennial monoculture and from an undisturbed native remnant prairie. Specifically, both Silphium and alfalfa strongly benefited from AM fungi. The presence of native prairie AM fungi had a greater benefit to Silphium in dry pots and alfalfa in wet pots than AM fungi present in the perennial monoculture soil. Kernza did not benefit from AM fungi. Crop mixtures that included Kernza overyielded, but overyielding depended upon inoculation. Specifically, mixtures with Kernza overyielded most strongly in sterile soil as Kernza compensated for poor growth of Silphium and alfalfa. This study identifies the importance of soil biota and the context dependence of benefits of native microbes and the overyielding of mixtures in perennial crops.

Co‐introduction of native mycorrhizal fungi and plant seeds accelerates restoration of post‐mining landscapes

Abstract Grasslands are among the most threatened terrestrial biomes, and habitat conservation alone will be insufficient to meet biodiversity goals. While restoration of indigenous grasslands is a priority, conflict with economic objectives means that incorporation of alternative habitats is necessary to offset grassland loss. With up to 800,000 km2 of land affected by mining globally, there is an opportunity to create additional grassland habitat in post‐mining landscapes. We aimed to assess whether co‐introduction of native arbuscular mycorrhizal (AM) fungi and plants is an efficient means of initializing species‐rich vegetation recovery in barren post‐mining landscapes. We established an experiment in three post‐mining areas in Estonia, where we seeded plots with native plant seeds and inoculated them with trap‐cultured native AM fungi from a similar habitat. We measured the abundance and composition of soil AM fungal and above‐ground plant communities in two consecutive years using relevés, high‐throughput sequencing and fatty acid profiling. Our results demonstrate that co‐introduction of native plants and AM fungi is an effective way to establish species‐rich vegetation in post‐mining areas. Co‐introduction of symbiotic partners resulted in higher richness, diversity and abundance of plants and AM fungi than when either partner was introduced individually. However, the plant and AM fungal communities in sown and inoculated plots were not distinct from those in uninoculated treatments; they rather formed a subset of all taxa present on the sites but exhibited higher diversity than in uninoculated plots. Synthesis and applications. This study shows that managing the below‐ground microbiome is an essential part of vegetation restoration. The availability of symbiotic partners can be considered a key aspect determining the diversity of restored vegetation. Targeted inoculations with native and habitat‐specific native arbuscular mycorrhizal fungi could therefore increase restoration success.

Effects of the soil microbiome on the demography of two annual prairie plants.

Both mutualistic and pathogenic soil microbes are known to play important roles in shaping the fitness of plants, likely affecting plants at different life cycle stages.In order to investigate the differential effects of native soil mutualists and pathogens on plant fitness, we compared survival and reproduction of two annual tallgrass prairie plant species (Chamaecrista fasciculata and Coreopsis tinctoria) in a field study using 3 soil inocula treatments containing different compositions of microbes. The soil inocula types included fresh native whole soil taken from a remnant prairie containing both native mutualists and pathogens, soil enhanced with arbuscular mycorrhizal (AM) fungi derived from remnant prairies, and uninoculated controls.For both species, plants inoculated with native prairie AM fungi performed much better than those in uninoculated soil for all parts of the life cycle. Plants in the native whole prairie soil were either generally similar to plants in the uninoculated soil or had slightly higher survival or reproduction.Overall, these results suggest that native prairie AM fungi can have important positive effects on the fitness of early successional plants. As inclusion of prairie AM fungi and pathogens decreased plant fitness relative to prairie AM fungi alone, we expect that native pathogens also can have large effects on fitness of these annuals. Our findings support the use of AM fungi to enhance plant establishment in prairie restorations.

Native plant abundance, diversity, and richness increases in prairie restoration with field inoculation density of native mycorrhizal amendments

Ecological restoration efforts can increase the diversity and function of degraded areas. However, current restoration practices cannot typically reestablish the full diversity and species composition of remnant plant communities. Restoration quality can be improved by reintroducing key organisms from the native plant microbiome. In particular, root symbionts called arbuscular mycorrhizal (AM) fungi are critical in shaping grassland communities, but are sensitive to anthropogenic disturbance, which may pose a problem for grassland restoration. Studies of mycorrhizal amendments include inoculation densities of 2–10,000 kg of inocula per hectare. These studies report variable results that may depend on inocula volume, composition, or nativeness. Here we test eight different densities of native AM fungal amendment, ranging from 0 to 8,192 kg/ha in a newly installed prairie restoration. We found that native plant establishment benefited from native mycorrhizal inocula, resulting in improvements in native plant abundance, richness, and community diversity. Moreover, the application of very low densities of native mycorrhizal inocula, as suggested on commercial mycorrhizal products, were ineffective, and higher concentrations were required to benefit native plant abundance and community diversity. These data suggest that higher densities of mycorrhizal amendment or perhaps alternative distribution methods may be required to maximize benefits of native mycorrhizal amendments in restoration practices.

Bacteria from native soil in combination with arbuscular mycorrhizal fungi augment wheat yield and biofortification

Plant growth promoting bacteria (PGPB) have been used to enhance crop productivity. The effect of native PGPB and arbuscular mycorrhizal (AM) fungi in combination on wheat yield, biofortification and soil enzymatic activity is a relatively unexplored area. Twenty seven bacterial isolates from three different soils were characterized for their plant growth promoting traits. A total of three native and five non-native bacteria were used with and without arbuscular mycorrhizal (AM) fungi in an open greenhouse pot experiment with two wheat varieties to evaluate their effect on wheat yield, nutrient uptake, and soil health parameters. Wheat plants subjected to native PGPB (CP4) (Bacillus subtilis) and AM fungi treatment gave the best results with reference to macronutrient (nitrogen and phosphorus), micronutrient (iron and zinc) content in wheat grains and yield-related parameters, including thousand grain weight, number of grains per spike and total tillers per plant in both wheat cultivars. Treatment with CP4 and CP4 plus AM fungi enhanced total chlorophyll in wheat leaves indicating higher photosynthetic activity. Significant improvement in soil health-related parameters, including soil organic matter and dehydrogenase activity, was observed. Significant correlation among grain yield-related parameters, nutrient enhancement, and soil health parameters was observed in PGPB and AM fungi treated plants, especially HD-3086. These results provide a roadmap for utilizing native PGPB and AM fungi for enhancing wheat production in Punjab state of India and exploring their utility in other parts of the country with different soil and environmental conditions.

Forage biomass yield and arbuscular mycorrhizal symbiosis in a legume and C3 and C4 grasses under increasing soil phosphorus availability

Phosphorus (P) is the main limiting factor for forage production in grasslands. It is important to determine levels of available P in soil that optimise production with minimum impact on arbuscular mycorrhizal (AM) symbiosis. We investigated the effects of increasing P availability on biomass production, root morphology, AM symbiosis and P acquisition of a forage legume (Lotus tenuis), a C3 grass (Schedonorus arundinaceus) and a C4 grass (Panicum coloratum) growing on a P-deficient soil in pots with P applied at rates of 0–160 mg kg–1 dry soil. The three forage species responded strongly to addition of P, with 90% of maximum shoot growth reached at available P levels of 24.3 mg kg–1 for L. tenuis, 14.4 mg kg–1 for P. coloratum and 11.2 mg kg–1 for S. arundinaceus. Lotus tenuis and P. coloratum produced higher yields of shoot biomass than S. arundinaceus. Root dry weight was higher in the legume than in the grasses, with the root-mass fraction being lowest in P. coloratum. AM colonisation was higher in L. tenuis roots than in grass roots, and decreased with increased soil P availability, especially in grasses. Low to moderate additions of P did not affect, and could even improve, AM colonisation in L. tenuis roots. For L. tenuis, it is possible to increase forage yield while maintaining high values of AM colonisation at 10–20 mg kg–1 of available P, but for grasses, especially S. arundinaceus, it is difficult to achieve both objectives. The presence of L. tenuis in grasslands or pastures may contribute to maintaining the native AM inoculum under a wide range of soil P availability in regions such as the Salado River basin of Argentina.