Occurrence Of Arbuscular Mycorrhizal Fungi Research Articles

Interactions between foredune morphologies and vegetation: Exploring the occurrence of arbuscular mycorrhizal fungi

Vegetation is a key trait for understanding the foredune morphologies. However, the rhizosphere in coastal dunes imposes high levels of water and nutrient stress on plants. In these conditions, arbuscular mycorrhizal fungi (AMF) are prominent root symbionts that play a crucial role in improving to abiotic stress and promoting plant growth. On the south coast of the state of São Paulo, foredunes were studied for their floristic composition, relative frequency of AMF and grain size of rhizosphere. Foredune was classified regarding the morphology as terrace, ridge I, and ridge II. The terrace has a low height (<0.5 m) and is composed of native species canopies low (<0.2 m) and high (0.5–1.5 m) characterized by AMF colonization close to 60%. In contrast, ridge I showed wavy crests that were about 1 m high and ∼30 m wide, with a predominance of plant species with low canopy and 68% AMF colonization. The morphology ridge II reaches the greatest height (3 m), to the detriment of a smaller width (up to 15 m) and the plants present high canopy (>0.5 m) with close to 75% AMF. The increase of the relative frequency AMF from the terrace to ridges I and II may indicate that the increase of sand accumulation with continuous burial of roots is rather positive to plant growth. Yet, varied canopy heights of the plants species control the verticalization and horizontalization of the foredune. Low-canopy species, gradually slow down wind flow, causing spatialized deposition and widening. Conversely, species with highest canopies swiftly reduce wind flow due to the density of their aerial portion (leaves), resulting in deposition just below their structure fostering foredune vertical growth.

Occurrence and diversity of arbuscular mycorrhizal fungi in yerba mate (Ilex paraguariensis - Aquifoliaceae) cultivation environments.

Yerba mate (Ilex paraguariensis) represents a culture of economic, social, and ecological importance for the cultivation regions. Due to the chemical, physical, and biological variations that occur in the different soils where yerba mate is economically exploited, the symbiotic associations with arbuscular mycorrhizal fungi (AMF) guarantee the plant's ability to absorb nutrients. The purpose of this study was to identify and quantify the occurrence of arbuscular mycorrhizal fungi in different environments of yerba mate cultivation. The research was performed in four areas located in the rural area of the municipality of Seberi/RS: Environment with production of yerba mate in the conventional system, silvopastoral system, organic system, and native forest. The normality of residuals and homogeneity of variances assumptions were verified using the Lilliefors and Chi-square tests and the averages compared by the Tukey's test at 5% probability of error. In addition to calculations of diversity, equivalent species, and evenness indices. The presence of AMF spores showed a direct relationship with the phosphorus (P) availability in each treatment, with a count reduction in the organic system, with P content lower than 3 mg kg-1 of soil. The species with the highest predominance were the Acaulosporaceae (Acaulospora colombiana, A. delicata, and A. tuberculata), followed by the Glomaceae (Glomus ambisporum and Glomus pansihalos) in the conventional and silvopastoral systems. The silvopastoral and conventional systems showed the highest levels of Shannon-Weaver diversity (H') and Pielou's evenness, demonstrating greater diversity and consequently greater richness and uniformity.

Colonization pattern of arbuscular mycorrhizal fungi in invasive plant species of tropical dry deciduous forest of Belgahna range of Central India

Arbuscular mycorrhizal fungi (AMF) are the key factor for the growth of plants in nature. In the present study, 10 common invasive plant species and one native dominant tree species Tectona grandis were selected to understand the colonization pattern of AMF in the roots. Rhizosphere soil and root samples of selected invasive plant species were taken from the Tropical Dry Deciduous Forest of Belgahna Range of Bilaspur district, Chhattisgarh. The roots were observed under a microscope followed by clearing with KOH and staining with lactophenol cotton blue. In all invasive plant species and in T. grandis, arbuscular mycorrhizal (AM) colonization was more than 85% (89.00 ± 1.70 to 97.70 ± 0.88). All three morphological types of AM colonization, i.e., Arum-type, Paris-type, and Intermediate-type were observed in all samples. The shape of vesicles ranged from irregular to rounded shape. Different intra-radical vesicles’ sizes and shapes suggested that different species of AM fungus had colonized roots. In most of the samples, vesicles were mostly irregular in shape, elliptical, oval, spherical, and rectangular, indicating the dominance of Acualospora spp. and Glomus spp. The present study, regarding the occurrence of AM fungi in 10 invasive plants and 1 native plant T. grandis will provide basic information on the diversity of AM colonization patterns, which may be utilized to understand the interaction between AMF and invasive plant’s roots. The similarity in colonization patterns in invasive and native species shows that AMF association may be one of the reasons for the existence and proliferation in the Tropical Forest of the Central region.

The Diversity of Arbuscular Mycorrhizal Fungi and Their Associations in South America: A Case Study of Argentinean and Brazilian Cattle Raising Productive Ecosystems: A Review

Mycorrhizal fungus diversity is an ecosystem health indicator, and thus, the appreciation of the aboveground as well as the belowground biota, such as fungi associated with natural and managed ecosystems, is essential to provide sustainable products and suggestions to farmers. Less is known about the totally arbuscular mycorrhizal fungi (AMF) and fungal endophytes useful to agroecology, which are environment friendly microbial biofertilizers to mitigate the complications of conventional farming. Specific AMF are found in most covers; grassy ecosystems are increasingly investigated through their exclusive fungal species that improve sustainable cultivation. Different grazed pastures, forages, and their diversity are important objects of study either in economic or ecological scope. Based on recent reports, the occurrence of AMF in grasslands and pastures is significant, supporting more diverse AMF than native forests. Therefore, we show current information on these topics. We conducted a Web of Science search of published articles on AMF, pastures, and grasslands and analyzed them. The results confirmed the important role of pH as the driver of AMF diversity distribution between the grassy ecosystems from Argentina and Brazil. In grasslands, the main family represented was Glomeraceae, while pastures maintain predominantly Acaulosporaceae. Brazilian grasslands and pastures presented four times the AMF richness of those from Argentina.

Recovering arbuscular mycorrhizal fungi (AMF) from decomposing litter: an unusual approach

ABSTRACT A few studies indicated a possible role of arbuscular mycorrhizal fungi (AMF) in leaf litter decomposition. Information about these fungi in leaf litter is limited by the availability of techniques to recover them from such substrates. In the present study we aimed to (i) test an alternative approach for AMF recovery from litter; (ii) investigate if the AMF community structure in leaf litter differs between plant species; (iii) assess whether glomoid spore type might be more abundant in litter and (iv) determine whether litter quality and soil chemical parameters influence AMF communities. Leaves and soil were collected in three areas in the Brazilian Atlantic Forest. AMF were obtained from the leaves using a moist chamber approach. AMF communities were evaluated for their species richness, abundance, and diversity. In addition, the influence of soil chemical properties and litter quality on the structure of AMF communities was evaluated. Thirteen AMF species representing the genera Acaulospora, Entrophospora, Diversispora, Gigaspora, and Glomus, were recovered from leaves. The highest richness was observed in Ziziphus joazeiro leaves at Fazenda Sapé, whereas the highest diversity was found in the leaves of Hymenaea courbaril at Flona. AMF communities were influenced by litter quality and the P content of the soil. Our data show that this alternative approach for recovering AMF from the litter was successful in detecting communities inhabiting tropical conditions. This pilot research is an essential attempt to address the gap of knowledge about the occurrence of AMF in leaf litter and delimit future strategies to assess their function in this substrate.

Competitive interactions in two different plant species: Do grassland mycorrhizal communities and nitrogen addition play the same game?

In the Tibetan Plateau grassland ecosystems, nitrogen (N) availability is rising dramatically; however, the influence of higher N on the arbuscular mycorrhizal fungi (AMF) might impact on plant competitive interactions. Therefore, understanding the part played by AMF in the competition between Vicia faba and Brassica napus and its dependence on the N-addition status is necessary. To address this, a glasshouse experiment was conducted to examine whether the grassland AMF community's inocula (AMF and NAMF) and N-addition levels (N-0 and N-15) alter plant competition between V. faba and B. napus. Two harvests took day 45 (1st harvest) and day 90 (2nd harvest), respectively. The findings showed that compared to B. napus, AMF inoculation significantly improved the competitive potential of the V. faba. In the occurrence of AMF, V. faba was the strongest competitor being facilitated by B. napus in both harvests. While under N-15, AMF significantly enhanced tissue N:P ratio in B. napus mixed-culture at 1st harvest, the opposite trend was observed in 2nd harvest. The mycorrhizal growth dependency slightly negatively affected mixed-culture compared to monoculture under both N-addition treatments. The aggressivity index of AMF plants was higher than NAMF plants with both N-addition and harvests. Our observation highlights that mycorrhizal associations might facilitate host plant species in mixed-culture with non-host plant species. Additionally, interacting with N-addition, AMF could impact the competitive ability of the host plant not only directly but also indirectly, thereby changing the growth and nutrient uptake of competing plant species.

First morphological and molecular investigation of the mycobiota associated with Astragalus nebrodensis in its natural environment (Madonie mountains, Sicily)

Although Astragalus nebrodensis plays a fundamental ecological role, mycorrhizal fungi associated with this species have never been investigated in natural habitats. Our aim was to check the presence and occurrence of Arbuscular Mycorrhizal Fungi (AMF) in roots of A. nebrodensis in a natural habitat and to screen the fungal diversity in the surrounding soil, considering the positive influence of mycotrophic shrub species on soil microbiota. A morphological analysis was performed on A. nebrodensis roots samples from the Madonie mountains (Sicily, Italy), while high-throughput-sequencing was carried out in A. nebrodensis roots and in the associated soil. Observations of A. nebrodensis roots revealed typical structures of AMF. Sequencing revealed that Ascomycota was the most abundant phylum in both roots and soil samples, followed by Basidiomycota and Mucoromycota. A. nebrodensis roots host a fungal community with lower richness as compared to soil and specific taxa were differentially abundant between roots and soil. The endomycorrhizal symbiosis in A. nebrodensis from a natural habitat is reported here for the first time. The fungal diversity between the two matrices (soil vs roots) supports the notion of a specialised and well-established root microbiome in A. nebrodensis enabling it to survive the stressful conditions of its harsh environment.

Modeling geographic distribution of arbuscular mycorrhizal fungi from molecular evidence in soils of Argentinean Puna using a maximum entropy approach.

The biogeographic region of Argentinean Puna mainly extends at elevations higher than 3,000 m within the Andean Plateau and hosts diverse ecological communities highly adapted to extreme aridity and low temperatures. Soils of Puna are typically poorly evolved and geomorphology is shaped by drainage networks, resulting in highly vegetated endorheic basins and hypersaline basins known as salar or salt flats. Local communities rely on soil fertility for agricultural practices and on pastures for livestock rearing. From this perspective, investigating the scarcely explored microbiological diversity of these soils as indicators of ecosystems functioning might help to predict the fragility of these harsh environments. In this study we collected soil samples from 28 points, following a nested design within three different macro-habitats, i.e., Puna grassland, hypersaline salar and family-run crop fields. Total fungi and arbuscular mycorrhizal fungi (AMF) occurrence were analyzed using eDNA sequencing. In addition, the significance of soil salinity and organic matter content as significant predictors of AMF occurrence, was assessed through Generalized Linear Mixed Modeling. We also investigated whether intensive grazing by cattle and lama in Puna grasslands may reduce the presence of AMF in these highly disturbed soils, driving or not major ecological changes, but no consistent results were found, suggesting that more specific experiments and further investigations may address the question more specifically. Finally, to predict the suitability for AMF in the different macro-habitats, Species Distribution Modeling (SDM) was performed within an environmental coherent area comprising both the phytogeographic regions of Puna and Altoandino. We modeled AMF distribution with a maximum entropy approach, including bioclimatic and edaphic predictors and obtaining maps of environmental suitability for AMF within the predicted areas. To assess the impact of farming on AMF occurrence, we set a new series of models excluding the cultivated Chaupi Rodeo samples. Overall, SDM predicted a lower suitability for AMF in hypersaline salar areas, while grassland habitats and a wider temperature seasonality range appear to be factors significantly related to AMF enrichment, suggesting a main role of seasonal dynamics in shaping AMF communities. The highest abundance of AMF was observed in Vicia faba crop fields, while potato fields yielded a very low AMF occurrence. The models excluding the cultivated Chaupi Rodeo samples highlighted that if these cultivated areas had theoretically remained unmanaged habitats of Puna and Altoandino, then large-scale soil features and local bioclimatic constraints would likely support a lower suitability for AMF. Using SDM we evidenced the influence of bioclimatic, edaphic and anthropic predictors in shaping AMF occurrence and highlighted the relevance of considering human activities to accurately predict AMF distribution.

Richness of Arbuscular Mycorrhizal Fungi in a Brazilian Tropical Shallow Lake: Assessing an Unexpected Assembly in the Aquatic-Terrestrial Gradient

Aquatic ecosystems are historically overlooked regarding the occurrence of Arbuscular Mycorrhizal Fungi (AMF). Tropical lakes in the southern hemisphere are generally impacted by human actions, such as those in Brazil, although they still preserve a great diversity of macrophyte species that can support AMF communities. Thus, the study aimed to test (i) whether AMF community structure (composition, richness, diversity, dominance, and evenness) differs between aquatic and terrestrial conditions, and (ii) between seasons—rainy and dry. A total of 60 AMF species, distributed in 10 families and 17 genera, were found, with a difference in AMF composition between conditions (terrestrial and aquatic) and seasons (dry and rainy). The absolute species richness differed between conditions, seasons, and interactions. The aquatic/rainy season, which retrieved the most significant number of species, had the highest absolute richness and number of glomerospores and differed significantly from the terrestrial/rainy season. The results suggest that a shallow oligotrophic lake harbors a high AMF richness. In addition, this environment has a distinct AMF community from the adjacent coastal sand plain vegetation and is affected by seasonality.

Environmental response of arbuscular mycorrhizal fungi under soybean cultivation at a regional scale.

Climate change, the shortage of fertilizers and reduced land for cultivation have drawn attention to the potential aid provided by soil-borne organisms. Arbuscular mycorrhizal fungi (AMF) offer a wide range of ecosystem benefits and hence, understanding the mechanisms that control AMF occurrence and maintenance is essential for resilient crop production. We conducted a survey of 123 soybean fields located across a 75,000-km2 area of Argentina to explore AMF community composition and to quantify the impact of soil, climate, and geographical distance on these key soil organisms. First, based upon morphological identification of spores, we compiled a list of the AMF species found in the studied area and identified Acaulospora scrobiculata and Glomus fuegianum as the most frequent species. G. fuegianum abundance was negatively correlated with precipitation seasonality and positively correlated with mean annual precipitation as well as mycorrhizal colonisation of soybean roots. Second, we observed that species richness was negatively correlated with soil P availability (Bray I), clay content and mean annual precipitation. Finally, based on partitioning variation analysis, we found that AMF exhibited spatial patterning at a broad scale. Therefore, we infer that geographical distance was positively associated with spore community composition heterogeneity across the region. Nevertheless, we highlight the importance of precipitation sensitivity of frequent species, overall AMF richness and community composition, revealing a crucial challenge to forthcoming agriculture considering an expected change in global climate patterns.

Occurrence of Arbuscular Mycorrhizal Fungi in Mangrove Forest of Achara in Maharashtra, IndiaOF ARBUSCULAR MYCORRHIZAL FUNGI IN MANGROVE FOREST OF ACHARA IN MAHARASHTRA, INDIA

Present work is an attempt to study the arbuscular mycorrhizal fungal diversity of Achara mangrove forest located at Maharashtra on the west coast of India. Of the twelve mangrove species screened for arbuscular mycorrhizal colonization 10 species viz ., Rhizophora apiculata , Rhizophora mucronata (Rhizophoraceae), Sonneratia alba (Sonneratiaceae), Avicennia marina, A. officinalis (Avicenniaceae), Excoecaria agallocha, Aegiceras corniculatum (Euphorbiaceae), Acanthus illicifolius (Acanthaceae) Xylocarpus granatum (Meliaceae) were found to be mycorrhizal. The non mycorrhizal plants were Kandelia candel and Ceriops tagal (Rhizophoraceae). Arbuscular mycorrhizal colonization was found to be maximum in Sonneretia alba (83%), and was least in Avicennia marina (6%). The spore density of AM fungal spores ranged from 14 spores/100g soil in Rhizophora mucronata to 78 spores/100g rhizosphere soil in Excoecaria agallocha .. Among the 15 AM species reported from 12 mangrove species Glomus macrocarpum (66%) was the most frequently occurring AM fungal species followed by Glomus fasciculatum (50%), Glomus claroideum (42%) and Acaulospora laevis (42%).

Short Communication: Occurrence of arbuscular mycorrhizal fungi associated with Casuarina equisetifolia in saline sandy environment, North Sumatra, Indonesia

Abstract. Delvian, Hartanto A. 2022. Short Communication: Occurrence of arbuscular mycorrhizal fungi associated with Casuarina equisetifolia in saline sandy environment, North Sumatra, Indonesia. Biodiversitas 23: 2520-2525. Arbuscular mycorrhizal fungi (AMF) form a mutualistic association with plant roots to cope in the extreme environments including the saline and sandy soils in the coastal areas. In this study, the occurrence of AMF associated with Casuarina equisetifolia that has been planted for coastal rehabilitation located at Cermin Beach, North Sumatra was investigated including its abiotic-biotic interactions from topsoils (0-20 cm) to subsoils (20-80 cm). A total of 10 AM fungal morphotypes were documented with Glomeraceae as the dominant AM fungal taxa (9 morphotypes) and a Glomoid morphotype exists in all soil depths. The number of AMF spores decreased as soil depth increased following other environmental conditions such as pH, soil P availability and soil moisture based on the result of Pearson’s correlation test. The results showed a moderate-to-low level of biodiversity of AMF based on Shannon’s diversity index. The findings revealed the vertical distribution of AMF in a saline environment and supported the planting of C. equisetifolia which successfully recruited the indigenous AMF to form a symbiosis to thrive in the stressful environment.

Diversity of Arbuscular mycorrhizal Fungal Association with Quercus oblongata D. Don

Arbuscular mycorrhizal fungi (AMF) form a pervasive, obligate, mutualistic association with plant roots to help and play an important role in their life. In the current study, the species diversity of AMF in the rhizosphere of Quercus oblongata D. Don was studied. Rhizospheric soil samples and roots were collected from three different locations (Ropadi Gad, Sakaryar, and Saron). The occurrence of AMF, species composition and the diversity of AM fungi were observed with Q. oblongata plants. At all the 3 locations, selected plants were found to be colonized with AMF, however, the extent of root colonization significantly varied at different locations. Morphologically different 12 AMF species were isolated and identified from the rhizosphere of Q. oblongata. Of those 12 AMF species, six were found from the Ropadi Gad location, seven from the Sakaryar, and the remaining five from the Saron location. The highest root colonization was observed in Q. oblongata at Sakaryar (53.32%), followed by Ropadi Gad (46.67%), while the least was observed at Saron (40.40%). The number of spores ranged from 185±2.54 to 312±3.60, with an average of 250.33±3.32 per 100 g of air-dried soil. The number of spores exhibited a significant positive correlation with root colonization. The number of arbuscules and vesicles also followed the same trend viz. the maximum number of arbuscules and vesicles at Sakaryar, followed by Ropadi Gad, and with a minimum at Saron.

Elevational distribution and occurrence of arbuscular mycorrhizal fungi in non-host Carex capillacea.

Little is known about Arbuscular mycorrhizal (AM) fungal colonization and community composition in non-mycorrhizal (NM) plants, especially along elevational gradients. This study explores this question using a NM plant, Carex capillacea, at Mount Segrila, Tibet. Here, C. capillacea, its rhizosphere soil, and the neighboring mycotrophic plant Poa annua were sampled at four elevations to evaluate and compare their AM fungi colonization and communities. The results showed that AM fungal colonization density of C. capillacea was negatively correlated with elevation and biomass of total NM plants per quadrat. AM fungal diversity and community composition between C. capillacea and P. annua showed a similar pattern. In addition, elevation and soil did not significantly influence the AM community in C. capillacea, while they were important abiotic factors for assemblages in rhizosphere soil and P. annua. These findings support that a broad array of AM fungi colonize the root of C. capillacea, and a mycelial network from a co-occurring host plant might shape the AM fungal communities in C. capillacea along the elevation gradient. The co-occurrence patterns of AM fungi associated with non-mycotrophic species and adjacent mycotrophic species have important implications for understanding AM fungal distribution patterns and plant-AM interactions.

Arbuscular Mycorrhizal Fungi Association with Some Selected Medicinal Plants

Arbuscular mycorrhizal fungi (AMF) are group of fungi of the order Glomales that form symbiotic association with plant roots and enhance the uptake of nutrients, and improve plant growth and yield. This study was conducted to investigate the occurrence of arbuscular mycorrhizal fungi in the rhizospheres of some commonly grown medicinal plants in Maiduguri viz; Aloe vera, Mentha, Cymbopogon citrates and Ocimum gratissimum. The results revealed all the plants have formed mycorrhiza symbiosis. Arbuscular mycorrhizal fungi spores from five genera (Glomus, Acaulospora, Dentiscutata, Scutellispora and Gigaspora were isolated and identified. Cymbopogon citrates significantly recorded the highest total AMF spore counts (90±4.17) while Aloe vera recorded the least (54±2.28). Amongst the five mycorrhiza genus Glomus species were comparatively higher under all plant species, while, Dentiscutata and Gigaspora had the lowest spore counts. Highest percent root colonization (72±4.23%) was recorded under Cymbopogon citrates and Aloe vera recorded the least (55.5 ±2.41%). The study confirmed mycorrhiza association with all the plants, however, AMF spore counts diversity varies with plant species. Arbuscular mycorrhizal fungi could be inoculated to soils with scanty or ineffective spores for enhanced plant nutrition and growth of medicinal plants.

Inoculation of arbuscular mycorrhizal fungi as a strategy to improve annatto (Bixa orellana L.) growth

This study aimed to assess the occurrence of arbuscular mycorrhizal fungi (AMF) in annatto (Bixa orellana L.) cultivars and their response to AMF inoculation using biometric parameters. The occurrence surveys were conducted in annatto fields in three municipalities from Pernambuco Forest Zone: Lagoa de Itaenga, Gloria de Goitá, and Vitoria de Santo Antão, and in four cultivars (Red Piave, Green Piave, Red Peruvian Paulista, and Green Peruvian Paulista). In a greenhouse, biometric parameters of annatto seedlings of Red Piave, Red Peruvian Paulista, Embrapa-36, and Embrapa-37 cultivars inoculated with AMF isolated from annatto fields. The Red Piave cultivar exhibited greater root colonization than the Green Peruvian Paulista in the Lagoa de Itaenga and Vitoria de Santo Antão municipalities. The cultivar Red Piave showed a more beneficial association with AMF in plants and soil than cultivar Green Peruvian Paulista did, in both Lagoa de Itaenga and Vitoria de Santo Antão. AMF inoculation was effective in promoting the growth of annatto plants, particularly those inoculants with S. heterogama and C. etunicatum.

Arbuscular mycorrhizal fungi-weeds interaction in cropping and unmanaged ecosystems: a review

Weeds are the cause of substantial yield loss and extinction of some native species resulting from competition with the associated species for water, sunlight, nutrients and space. Due to the widespread occurrence of arbuscular mycorrhizal fungi (AMF) and their important role in communities and ecosystems, the interaction between weed species and AMF might have an important role in ecosystem functioning. The present review characterizes AMF-weeds interactions, targeting natural and crop ecosystems. In agroecosystems, AMF have the potential to contribute to weed control (i) directly by suppressing growth of many weeds belonging to families that are non-mycorrhizal, or (ii) indirectly by enhancing competitive ability of crop species to the detriment of both mycorrhizal and non mycorrhizal weeds. Some advantages conferred by AMF-weed interaction to associated species make evidence of the importance to identify weed species that can play an important role in ecosystem performance. In unmanaged ecosystems, AMF could play a crucial role in invasive plants control through enhancing the competitive ability of local species to the detriment of invasive ones. Additional methodologies are required to manage highly mycorrhizal invasive species.

Occurrence of arbuscular mycorrhizal fungi in leaf litter and roots of shaded coffee plantations under organic and conventional management

ABSTRACT Evidence of arbuscular mycorrhizal fungal colonization of mat litter in various ecosystems plus previous reports of external mycelium of those fungi and mycorrhizal roots in litter from coffee plants and shade trees on coffee plantations suggest that they have a relationship with closed direct nutrient cycling between organic matter and living roots. This relationship was first proposed more than 50 years ago. Mycorrhizal symbiosis in tropical crops is affected by agricultural management practices. This study aimed to assess the [...]

Occurrence of indigenous arbuscular mycorrhizal fungi associated with the rhizosphere of the naidí palm in Colombia

In the Colombian Pacific region, the naidí palm, Euterpe oleracea Mart. (Arecaceae) produces high-value fruit due to its high nutritional quality, representing an economic benefit to the families of the region. In this study, we evaluated the occurrence of arbuscular mycorrhizal fungi (AMF) in the rhizospheric soil of E. oleracea in Bajo Calima, Buenaventura. This is the first report of AMF of E. oleracea in Colombia. Surface soil samples (0-10 cm) were collected in two areas (L1 - under the influence of rice cropping and L2 - tropical rainforest). The chemical properties of the soil, the number of spores, and the mycorrhizal colonization in the root were established. We observed low mycorrhizal colonization (10 % in L1 and 4 % in L2), negatively correlated to the content of available phosphorus in the soil. However, significant differences between areas (p = 0.009) were recorded. Globose, subglobose, and ovoid spores were observed (660 and 791 spores/100 g soil in L1 and L2, respectively). Spores are represented in several morphotypes that can be classified as Claroideoglomeraceae, Glomeraceae, Diversisporaceae, Paraglomeraceae, and Ambisporaceae. High available P content (13.1 mg/kg in L1 and 20.5 mg/kg in L2), among other edaphic factors associated, could explain the low mycorrhizal colonization observed, especially when there are not enough studies linking ecological factors with AMF dynamics in tropical rainforests. On the other hand, spore abundances reported in the rhizospheric soil of E. oleracea suggest a high potential to explore indigenous AMF activity in the Colombian Pacific region to achieve sustainable production practices in this palm.

Effects of crop rotation on enhanced occurrence of arbuscular mycorrhizal fungi and soil carbon stocks of lowland paddy fields in seasonaly dry tropics

The impacts of crop rotation systems on the arbuscular mycorrhizal fungal (AMF) spore density, mycorrhizal colonization of rice roots, soil C fractions and C stocks in seasonally dry climatic zone of Sri Lanka were examined in Rice–Soybean (RS) and Rice–Onion (RO) crop rotation systems during the subsequent rice cultivation season and, compared these with a rice monoculture, i.e. Rice–Rice (RR). The study also examined the correlations between AMF occurrence and soil carbon stocks. Results revealed that RS crop rotation system significantly enhances the occurrence of AMF spores in soil with a higher fraction of large sized spores, the total organic C (TOC), microbial biomass C (MBC), water soluble C (WSC), labile C and a high AMF colonization in rice roots in the subsequent rice cultivation season. The diversity of AMF morphospecies were also the highest in RS. Reduction in AMF density in the soil in RR crop rotation system may be due to prolonged anaerobic conditions prevailed. The growth of onion has drastically reduced the AMF colonization in rice and soil C contents. Soil carbon stocks showed positive correlations with % root colonization and AMF spore number in soil. Thus, the study confirmed that C stocks in paddy soils can be improved by intercropping with AMF supporting plants like soya bean. This is the first report that shows positive correlations of AMF sporulation and % root colonization in lowland rice with soil carbon stocks.