RESUMO O objetivo deste estudo foi identificar as comunidades dos fungos micorrízicos arbusculares (FMAs) presentes em solos sob ecossistemas de silvipastagens, pastagens e mata de cerrado, além de avaliar a influência do sistema de uso do solo, textura do solo e da sazonalidade na dinâmica das comunidades destes fungos, no município de Alta Floresta D’Oeste - RO. As amostras de terra foram coletadas aleatoriamente na profundidade de 0 a 20 cm, em cada um dos ecossistemas em Julho/2010 (período seco) e Janeiro/2011 (período chuvoso). Após extraídos, os esporos foram contados e identificados. Estimou-se a densidade dos esporos e a densidade de cada espécie de FMA. Calcularam-se a frequência de ocorrência de cada espécie, o índice de diversidade de Shannon e o índice de diversidade de Simpson. Realizou-se uma análise multivariada de agrupamento baseado no número de indivíduos das espécies dos FMAs. Houve tendência de um maior número de esporos no ecossistema de mata de Cerrado independente da textura do solo ou da estação do ano, quando comparado as áreas de pastagem e silvipastagem. A espécie de Glomus macrocarpum apresentou 100% de frequência de ocorrência na estação chuvosa em ambas as texturas do solo. A influência da textura e da sazonalidade na composição e diversidade da comunidade dos FMAs foi mais expressiva no ecossistema de mata de Cerrado. O clima, a textura do solo, o manejo e o sistema de uso do solo afetam a composição e diversidade de espécies de FMAs.

ABSTRACT The objective of this study was to identify communities of arbuscular mycorrhizal fungi (AMF) in soils under pasture, silvopasture, and Cerrado forest ecosystems, and evaluate the effects of land use system, soil texture, and seasonality on the dynamics of AMF communities, in Alta Floresta D'Oeste, Rondônia, Brazil. Samples of the soil 0-20 cm layer were randomly collected in each ecosystem in July, 2010 (dry season) and January, 2011 (rainy season). Spores were extracted, counted, and identified. The spore density and density of each species of AMF were estimated. The frequency of occurrence, Shannon diversity index, and Simpson diversity index were calculated for each species. Multivariate clustering analysis was carried out, considering the number of AMF of each species. The results showed a trend of higher number of spores in the Cerrado forest ecosystem, regardless of the soil texture or season, when compared to pasture and silvopasture areas. The Glomus macrocarpum species presented 100% frequency of occurrence in the rainy season in both soil textures. The effects of texture and seasonality on the composition and diversity of AMF communities was more expressive in the Cerrado forest ecosystem. The climate, soil texture, and land use and management affected the composition and diversity of AMF species.

ABSTRACT. The present study aimed to select efficient arbuscular mycorrhizal fungi (AMF) for sugarcane growth and P nutrition in four soils that spontaneously contained dark septate endophytes (DSE). The effect of nine AMF isolates was evaluated individually in sugarcane presprouted seedlings (SP81-3250) grown under greenhouse conditions for a 120-day period. The isolates that stimulated plant growth in the soils with low P availability were Acaulospora colombiana (ACOL), Claroideoglomus etunicatum (CETU), Gigaspora margarita (GMAR), Rhizophagus clarus (RCLA) and Scutellospora calospora (SCAL). Compared to the Yellow Argisol, which had the highest P level, the Red-Yellow Argisol, with an intermediate P content, increased plant height. Compared to the other treatments, inoculation with ACOL, RCLA, and SCAL resulted in higher foliar P content in plants grown in soils with high to intermediate P levels. Root colonization by AMF and DSE was verified in the plants, with the coexistence of both fungal groups in the same plant and/or root fragment. However, AMF colonization was low compared to DSE colonization. The cooccurrence of DSE and AMF was higher in the plants inoculated with ACOL, RCLA, SCAL, and Dentiscutata heterogama. ACOL, CETU, GMAR, RCLA, and SCAL are AMF isolates that have the potential to establish a mycorrhizal inoculant for sugarcane that would be effective in several soils.

ABSTRACT Plants response to symbiosis with arbuscular mycorrhizal fungi (AMF) under water stress is important to agriculture. Under abiotic stress conditions native fungi are more effective than exotics in improving plant growth and water status. Mycorrhization efficiency is related to soil fungi development and energy cost-benefit ratio. In this study, we assessed the effect on growth, water status and energy metabolism of Cucurbita pepo var. pepo when inoculated with native AMF from the Sonoran desert Mexico (mixed isolate and field consortium), and compared with an exotic species from a temperate region, under drought, low and high salinity conditions. Dry weights, leaf water content, water and osmotic potentials, construction costs, photochemistry and mycorrhization features were quantified. Under drought and low salinity conditions, the mixed isolate increased plant growth and leaf water content. Leaf water potential was increased only by the field consortium under drought conditions (0.5-0.9 MPa). Under high salinity, the field consortium increased aerial dry weight (more than 1 g) and osmotic potential (0.54 MPa), as compared to non-mycorrhized controls. Plants inoculated with native AMF, which supposedly diminish the effects of stress, exhibited low construction costs, increased photochemical capacity, and grew larger external mycelia in comparison to the exotic inoculum.

ABSTRACT At the Brazilian Amazon forest, studies were carried out to estimate the community of arbuscular mycorrhizal fungi (AMF), from this it was used a bioassay of dilutions of samples collected from preserved and regenerated areas after bauxite extraction. To regenerate areas, tree species were introduced and samples were taken after 2, 6, 12, and 16 years, the spores obtained were compared to those obtained by direct extraction and the number of species recovered from the bioassay was significantly higher. Therefore, the species founded after different periods regeneration was similar to the ones from the native forest. Since the early years of revegetation, the number of rare species was high with strong dominance of G. macrocarpum. Among older communities this high dominance decreased while at the same time, there was an increase in the number of individuals from other AMF species, concluding that the number of species did not change with the age of the revegetation.

Abstract Abiotic stress is one of the major limiting factors for plant development and productivity, which makes it important to identify microorganisms capable of increasing plant tolerance to stress. Dark septate endophytes can be symbionts of plants. In the present study, we evaluated the ability of dark septate endophytes isolates to reduce the effects of water stress in the rice varieties Nipponbare and Piauí. The experiments were performed under gnotobiotic conditions, and the water stress was induced with PEG. Four dark septate endophytes were isolated from the roots of wild rice (Oryza glumaepatula) collected from the Brazilian Amazon. Plant height as well as shoot and root fresh and dry matter were measured. Leaf protein concentrations and antioxidant enzyme activity were also estimated. The dark septate endophytes were grown in vitro in Petri dishes containing culture medium; they exhibited different levels of tolerance to salinity and water stress. The two rice varieties tested responded differently to inoculation with dark septate endophytes. Endophytes promoted rice plant growth both in the presence and in the absence of a water deficit. Decreased oxidative stress in plants in response to inoculation was observed in nearly all inoculated treatments, as indicated by the decrease in antioxidant enzyme activity. Dark septate endophytes fungi were shown to increase the tolerance of rice plants to stress caused by water deficiency.

The humic acids (HA) from two different vermicompost were extracted, isolated, purified and partially characterized, to evaluate their possible protection in rice (Oryza sativa L.) plants against an hydric stress. Differences in elemental composition, as the coagulation threshold value and E4/E6 relation in their UV-Vis spectra were found. Two concentrations (40 and 60 mg L-1) of both HA were included in the nutritive solutions for rice plants in controlled conditions. It was verified that the previous treatment with the HA during six days stimulated the root biomass production. Later the HA were excluded and was an hydric deficit induced by adding polietilenglicol (PEG-6000) in the initially treated plants and in a group of those used as control. After 96 hours of this final condition the net radical biomass, the photosynthetic pigments content and the root membrane permeability were evaluated. In the plants previously treated with HA (at the concentration 60 mg HA L-1), the root membrane permeability, the net radical biomass production and the “a” chlorophyll content had no differences when compared with those without stress. It was concluded that the previous treatment with the HA protected the rice plants against a posterior hydric stress that was induced

Los ácidos húmicos (AH) de dos diferentes vermicompost fueron extraídos, aislados, purificados y parcialmente caracterizados, para evaluar su posible efecto protector en plantas de arroz (Oryza sativa L.) ante un estrés hídrico. En los AH se encontraron diferencias en la composición elemental, en el valor del umbral de coagulación y en la relación E4/E6 de sus espectros UV-Vis. Dos concentraciones (40 y 60 mg L-1) de ambos AH se incluyeron en disoluciones nutritivas para el cultivo de plantas de arroz en condiciones controladas. Se verificó que el tratamiento previo con los AH durante seis días, estimuló la producción de biomasa radical. Después se excluyeron los AH y tanto en las plántulas inicialmente tratadas, como en un grupo de las utilizadas como control, se indujo un déficit hídrico adicionando polietilenglicol (PEG-6000) en la disolución nutritiva. Luego de 96 horas de establecida esa condición final se evaluaron la producción neta de biomasa radical, el contenido de pigmentos fotosintéticos foliares y la permeabilidad de la membrana de las raíces. En las plantas previamente tratadas con AH (a la concentración de 60 mg AH L-1), la permeabilidad de la membrana de las raíces, la producción neta de biomasa en este órgano, así como el contenido de clorofila “a” no manifestaron diferencias al compararlas con aquellas sin estrés. Se concluye que el tratamiento previo con los AH consiguió proteger a las plantas de arroz ante el estrés hídrico posterior que se indujo

Abstract In order to obtain an arbuscular mycorrhizal fungi (AMF) native inoculum from Sierra de Moa and determine the most appropriate conditions for its big scale production, four light and temperature combinations were tested in three plant species (Calophyllum antillanum, Talipariti elatum and Paspalum notatum). Growth and development parameters, as well as the mycorrhizal functioning of the seedlings were evaluated. The natural light treatment under high temperatures (L-H) was the most suitable for the growth and development of the three plant species, showing the highest total biomass values, mainly of root, and a positive root-shoot ratio balance. This treatment also promoted higher values of root mycorrhizal colonization, external mycelium and AMF spore density. A total of 38 AMF species were identified among the plants and environmental conditions tested. Archaeospora sp.1, Glomus sp.5, Glomus brohultii and G. glomerulatum were observed in all the treatments. The L-H condition can be recommended for native inoculum production, as it promotes a better expression of the AM symbiosis and an elevated production of mycorrhizal propagules.

Abstract The family Leguminosae comprises approximately 20,000 species that mostly form symbioses with arbuscular mycorrhizal fungi (AMF) and nitrogen-fixing bacteria (NFB). This study is aimed at investigating and confirming the dependence on nodulation and biological nitrogen fixation in the specie Piptadenia gonoacantha (Mart.) Macbr., which belongs to the Piptadenia group. Two consecutive experiments were performed in a greenhouse. The experiments were fully randomized with six replicates and a factorial scheme. For the treatments, the two AMF species and three NFB strains were combined to nodulate P. gonoacantha in addition to the control treatments. The results indicate this species’ capacity for nodulation without the AMF; however, the AMF + NFB combinations yielded a considerable gain in P. gonoacantha shoot weight compared with the treatments that only included inoculating with bacteria or AMF. The results also confirm that the treatment effects among the AMF + NFB combinations produced different shoot dry weight/root dry weight ratios. We conclude that AMF is not necessary for nodulation and that this dependence improves species development because plant growth increases upon co-inoculation.

RESUMO A matéria orgânica do solo é uma importante fonte primária de nutrientes às plantas e influencia a infiltração, retenção de água, suscetibilidade à erosão e agregação do solo. No entanto, esse processo está condicionado à qualidade e quantidade da matéria orgânica aportada. O objetivo deste trabalho foi avaliar a influência do desastre ambiental causado pela chuva em áreas de produção de oleráceas na região Serrana do Rio de Janeiro. Foram selecionadas as seguintes áreas: A1: sem impacto (testemunha); A2: soterramento total e cultivo de aveia + ervilhaca; A3: transbordamento do rio e cultivo de milheto + girassol; A4: transbordamento do rio e grande deposição de areia com cultivo de aveia-preta; A5: transbordamento do rio com grande deposição de areia e sem cultivo; e A6: transbordamento do rio em pequena escala e sem cultivo. As propriedades edáficas analisadas foram: textura; densidade do solo (Ds); densidade de partículas (Dp); diâmetro médio ponderado (DMP) e diâmetro médio geométrico (DMG) de agregados estáveis em água; pH(H2O), Al3+, Ca2++Mg2+, Na+, H+Al, K, P e carbono orgânico total (COT); e frações granulométricas e químicas da matéria orgânica. Os maiores valores de DMP e DMG foram observados nas áreas A3 e A6, que seguem a mesma tendência dos maiores teores de argila. Os teores de COT e suas frações químicas e físicas apresentaram diferenças em relação à testemunha com os menores valores verificados nas áreas que foram submetidas ao impacto pelo transbordamento do rio e grande deposição de areia. As áreas que foram impactadas pelo soterramento com predomínio da fração argila apresentaram valores semelhantes ou superiores aos da testemunha. As variáveis foram selecionadas e avaliadas por meio da análise de componentes principais, que evidenciou distinção entre as áreas estudadas, com separação entre elas associada à textura do solo e densidade de partículas.

ABSTRACT Soil organic matter is an important primary source of nutrients for plants and influences infiltration, water retention, susceptibility to erosion, and soil aggregation. However, this process is conditioned on the quality and quantity of organic matter supplied. The objective of this study was to evaluate the influence of the environmental disaster caused by rain in areas of horticulture production in the mountainous region of Rio de Janeiro. The following areas were selected: A1- no impact (control); A2 - totally covered by landslide and cultivation of oats + vetch; A3 - river overflow and cultivation of millet + sunflower; A4 - river overflow and extensive deposition of sand and growing of black oats; A5 - river overflow with extensive deposition of sand and no cultivation; and A6 – river overflow on a small scale and no cultivation. The soil properties analyzed were texture; bulk density (BD); particle density (Pd); mean weight diameter (MWD) and geometric mean diameter (GMD) of water-stable aggregates; pH(H2O), Al3+, Ca2++Mg2+, Na+, H+Al, K, P, and total organic carbon (TOC); and particle size and chemical organic matter fractions. The highest values of the DMG and DMP were observed in areas A6 and A3, which also have the highest clay contents. The TOC content and its chemical and physical fractions showed differences compared to the control, with the lowest values observed in areas that underwent the impact of river overflow and extensive sand deposition, since the areas that were affected by landslide with predominance of the clay fraction showed values similar or superior to reference values. Principal component analysis clearly showed a distinction among the areas studied, and this distinction is clearly associated with soil texture and particle density.

RESUMO A mesofauna edáfica compreende organismos de dimensões entre 100 μm e 2 mm, sendo importante avaliar os métodos utilizados para sua caracterização. Os objetivos deste trabalho foram definir o período de tempo de permanência do material de solo no extrator Berlese-Tüllgren para a captura dos organismos da mesofauna e determinar o tempo mínimo de extração para a correta utilização dos índices de Shannon, Simpson, Pielou e Margalef, empregados na avaliação da diversidade, dominância e equabilidade das comunidades da mesofauna. O estudo foi conduzido no Departamento de Solos do Instituto de Agronomia da Universidade Federal Rural do Rio de Janeiro, Seropédica, Rio de Janeiro, em terreno altamente antropizado. Foram instaladas parcelas experimentais com os seguintes tratamentos: feijão-de-porco (Canavalia ensiformis), mucuna-preta (Mucuna aterrima), feijão-bravo-do-Ceará (Canavalia brasiliensis), guandu (Cajanus cajan) e vegetação espontânea, em delineamento de quadrado latino. Em cada uma das unidades experimentais, foram coletadas amostras formadas por serapilheira e material de solo, nos primeiros 5 cm da camada superficial do solo realizada um dia antes do plantio das leguminosas (outubro) e, posteriormente, por ocasião do corte da parte aérea das plantas (março). As amostras foram submetidas a uma bateria de extratores do tipo Berlese-Tüllgren, por um período de 15 dias, realizando-se a contagem diária dos organismos. A partir da contagem e identificação em nível de grupo (Ordem/Família) dos organismos capturados, foram determinados os índices de Margalef, Simpson, Shannon e Pielou, bem como verificou-se a correlação por ordem de Kendall entre os valores obtidos dia a dia até o 8º dia de extração, usando-se o índice de Shannon como referência. Concluiu-se que é possível a redução do tempo de permanência das amostras de material de solo nos funis Berlese-Tüllgren, não sendo recomendável a adoção de período de tempo inferior a seis dias para se determinar a composição da mesofauna edáfica ou para se obterem dados mais consistentes e confiáveis para se avaliarem os índices de diversidade, quando se utiliza esse procedimento.

ABSTRACT Soil mesofauna consists of organisms that measure from 0.100 μm to 2 mm, being important to evaluate methods employed for its characterization. The objectives of this study were to define how long the soil material must remain in the Berlese-Tüllgren extraction device to capture organisms of the mesofauna and determine the minimum extraction time for correct use of the Shannon, Simpson, Pielou, and Margalef indices used to evaluate the diversity, dominance, and richness of the mesofauna communities. The study was conducted at the Department of Soil Science at the Institute of Agronomy of the Universidade Federal Rural do Rio de Janeiro, Seropédica, Rio de Janeiro, Brazil, in highly anthropic land. Experimental plots were set up with the following treatments: jack bean (Canavalia ensiformis), velvet bean (Mucuna aterrima), Ceará bravo bean (Canavalia brasiliensis), pigeon pea (Cajanus cajan), and spontaneous vegetation in a Latin square design. Samples were collected from each of the experimental units, made up of plant litter and soil material in the first 5 cm of topsoil the day before planting legumes (October), and, subsequently, at the time of cutting plant shoots (March). The samples were subjected to a battery of the Berlese-Tüllgren type funnels for a period of 15 days, performing a daily count of organisms. From the count and group-level identification (Order/Family) of the captured organisms, the Margalef, Simpson, Shannon, and Pielou indices were determined and verified by Kendall rank correlation between the values obtained from one day to the next until the 8th day of extraction, using the Shannon index as a reference. From the study, it may be concluded that it is possible to reduce the time the material samples remain in the Berlese-Tüllgren funnels, but adoption of a time less than six days is not recommended to determine the composition of the soil mesofauna or to obtain more consistent and reliable data for evaluating diversity indices when using this procedure.

En el presente estudio se evaluó, durante dos años, la influencia de los períodos seco y lluvioso sobre el funcionamiento de hongos formadores de micorrizas arbusculares (HFMA) simbiontes de plantas nativas de una sabana semi natural, una sabana recuperada de la actividad agrícola y un agroecosistema, ubicados en la Reserva Florística Manejada San Ubaldo-Sabanalamar, Pinar del Río, Cuba. Se recolectaron muestras de suelo en abril y octubre (período seco y húmedo de 2008 y 2010, respectivamente). Dentro de cada ecosistema se seleccionaron cuatro parcelas y se recolectaron cinco submuestras al azar, las que fueron homogeneizadas para formar una muestra compuesta por parcela. Se cuantificó la biomasa de raicillas, la colonización micorrízica de las plantas hospedadoras en el campo, el micelio extrarradical, el micelio endófito y la densidad de esporas. La biomasa de raicillas en la sabana semi natural incrementó durante los períodos secos, la cual alcanzó hasta 12.85 g/dm3 de suelo. En todos los ecosistemas, la mayor colonización micorrízica ocurrió en la época lluviosa del segundo año con valores que oscilaron entre 79 y 89 %. Las mayores biomasas de micelio externo fueron registradas en los tres ecosistemas durante el período seco del segundo año, con un valor máximo de 279 mg/dm3 de suelo en la sabana recuperada. La mayor densidad de esporas de HFMA fue determinada en el periodo seco del segundo año para los tres ecosistemas estudiados, con el valor más alto en la sabana recuperada con 5 670 esporas/100 g de suelo seco. De manera general, se evidenció un efecto de la estacionalidad de la lluvia más que del manejo de ecosistema sobre el funcionamiento de los HFMA. La mayor actividad colonizadora se evidenció en períodos húmedos, mientras que mayor biomasa de raicillas y micelio externo durante los períodos secos, lo que sugiere estrategias de incremento del volumen del suelo explorado por parte de los HFMA como de las plantas hospedadoras. La proliferación de esporas evidenció la formación de estructuras de resistencia de los HFMA ante condiciones adversas. Los resultados obtenidos pondrían en evidencia la plasticidad de la simbiosis micorrízica ante variaciones en la disponibilidad de agua.

Despite the ubiquity and importance of indigenous arbuscular mycorrhizal fungi (AMF) for plant ecosystems; functioning of indigenus mycorrhizal symbiosis (IMS) and related environmental factors at coastal Caribbean ecosystems remains still scarce. In order to determine functionality of IMS under contrasting land uses and wet seasons from Cuba, the influence of the water stress on some AMF functionality parameters from a semi-natural savannah (NS), a recovered savannah (RS) and an agro-ecosystem (AG) from the Managed Floristic Reserve San Ubaldo-Sabanalamar, Pinar del Rio, Cuba were assessed during two-years. Soil and root samples were collected in April and October, during the dry and wet seasons, respectively, in 2008 and 2010. Four plots in each ecosystem were selected, and five soil sub-samples were randomly collected, bulked, mixed homogeneously and used as the composite sample per plot. The host plant root biomass, arbuscular mycorrhizal colonization of the host plant, density of the intraradical and extraradical AMF mycelia, fungal endophyte biomass and AMF spore density were assessed. The host plant root biomass increased in the NS environment during the dry season, and approximately 12.85g root/dm³ dry soil was recorded. The colonization degree were significantly higher in all environments during the wet season of the second year, with means ranging from 79% to 89%. The extraradical mycelia were significantly more abundant in the dry season of the second year in all environments, with a maximum of 279mg/dm³ in the RS ecosystem. The density of AMF spores was highest in the dry season of the second year for the three studied ecosystems. The RS ecosystem hosted 5 670 spores/100g dry soil. In general, the influence of rainfall seasonality on the function of AMF was stronger than the influence of ecosystem management. The root biomass and extraradical mycelia were high in the dry seasons, suggesting strategies to increase the volume of soil for the mutual benefit of the symbionts. The increase in spore density during the dry seasons appears as an adaptation allowing AMF to survive period of water shortage. This study improves our understanding of the adaptative responses of arbuscular mycorrhizal symbiosis to seasonal variations in soil water availability. Rev. Biol. Trop. 63 (2): 341-356. Epub 2015 June 01.

Foram examinadas quatro estratégias (Tris / EDTA, dodecilsulfato de sódio, resina Chelex 100 e brometo de cetiltrimetilamónio -CTAB-) para a extração de ácido nucleico (DNA) das comunidades de nematóides. Os nematóides foram isolados a partir de uma área agrícola sob manejo diferente num experimento de rotação de culturas de longo prazo, durante três temporadas na Argentina. Após a extração de DNA, a reação em cadeia da polimerase e amplificações foram realizadas e consideradas como indicadoras da extração de DNA com sucesso. O CTAB combinada com proteinase K e álcool fenol-clorofórmio-isoamílico foi o único método bem sucedido porque as amplificações positivas foram obtidas utilizando ambos os primers específicos para os eucariótas e nematóides. Este trabalho poderá contribuir para o estudo da biodiversidade de nematóides em agroecossistemas.

We examined four strategies (Tris/EDTA, sodium dodecyl sulfate, Chelex 100 resin and cetyltrimethylammonium bromide -CTAB-) for extracting nucleic acid (DNA) from communities of nematodes. Nematodes were isolated from an agricultural area under different management of long-term crop rotation experiment from Argentina during three seasons. After DNA extraction, Polymerase Chain Reaction-amplifications were performed and considered as indicators of successful DNA extraction. The CTAB combined with proteinase K and phenol-chloroform-isoamyl alcohol was the unique successful method because positive amplifications were obtained by using both eukaryotic and nematode specific primers. This work could contribute to biodiversity studies of nematodes on agroecosystems.

In this study, we evaluated the growth of the liverwort Lunularia cruciata, inoculated or not with the arbuscular mycorrhizal fungi (AMF) Glomus proliferum (15 spores per Petri dish), in Strullu-Romand Variant (SRV) medium modified and enriched with humic acid (HA) at different concentrations (0, 20, 40 and 80 mg C L−1), as well as the sporulation of the AMF. We assessed the absolute growth rate (AGR) and relative growth rate (RGR) at inoculation, as well as at 7, 14, 21, 28, 43, 52 and 60 days after inoculation (DAI), whereas we assessed sporulation at 25, 43, 60 and 70 DAI. The main determinant of L. cruciata growth was the presence of AMF. With and without G. proliferum inoculation, respectively, the AGR peaked at 39 and 42 DAI, and the RGR was 0.0474 and 0.0387 cm² cm−2 d−1. Doses of 20 and 80 mg C L−1 of HA had a positive influence on the growth of L. cruciata. With and without HA, respectively, the AGR peaked at 38 and 39 DAI, and the RGR was 0.0484 and 0.0422 cm² cm−2 d−1. The sporulation of G. proliferum, which was as high as 199 spores plate−1, was influenced by HA, especially at 20 and 80 mg C L−1.

Os experimentos objetivaram avaliar em condições de casa de vegetação o biocontrole dos fitopatógenos Rhizoctonia solani (RS) e Fusarium oxysporum f.sp. phaseoli (FOP) em alface (Lactuca sativa L.) cultivar Regina, e feijão-vagem (Phaseolus vulgaris L.) cultivar Alessa, respectivamente, utilizando como agentes antagonistas, 10 isolados de Trichoderma spp. selecionados em testes in vitro. Foram feitos biopreparados à base de arroz previamente colonizado por isolados de Trichoderma spp. e posteriormente triturados. Para a realização dos testes, os biopreparados foram inoculados previamente na proporção de 10(9) conídios.mL-1, em substrato comercial para produção de mudas. Após sete dias, os patógenos foram introduzidos separadamente em duas concentrações distintas: R. solani na proporção de 144 mg de meio de arroz por kg de substrato e F. oxysporum f.sp. phaseoli inoculado na forma de suspensão contendo 4,75 x 10(6) conídios.mL-1. Avaliou-se a influência dos biopreparados na % de damping-off de pós-emergência em plantas de alface e a severidade de murcha em plantas de feijão-vagem. O biopreparado referente ao isolado T-03 foi o mais eficiente no controle de R. solani em plantas de alface cultivar Regina, por ter reduzido a incidência de damping-off de pós-emergência nessa cultura. Por outro lado, nenhum dos biopreparados apresentou efeito antagonista satisfatório à F. oxysporum f.sp. phaseoli em plantas de feijão-vagem.

The experiments aimed to evaluate under greenhouse conditions the biocontrol of plant pathogens Rhizoctonia solani (RS) and Fusarium oxysporum f.sp. phaseoli (FOP) in lettuce (Lactuca sativa L.) cultivar Regina and in common bean (Phaseolus vulgaris L.) cultivar Alessa, respectively, using as antagonistic agents 10 Trichoderma spp. isolates selected from in vitro tests. Inoculants were prepared with rice previously colonized by Trichoderma spp. and subsequently ground. For the tests, the antagonists were previously inoculated at a ratio of 10(9) conidia mL-1 on commercial substrate for seedling production. Following seven days, the pathogens were separately introduced at two different concentrations: R. solani at a ratio of 144 mg rice medium per kg of substrate and F oxysporum f.sp. phaseoli inoculated as a suspension containing 4.75 x 10(6) conidia mL-1. The influence of antagonists on % post-emergence damping-off in lettuce and the severity of wilt in common beans were evaluated. The biopreparation with T-03 isolate was most effective in controlling R. solani in lettuce cultivar Regina, for having reduced the incidence of post-emergence damping-off in this culture. On the other hand, none of the biopreparations showed satisfactory antagonistic effect on F. oxysporum f.sp. phaseoli in common bean plants.

Estudou-se a comunidade de nematoides do solo em quatro sistemas de manejo no Sistema Integrado de Produção Agroecológica (SIPA): pasto, capoeira, figo com Paspalum notatum e horta. As amostras de solo foram coletadas a cada quatro meses durante um ano. A comunidade de nematoides foi identificada e descrita com os parâmetros: riqueza de famílias, diversidade de Shannon-Weaner, de dominância de Simpson, além da diversidade trófica e dominância trófica. Os fitoparasitas e bacteriófagos dominaram as comunidades de nematoides nas áreas. Os onívoros foram menos abundantes em todos os sistemas estudados. O sistema pasto apresentou maior diversidade de famílias de nematoides enquanto que, no sistema capoeira se encontraram valores de diversidade baixos, porém constantes no tempo, indicando condição de maior estabilidade. A ação antrópica induzida pelo manejo modificou a distribuição trófica em benefício dos nematoides bacteriófagos, normalmente associados à maior taxa de decomposição da matéria orgânica. Nematoides fitoparasitas e bacteriófagos foram dominantes nos sistemas estudados, o que sugere a influência de densidade radicular elevada no pasto e alta taxa de mineralização na horta. A distribuição relativa de grupos tróficos de nematoides do solo confirmou ser uma eficiente forma de se determinar o nível de perturbação de solos submetidos a distintos manejos.

Soil nematode communities were studied in four differents crop systems at the Integrated System of Agroecological Production. Soil samples were collected at four-month intervals during one year, with three replications for each location. Nematode communities were measured by the following parameters: family richness, Shannon-Weaner's index, Simpson's index, trophic diversity (T) and dominance index (Ig). These data were submitted to ANOVA statistical analysis at 5% level of Tukey's test. The population of bacterivores and herbivore nematodes was high in all areas. Omnivores were found in lower abundance in all systems. The highest diversity of nematode families was found on pasture. In forests, the values of richness and abundance were always lower but constant in time, suggesting an ecosystem of higher stability. Soil management induced the proliferation of bacterivores usually associated with higher decomposition rates of organic matter. Herbivores and bacterivores were dominant in all systems, suggesting it is important to have high root (for pasture) or high decomposition rates (for horticulture system). The relative distribution of trophic groups of soil nematodes proved to be a good way to determine the level of perturbation of ecosystems.