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1.
Crop rotation adoption in no‐tillage systems (NTS) has been recommended to increase the biological activity and soil aggregation, suppress soil and plant pathogens, and increase the productivity aiming at the sustainability of agricultural areas. In this context, this study aimed to assess the effect of crop rotation on the arbuscular mycorrhizal fungi (AMF) community and soil aggregation in a soil cultivated for nine years under NTS. Treatments consisted of combinations of three summer crop sequences and seven winter crops. Summer crop sequences consisted of corn (Zea mays L.) monoculture, soybean (Glycine max L. Merrill) monoculture, and soybean–corn rotation. Winter crops consisted of corn, sorghum (Sorghum bicolor (L.) Moench), sunflower (Helianthus annuus L.), sunn hemp (Crotalaria juncea L.), pigeon pea (Cajanus cajan (L.) Millsp.), oilseed radish (Raphanus sativus L.), and millet (Pennisetum americanum (L.) Leeke). Soil samples were collected at a depth of 0–0.10 m for analyses of soil chemical, physical, and biological attributes. Spore abundance, total glomalin, and soil aggregate stability index were higher in the soil under corn monoculture. The highest values of aggregate mean weight diameter were observed in the soybean–corn rotation (3.78 mm) and corn monoculture (3.70 mm), both differing from soybean monoculture (3.15 mm), while winter crops showed significant differences only between sorghum (3.96 mm) and pigeon pea (3.25 mm). Two processes were identified in the soil under summer crop sequences. The first process was observed in PC1 (spore abundance, total glomalin, easily extractable glomalin, pH, P, and Mg2+) and was related to AMF; the second process occurred in PC2 (aggregate mean weight diameter, soil aggregate stability index, K+, and organic matter) and was related to soil aggregation. The nine‐year no‐tillage system under the same crop rotation adoption influenced AMF abundance in the soil, especially with corn cultivation in the summer crop sequence, which promoted an increased total external mycelium length and number of spores of AMF. In addition, it favored an increased soil organic matter content, which is directly related to the formation and stability of soil aggregates in these managements.  相似文献   

2.
The decomposition of plant organic matter and the stability of soil aggregates are important components of soil carbon cycling, and the relationship between decomposition rate and arbuscular mycorrhizal fungi (AMF) has recently received considerable attention. The interaction of AMF with their associated microorganisms and the consequences for litter decomposition and soil aggregation still remain fairly unclear. In a laboratory pot experiment we simultaneously tested the single and combined effects of one AMF species (Rhizophagus irregularis) and a natural non-AMF microbial community on the decomposition of small wooden sticks and on soil aggregation. To disentangle effects of hyphae and roots we placed mesh bags as root exclusion compartments in the soil. The decomposition of the wooden sticks in this compartment was significantly reduced in the presence of AMF, but not with the non-AMF microbial community only, compared to the control, while aggregation was increased in all treatments compared to the control. We suggest that AMF directly (via localized nutrient removal or altered moisture conditions) or indirectly (by providing an alternative carbon source) inhibited the activity of decomposers, leading to different levels of plant litter degradation under our experimental settings. Reduced decomposition of woody litter in presence of AMF can be important for nutrient cycling in AMF-dominated forests and in the case of woody plants and perennials that develop lignified roots in grasslands.  相似文献   

3.
Arbuscular mycorrhizal fungi influence tomato competition with bahiagrass   总被引:2,自引:0,他引:2  
A strip-tillage production system for tomatoes (Lycopersicon esculentum Mill.) is impacted by nutrient competition from bahiagrass (Paspalum notatum Flügge). Tomato and bahiagrass differ in mycorrhizal responsiveness and our objective was to evaluate the influence of arbuscular mycorrhizal (AM) fungi on the competitive pressure of bahiagrass on growth of tomato. The first experiment evaluated the effect of bahiagrass competition, soil pasteurization, and AM fungal inoculation on tomato growth, P content, and root colonization in a low-P soil. Tomato grown alone was very responsive to mycorrhizal colonization - shoot dry mass of inoculated plants was up to 243% greater than that of noninoculated plants. Tomato grown with bahiagrass had reduced root and shoot growth across all treatments compared with tomato grown alone, but there was an increase in shoot mass following AM fungal inoculation across both pasteurized and nonpasteurized treatments resulting in a >50% increase in shoot dry mass of tomato compared to noninoculated controls. A second experiment was conducted to test bahiagrass competition, soil pasteurization, AM fungal inoculation, and P amendment on tomato growth in a moderate-P soil. With bahiagrass competition and no P addition, inoculation increased root mass by 115% and shoot mass by 133% in pasteurized soil; however, with the application of 32 mg P kg-1 the trend was reversed and inoculated plants were smaller than noninoculated controls. We conclude that the role of mycorrhizae in plant competition for nutrients is markedly impacted by soil nutrient status and reduced P application may allow tomatoes to take advantage of their inherent responsiveness to mycorrhizae in a low to moderate soil-P environment.  相似文献   

4.
Salinity stress is considered one of the most harmful environmental plant stresses, as it reduces irrigated land crop production by over 20%worldwide.Hence, it is imperative to develop salt-tolerant crops in addition to understanding various mechanisms enabling plant growth under saline stress conditions.Recently, a novel biological approach that aims to address salinity stress has gained momentum, which involves the use of arbuscular mycorrhizal (AM) fungi in plant-microbe interactions. It has ...  相似文献   

5.
Glyphosate is a systemic non-selective herbicide, the most widely used in the world. Alongside with its use in agricultural and forestry systems, this herbicide is used in grasslands in late summer with the aim of promoting winter species with the consequent increase in stocking rate. However, its effects on non-target organisms, such as arbuscular mycorrhizal fungi (AMF), are unclear. Arbuscular mycorrhizal fungi (AMF) colonize the root of more than 80% of terrestrial plants, improving their growth and survival, and therefore playing a key role in ecosystem structure and function. The aim of this work was to investigate the possible pathways through which glyphosate application affects AMF spores viability and root colonization in grassland communities. Our hypothesis is that glyphosate application can damage AMF directly (through contact with spores and external hyphae) or indirectly through the changes it generates on host plants. The experiment had a factorial array with three factors: (1) plant species, at two levels (Paspalum dilatatum and Lotus tenuis), (2) doses of glyphosate, at three levels (0 l ha−1, 0.8 l ha−1 and 3 l ha −1), and (3) application site, at two levels: soil (direct pathway) and plant foliage (indirect pathway). Spore viability was reduced even under the lowest glyphosate rate, but only when it was applied on the soil. Total root colonization for both species was similarly decreased when glyphosate was applied to plant foliage or on soil, with no difference between 0.8 and 3 l ha−1. The number of arbuscules was 20% lower when glyphosate was applied on plant foliage, than when it was applied on the soil. Our findings illustrate that glyphosate application negatively affects AMF functionality in grasslands, due to different causes depending on the herbicide application site. While, under field conditions, the occurrence of direct and/or indirect pathways will depend on the plant cover at the time of glyphosate application, the consequences of this practice on the plant community structure will vary with the mycorrhizal dependence of the species composition regardless of the pathway involved.  相似文献   

6.
Pre-inoculation of seedlings with commercial, typically non-indigenous, AMF inoculants is common practice in horticultural and land reclamation industries. How these practices influence AMF community composition in pre-inoculated seedlings after they are planted in soil containing a resident AMF community is almost completely unknown. However, there may be important implications regarding success of horticultural practices, as well as unexpected ecological consequences. In this study we exposed Leucanthemum vulgare seedlings to five different AMF treatments (pre-inoculation with a representative of Glomus group A and Glomus group B, one of two Gigaspora spp., or no AMF) prior to exposure to a whole-soil, mixed-AMF community inoculum. After a growth period of 75 additional for 28 days, AMF community composition within the roots was analyzed using an approach combining LSU rDNA sequencing and T-RFLP analysis. Our results indicate that the AMF communities that assemble within roots were strongly influenced by AMF pre-inoculant identity. Pre-inoculation with either Glomus spp., unlike what was found for Gigaspora, greatly restricted numbers of other AMF ribotypes able to subsequently colonize roots after exposure to our Glomeraceae-dominated field soil; this suggested that phylogenetic relatedness and life history strategies may play a role in AMF community assembly. Our results further revealed concurrent changes in AMF community functions, as indicated by differences in plant biomass and foliar nutrients. These results serve to highlight the importance of considering life history differences when designing AMF inoculants and may have important implications regarding the introduction of non-indigenous AMF.  相似文献   

7.
Arbuscular mycorrhizal (AM) fungi may have some potential use in the restoration of degraded grassland through beneficial effects on plant growth and soil quality. A field investigation was conducted in three grassland sites of typical steppe in Inner Mongolia. The three plant communities, one of which was undegraded, one moderately degraded and the third severely degraded, were studied by collecting soil samples and samples of four plant species that occurred in all three sites. The percentage of root length colonized by AM fungi was estimated and the species composition and diversity of AM fungus spores recovered from the soil were determined using spore morphological characteristics. Although differences between the sites may have been due partly to other factors, it is likely that the degree of degradation was an important factor. No decline was found in the AM colonization of the roots of the indicator plant species in the moderately or severely degraded plant communities, and two plant species showed higher colonization status in the two degraded areas. Glomus geosporum and Scutellospora calospora were the dominant AM fungi in the undegraded steppe, while G. geosporum and Glomus aggregatum dominated the two degraded sites which also had low spore densities, species richness and diversity indices. However, different AM species showed different distributions among the three plant communities and the results indicate that both biotic and abiotic factors were important in determining the AMF communities, with biotic factors possibly the more important. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   

8.
AM 真菌对花生与甘薯产量的影响   总被引:7,自引:1,他引:7       下载免费PDF全文
在大田条件下试验研究了丛枝菌根(Arbuscular mycorrhiza,AM)真菌Glomus versiforme Berch及混合菌种[Glomus mosseae Nicolson&Gedermann+Sclerocystis smuosa(Gerd.Bakshi)Almeida & Schenck]对花生与甘薯生长及产量的影响结果表明,供试AM真菌能显著促进花生植株生长健壮,增加单株果数,单位面积产量比对照增加21.3%.接种Glomus versiforme处理的甘薯植株高度和茎叶质量均低于对照,未增加植株生长量和产量;混合菌种处理则提高甘薯的生长量和增加单株薯块数,其单株产量、单位面积产量分别为对照的1.6和1.4倍,表明大田应用时不同作物应采用不同AM真菌.  相似文献   

9.
补光光源对AM真菌生长发育的影响   总被引:1,自引:0,他引:1  
温室条件下,研究不同补光光源对丛枝菌根(Arbuscular mycorrhizae,AM)真菌Glomus mosseae生长发育的影响。结果表明:不同补光光源的光谱不同,对菌根共生体生长发育的影响不同,以农艺钠灯作为补光光源处理的宿主植物的光合速率及可溶性糖含量高于其它两种光源处理,综合比较菌根长度、根外菌丝量及孢子数三项指标,以农艺钠灯作为补充光源对真菌G. mosseae的生长发育最为有利。金属卤灯、荧光灯两处理宿主植物中氮、磷浓度高于农艺钠灯处理,可能对菌根真菌的生长发育有不利影响。因此,工厂化AM菌剂生产中,如果需要补充光照,应以农艺钠灯作为补光光源。  相似文献   

10.
Abundance of arbuscular mycorrhizal fungi (AMF) in the roots of plant species was assessed in two areas in Greece in a 4-year study (2004–2007). The field experiment was conducted in a mountainous and herbaceous grassland in Greece in which both nitrogen (N)- and phosphorus (P)-limited plant community productivity. In 2006, data were also collected from a pot experiment in which 14 herbaceous plant species were grown as monocultures in P-limited soil. A factorial design of two levels of N and P was established in the mountainous field to test plant response to nutrient additions with respect to AMF colonization levels. Effects of fungicides were also investigated over year in the pot experiment and over three years in the field experiment. In addition, the effect of irrigation on AMF colonization was determined in a 1-year field study. Measurements included estimating the level of plant species specific hyphal colonization of roots according to the McGonicle et al. [McGonigle, T.P., Miller, M.H., Evans, D.G., Fairchild, D.L., Swan, J.A., 1990. A new method which gives an objective measure of colonization of roots by vesicular–arbuscular mycorrhizal fungi. New Phytol. 115, 495–501] method. AMF colonization was highest in the leguminous species, intermediate in the forbs and lowest in the grasses. AMF responses to N and P additions were not uniform. P addition in the field experiment increased the colonization level of the high P demanding annual forb (non-leguminous dicot) Galium lucidum, decreased hyphal abundance of the forb Plantago lanceolata and the grass Agrostis capillaris, and appeared to have a negligible effect on the forb Prunella vulgaris and on leguminous species. Effects of N addition were influenced by P addition and were only significant in plots not enriched with P where N addition increased the AMF colonization. Irrigation increased colonization of the tested species A. capillaris and P. lanceolata but only significantly increased that of P. lanceolata. There was interannual variation in the effects of fungicides on AMF colonization, which was partly due to differences in the active ingredient and formulation used. Among the tested species, A. capillaris was the most susceptible to fungicides.  相似文献   

11.
Symbiotic fungi are involved in plant flooding tolerance, while the underlying mechanism is not yet known. Since polyamines (PAs) and proline are also associated with stress tolerance, it is hypothesized that the enhancement of stress resistance by symbiotic fungi is associated with changes in PAs and/or proline. The aim of this study was to analyze the effect of inoculation with Funneliformis mosseae and Serendipita indica on plant growth, PAs, and proline and the metabolisms in peach (Prunus persica) under flooding. Two-week flooding did not affect root colonization frequence of F. mosseae, while it promoted root colonization frequence of S. indica. Under flooding, plants inoculated with F. mosseae and S. indica maintained relatively higher growth rates than uninoculated plants. Funneliformis mosseae promoted root ornithine (Orn) contentration and arginine (Arg) and Orn decarboxylase activities under flooding, which promoted putrescine (Put), cadaverine (Cad), and spermidine (Spd) contentrations. Conversely, S. indica decreased contentrations of Arg, Orn, and agmatine and Arg decarboxylase activities, thus decreasing PA contentrations under flooding. Polyamines were negatively correlated with the expression of PA uptake transporter genes, PpPUT1 and PpPUT2, in peach. Polyamine transporter genes of F. mosseae (FmTPO) and S. indica (SiTPO) were regulated by flooding, of which FmTPO1 was positively correlated with Put, Cad, and Spd, along with positive correlations of Spd with SiTPO1, SiTPO2, and SiTPO4. Under flooding, F. mosseae decreased proline concentration, while S. indica increased proline concentration and correlated with expression of a △1-pyrroline-5-carboxylate synthetase gene, PpP5CS2. It was thus concluded that F. mosseae modulated polyamine accumulation, while S. indica induced proline accumulation to tolerate flooding.  相似文献   

12.
Lettuce can be associated with arbuscular mycorrhizal fungi (AMF). This symbiosis involves a molecular dialogue between fungus and plant that includes the activation of antioxidant, phenylpropanoid, or carotenoid pathways. The objective of this study was to test if the association of lettuce with AMF benefited plant growth and increased the contents of compounds potentially beneficial for human health. Results showed that AMF improved growth of lettuce, thus producing a dilution effect on the concentrations of some mineral nutrients (e.g., Ca and Mn). However, Cu, Fe, anthocyanins, carotenoids, and, to a lesser extent, phenolics appeared in higher concentrations (on a wet basis) in mycorrhizal than in nonmycorrhizal plants.  相似文献   

13.
Ammonia (NH3) emissions, the most important nitrogen (N) loss form, always induce a series of environmental problems such as increased frequency of regional haze pollution, accelerated N deposition, and N eutrophication. Arbuscular mycorrhizal (AM) fungi play key roles in N cycling. However, it is still unclear whether AM fungi can alleviate N losses by reducing NH3 emissions. The potential mechanisms by which AM fungi reduce NH3 emissions in five land-use types (grazed grassland, mowed grassland, fenced grassland, artificial alfalfa grassland, and cropland) were explored in this study. Results showed that AM fungal inoculation significantly reduced NH3 emissions, and the mycorrhizal responses of NH3 emissions were determined by land-use type. Structural equation modeling (SEM) showed that AM fungi and land-use type directly affected NH3 emissions. In addition, the reduction in NH3 emissions was largely driven by the decline in soil NH+4-N and pH and the increases in abundances of ammonia-oxidizing archaea (AOA) amoA and bacteria (AOB) amoB genes, urease activity, and plant N uptake induced by AM fungal inoculation and land-use type. The present results highlight that reducing the negative influence of agricultural intensification caused by land-use type changes on AM fungi should be considered to reduce N losses in agriculture and grassland ecosystems.  相似文献   

14.
Arbuscular mycorrhizal (AM) fungi are important components of agroecosystems as they form symbiotic associations with the majority of agricultural crops. The mycorrhizal association is normally mutualistic and can provide a number of benefits to the host plant including increased nutrient uptake, improved water relations, and protection from pathogens. However, conventional agricultural practices have been shown to have a negative impact on the abundance and diversity of AM fungi. The use of more diverse and sustainable land use practices such as tree-based intercropping can have the potential to reduce the negative impact of agricultural practices on AM fungi. This paper reviews the literature to investigate the effect of temperate and tropical tree-based intercropping systems on the abundance and diversity of AM fungi. Evidence from these studies suggests that tree-based intercropping systems support a more abundant and diverse AM fungal community compared to conventionally managed systems. However, there are studies that observed zero or negative significant effects on the AM fungal community as a result of incorporating trees into agricultural systems. The variable effect of tree-based intercropping systems on AM fungi observed may be a function of the different cultivation techniques, climatic variation, or diverse tree-crop combinations used within the different tree-based intercropping systems. To further our understanding of AM fungal dynamics in tree-based intercropping systems, future research should focus on the influence of tree species with varying mycorrhizal associations and the functional role of common mycelial networks in these systems, while utilizing applicable molecular techniques.  相似文献   

15.
Over the last three decades, the presence and functional roles of arbuscular mycorrhizal (AM) fungi in wetland habitats have received increasing attention. This review summarized the mycorrhizal status in wetlands and the effect of flooding on AM fungal colonization. Plants of 99 families living in 31 different habitats have been found to be associated with AM fungi, even including submerged aquatic plants and several plant species that were thought to be nonmycorrhizal (Cyperaceae, Chenopodiaceae, and Plumbaginaceae). The functions of AM fungi in wetland ecological systems could be concluded as their influences on the composition, succession, and diversity of the wetland plant community, and the growth and nutrition of wetland plants. Affecting the composition, succession, and diversity of the wetland plant community, AM fungi have positive, negative, or neutral effects on the performance of different wetland species under different conditions. The factors that affect the application effect of AM fungi in constructed wetland (CW) include flooding, phosphorus, plant species, aerenchyma, salinity, CW types, operation modes of CW, and wastewater quality. The generalist AM fungi strains can be established spontaneously, rapidly, and extensively in wastewater bioremediation technical installations; therefore, AM fungi can be considered ideal inhabitants of technical installations for the plant-based bioremediation of groundwater contaminated by organic pollutants or other contaminants. In the future, roles of AM fungi and factors that affect the purifying capacity of AM-CW system must be understood to optimize CW ecosystem.  相似文献   

16.
Arbuscular mycorrhizal fungi (AMF) are of great importance for the successful regeneration of degraded natural areas. The objective of this study was to examine how the time of environmental recuperation is affecting the occurrence and diversity of AMF species in riparian areas belonging to the Atlantic Forest biome in the State of São Paulo, Brazil. The study involved a native forest area (NT) and a gradient of environmental restoration: five (R05), ten (R10), and twenty (R20) years after reforestation. Soil samples were collected in the rainy (January) and dry season (June). Chemical, physical and microbiological analyses were performed including the amount of glomalin and quantification of AMF spores. The frequency of occurrence of genera and ecological indices, as richness (R), Shannon's diversity (H) and Simpson's dominance index (Is) were calculated. The largest spore number was found in R05 and the highest richness and diversity indices of AMF species in NT. Considering the two sampling periods and the four areas studied, we found 22 AMF species, and the genera Glomus and Acaulospora were the most frequent. A Canonical Discriminant Analysis showed that Glomus viscosum, Acaulospora scrobiculata, Acaulospora mellea and Scutellospora heterogama were the species that contributed the most to distinguishing the areas. Moisture, density and glomalin were positively correlated with the number of spores, however, soil nitrate showed a negative correlation. This work gives a better understanding of the interactions between AMF and forest soils and allows to know the distribution of AMF species according to environmental recovery time.  相似文献   

17.
烟草与丛枝菌根真菌的共生效应研究进展   总被引:1,自引:0,他引:1       下载免费PDF全文
丛枝菌根(Arbuscular mycorrhiza,AM)真菌是陆地生态系统中广泛存在的一类专性共生土壤微生物,是根系土壤区域中重要的功能菌群之一.AM真菌可侵染植物根系形成丛枝菌根共生体,改变植物根系形态和改善营养状况,从而提高宿主植物的生长发育、产量、质量和抗逆性.目前从烟草根系土壤分离报道的AM真菌已达13属5...  相似文献   

18.
Increasing evidence suggests that accretion of microbial turnover products is an important driver for isotopic carbon (C) and nitrogen (N) enrichment of soil organic matter (SOM). However, the exact contribution of arbuscular mycorrhizal fungi (AMF) to soil isotopic patterns remains unknown. In this study, we compared 13C and 15N patterns of glomalin-related soil protein (GRSP), which includes a main fraction derived from AMF, litter, and bulk soil in four temperate rainforests. GRSP was an abundant C and N pool in these forest soils, showing significant 13C and 15N enrichment relative to litter and bulk soil. Hence, cumulative accumulation of recalcitrant AMF turnover products in the soil profile likely contributes to 13C and 15N enrichment in forest soils. Further research on the relationship between GRSP and AMF should clarify the exact extent of this process.  相似文献   

19.
A preliminary investigation was conducted on the arbuscular mycorrhizal (AM) status of the dominant and common wild forage plants in typical steppe of eastern Inner Mongolia, a major semi-arid grassland region in China. Fifty-four wild forage plant species were collected and examined, and 27 of these were colonized by AM fungi. Some plants belonging to families that are presumed to lack mycorrhizas (Cyperaceae, Caryophyllaceae and Chenopodiaceae) were also found to be mycorrhizal. Higher proportions of arbuscular mycorrhizal plants were found in perennial (56.1%) and monocotyledonous (64.7%) forage species. However, neither percentage of root length colonized nor spore density varied significantly between the two life forms or cotyledon types. Twenty-seven species belonging to 7 genera of AM fungi were identified in total according to the morphological characteristics of the spores from field soil and trap cultures, and the results indicate that Glomus was the dominant AM genus and Glomus geosporum (Nicolson & Gerdemann) Walker and Glomus mosseae (Nicolson & Gerdemann) Gerdemann & Trappe were the dominant species in field soil and trap cultures, respectively. Glomus intraradices Schenck & Smith, Glomus etunicatum Becher & Gerdemann, Glomus claroideum Schenk & Smith emend Walker & Vestberg, Glomus clarum Nicolson & Schenck and Scutellospora callospora (Nicolson & Gerdemann) Walker & Sanders also occurred with high frequencies.  相似文献   

20.
In this work we have determined the community composition of spore-forming arbuscular mycorrhizal fungi (AMF) in a maquis site on Pianosa island, a protected area within the Tuscan Islands UNESCO Biosphere Reserve, Italy. We have analysed rhizosphere soil of the dominant plant species Pistacia lentiscus, Smilax aspera, Rosmarinus officinalis and of the endemic plant Helichrysum litoreum. The AMF species recovered were: Scutellospora dipurpurescens, Glomus coronatum, Glomus mosseae, Glomus etunicatum, Glomus geosporum, Glomus viscosum, Entrophospora sp., Pacispora sp. and Glomus rubiforme. The identification of native S. dipurpurescens and G. coronatum was carried out on spores isolated from rhizosphere soil of H. litoreum, by combining morphological traits and 18S (SSU) and ITS rDNA sequences. Therefore, AMF species of Pianosa rhizosphere soils represent an important repository for the conservation and maintenance in their natural habitat of such beneficial symbionts, key microorganisms of soil fertility.  相似文献   

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