ABSTRACT This study aimed to calibrate and test the SARRA-H (Système d’Analyse Régionale des Risques Agroclimatologiques) crop model for cowpea, as well as conducting a climate risk zoning for this crop in a region located in Eastern Amazon, allowing the identification of locations and sowing dates that favor the production considering both the water deficit and the probability of occurrence of severe rains during the harvest period. The model was calibrated and validated with data from experiments conducted between 2013 and 2016 in the municipality of Castanhal, PA, Brazil. Low climate risk areas were defined as those that had a water requirement satisfaction index (WRSI) greater than or equal to 0.5 in the reproductive phase combined with the occurrence of rainfall below 20 mm at the harvest for, at least, 80% of the years for which planting was simulated. The model was able to simulate the water balance, growth and development of cowpea under the climate and soil conditions of the studied location with high precision and accuracy. The optimal period for sowing cowpea comprises the interval between June 5th and 25th for regions located above 2° S and between March 25th and April 15th for regions below 2º S.

RESUMO Esta pesquisa teve como objetivo calibrar e testar o modelo de cultura SARRA-H (Système d’Analyse Régionale des Risques Agroclimatologiques) para o caupi, bem como realizar o zoneamento de risco climático para esta cultura em uma região localizada na Amazônia Oriental, a fim de permitir a identificação de locais e datas de semeadura que favoreçam a produção considerando tanto o déficit hídrico como a probabilidade de ocorrência de chuvas severas durante o período da colheita. O modelo foi calibrado e validado com dados de experimentos realizados entre 2013 e 2016 no município de Castanhal, PA. As áreas de baixo risco climático foram definidas como aquelas que apresentaram índice de satisfação da necessidade hídrica (WRSI) maior ou igual a 0,5 na fase reprodutiva combinado com a ocorrência de chuvas abaixo de 20 mm na colheita por, pelo menos, 80% dos anos onde foi simulado o plantio. O modelo foi capaz de simular o balanço hídrico, crescimento e desenvolvimento do feijão-caupi nas condições climáticas e de solo da região estudada com boa precisão e exatidão. O período de ótima semeadura para o feijão-caupi compreende o intervalo entre 5 e 25 de junho para regiões localizadas acima de 2° S, e entre 25 de março e 15 de abril para regiões abaixo de 2º S.

ABSTRACT The objective of this work was to evaluate the application efficiency of different nozzle tips associated with increasing application rates. A field experiment was conducted in a factorial 3 × 4 randomized block design with four replicates. The first factor consisted of three types of nozzle tips (simple flat fan, hollow cone, and hollow cone with the electrification of the drops), and the second factor constituted the four application rates (50, 100, 200, and 250 L ha-1). Electrostatic technology and a hollow cone tip increased the deposited volume on leaves on the upper and medium strata of the common bean plant, regardless of the application rate used. The increase in the application rate increased the volume of spray solution captured in the upper, medium, and lower strata, the drop density, the volumetric median diameter (VMD), and the percentage of foliar coverage, regardless of the spray tip evaluated. The percentage of leaf coverage on the adaxial and abaxial leaf was not influenced by the simple fan or hollow cone spray tips, with or without the association of electrostatic technology.

RESUMO O objetivo deste trabalho foi avaliar a eficiência de aplicação de diferentes pontas de bicos associada a taxas crescentes de aplicação. Foi conduzido um experimento de campo no delineamento em blocos ao acaso, em esquema fatorial 3 x 4, com quatro repetições. O primeiro fator consistiu em três tipos de bicos: leque plano simples, cone oco e cone oco com eletrificação das gotas; e o segundo fator por quatro taxas de aplicação (50, 100, 200 e 250 L ha-1). A tecnologia eletrostática e o cone oco aumentaram o volume depositado nas folhas dos estratos superior e médio do feijoeiro, independentemente da dose de aplicação utilizada. O aumento da taxa de aplicação aumentou o volume de calda captado nos estratos superior, médio e inferior do feijoeiro, a densidade de gotas, o diâmetro médio volumétrico (DMV) e a porcentagem de cobertura foliar, independente da ponta de pulverização avaliada. A porcentagem de cobertura foliar na face adaxial e abaxial não foi influenciada pelas pontas de pulverização em leque simples e cone oco com ou sem a associação da tecnologia eletrostática.

ABSTRACT Cowpeas are of high socioeconomic importance in the North and Northeast regions of Brazil, whereby the search for alternatives that offer increased productivity with financial returns has become an important challenge. Thus, the objective of this study was to estimate and evaluate the economic indicators of cowpea production in 2015 and 2016 when applying drip irrigation to different depths. Irrigation treatments were based on crop evapotranspiration (ETc). The experiment was laid in a randomized complete blocks design with four treatments (0, 25, 50, and 100% ETc) and six replications. For economic analysis, the results were extrapolated to an area of one hectare. Productivity in 2015 was lower than that in 2016; however, in all treatments, it was always higher when plants were grown under adequate water supply. In both years, the total operating costs were higher under irrigation than under rainfed conditions. The 100% ETc treatment resulted in a greater number of cowpea bags (60 kg) produced and a higher gross revenue than the rainfed treatment by 17 bags ha-1, equivalent to 1,020 kg ha-1 (gross revenue US$ 711.48) and 16 bags ha-1, equivalent to 960 kg ha-1 (gross revenue US$ 867.12), in 2015 and 2016, respectively. Water deficit limited cowpea yield in both years but made cultivation economically unfeasible only in 2015.

RESUMO O feijão-caupi apresenta grande importância socioeconômica nas regiões Norte e Nordeste do Brasil, sendo que a busca por alternativas que ofereçam aumento de produtividade com retorno financeiro tem se tornado um importante desafio. Assim, o objetivo deste trabalho foi estimar e avaliar os indicadores econômicos da produção de feijão-caupi nos anos de 2015 e 2016 quando da aplicação de irrigação por gotejamento em diferentes lâminas. Os tratamentos de irrigação foram baseados na evapotranspiração da cultura (ETc). O experimento foi instalado em blocos ao acaso com quatro tratamentos (0, 25, 50 e 100% da ETc) e seis repetições. Para análise econômica, os resultados foram extrapolados para uma área de um hectare. A produtividade em 2015 foi inferior à de 2016; porém, em todos os tratamentos, a produtividade foi sempre maior quando as plantas foram cultivadas sob irrigação adequada. Em ambos os anos, os custos operacionais totais foram maiores sob irrigação do que sob condições de sequeiro. O tratamento 100% ETc resultou em maior número de sacas de feijão-caupi (60 kg) produzidas e receita bruta superior ao tratamento de sequeiro em 17 sacas ha-1, equivalente a 1.020 kg ha-1 (receita bruta US$ 711,48) e 16 sacas ha-1, equivalente a 960 kg ha-1 (receita bruta US$ 867,12), em 2015 e 2016, respectivamente. A deficiência hídrica limitou a produtividade do feijão-caupi nos dois anos, mas inviabilizou economicamente o cultivo apenas em 2015.

ABSTRACT The increase in distributed generation (DG) interferes with the energy distribution system, which may present low voltages due to voltage drops and high voltages due to the insertion of distributed generation, resulting from renewable energy sources in rural areas. These voltage levels must be controlled to comply with the limits imposed by the distribution rules and procedures (PRODIST). This study aims to evaluate the voltage rise caused by DG, simulating three DG insertion scenarios, as well as simulate strategies to correct these voltage levels, such as the limitation of the active power supply, the reactive supply by the consumer and the utility, and the installation of on-load tap changers. The simulations were performed using the MATLAB® program, more specifically the PSAT toolbox. Correction techniques were simulated using the active power supply limitation method, the reactive power supply method by consumers, and the voltage regulator process once the voltage rise effect was identified. The first two proved to be ineffective in this case, while the last one meets the voltage levels required by the National Electric Energy Agency.

The NixCu(1-x)Fe2O4 (x = 0, 0.2, 0.8, 1) mixed nickel and copper ferrites were synthesized using the EDTA-Citrate complexation method and calcined at 700°C. The structure, properties and characterization of the samples were analyzed by DRX, Rietveld refinement, SEM, and DRE UV-Vis, indicating the phase formation of tetragonal (CuFe2O4 and Ni0.2Cu0.8Fe2O4) and cubic (Ni0.8Cu0.2Fe2O4 and NiFe2O4). The materials exhibited morphologies suitable for photocatalytic applications and a UV-Vis absorption range near 2 eV as expected for spinel ferrites. These materials were evaluated as photocatalysts for the degradation of Rhodamine B dye under heterogeneous photocatalysis conditions, simulating solar light irradiation, air injection, and different pH levels (2, 6, and 10). The results showed that the catalytic efficiency was higher for samples with a higher copper content and in a basic medium. Therefore, NixCu(1-x)Fe2O4 mixed ferrites have promising potential as photocatalysts.

ABSTRACT The no-tillage system is a conservation system that helps sustainability and agricultural production. The effectiveness of glyphosate control, applied alone or in combination with other herbicides, can be altered depending on the product’s formulation. The objective of the present study was to evaluate the effectiveness of glyphosate in formulations containing different salts and concentrations, applied alone and in combination with other herbicides, in controlling weeds in advanced stages in the pre-sowing burndown operation. The experiment was carried out in the field in an area with a history of high weed infestation. The experiment was conducted in a randomized block design, evaluating eleven treatments and four replicates. The treatments consisted of the application of three glyphosate-based formulations alone and in combination with clethodim and 2,4-D amine herbicides, in addition to a control without herbicide application. The evaluated variables were percentage of weed control and percentage of desiccation. A comparison of means by contrasts was performed to analyze the percentage of weed control. In general, treatments containing products based on glyphosate potassium salt in the composition have slightly better control performance compared to those consisting of glyphosate isopropylamine salt.

RESUMO O sistema de plantio direto é um sistema conservacionista que auxilia na sustentabilidade e a produção agrícola. A eficácia de controle do glyphosate, aplicado isoladamente ou em associação a outros herbicidas, pode ser alterada em função da formulação do produto. O objetivo do presente trabalho foi avaliar a eficácia de glyphosate em formulações contendo diferentes sais e concentrações, aplicado isolado e em associações a outros herbicidas, no controle de plantas daninhas em estádios avançados na operação de dessecação pré-semeadura. O experimento foi realizado a campo em área com histórico de elevada infestação de plantas daninhas. O experimento foi conduzido no delineamento de blocos casualizados, avaliando-se onze tratamentos e quatro repetições. Os tratamentos foram compostos pela aplicação de três formulações à base de glyphosate isolado e em associações com os herbicidas clethodim e 2,4-D amina, além de uma testemunha sem aplicação. As variáveis avaliadas foram porcentagem de controle das plantas daninhas e porcentagem de dessecação. Foi realizado uma comparação de médias por contrastes para analisar a porcentagem de controle de plantas daninhas. De maneira geral, tratamentos contendo produtos à base de glyphosate sal potássico na composição apresentam performance de controle ligeiramente superior em comparação com àqueles constituídos por glyphosate sal de isopropilamina.

ABSTRACT Background: Brazil Nuts (BN) tree is a species of high importance in Amazon region. Their continuous use by traditional communities is often related to disturbances that lead to larger degraded areas where this species is commonly found (“BN groves”). Here we aimed to explore the ecological patterns of BN groves vegetation and its relationship with BN trees and evaluate their potential as a source of carbon credits. We sampled 15 circular plots, with Brazilian Nut trees as the center (focal trees) and collected morphometric data from the focal trees. Additionally, we evaluated fruit production for a period of 5 years to obtain annual measurements, which were used as a proxy of the anthropic impact associated with the collection process. Through analysis of the data, we: i) examined the effects of BN trees on the adjacent vegetation; ii) quantified the potential amount of carbon credits in the adjacent vegetation and in the focal trees by converting carbon stock to equivalent CO2. Results: The adjacent vegetation structure was influenced by the size of BN trees (focal trees). No important effects of BN trees on the adjacent vegetation floristic composition and functional attributes were found. Additionally, we found that Brazilian Nut groves possess a significant potential for carbon credits that could be leveraged in the future carbon credit market, Conclusion: The study highlights the potential for carbon credit generation in Brazil nut groves in the Southeast Amazon as a means of supporting conservation and restoration efforts in these environments.

RESUMO Objetivo: Avaliar mudanças na resposta imunológica (diminuição de citocinas pró-inflamatórias no sangue) e na microbiota fecal (principalmente Bacteroidetes e Firmicutes) após a administração de probióticos em crianças com doença celíaca que seguiam uma dieta livre de glúten. Fontes de dados: Foram utilizadas para esta revisão as bases de dados Medical Literature Analysis and Retrieval System Online (MEDLINE), Literatura Latino-Americana e do Caribe em Ciências da Saúde (LILACS), Springer e Scientific Electronic Library Online (SciELO), com os descritores “celiac disease AND probiotics”. No fim da busca, foram recuperados 168 artigos, dos quais quatro foram incluídos na síntese qualitativa final. Os critérios de inclusão foram ensaios clínicos randomizados e população pediátrica (1–19 anos) e os critérios de exclusão, intervenções que não fossem com probióticos, estudos com pacientes portadores de outras doenças associadas à doença celíaca, ou que não preenchessem critérios para o diagnóstico. Todos os estudos eleitos foram publicados até setembro de 2020, sem restrição de idioma, com pacientes recebendo cepas de Bifidobacterium breve ou B. longum e em uma dieta livre de glúten. Síntese dos dados: Os estudos demonstram que a administração de probióticos associada a uma dieta livre de glúten pode aproximar a microbiota fecal desses pacientes às condições típicas de um indivíduo saudável ao restaurar a abundância de algumas comunidades microbianas que caracterizam uma condição tipicamente fisiológica. Além disso, a administração de probióticos pode reduzir as citocinas pró-inflamatórias (principalmente TNF-alfa). Conclusões: Apesar da correlação positiva entre probióticos e microbiota fecal/marcadores sorológicos nos pacientes pediátricos portadores de doença celíaca, ressalta-se a necessidade de estudos multicêntricos futuros que abranjam um maior número de pacientes e maior tempo de acompanhamento.%

ABSTRACT Objective: To evaluate changes in peripheral immunological response (decrease in blood proinflammatory cytokines) and fecal microbiota (especially Bacteroidetes and Firmicutes) after administration of probiotics in children with celiac disease on a gluten-free diet. Data source: The databases MEDLINE, LILACS, Springer and SciELO were used for this review, with the descriptors “celiac disease AND probiotics”. At the end of the search, 168 articles were retrieved, four of which were included in the final qualitative synthesis, having as inclusion criteria randomized clinical trials and pediatric population (1–19 years) and, as exclusion criteria, interventions other than probiotics, studies with patients with other diseases associated with celiac disease, or patients who did not meet the diagnostic criteria. All elected studies were published until September 2020, without language restriction, with patients receiving strains of Bifidobacterium breve or B. longum and on a gluten-free diet. Data synthesis: The studies show that the administration of probiotics along with a gluten-free diet, can approximate the fecal microbiota of celiac patients to typical conditions of healthy individuals, by restoring the abundance of some microbial communities that characterize the typical physiological condition. In addition, the administration of probiotics can reduce serum proinflammatory cytokines (mainly TNF-alpha). Conclusions: Despite the positive correlation between probiotics and fecal microbiota/serological markers in pediatric patients with celiac disease, we emphasize the need for future multicentric studies that should include a larger number of patients and a longer follow up period.%

Abstract We present the first records of insect visitors and pollinators of Bertholletia excelsa (Lecythidaceae) in a 25 years plantation outside the Amazon biome, flowering and producing Brazil nuts. We installed a platform to observe and photograph the insects. The collected insects were stored, mounted, and identified by specialists. Six species were observed, three of them classified as potential pollinators (Centris lutea, Eulaema nigrita, Eulaema cingulata). The species E. nigrita and E. cingulata were already reported as a pollinators of Brazil nut in Amazon. This is the first record of C. lutea as potential pollinators for B. excelsa.

Abstract This study evaluated of the effects of açai oil during the close-up dry period of Holstein cows on colostrum quality, as well as on the immune and antioxidant responses of their calves. Sixteen multiparous cows were assigned randomly to two treatments: 1) CONTROL (n = 8) - 4.48% of soybean oil/concentrate; 2) AÇAI (n =8) - 4.48% of açai oil/concentrate. Cows fed with açai oil had greater (P≤0.04) colostrum concentrations of immunoglobulins (Ig) G (1st and 2nd milking), IgG heavy chains, IgA (only at 1st milking), alpha-lactalbumin (1st milking), total protein, and antioxidant capacity against peroxyl radicals (only at 1st milking). Cows fed with açai oil had greater serum concentrations of globulin (only on the day of calving) and total protein (only on the day of calving) (P = 0.03). Calves born of cows fed with açai oil had greater serum concentrations of total protein (only 24 and 48 h after calving) and serum concentration of IgG heavy chain (only 24 h after calving) and globulin (only 24 and 48 h after calving) (P = 0.01). These data suggest that the addition of açai oil in the cow feed during the close-up dry period boosted immunity in their calves by altering the composition of colostrum.

RESUMO O estresse provocado pelo déficit de água no solo tem sido um dos principais fatores que prejudicam o crescimento das plantas. O entendimento dos fatores relacionados ao comportamento das plantas daninhas em condições de estresse hídrico pode contribuir para a elaboração de estratégias eficientes de manejo. Dois experimentos foram realizados para avaliar os efeitos e duração do estresse hídrico sobre indicadores fisiológicos e de crescimento de Bidens pilosa L. e Bidens subalternans DC. O grau de estresse foi realizado avaliando-se quatro níveis de capacidade de vaso: 100, 75, 50 e 25%. A duração do estresse hídrico incluiu cinco tratamentos: 0, 1, 2, 3, 4, 5 e 6 dias de intervalo de irrigação. Os experimentos foram realizados em blocos casualizados, com seis repetições. Foram avaliadas a taxa fotossintética (A; μmol CO2 m-2), condutância estomática (gs; μmol H2O m-2 s-1), transpiração (E; mmol H2O m-2 s-1), número de folhas por plantas e matéria seca de raízes, caules, folhas e total. Os resultados demostraram que a B. pilosa e B. subalternans podem suportar condições de baixa disponibilidade hídrica no solo. Os mecanismos envolvidos para essa habilidade podem estar relacionados com a redução da abertura estomática e a perda de folhas pela planta. Porém, esses mecanismos poderão ocorrer apenas quando a disponibilidade hídrica no solo aproxima a valores de 25% da capacidade de campo. A B. subalternans teve maior sensibilidade a redução de água disponível do solo, demostrando uma maior redução na matéria seca de folha, caule e raiz comparado a B. pilosa.

ABSTRACT Stress caused by soil water deficit has been one of the main factors that inhibit plant growth. The knowledge of the factors related to the behavior of weed species under water stress conditions can contribute to the elaboration of effective control strategies. Two experiments were carried out to evaluate the effects of the degree and duration of water deficit on physiological and growth indicators of two weed species (Bidens pilosa L. and Bidens subalternans DC.). The stress degree was simulated by four soil moisture: 100, 75, 50, 25% of total soil capacity. The water deficit duration was evaluated by five intervals of water supply: 0, 1, 2, 3, 4, 5, and 6 days. The experiments were carried out in a randomized complete block design with six replicates. The evaluated variables were: the photosynthetic rate (A; μmol CO2 m-2), stomatal conductance (gs; μmol H2O m-2 s-1), transpiration (E; mmol H2O m-2 s-1), number of leaves per plant, and dry matter of the roots, stems, leaves, and total. The results showed that the species of B. pilosa and B. subalternans tolerate low water availability conditions. Low stomatal opening and loss of leaves are mechanisms that ensure the survival of Bidens plants to the water deficit. However, water stress close to 25% of field capacity caused the death of species. The B. subalternans had higher sensitivity to the water deficit, showing a lower dry matter of leaf, stem, and root than B. pilosa.

ABSTRACT Background: We have developed a micropropagation technique methodology to clonal micro-garden formation of Bambusa vulgaris selected adult plant. Collection site (i.e., stock plant cultivated in different environments) and seasonality of shoot collection (i.e., months of the year) effects on in vitro culture were evaluated. Explants that showed normal development were ex vitro rooted in mini-incubator system, and three culture media (WPM, MS and deionized water + agar) supplemented with plant growth regulators (IBA, NAA and BAP) and antibiotic (streptomycin sulphate and culture medium free - control) were evaluated. Micropropagated plants were acclimatized in a shadow house and transferred to a semi-hydroponic system for establishment of a clonal micro-garden. The efficacy of the cloning protocol was determined with genetic fidelity analysis by ISSR molecular markers. Results: Considering all inoculations, 21.9% of nodal segments were in vitro established in nine shoot collections. The rooting percentage was 36.6%, and no interactions were observed between the use of culture medium and antibiotic. Culture medium free antibiotic resulted in 80.0% of survival and 50.0% of adventitious rooting. Micropropagated plants presented adequate growth and adaptation to ex vitro conditions in the clonal micro-garden. Molecular analyses by ISSR markers indicated the absence of genetic variations, and histological analyses revealed normal adventitious root formation originating from meristematic cells. Conclusion: The formation of a clonal micro-garden was demonstrated, proving the feasibility of the tested technique. Our results contribute to the development of a clonal propagation protocol for B. vulgaris selected adult plants.

Resumo A espécie de trombiculídeo, Blankaartia sinnamaryi (Floch & Fauran) tem sido coletada principalmente parasitando aves, com alguns registros em répteis e mamíferos. No Brasil, essa espécie foi encontrada em aves nos estados de Minas Gerais e Rio de Janeiro. No presente estudo, relatamos o primeiro registro de B. sinnamaryi parasitando a coruja-listrada, Pseudoscops clamator (Vieillot), no estado da Paraíba, Brasil (região Nordeste).

Abstract The chigger species Blankaartia sinnamaryi (Floch & Fauran) has been collected mainly from birds with a few records from reptiles and mammals. In Brazil, this species has been found on birds in the Minas Gerais and Rio de Janeiro states. Here, we report the first record of B. sinnamaryi parasitizing the striped owl, Pseudoscops clamator (Vieillot), in the Paraíba state, Brazil (northeastern region).

RESUMO A podridão escorregadia da cebola (Allium cepa) ocasionada pela bactéria Burkhoderia gladioli pv. alliicola é uma das doenças de origem bacteriana que se destaca nas regiões produtoras do semiárido do Nordeste brasileiro. Tendo em vista a importância da doença, a ausência de variedades resistentes e a potencial ameaça desta enfermidade à cebolicultura, este estudo teve como objetivo avaliar a reação de genótipos de cebola à doença. Nove isolados de B. gladioli pv. alliicola foram inoculados artificialmente em bulbos de cebola cv. Baia Periforme e os três isolados mais agressivos (CCRMBG39, CCRMBG172 e CCRMBG212) foram selecionados para avaliar a resistência à doença. Cinquenta e oito genótipos de cebola foram avaliados utilizando o isolado mais agressivo (CCRMBG39), sendo 34 genótipos considerados tolerantes, com severidade variando de 9,79 a 13,42 mm. Os 15 genótipos mais promissores e o genótipo mais suscetível foram selecionados para estudar a estabilidade da resistência utilizando-se os três isolados selecionados. Os genótipos F2 (EHCEB 20151030 x EHCEB 20133015), Cascuda T5, Crioula Mercosul, Juporanga, EHCEB 20111036, Cascuda T6 e EHCEB 20142028 mantiveram-se estáveis quanto a tolerância à doença quando inoculados com os três isolados, apresentando severidade variando de 9,13 a 14,19 mm. Diante desses resultados, concluímos que esses genótipos apresentaram-se como potenciais fontes de tolerância à podridão escorregadia da cebola.

ABSTRACT Onion’s (Allium cepa) slippery skin caused by Burkholderia gladioli pv. alliicola is one of the bacterial diseases that stand out in producing regions of the Brazilian Northeast. Given the importance and potential threat of this disease, and the absence of resistant varieties, the aim of this study was to evaluate the reaction of onion genotypes to slippery skin and to analyze the tolerance stability of the most promising genotypes to different strains of the bacteria. Nine strains of B. gladioli pv. alliicola were artificially inoculated in onion bulbs cv. Baia Periforme and the three most aggressive strains (CCRMBG39, CCRMBG172 and CCRMBG212) were selected to evaluate the tolerance to the disease. Fifty-eight onion genotypes were challenged with the most aggressive strain (CCRMBG39) and 34 genotypes were considered as tolerant, with a disease severity varying from 9.79 to 13.42 mm. The fifteen most promising genotypes and the most susceptible genotype were selected to study the stability of tolerance using the three selected strains. The genotypes F2 (EHCEB 20151030 x EHCEB 20133015), Cascuda T5, Crioula Mercosul, Juporanga, EHCEB 20111036, Cascuda T6 and EHCEB 20142028 remained tolerant to the disease when inoculated with the three strains, with a disease severity ranging from 9.13 to 14.19 mm. In view of these results, we conclude that these genotypes can be used as potential sources of tolerance to onion slippery skin.

RESUMO Macrophomina pseudophaseolina foi recentemente relatada em áreas produtoras de melão em associação com plantas daninhas na região Nordeste. Espécies do gênero são agentes da podridão radicular e declínio das ramas (PRDR) do meloeiro, doença que reduz sua produtividade. O conhecimento da diversidade genética do patógeno é importante no desenvolvimento de métodos de controle eficientes. Nesse contexto, o objetivo desse trabalho foi analisar a variabilidade genética de isolados de M. pseudophaseolina coletados das plantas daninhas Trianthema portulacastrum L. e Boerhavia diffusa L. por meio dos marcadores moleculares ISSR e RAPD. Para isto, 41 isolados de M. pseudophaseolina foram submetidos à amplificação com cinco iniciadores ISSR e dez RAPD. A similaridade genética foi analisada através do coeficiente de Jaccard e o agrupamento obtido com o método UPGMA. Com a combinação dos dados dos marcadores os 41 isolados foram agrupados em 8 grupos principais. Não foi observado, para grande maioria dos grupos gerados, a relação do agrupamento de acordo com hospedeiro ou local de coleta. A similaridade genética entre os isolados variou de 0,15 a 0,87. A maior dissimilaridade genética (85%) foi observada entre o isolado MpBr11, coletado de T. portulacastrum no município de Icapuí/CE, do isolado MpBr65, coletado de B. diffusa em Assú/RN. Estas informações podem ser úteis para auxiliar programas de melhoramento genético na seleção de fontes de resistência e/ou em testes de métodos de controle contra PRDR do melão.

ABSTRACT Macrophomina pseudophaseolina has recently been reported in association with weeds in melon producing areas in Northeastern Brazil. Species from this genus are the causal agents of root rot and vine decline (RRVD) in melon, reducing its productivity. It is needed to know the genetic variability of the pathogen to develop effective control methods. Thus, this work aimed to assess the genetic diversity among M. pseudophaseolina isolates collected from the weeds Trianthema portulacastrum L. and Boerhavia diffusa L. using ISSR and RAPD markers. For this, 41 M. pseudophaseolina isolates were submitted to amplification with five ISSR and ten RAPD primers. Genetic similarity was analyzed using the Jaccard’s coefficient and cluster analysis was performed by the UPGMA method. Combining data from both markers, the 41 isolates were separated into eight groups. Most groups were not arranged according to geographical origin and host of the pathogen. The genetic similarity among isolates ranged from 0.15 to 0.87. On the other hand, the highest genetic dissimilarity (85%) was observed between the isolate MpBr11, collected from T. portulacastrum in Icapuí (CE), and MpBr65, collected from B. diffusa in Assú (RN). Results obtained herein can assist breeding programs for the selection of resistance sources and the development of effective control methods against RRVD in melon.