Resumo A reabilitação de campos agrícolas abandonados é uma tarefa multidisciplinar, que busca o desenvolvimento de sistemas produtivos sustentáveis. O objetivo deste estudo foi avaliar o efeito da técnica de microtopografia e condicionadores de solo na sobrevivência, crescimento e nutrição de Eucalyptus saligna de uma área agrícola abandonada. Parcelas de microtopografia e parcelas planas foram estabelecidas em um campo agrícola abandonado (27º 12.08' S e 49º 07.60' W). Dentro das parcelas, subparcelas com plantas foram estabelecidas e receberam a aplicação de condicionadores de solo, que incluíram fonolito (100 g), inoculante micorrízico (200 cm3), lodo de celulose e casca de arroz carbonizada (200 cm3), fonolito (100 g) e inoculante micorrízico (200 cm3) e controle. O experimento foi monitorado entre novembro de 2013 e outubro de 2014 e parâmetros de crescimento foram mensurados após 30, 90, 150, 210, 270 e 330 dias do início do experimento. De cada planta, foram mensuradas altura, diâmetro do caule e área da copa. Ao final do experimento, 50 folhas de cada planta foram coletadas para determinar a concentração de fósforo e potássio. A comunidade micorrízica nativa foi caracterizada por um bioensaio e as espécies identificadas a partir de esporos coletados em campo. Taxas de sobrevivência de Eucalyptus saligna tenderam a ser mais altas em parcelas de microtopografia. Altura da planta, diâmetro do caule, área da copa e concentração de P e K na biomassa foram significativamente maiores em plantas em parcelas de microtopografia. Condicionadores do solo influenciaram significativamente a concentração de K na biomassa. A aplicação da técnica de microtopografia melhora a sobrevivência, crescimento e nutrição de Eucalyptus saligna e representa uma importante estratégia para reabilitar áreas agrícolas abandonadas.

Abstract Rehabilitation of abandoned agricultural fields is a multidisciplinary task, in pursuit of the development of sustainable productive systems. The objective of this study was to evaluate the effect of microtopography technique and soil conditioners on survival, growth and nutrition of Eucalyptus saligna of an abandoned agriculture field. Plots of microtopography and flat plots were established in an abandoned agriculture field (27º 12.08' S and 49º 07.60' W). Within plots, we stablished subplots with plants, which received the application of soil conditioners, including phonolite (100 g), mycorrhizal inoculant (200 cm3), pulp sludge and carbonized rice husk (200 cm3), phonolite (100 g) and mycorrhizal inoculant (200 cm3) and control. The experiment monitoring occurred between november 2013 to october 2014 and growth parameters were measured after 30, 90, 150, 210, 270 and 330 days of the experiment onset. From each plant, height, stem diameter and canopy area were measured. At the end of the experiment, 50 leaves were collected from each plant to determine potassium and phosphorus concentrations. The native mycorrhizal community was characterized by bioassay and species identification of field-collected spores. Survival rates of Eucalyptus saligna tended to be higher in microtopography plots. The Plant height, stem diameter, canopy area, and shoot P and K concentration were significantly higher in plants at microtopography plots. Soil conditioners influenced significantly the shoot K concentration. The application of microtopography technique improved survival, growth, and nutrition of Eucalyptus saligna, and it represents an important strategy to rehabilitate abandoned agricultural fields.

RESUMO: Este trabalho teve como objetivo identificar fungos micorrízicos arbusculares (FMA) em solo rizosférico de videiras com sintomas de declínio e morte da videira (D) e em plantas saudáveis (S), e caracterizar a relação das comunidades de FMA com atributos químicos do solo. O número de esporos de FMA variou de 287 a 432 esporos 50 cm-3 em solo em plantas D, e de 357 a 464 esporos 50 cm-3 em plantas S, sem diferenças entre vinhedos ou entre plantas D e S dentro de cada vinhedo. Detectamos 42 espécies e 17 gêneros, sendo que a maioria dos táxons pertencia a Acaulosporaceae ou Glomeraceae. Claroideoglomus etunicatum, Funneliformis mosseae e Archaeospora trappei foram as espécies mais frequentes em todos os vinhedos. Os atributos químicos do solo não foram determinantes para a ocorrência da maioria das espécies de fungos, embora Entrophospora infrequens, Diversispora sp1 e Diversispora sp2 estivessem associados a um vinhedo com alto teor de cobre do solo. Os vinhedos abrigam comunidades FMA altamente diversificadas, que são determinadas pela localização.

ABSTRACT: This research identified arbuscular mycorrhizal fungi (AMF) in rhizosphere soil of grapevines with Grapevine Death and Decline symptoms (GDD) or asymptomatic healthy (H) plants, and characterized the relationship of AMF communities with soil chemical attributes. The AMF spore number ranged from 287 to 432 spores 50 cm-3 in soil with GDD plants, and from 357 to 464 spores 50 cm-3 in H plants, with no differences among vineyards or between GDD and H plants within each vineyard. We detected 42 species and 17 genera, and most taxa belonged to Acaulosporaceae or Glomeraceae. Claroideoglomus etunicatum, Funneliformis mosseae, and Archaeospora trappei were the most frequent species in all vineyards. Soil chemical attributes were not determinant for the occurrence of most fungal species; although, Entrophospora infrequens, Diversispora sp1 and Diversispora sp2 were associated with a vineyard having high soil copper. Vineyards harbor highly diverse AMF communities, which are determined by location.

ABSTRACT Canga ecosystems develop over superficial iron crusts with shallow and nutrient-poor soils. Under these conditions, arbuscular mycorrhizal fungi (AMF) play an important role in helping plants to overcome abiotic and biotic stresses. Canga can suffer periodic burning and yet it is unknown what the impacts of fire are to AMF communities. We aimed to compare AMF in Canga areas affected by burning (BC) with those with no previous history of burning (NC). We compared AMF species composition, spore numbers, species richness, and mycorrhizal inoculum potential. The total number of spores, AMF species richness and mycorrhizal colonization measured in the infectivity bioassay were not significantly different between areas. A total of 23 species in 10 genera were recovered, with most species belonging to Gigasporaceae and Acaulosporaceae. BC and NC shared 52 % of AMF species. Gigaspora albida, Gigaspora gigantea, and Dentiscutata heterogama sporulated exclusively in trap cultures. We concluded that AMF spore communities were not affected by burning in Canga soils as measured by spore abundance, species richness and infectivity. Our data contribute to the inventory of soil biodiversity associated with Canga, a high biodiverse and threatened Brazilian ecosystem.

ABSTRACT Arbuscular mycorrhizal fungi (AMF) play an important role in plant community productivity and structure, and so studying the factors that affect the diversity and structure of this fungal community is important for understanding their ecology in tropical forests. We investigated AMF spore communities and root colonization under three forest phytophysiognomies (Restinga Forest, REF; Lowland Ombrophilous Dense Forest, LLF; and Montane Ombrophilous Dense Forest, MTF). Spore abundance was lowest in LLF and highest in REF, with no statistical differences relative to MTF. Spore diversity indices and root colonization rates were not statistically different among the phytophysiognomies. However, principal components analysis revealed that AMF community structure differed according to forest phytophysiognomy. Hierarchical partitioning analysis indicated that most of the AMF community variables were better explained by phytophysiognomy than by chemical and physical attributes of the soil. In addition to the plant community, clay content, pH, Boron, P, S and CEC best explained some of the AMF community variables. Thus, we conclude that while several factors determine AMF community structure in the Atlantic Forest, phytophysiognomy is the most significant.

ABSTRACT The production of inoculum from arbuscular mycorrhizal fungi (AMF) at a large scale and low cost is essential for establishing methods to assist in producing pineapple plantlets with high nutritional and phytosanitary quality. However, this objective is difficult to accomplish because of the biotrophic nature of these fungi. The on-farm multiplication method for AMF inoculum presents a good alternative to supply the demand for the production of glomerospores. This study aimed to multiply and evaluate AMF inoculum originating from isolated species (including Rhizophagus clarus, Claroideoglomus etunicatum) versus native AMF from pineapple and coffee plantations multiplied by the on-farm method on the colonization in pineapple plantlets. Initially, inocula of R. clarus, C. etunicatum, and native AMF (pineapple and coffee) were multiplied by the on-farm method in Sorghum bicolor. After four months, the number of AMF spores and the percentage of viable spores at the layers of 0.00-0.05 and 0.05-0.10 m were evaluated. There were no differences in spore numbers in relation to the source of the inoculum (R. clarus, C. etunicatum, pineapple, and coffee) and evaluated layers, with an average number of 605 spores per 100 cm3 of soil. The percentage of viable spores was greater at the layer of 0.00-0.05 m (76.32 %) compared to the layer of 0.05-0.10 m (72.05 %), regardless of the inoculum source. The viability of the inoculum obtained from C. etunicatum was higher than that from the coffee crop (77.93 and 68.06 %, respectively). Subsequently, the spores were inoculated in pineapple plantlets to assess the rate of colonization. Pineapple plantlets inoculated with AMF had an average of colonization of 18 and 67.73 % after 50 and 180 days cultivation, respectively, with no significant difference being detected between treatments. Therefore, on-farm inoculum production was effective at multiplying the AMF of both isolates of R. clarus and C. etunicatum, as well as for commercial crops (pineapple and coffee), with spores having high viability. Arbuscular mycorrhizal fungi colonized pineapple plantlets independently of the inoculum utilized and favored its growth.

RESUMO Fungos micorrízicos arbusculares (AMF) interagem simbioticamente com a maioria das espécies de plantas, facilitando a revegetação de áreas sob reabilitação. O objetivo deste trabalho foi de avaliar o potencial de inóculo, densidade e diversidade de esporos de AMF em cinco ambientes, e a relação das espécies com atributos do solo. Amostras de solo foram coletadas em cinco ambientes em área de mineração e seu entorno no Quadrilátero Ferrífero, Minas Gerais (Brasil): pilha de rejeitos em reabilitação com capim, canga, Cerrado, mata nativa e plantação de eucalipto, e submetidas a análises química e física. A extração de esporos direto de amostras de campo e de culturas armadilha (TCs), estabelecidas em dois locais nas regiões Sul e Sudeste do Brasil, foi feita para identificação taxonômica das espécies. Foram determinados riqueza de espécies, índice de diversidade de Shannon (H’) e equitabilidade. Análise de componentes principais (PCA) foi utilizada para identificar atributos do solo que mais influenciaram a ocorrência de AMF. A densidade de esporos não diferiu significativamente entre os ambientes. Um total de 59 espécies de AMF foram encontradas, destacando-se o primeiro relato de ocorrência de Acaulospora nivalis e Acaulospora alpina no Brasil. Maiores H’ e riqueza de espécies no campo foram encontradas em pilhas de rejeitos e menores em canga, embora canga tenha apresentado maior potencial de inóculo. A condução de TCs em dois locais proporcionou captura de maior diversidade de espécies de AMF. Ambientes do Quadrilátero Ferrífero são hotspots de diversidade de AMF e o pH do solo e teores trocáveis de S e P são os atributos que melhor explicam a distribuição das espécies de AMF.

ABSTRACT Arbuscular mycorrhizal fungi (AMF) interact symbiotically with most plant species, facilitating revegetation of areas under rehabilitation. The aim of this study was to evaluate the inoculum potential, density, and diversity of AMF spores in five environments, as well as the relation of species with soil properties. Soil samples were collected in five environments in a mining area and its surroundings in the Quadrilátero Ferrífero, Minas Gerais (Brazil): tailings piles in rehabilitation with grass, canga, Cerrado, native forest, and eucalyptus plantation; these samples were subjected to chemical and physical analyses. Spores were directly extracted from field samples and from trap cultures (TCs) established in two locations in the Southeast and South regions of Brazil for taxonomic identification of the species. Species richness, the Shannon diversity index (H’), and equitability were determined. Principal component analysis (PCA) was used to identify soil properties that most influenced AMF occurrence. Spore density showed no significant difference among the environments. A total of 59 AMF species were found. This is the first report of the occurrence of Acaulospora nivalis and Acaulospora alpina in Brazil. Higher H’ and species richness in the field were found in tailings piles and lower in canga. Canga showed higher inoculum potential. The development of TCs in two locations allowed a wider diversity of AMF species to be captured. Environments of the Quadrilátero Ferrífero are hotspots of AMF diversity, and the soil pH and exchangeable S and P contents are the properties that best explain the distribution of AMF species.

ABSTRACT Knowledge of the occurrence and diversity of arbuscular mycorrhizal fungi (AMF) in National Parks is essential for the establishment of policies for conservation. The aim of this study was to characterize the AMF communities in the Patagonian Altoandina region in Nahuel Huapi National Park, Argentina. We surveyed AMF spores associated with the rhizospheres of 9 plant species in the Patagonian Steppe (PS), Challhuaco Hill (ChH), Catedral Hill (CH), and Tronador Hill (TH) regions and detected a total of 27 Glomeromycota species. Acaulospora laevis was dominant at all sites. The AMF community was dominated by Acaulosporaceae, as regards the number of species and contribution of each one to the total number of spores. Three Glomeromycota families were detected at PS, the site with the lowest elevation; whereas five to six families were detected at ChH, CH, and TH. Cluster analysis indicated that the AMF communities were grouped according to habitat. We concluded that certain patterns of the AMFcommunity structure detected were equivalent to those of high-altitude environments from other studies, while others were unique to the Patagonian region; thus suggesting that historical influences like dispersion and speciation played a critical role in shaping AMF community composition in such high-altitude environments.

RESUMO Syngonanthus elegans é uma espécie vegetal em vias de extinção que ocorrem no Cerrado brasileiro, cuja interação com fungos micorrízicos arbusculares (FMA) é deficientemente compreendida. O objetivo deste trabalho foi avaliar a ocorrência de espécies de FMA e colonização micorrízica de S. elegans. Em duas áreas de amostragem denominadas Córrego do Soberbo (Soberbo) e Parque Nacional das Sempre-Vivas (Parque), ambas localizadas em Diamantina-MG, Brasil, uma parcela de 100 x 100 m foi estabelecida e solo da rizosfera e raízes foram coletados de 10 plantas em cada parcela. Além disso, amostragem incluiu três espécimes de cada Loudetiopsis chrysothrix e Xyris sp.. Estruturas típicas de colonização micorrízica foram observadas nas raízes de S. elegans e a colonização medida foi de 75%. Considerando as duas áreas e os três hospedeiros, 26 espécies de FMA foram recuperados, 8 delas identificadas apenas até gênero. Glomus sp. 1, Scutellospora pernambucana, Acaulospora cavernata e Acaulospora mellea foram classificados como dominantes em ambas as áreas. Além dessas, também foram consideradas dominantes Glomus sp. 4 em Soberbo, e Dentiscutata biornata e Gigaspora albida no Parque. Culturas armadilhas revelaram a presença de sete espécies adicionais. Para S. elegans, a riqueza de espécies de FMA foi ligeiramente superior no Parque do que no Soberbo. Diversidade de Simpson e equitabilidade foram ligeiramente maiores no Soberbo para as comunidades de FMA associados com S. elegans. S. elegans é altamente colonizadas por fungos micorrízicos arbusculares e associada a uma grande variedade de espécies de FMA em condições de campo, sugerindo que essa associação é importante para o estabelecimento e sobrevivência desta espécie ameaçada. Algumas espécies observadas podem ser novas para a ciência.

ABSTRACT Syngonanthus elegans is an endangered plant species occurring in the Brazilian Cerrado whose interaction with arbuscular mycorrhizal fungi (AMF) is poorly understood. The aim of this work was to evaluate the occurrence of AMF species and mycorrhizal colonization of S. elegans in two sampling areas named "Soberbo" stream (Soberbo) and "Parque Nacional das Sempre-Vivas" (Park), both found in Diamantina-MG, Brazil. In each area, one plot (100 x 100 m) was established, and roots and soil samples near the roots were collected from 10 plants in each plot. Further sampling included three specimens each of Loudetiopsis chrysothrix and Xyris sp.. Typical mycorrhizal colonization structures were observed in S. elegans roots, and colonization was measured at 75%. Considering both sites and all three hosts, 26 AMF species were recovered, 8 of which were identified only at the genus level. Glomus sp. 1, Scutellospora pernambucana, Acaulospora cavernata and Acaulospora mellea were classified as dominant in both areas. Other species were also considered dominant, including Glomus sp. 4 in Soberbo and Dentiscutata biornata and Gigaspora albida in Park. Trap cultures revealed the presence of seven additional species. For S. elegans, AMF species richness was slightly higher in Park than in Soberbo. Simpson diversity and evenness were slightly higher in Soberbo for S. elegans-associated AMF communities. Overall, S. elegans is highly colonized by arbuscular mycorrhizal fungi and is associated with a wide range of AMF species in the field, suggesting that this association is important for the establishment and survival of this threatened species. Some of the observed species may be new to science.

Mycorrhizal fungus inoculum produced on-farm can be used during production of woody plant seedlings to reduce costs associated with purchase of commercial inoculant and fertilization. This study aimed to test the efficiency of a mycorrhizal inoculant produced on-farm to promote growth and nutrition of woody species in combination with different levels of phosphorus. Plants were submitted to different treatments of phosphorus (0, 40 and 80 mg P/dm3) and mycorrhizal inoculation (uninoculated, and inoculation with Rhizophagus clarus [Rc] or Claroideoglomus etunicatum [Ce]). Species included were Luehea divaricata, Centrolobium robustum, Schinus terebinthifolius, Garcinia gardneriana, Cedrella fissilis, and Lafoensia pacari. The inoculum was produced using the on-farm methodology. Mycorrhizal colonization of plants inoculated with Rc and Ce ranged from 44.8 to 74.8%, except forGarcinia gardneriana. Inoculation treatment increased plant height and stem diameter of Luehea divaricata, Centrolobium robustum and Cedrella fissilis while phosphorus, inoculation and the interaction affected these parameters for G. gardneriana and Lafoensia pacari. Shoot biomass increased significantly with inoculation treatment in four species. For most species, mycorrhizal fungus inoculation and the addition of phosphorus increased the shoot phosphorus content. Mycorrhizal fungus inoculum produced on-farm successfully colonized tree seedlings and improved growth and/or nutrition under nursery conditions, producing seedlings useful for revegetation of degraded lands.

ABSTRACT: The production of tree seedlings with high survival rate and growth is influenced by the substrate, which may be composed of biological and non-biological materials that help plant growth. The objective of this study was to evaluate the efficiency of a mycorrhizal inoculant on farm and the use of a potassic rock (phonolite) on growth and nutrition of Eucalyptus saligna Sm. and Schinus terebinthifolius Raddi under greenhouse conditions. Both species were assigned to three mycorrhizal treatments [no inoculated control (SP), no inoculation + pulp sludge and carbonized rice husk (LC), and mycorrhizal inoculant (IN)] and four phonolite rock treatments [no phonolite (F0) and addition of phonolite in particle sizes of 0.037 mm (F1), 0.074 mm (F2), and 0.149 mm (F3)]. The IN treatment consisted of inoculum of Claroideoglomus etunicatum (Becker & Gerd.) C. Walker & A. Schussler (isolate MGR288A) and Dentiscutata heterogama (Nicol. & Gerd.) Sieverd. F.A. Souza & Oehl (isolate PNB102A) produced on farm with pulp sludge and carbonized rice husks. After 120 days, plants were evaluated for height, stem diameter, shoot and root dry weight, shoot K and P, and mycorrhizal colonization. Growth parameters were used to calculate the Dickson Quality Index (DQI) for seedlings. Growth parameters of S. terebinthifolius demonstrated synergistic and positive effects when different particle sizes of phonolite and on-farm mycorrhizal inoculum were used together. For E. saligna, phonolite and on-farm mycorrhizal inoculum had little effect on growth parameters, although the mycorrhizal inoculum increased K and P content in the F0 and F2 treatments. The DQI of S. terebinthifolius was higher with IN compared to SP and LC with phonolite, whereas this index was not influenced by most treatment combinations for E. saligna. Overall, the percentage of mycorrhizal root colonization for both species was significantly higher when phonolite was present in the substrate. The interaction of mycorrhizal inoculum produced on farm and phonolite rock has the potential to increase growth and nutrition of S. terebinthifolius and E. saligna.

RESUMO A mandioca é uma planta altamente micotrófica, e o sistema de pré-cultivo pode influenciar a densidade de propágulos de fungos micorrízicos arbusculares (FMAs) e a composição de suas comunidades. O objetivo deste trabalho foi avaliar a ocorrência e estrutura de comunidades de FMAs por reação em cadeia da polimerase (PCR) e eletroforese em gel de gradiente desnaturante (DGGE) na cultura da mandioca (Manihot esculenta Crantz), após cultivo de plantas de cobertura (PC), bem como a influência das comunidades de FMAs sobre a nutrição mineral e produção da mandioca em sistema de cultivo orgânico. Foram testados seis tratamentos de pré-cultivo de PC, incluindo: Aveia (A), Ervilhaca (E), Nabo (N), consórcio A + E e consórcio A + E + N , além de um tratamento-controle com roçadas a cada 15 dias em delineamento em blocos casualizados com quatro repetições. O pré-cultivo com aveia e seu consórcio com ervilhaca e nabo favoreceram o potencial de inóculo de FMAs em solo com baixo número de propágulos, beneficiando a colonização micorrízica da mandioca. O pré-cultivo de plantas de cobertura não influenciou a estrutura de comunidades de FMAs no solo; no entanto, houve similaridade da comunidade de FMAs entre os tratamentos de PC nas raízes da mandioca em sucessão. Mesmo com alta disponibilidade de P no solo, a colonização micorrízica da mandioca foi elevada e esses fatores contribuíram para os teores foliares de P e o rendimento da cultura, independentemente das plantas de cobertura utilizadas. Um ciclo de cultivo das PC no cultivo da mandioca não foi suficiente para obter resposta significativa nas variáveis P no tecido vegetal, rendimento da cultura, ocorrência e na estrutura de comunidades de FMAs no solo. Nas raízes da mandioca em sucessão, o estádio de desenvolvimento da planta interferiu nos agrupamentos da estrutura de comunidade de FMAs.

ABSTRACT Cassava (Manihot esculenta Crantz) is a highly mycotrophic crop, and prior soil cover may affect the density of arbuscular mycorrhizal fungi (AMFs), as well as the composition of the AMFs community in the soil. The aim of this study was to evaluate the occurrence and the structure of AMFs communities in cassava grown after different cover crops, and the effect of the cover crop on mineral nutrition and cassava yield under an organic farming system. The occurrence and structure of the AMFs community was evaluated through polymerase chain reaction (PCR) and denaturing gradient gel electrophoresis (DGGE). A randomized block experimental design was used with four replications. Six different cover crop management systems before cassava were evaluated: black oats, vetch, oilseed radish, intercropped oats + vetch, intercropped oats + vetch + oilseed radish, plus a control (fallow) treatment mowed every 15 days. Oats as a single crop or oats intercropped with vetch or with oilseed radish increased AMFs inoculum potential in soil with a low number of propagules, thus benefiting mycorrhizal colonization of cassava root. The treatments did not affect the structure of AMFs communities in the soil since the AMFs communities were similar in cassava roots in succession to different cover crops. AMFs colonization was high despite high P availability in the soil. The cassava crop yield was above the regional average, and P levels in the leaves were adequate, regardless of which cover crop treatments were used. One cover crop cycle prior to the cassava crop was not enough to observe a significant response in variables, P in plant tissue, crop yield, and occurrence and structure of AMFs communities in the soil. In the cassava roots in succession, the plant developmental stage affected the groupings of the structure of the AMF community.

Os fungos micorrízicos arbusculares (FMAs) desempenham importante papel nos ecossistemas naturais pelo seus impactos na nutrição vegetal e estrutura do solo. O objetivo deste estudo foi determinar o potencial do inóculo micorrízico e a relação do comprimento do micélio micorrízico (CMM) dos FMAs na agregação de solos de ambientes fluviais. Foram realizadas coletas em áreas de ambiente fluvial da bacia hidrográfica do rio Itajaí-Açu, entre os municípios de Gaspar e Navegantes, em Santa Catarina. Oito áreas foram amostradas em três classes de solos, sendo elas: Cambissolo (C), Gleissolo (G) e Organossolo (O). Nos solos coletados, foram avaliadas as seguintes variáveis: potencial de inóculo micorrízico, número de esporos, CMM e análise dos atributos físicos e químicos do solo. A porcentagem de colonização micorrízica da Brachiaria brizantha no ensaio do potencial de inóculo variou de 13,8 a 55,3 % e nenhum padrão foi observado de acordo com a classe de solo. O CMM no solo variou de 10,48 a 44,67 mg g-1. O número de esporos em 100 cm3 de solo variou de 2,4 a 80. Foi observada correlação negativa entre o CMM e a proporção de macroagregados estáveis em água e correlação positiva entre CMM com microagregados. Este trabalho demonstrou que os solos da bacia do rio Itajaí-Açu possuem potencial de inóculo micorrízico suficiente para iniciar a colonização das raízes das plantas em curto período de tempo, o que pode ser importante facilitador no crescimento de espécies arbóreas usadas no processo de recuperação desses ambientes.

Arbuscular mycorrhizal fungi (AMF) play an important role in natural ecosystems as they influence plant nutrition and soil structure. The aim of this study was to determine the mycorrhizal inoculum potential and the relationship between mycorrhizal mycelium length of AMF and aggregation of riparian soils. Soil samples were collected in riparian areas in the Itajai Açu river watershed, between the municipalities of Gaspar and Navegantes, Santa Catarina, Brazil. Eight areas were sampled within three soil classes: Cambissolo (Inceptisol) (C), Gleissolo (Aquoll) (G), and Organossolo (Histosol) (O). For each area, the following measurements were made: mycorrhizal inoculum potential, number of spores, mycorrhizal mycelium length, and soil physical and chemical properties. Mycorrhizal colonization of Brachiaria brizantha in the inoculum potential bioassay ranged from 13.8 to 55.3 %, and no pattern was observed according to soil class. Mycorrhizal mycelium length ranged from 10.48 to 44.67 m g-1, according to the area sampled. Number of spores ranged from 2.4 to 80 spores in 100 cm3 of soil. A negative correlation was observed between mycorrhizal mycelium length and the proportion of water stable macroaggregates and a positive correlation between the former and the proportion of microaggregates. Results showed that riparian soils from the Itajai Açu river watershed have a moderate to high mycorrhizal inoculum potential sufficient to start colonization of plant roots in a short period of time, an important property to facilitate growth of native woody species used in recovering these habitats.

A produção de inoculante à base de fungos micorrízicos arbusculares (FMAs) utilizando o método on farm é uma alternativa para estimular o uso de inoculante microbiano no sistema de produção vegetal e reduzir os custos associados com a compra desse produto. O objetivo deste estudo foi avaliar o potencial de resíduos do setor florestal, a casca de Pinus (CP) e o lodo de celulose (LC), como componentes do substrato para a produção de inoculante micorrízico on farm . Plantas de sorgo pré-colonizadas com os FMAs, Claroideoglomus etunicatum RJN101A e Dentiscutata heterogama PNB102A, foram estabelecidas em casa de vegetação por três meses em substrato formado por areia:argila expandida:solo (2:2:1). Após, essas foram transplantadas para sacos plásticos de 20 L contendo substrato formado por CP ou LC, misturados com casca de arroz carbonizada + solo de barranco (1:1:1). O experimento seguiu um fatorial 2 × 2, sendo dois isolados fúngicos e dois resíduos, com cinco repetições, em delineamento inteiramente casualizado. As plantas cresceram por três meses sob condições ambientais e, após esse período, o substrato foi analisado quanto ao número de esporos de FMAs, à colonização micorrízica da planta hospedeira e ao potencial de inóculo pelo método do NMP (número mais provável). O substrato foi dividido em três camadas (superior, mediana e inferior) e apenas o número de esporos foi avaliado individualmente para cada camada. O número de esporos de ambos FMAs não foi influenciado pelo tipo resíduo, mas diminuiu da parte superior para a inferior dentro de cada unidade experimental. D. heterogama tendeu a produzir maior número de esporos do que C. etunicatum . A porcentagem de colonização micorrízica do sorgo pelos FMAs foi significativamente maior no resíduo LC do que CP. O número de propágulos infectivos de FMAs tendeu também a ser maior em LC (22 a 28 propágulos cm-3 substrato) do que em CP (1,6 a 6,5 propágulos cm-3 substrato). O resíduo LC tem potencial para ser utilizado como componente do substrato em sistemas de produção de inoculante micorrízico on farm.

Production of arbuscular mycorrhizal fungi (AMF) inoculum using the on-farm method is an alternative to stimulate the use of microbial inoculant in plant production systems and to reduce the cost associated with purchase of this product. The goal of this study was to evaluate the potential of residues from the forestry industry, pine bark (CP) and pulp sludge (LC), as components of the substrate used to produce on-farm mycorrhizal inoculum. Sorghum plants pre-colonized with the AMFs Claroideoglomus etunicatum RJN101A and Dentiscutata heterogama PNB102A were established in a greenhouse for three months in a substrate of sand:expanded clay:soil (2:2:1). After this period, plants were transplanted to 20 L plastic bags containing a substrate with CP or LC mixed with carbonized rice hulls + soil (1:1:1). The experiment followed a 2 x 2 factorial arrangement, of two fungal isolates and two residues, with five replicates, in a completely randomized design. Plants were grown outdoors for three months and then the substrate was analyzed for AMF spore numbers, mycorrhizal colonization of the host plant, and inoculum potential by the MPN (most probable number) method. The substrate of each bag was divided into three layers (upper, middle, and lower portion) and only the number of spores was analyzed separately for each layer. The type of residue did not affect the number of spores of either AMF, but this number decreased from the upper to the lower layer within each experimental unit. D. heterogama tended to produce more spores than C. etunicatum . Sorghum mycorrhizal colonization by AMF was significantly greater in the LC residue than in the CP residue. The number of AMF infective propagules also tended to be higher in LC (22 to 28 propagules cm-3 substrate) than in CP (2 to 7 propagules cm-3 substrate). The LC residue showed potential for use as a component of the substrate in mycorrhizal inoculum production systems using the on-farm method.

Os campos de murundus são fitofisionomias de ocorrência no bioma Cerrado com funções ecológicas importantes para a manutenção da sustentabilidade do solo; e a conversão para sistemas agrícolas pode provocar alterações nos atributos físicos, químicos e biológicos do solo ainda não avaliados, como a redução da biodiversidade de fungos micorrízicos arbusculares. O objetivo deste estudo foi avaliar como a conversão dos campos de murundus em áreas de sistema agrícola altera a comunidade de fungos micorrízicos arbusculares (FMAs). Os tratamentos constituíram-se de três áreas agrícolas submetidas ao mesmo manejo e uso agrícola em uma cronossequência (7, 11 e 14 anos) e duas na área referência [campo de murundus, em topo (TM) e entre os murundus (EM)]. Os esporos de FMAs foram extraídos, contados, e as espécies de FMAs identificadas pelas características morfológicas. O total de FMAs recuperado foi de 27 espécies, sendo nove espécies da família Acaulosporaceae, uma Ambisporaceae, sete Glomeraceae, duas Claroideoglomeraceae e oito Gigasporaceae. Desse total, as espécies Acaulospora scrobiculata, Glomus macrocarpum, e Gigaspora sp. ocorreram em todas as áreas nos dois anos estudados. As espécies Acaulospora mellea, Acaulospora cavernata, Acaulospora colombiana, Glomus diaphanum, Scutellospora reticulata e Scutellospora sp. só foram encontradas nos campos de murundus. A conversão de campos de murundus em área agrícola modificou a ocorrência e composição da comunidade de FMAs; as espécies Acaulospora scrobiculata, Glomus macrocarpum, Claroideoglomus etunicatus e Gigaspora sp ocorreram em todas as áreas e a não ocorrência de algumas espécies nas áreas de cultivo, como as espécies Acaulospora cavernata, Acaulospora colombiana, Rhizophagus diaphanus, Scutellospora reticulata e Scutellospora sp. representa perda de diversidade desses fungos. Portanto, este estudo tratou-se do primeiro relato da ocorrência e da estrutura da comunidade de FMAs em fitofisionomia de campos de murundus, contribuiu para o maior entendimento dos FMAs no bioma Cerrado e demonstrou que as alterações promovidas pela conversão da área alteraram a ocorrência e a diversidade dos fungos micorrízicos arbusculares.

The murundu fields (Campos de Murundus) are characterized by mounds occurring in some parts of the Cerrado (Brazilian tropical savanna) biome with important ecological functions for the maintenance of soil sustainability. Conversion to agricultural systems may lead to changes in physical, chemical, and biological soil properties not yet assessed, such as reduction in the biodiversity of arbuscular mycorrhizal fungi. The aim of this study was to evaluate how the conversion of mound fields into agricultural areas changes the community of arbuscular mycorrhizal fungi (AMF). Treatments consisted of three agricultural areas subjected to the same agricultural management and use in a chronosequence (seven, 11, and 14 years) and two in the mound fields, sampling at the top (TM) and between the mounds (EM)). AMF spores were extracted and counted, and AMF species were identified by morphological characteristics. The total AMF recovered was 27 species, made up of nine species of the Acaulosporaceae family, one Ambisporaceae, seven Glomeraceae, two Claroideoglomeraceae, and eight Gigasporaceae. Of this total, the species Acaulospora scrobiculata , Glomus macrocarpum , and Gigaspora sp occurred in all areas in the two years studied. The species Acaulospora melle a, Acaulospora cavernata , Acaulospora colombiana , Glomus diaphanum , Scutellospora reticulata , and Scutellospora sp only occurred in the mound fields. The conversion of mound fields into an agricultural area modified the occurrence and composition of the arbuscular mycorrhizal fungi community, and the species Acaulospora scrobiculata , Glomus macrocarpum , Gigaspora sp, and Claroideoglomus etunicatus occurred in all areas. The non-occurrence of some species in the crop areas, such as the species Acaulospora cavernata , Acaulospora columbiana , Rhizophagus diaphanus , Scutellospora reticulata , and Scutellospora sp, represents a loss of diversity of these fungi. Therefore, this study is the first report of the occurrence and community structure of AMF in the mound field vegetation type. It contributes to better understanding of AMF in the Cerrado biome and shows that the changes introduced by conversion of the area alter the occurrence and diversity of arbuscular mycorrhizal fungi.

Sugarcane (Saccharum spp.) is grown on over 8 million ha in Brazil and is used to produce ethanol and sugar. Some sugarcane fields are burned to facilitate harvesting, which can affect the soil microbial community. However, whether sugarcane pre-harvest burning affects the community of arbuscular mycorrhizal fungi (AMF) and symbioses development is not known. In this study, we investigated the early impacts of harvest management on AMF spore communities and root colonization in three sugarcane varieties, under two harvest management systems (no-burning and pre-harvest burning). Soil and root samples were collected in the field after the first harvest of sugarcane varieties SP813250, SP801842, and RB72454, and AMF species were identified based on spore morphology. Diversity indices were determined based on spore populations and root colonization determined as an indicator of symbioses development. Based on the diversity indices, spore number and species occurrence in soil, no significant differences were observed among the AMF communities, regardless of harvest management type, sugarcane variety or interactions between harvest management type and sugarcane variety. However, mycorrhiza development was stimulated in sugarcane under the no-burning management system. Our data suggest that the sugarcane harvest management system may cause early changes in arbuscular mycorrhiza development.