Among the factors negatively impacting guava ( Psidium guajava ) crop in Brazil, one of the most important is the root - knot nematode, Meloidogyne enterolobii , which may cause considerable yield losses and even the cessation of guava cultivation in some areas. In addition to affecting guava, the pathogen has been reported as a parasite in various other crops, among them both oleraceous and ornamental crops, as well as in spontaneous vegetation. The aim of this study was to verify the occurrence of M. enterolobii in plants collected in guava orchards in different counties of Ceará state, identified through electrophoresis with the isoenzyme esterase, and to observe its infecting behavior into Meloidogyne differentiating plants . Fifty root samples from guava, tasselflower ( Emilia fosbergii ), and jurubeba ( Solanum paniculatum ), were collected in 13 counties from eight micro - regions in the state of Ceará. In all analyzed samples, only esterase phenotype M2 (Rm: 0.6; 0.9), characteristic of M. enterolobii , was detected, showing that the nematode is widespread in orchards throughout the state, where is affecting these fruit tree, and that it is also able to parasitizing plants of the spontaneous vegetation. Based on the results, this nematode currently constitutes a serious threat to guava plantations in Ceará, and effective control mechanisms are crucial to prevent the spread of this pathogen to other, still unaffected, areas.

The development of technologies to increase stand establishment efficiency and seed vigor, as well as to maximize profits, is of fundamental importance for the sustainability of agriculture. Products based on humic substances, such as humic acids, have been recently used in Brazilian agriculture to produce seedlings with high vigor, which positively influences the establishment of the initial stand. Thus, this study aimed to evaluate the effect of treatment of corn seeds with a commercial humic acid-based product, Humykos® (18% of humic acid content), on germination and seedling vigor. The treatments consisted of six doses (0, 100, 200, 300, 400, and 500 mL 100 kg-1 seed) of Humykos®, and the treated seeds were analyzed for germination and vigor (first count, emergence, emergence speed index, length, and dry mass of shoots and roots). Our results show that humic acid promotes greater seedling growth and increased shoot dry mass in corn; in addition, it has a positive influence on the emergence speed index up to a dose 158 mL 100 kg-1 seeds.

The objective of this work was to evaluate seeds of cowpea, cultivar BRS Tumucumaque, subjected to different water stresses induced by polyethylene glycol (PEG-6000) and mannitol and different salt stresses induced by NaCl and CaCl2 solutions. The water and salt stresses was evaluated in laboratory using completely randomized experimental designs in 2x6 factorial arrangements, with six osmotic potentials (0.0, -0.2, -0.4, -0.6, -0.8 and -1.0 MPa) and two stress inducers for each experiment, with four replications of 50 seeds. The percentage of germination, germination speed index, root and shoot lengths and seedling fresh weight were evaluated at the tenth day (end of the evaluation period). The simulated water stress showed effects on the cowpea seed germination and seedling initial growth by decreasing the rates of the variables evaluated, which had greater effect in treatments with PEG-6000. The salt stress induced by NaCl showed greater effect on the variables evaluated than that induced by CaCl2, due to the sodium toxicity in the salt chemical composition.

In Brazil, species of the genus Liriomyza are widely distributed and have economic importance as they cause damage to at least 14 plant families, especially Solanaceae, Cucurbitaceae, Asteraceae, and Fabaceae. Studies suggest existence of a species complex within this genus, based on the presence of morphological similarities among the species Liriomyza trifolii (Burgess), L. sativae Blanchard and L. huidobrensis (Blanchard). The present study aimed to use DNA barcoding to establish new distribution records of L. sativae in distinct regions in Brazil, determine intra- and inter-population genetic diversity, and reconstruct the phylogeny of Liriomyza species using the DNA barcode sequences. Identity values were between 97% and 99%, confirming that all the examined Brazilian populations belonged to the species L. sativae. Phylogenetic analyses indicated the presence of a single clade of L. sativae, composed of seven populations. Intra-population analysis on individuals of these populations indicated low levels of nucleotide and haplotype diversity. The haplotype network indicated presence of only 14 haplotypes distributed among the Brazilian populations. The genetic similarities shared by the Brazilian populations of L. sativae suggest that these populations are closely related. Genetic patterns observed among populations of L. sativae might be associated with bottleneck events or founder effect during establishment of this leafminer in Brazil.

The objective of this study was to evaluate the resistance of a group of clones and cultivars from the potato breeding program of Embrapa to Meloidogyne javanica . The experiment was conducted at Embrapa Temperate Climate, Pelotas / RS, under greenhouse conditions at temperatures of 25 ± 5°C. Individual potato plants of different genotypes [BRSIPR Bel, BRS F63 (Camila), CL02 - 05, F23 - 11 - 06, F32 - 02 - 06, F38 - 03 - 07, F189 - 09 - 06, F23 - 24 - 06 and F22 - 01 - 08], kept in pots with sterilized soil were inoculated with 5,000 eggs and J2 of M. javanica , using six replicates per treatment. The susceptible control, potato cultivar BRS Ana was inoculated with the same level of inoculum. Fifty - five days after inoculation, the number of galls on the roots of each plant was determined as well as the number of protuberances caused by nematodes in the different treatments. Then, the roots of each plant were processed for counting the number of eggs and J2, as well as determining the nematode reproduction factor (FR: final population / initial population). All genotypes were susceptible (FR> 1.00) to M. javanica . However, there were different levels of susceptibility among the cultivars tested.

RESUMO A realização e difusão dos trabalhos referentes ao desempenho de plantas de cobertura em sistemas produtivos de culturas anuais no Piauí são importantes na busca por aumento de produtividade, maior eficiência no uso de fertilizantes e mitigação dos impactos ambientais. O objetivo deste trabalho foi avaliar o desempenho de plantas de cobertura na produção de fitomassa, acúmulo e liberação de nutrientes, durante o período de safra (novembro à abril), em Latossolo Vermelho distrófico no Cerrado piauiense em sistemas de produção com soja, milho e arroz de sequeiro. O experimento foi instalado nas safras agrícola de 2010/11 e 2011/2012 no município de Bom Jesus, PI. O delineamento utilizado foi o de blocos casualizados, em parcelas subdivididas. Nas parcelas estavam os sistemas de manejo do solo (preparo convencional e plantio direto) e nas subparcelas, os sistemas de produção com uso de plantas de cobertura na entressafra intercaladas com culturas anuais. Os sistemas com uso de Urochloa ruziziensis e Pennisetum glaucum semeadas em sobressemeadura na soja e U. ruziziensis consorciado de forma simultânea com milho apresentam-se como melhores opções na produção de fitomassa, acúmulo e liberação de nutrientes. As culturas do arroz e milho apresentam redução significativa na produtividade em áreas sob plantio direto recém-implantadas. | ABSTRACT Research on the performance of cover crops in crop systems of annual crops in the Brazilian state of Piauí contributes to increases in yield, greater efficiency of fertilizers and mitigation of environmental impacts. The aim of this study was to evaluate the performance of cover crops in terms of biomass production and the accumulation and release of nutrients during the crop season (November to April) in an oxisol in the Brazilian Cerrado in the state of Piauí that was submitted to different crop production systems including soybeans, maize and upland rice. The experiment was established during the 2010/11 and 2011/12 crop years in the rural area near the municipality of Bom Jesus, Piauí. The experimental design was a randomized block in a split-plot array. Different soil management systems (conventional and no-till) were evaluated in the main plots. Different crop production systems consisting of cover crops sown in the off-season (April to November), and annual crops sown during the crop season (November to April) were implemented in the subplots. The crop production systems that included Urochloa ruziziensis and Pennisetum glaucum overseeded on soybeans and Urochloa ruziziensis simultaneously intercropped with maize stood out in terms of biomass production and the accumulation and release of nutrients. Yields of maize and upland rice declined when sown under newly implemented no-till soil management.

RESUMO O trabalho foi conduzido no campo experimental do Departamento de Tecnologia e Ciências Sociais (DTCS), Campus III, da Universidade do Estado da Bahia - UNEB, Juazeiro-BA. O delineamento experimental foi em blocos casualizados, com parcelas subsubdivididas, com quatro repetições, as parcelas compostas de três ambientes sombreados, tela de sombreamento cinza, tela de sombreamento vermelha, e tela de sombreamento azul, mais o tratamento controle, sem sombreamento, as subparcelas formadas por três cultivares de minitomates ("Sweet Million", "Red Sugar", e "Shani") e as sub-subparcelas constituída de sete épocas de amostragens das plantas. As características avaliadas foram: acúmulo de massa seca nas folhas; no caule; nas raízes; nos frutos e total, além do comprimento da parte aérea, comprimento da raiz, o número total de frutos e produtividade. Os resultados de análise de crescimento apresentaram acúmulo de massa seca nos diferentes órgãos das plantas de minitomates, para todos os tipos de ambientes e que o maior acúmulo de massa seca total ocorreu no ambiente com tela vermelha. Em todos os ambientes analisados, o dreno preferencial da planta foi o fruto, contudo, a cultivar Red Sugar acumulou maior massa seca nos outros órgãos da planta em comparação com as demais cultivares. A cultivar Red Sugar obteve a maior quantidade de frutos por planta, entretanto, quando avaliou-se a produtividade total, as cultivares Sweet Million e Shani não diferiram entre si, sendo, superiores aos valores obtidos para a cultivar Red Sugar. | ABSTRACT Our study was conducted in the experimental field of the Department of Technology and Social Sciences (DTCS) of the State University of Bahia - UNEB, Juazeiro-BA. The experimental design was comprised of randomized blocks, sub-subdivided in plots, with four replicates comprising the plots of three different shading methods, gray shading screen (GS), red shading screen (RS), and blue shading screen (BS), and the control treatment with no shading. The subplots comprised three mini-tomato cultivars (“Sweet Million”, “Red Sugar”, and “Shani”), and sub-subplots consisted of seven sampling times. The traits evaluated were: dry matter accumulation in leaves, stems, roots, and fruits, total dry matter, shoot length, root length, total number of fruits, and overall yield. The results of the growth analysis showed that dry matter accumulation in organs of mini tomatoes was similar in all treatments and that the highest total dry matter accumulation occurred under RS. In all treatments, fruit was the preferential drainage; however, the cultivar “Red Sugar” showed higher dry matter accumulation in other plant organs. “Red Sugar” also showed the highest number of fruits per plant; however, when we evaluated total productivity, “Sweet Million” and “Shani” showed similar, higher values than “Red Sugar”.

ABSTRACT The objective of this work was to evaluated the precipitation characteristics (depth, I30 and erosivity) and their effects on sediment production in three watersheds under different managements of land use 35-year regenerating Caatinga (RC), thinned Caatinga (TC), which underwent thinning of trees with diameter smaller than 10 cm; and deforested Caatinga (followed by burning and pasture) (DC). The experimente was conducted in the central, tropical semiarid region of the State of Ceará, Brazil. The precipitation events, surface runoff and sediment production were monitored from 2010 to 2015. The precipitation characteristics were subjected to Pearson's correlation at 1 and 5% of significance and the events that produced sediments in each watershed were hierarchically grouped by hierarchical cluster analysis technique. Two hundred precipitation events were recorded, with 23 (RC), 18 (TC) and 43 (DC) events producing sediments. The use of thinning (TC) decreased the sediment production by 53.5%, while the deforestation, burn and pasture cultivation (DC) increased soil losses by 14%, compared with the RC. The sediment production was greatly correlated with the I30 in the three watersheds, denoting the erosion process great dependence on the precipitation intensity. | RESUMO Obejtivou-se com este estudo investigar as caracteristicas das chuvas (altura precipitada, I30 e erosividade) e suas correlações com a produção de sedimentos em três microbacias submetidas aos seguintes manejos: Caatinga em Regeneração (CER) há 35 anos; Caatinga Raleada (CRA) passou pelo raleio das árvores com diâmetro menor que 10 cm; Desmatamento/Queima/Plantio de Pastagem (DQP). A área de estudo é representative de região semiárida tropical e está localizada na parte central do estado do Ceará. Foram monitorados eventos puviométricos, escoamento superficial e produção de sedimentosdos anos de 2010 a 2015. As características das chuvas foram submetidas a correlação de Pearson a nível de 1 e 5 % de significância e os eventos que produziram sedimentos em cada microbacia foram agrupados hierarquicamente pela técnica de Análise de Agrupamento Hierárquico. Ao todo foram registrados 200 eventos pluviométricos dos quais 23, 18 e 43 eventos produziram sedimentos nas microbacias CER, CRA e DQP respectivamente. A adoção do manejos de raleamento reduziu a produção de sedimentos em 53,5 %, enquanto que o DQP promoveu um aumento das perdas de solo em 14 % em relação à CER. A produção de sedimentos expressou uma maior correlação com o I30 para as três microbacias expressando a maior dependência do processo erosive da intensidade das chuvas.

ABSTRACT This study aimed to characterize buffel grass accessions of the Cenchrus Germplasm Active Bank (CGAB) from Embrapa Semi-Arid in a morphoagronomic way, checking the descriptors variability and efficiency in accessions on two consecutive cuts. Twenty-five accessions and five buffel grass cultivars were used in randomized complete block design with three replications. Evaluations were conducted after two consecutive cuts, each evaluation performed 90 days after each cut. Characterization was based on 15 quantitative and qualitative morphoagronomic descriptors. Quantitative descriptors were subjected to individual and joint univariate analysis of variance, followed by the Scott-Knott’s test at 5% significance. Yet qualitative descriptors were submitted to descriptive analysis. Both quantitative and qualitative descriptors were grouped based on the Gower algorithm for divergence analysis. A dendrogram and calculations of the characters relative importance for divergence were established. Genotype and cutting effects were significant for almost all descriptors in the joint analysis. This result indicates a genetic variability between genotypes and, regarding the cut, it indicates mainly differences in growth rate of each genotype in each cutting season. Genotypes were separated into three groups, which showed good genotype variation. The number of tillers per clump, followed by number of inflorescence and color of seeds, were the most relevant characters in genotype separation. | RESUMO O estudo objetivou caracterizar morfoagronomicamente acessos de capim buffel do Banco de Germoplasma de Cenchrus (BGC) da Embrapa Semiárido, verificando a variabilidade e eficiência dos descritores nos acessos em dois cortes consecutivos. Foram utilizados 25 acessos e cinco cultivares de capim buffel em delineamento em blocos casualizados completos com três repetições. As avaliações foram realizadas após dois cortes consecutivos, cada avaliação foi realizada 90 dias após cada corte. A caracterização foi realizada com base em 15 descritores morfoagronômicos quantitativos e qualitativos. Os descritores quantitativos foram submetidos a análise de variância univariada individual e conjunta e, em seguida, aplicado o teste de Scott-Knott a 5% de significância. Os descritores qualitativos foram submetidos a análise descritiva. Para as análises de divergência tanto descritores quantitativos quanto qualitativos foram agrupados com base no algoritmo de Gower. Foi estabelecido também um dendrograma e calculada a importância relativa dos caracteres para a divergência. Na análise conjunta, os efeitos de genótipo e corte foram significativos para quase todas os descritores. Esse resultado indica variabilidade genética entre os genótipos e quanto ao corte indica, principalmente, diferenças na velocidade de crescimento de cada genótipo em cada época de corte. Os genótipos foram separados em três grupos demonstrando boa variabilidade entre os genótipos. O número de perfilhos por touceira, seguida por quantidade de inflorescência e cor das sementes foram os caracteres de maior relevância na separação dos genótipos.

RESUMO Objetivou-se avaliar a qualidade de mandioca de mesa minimamente processada com o uso de antioxidantes e revestimento comestível a base de amido. Raízes de mandioca de mesa foram lavadas, resfriadas, imersas em água fria, cortadas e descascadas. Os pedaços foram imersos em solução clorada, centrifugados e imersos em suspensão de amido (3%) ou em solução contendo antioxidantes (ácido cítrico 3% e ácido ascórbico 3%) ou em ambos (revestimento + antioxidantes). Os pedaços contendo revestimento foram secos em sala climatizada a 18 ± 2 °C por 1 hora. Os pedaços foram embalados em polipropileno, contendo 150 g por embalagem, e mantidos a 5 ± 2 °C por 15 dias, com avaliações a cada três dias. Foi utilizado o DIC, em esquema fatorial 4 x 6 [controle, revestimento, antioxidantes e revestimento + antioxidantes x dias de conservação (0; 3 6; 9; 12 e 15 dias)] com 3 repetições. Verificou-se que os valores de pH, área escurecida e as atividades da peroxidase e polifenoloxidase foram menores e as notas da análise visual e o teor de fenólicos totais foram superiores nos tratamentos contendo antioxidantes. O uso dos antioxidantes foi eficiente na redução do escurecimento em mandioca de mesa minimamente processada, mantendo os pedaços com qualidade por 15 dias a 5 ± 2 ºC e a associação de antioxidantes e revestimento comestível não apresentou melhorias em comparação aos antioxidantes isolados. | ABSTRACT This study aimed to evaluate the quality of minimally-processed cassava treated with antioxidants and a starch-based edible coating. Cassava roots were washed, cooled, immersed in cold water, peeled and then cut. Root pieces were then immersed in a chloride solution, centrifuged, and subsequently immersed in either a starch suspension (3%), a solution containing antioxidants (3% citric acid and 3% ascorbic acid), or in both the coating and antioxidant solutions. Coated root pieces were dried at 18 ± 2°C for 1 hour, then packaged into polypropylene bags (150 g per pack) and kept at 5 ± 2°C for 15 days, and assessed every 3 days. A completely randomized design was used in a 4 × 6 factorial consisting of the treatment (control, coating, antioxidant, or coating and antioxidant) and the storage period (0, 3 6, 9, 12 or 15 days), with three replicates in each group. The pH, blackened area and peroxidase and polyphenol oxidase activities of the cassava was reduced in treatments containing antioxidants and the scores of visual analysis and phenolic content were higher. Therefore, treatment with antioxidants was effective for reducing browning in minimally- processed cassava, retaining the quality of cassava pieces stored for 15 days at 5 ± 2°C. The combination of antioxidants and the edible coating showed no improvement compared to treatment with antioxidants alone.