Physical and hydrological characteristics and modelling of the soil water retention curve in the brazilian semi-arid region

Semiarid regions are characterised by water scarcity, a limiting factor on plant growth and development. The Sertão Canal was built in the semiarid region of Brazil, more specifically in the state of Alagoas, with the aim of making year-round irrigation possible. However, for the best water management, a physical and hydrological knowledge of the soils is necessary. As such, the aim of this study was to determine the physical and hydrological characteristics of three different types of soil (Argisol, Quartzarenic Neossol and Regolithic Neossol) under native vegetation (Caatinga) and agricultural systems in the semiarid region of Alagoas, as well as to adjust the soil water retention characteristic curves. Soil samples were collected at depths of 0-10, 10-20 and 20-30 cm in the municipalities of Inhapi, Delmiro Gouveia and Pariconha, in the state of Alagoas. The points of the moisture characteristic curve were determined by the Richards method, at pressures of 33, 100, 500, 1000 and 1500 kPa. Retention curves were modelled using the exponential decay equation and compared using the van Genuchten equation, modelled with the help of the RETC computer software. Particle size varied according to the textural classification of the different soils, from Sand to a Sandy Clay Loam. The retention curve fluctuated due to the particle size of the soil, with the Red-Yellow Argisol (Inhapi) having a greater capacity for water retention. Extremely sandy soils, such as those in the Delmiro Gouveia region, had a low capacity for retaining water. For each soil sample, the exponential decay equation gave the best fit, with values for R2adjust of greater than 0.93. When the measured soil moisture levels were compared with the levels estimated by the RETC model, some of the treatments were unable to estimate accurately the moisture levels obtained with the soil water retention curves.

Physiological and metabolic alterations in basil (Ocimum basilicum L) varieties under distinct soil water levels / Alteraciones fisiológicas y metabólicas en variedades de albahaca (Ocimum basilicum L) bajo distintos niveles de agua del suelo

Basil (Ocimum basilicumL.) is a medicinal species used in several areas, such as food, medicines and cosmetics, and the understanding of its physiological behavior under environmental conditions is of paramount importance for the improvement of cultivation methods. The objective of this study was to evaluate the influence of different water availability under physiological, biochemical and metabolic characteristics, in three distinct genotypes: 'Alfavaca basilicão', 'Gennaro de menta' and 'Grecco à palla', during two different phenological stages (vegetative and reproductive). It was found that the water deficit promotes physiological changes to tolerate water stress, and the studied genotypes have different routes to achieve this physiological tolerance, which culminates in a distinct accumulation of metabolites in plants, and can be considered interesting if the final product is the production of essential oils.

La albahaca (Ocimum basilicum L.) es una planta medicinal utilizada en varias áreas: alimenticia, medicinal e industria cosmética; es de suma importancia el entendimiento de su comportamiento fisiológico bajo diferentes condiciones ambientales con el fin de mejorar los procesos del cultivo. El objetivo de este estudio fue evaluar la influencia de diferentes disponibilidades hídricas en las características fisiológicas, bioquímicas y metabólicas en tres genotipos de albahaca: "Alfavaca basilicão", "Gennaro de menta" y "Grecco à palla" durante dos etapas fenológicas (vegetativa y reproductiva). Fue encontrado que el déficit hídrico promueve cambios fisiológicos con el fin de tolerar el estrés hídrico. Los genotipos estudiados presentaron diferentes rutas para alcanzar esta tolerancia fisiológica, la cual culmina con distintas acumulaciones de metabolitos en las plantas, y puede ser considerado interesante si el producto final es la producción de aceites esenciales.

Root deformation affects mineral nutrition but not leaf gas exchange and growth of Genipa americana seedlings during the recovery phase after soil flooding / A deformação de raízes afeta a nutrição mineral mas não as trocas gasosas foliares e o crescimento de mudas de Genipa americana durante a fase de recuperação após o alagamento do solo

Root deformation (RD) caused by errors in the pricking out process are irreversible and very difficult to detect in container-grown seedlings at the time of planting in the field. The objective of this study was to evaluate the effects of RD on leaf gas exchange, growth, biomass allocation and mineral nutrition of G. americana seedlings during the recovery phase after soil flooding. Four-months-old seedlings, with and without RD, were flooded for 42 days and their recovery was evaluated 28 days after soil drainage. There were no significant interactions between RD and soil flooding for all leaf gas exchange, growth and mineral nutrition after soil drainage, with the exception of leaf P concentrations. In plants with no RD, the P concentration in leaves of non-flooded plants was significantly higher than that of plants with RD. Soil flooding and RD did not influence leaf or root N concentrations or whole-plant N content. RD increased the K concentration in the roots, but not in the leaves. Changes in the nutrient concentrations in leaves and roots indicate that RD may affect physiological performance of seedlings after planting in the field.

A deformação da raiz (RD) causada por erros no processo de repicagem é irreversível e difícil de detectar em mudas produzidas em embalagens no momento do plantio no campo. O objetivo deste estudo foi avaliar os efeitos do RD nas trocas gasosas foliares, crescimento, alocação de biomassa e nutrição mineral de mudas de G. americana na fase de recuperação após o alagamento do solo. Mudas com quatro meses de idade, com e sem RD, foram alagadas por 42 dias e a sua recuperação foi avaliada 28 dias após a drenagem do solo. Não houve interação significativa entre RD e alagamento do solo nas trocas gasosas foliares, crescimento e nutrição mineral após a drenagem, com exceção das concentrações de P foliar. Em plantas sem RD, a concentração de P nas folhas de plantas não alagadas foi significativamente maior que a das plantas com RD. O alagamento do solo e a RD não influenciaram as concentrações de N nas folhas e raízes, e no conteúdo de N na planta inteira. A RD aumentou a concentração de K nas raízes, mas não nas folhas. Alterações nas concentrações de nutrientes nas folhas e raízes indicam que a RD pode afetar o desempenho fisiológico das mudas após o plantio no campo.

Osmoprotection in Salvia hispanica L seeds under water stress attenuators / Osmoproteção em sementes de Salvia hispanica L sob atenuadores do estresse hídrico

Salvia hispanica cultivation is recent in Brazil and occurs in the off-season, when there is lower water availability in the soil. Water deficit is one of the abiotic factors that most limit germination for compromising the sequence of metabolic events that culminate with seedling emergence. Several attenuating substances have been used to mitigate the effects resulting from this stress and give higher tolerance to the species. Thus, the objective of this study was to evaluate the action of different agents as water stress attenuators in the germination and accumulation of organic compounds in S. hispanica seedlings. The treatments consisted of pre-soaking the seeds for 4 hours in salicylic acid (1 mM.L-¹), gibberellic acid (0.4 mM.L-¹), distilled water and control treatment (without soaking). The seeds were germinated at osmotic potentials of 0.0, -0.1, -0.2, -0.3 and -0.4 MPa, using PEG 6000 as an osmotic agent. The variables germination percentage, germination speed index, shoot and primary root lengths, total dry mass, proline, total soluble sugars and total free amino acids were analyzed. Salicylic acid and gibberellic acid led to the best results among the attenuators tested, increasing germination, length, dry mass and biochemical components of S. hispanica seedlings under water deficit. Therefore, salicylic and gibberellic acids are efficient in mitigating water stress in S. hispanica seeds up to the potential of -0.4 MPa.

O cultivo da Salvia hispanica é recente no Brasil e se dá no período de entressafra, quando há menor disponibilidade hídrica no solo. O déficit hídrico é um dos fatores abióticos que mais limitam a germinação por comprometer a sequência de eventos metabólicos que culminam com a emergência da plântula. Diversas substâncias atenuadoras têm sido empregadas com a finalidade de mitigar os efeitos resultantes desse estresse e conferir maior tolerância às espécies. Desse modo, objetivou-se avaliar a ação de diferentes agentes como atenuadores do estresse hídrico na germinação e acúmulo de compostos orgânicos em plântulas de S. hispanica. Os tratamentos consistiram na pré-embebição das sementes durante 4 horas em ácido salicílico (1 mM.L-¹), ácido giberélico (0,4 mM.L-¹), água destilada e o tratamento controle (sem embebição). As sementes foram germinadas sob os potenciais osmóticos 0,0, -0,1, -0,2, -0,3 e -0,4 MPa, utilizando PEG 6000 como agente osmótico. Analisaram-se as variáveis porcentagem de germinação, índice de velocidade de germinação, comprimento da parte aérea e da raiz primária, massa seca total, prolina, açúcares solúveis totais e aminoácidos livres totais. O ácido salicílico e o ácido giberélico apresentaram os melhores resultados, dentre os atenuadores testados, incrementando a germinação, o comprimento, a massa seca e os componentes bioquímicos de plântulas de S. hispanica sob déficit hídrico. Logo, os ácidos salicílico e giberélico são eficientes na mitigação do estresse hídrico em sementes de S. hispanica até o potencial -0,4 MPa.

Effect of pH soil and irrigation regimes on management of potato scab

Potato scab caused by different species of phytopathogenic Streptomyces is considered one of the main bacterial diseases of economic crop importance worldwide. Several studies are being carried out in order to control the disease, but until now, there is no efficient way to do this. Some management strategies have been investigated including application of chemical and biological products and utilization of resistant cultivars of potato but there are few reports about the impact of pH and irrigation regimes on the disease. The present study aimed to evaluate the effects of these last two factors on the incidence and severity of potato scab caused by S. scabiei, S. acidiscabies, Streptomyces sp., S. caviscabies and S. europaeiscabiei in assays at pH 4.0, 4.5, 5.0, 5.5, 6.5 and 7.5; and irrigation regimes of once a week, alternate days and daily in greenhouse conditions. The experimental design for the pH tests was randomized blocks arranged in a 5x2 factorial scheme, with 5 replications and 3x2 for the irrigation regimes with 5 replications. The pH tests showed significant differences between the treatments and pH 4,0 - 4,5 presented lower incidence and severity of the disease for the most species tested but no significant differences were observed between the irrigation regimes. The soil acidification is considered a classic strategy for management of the disease and the results obtained herein corroborated this hypothesis.

Why despite the lower prevalence, is asthma more severe in the semiarid region?

Introduction and objectives: Asthma is a chronic inflammatory disease which is very prevalent throughout the world, and climatic factors, especially air humidity, have been considered fundamental to its development. This study aims to evaluate the relationship between the climate factor and the severity of asthma episodes in the semiarid region, comparing it to the coast and an intermediate climate region, considering the use of medication as an intervening factor. Materials and methods: Ecological study in cities with different climatic conditions (semiarid, intermediate region and Coast). Prevailing data was obtained from the International Study of Asthma and Allergies in Childhood (ISAAC) protocol. We evaluated the temperature, humidity and use of drugs for asthma/100,000 inhabitants. Results: The prevalence of asthma was lower in the semiarid (14%; 95% CI = 12.1-15.7) than the intermediate region (19.1%; 95% CI = 17.7-20.6) and coast (17.9%; 95% CI = 16.6-19.2). Episodes of severe asthma attacks were surprisingly higher in semiarid (10.4%; 95% CI=8.9-11.9) when compared to coast (4.1%; 95% CI = 3.4-4.9) and intermediate region (5.0%; 95% CI = 4.3-5.8). In the semiarid region, the humidity was lower and the temperature higher than the other cities evaluated. The dispensing of medications was lower in the semiarid region. Conclusions: Temperature and humidity may have contributed to a lower prevalence and greater severity of asthma in the semiarid region. The dispensing of medications was lower in the semiarid region, indicating that access to both relief and control drugs was lower in this city. The possibility of lack of health care in the semiarid region can also be another explanatory factor associated

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Assessing pedotransfer functions to estimate the soil water retention / Validação de funções de pedotransferência para estimativa da retenção de água no solo

Considering the importance of soil water retention for agricultural and environmental purposes, the objective of this study was to assess three pedotransfer functions (PTFs) used to estimate the soil moisture at field capacity (FC) based on soil attributes easily determined. A collection of 17 soils from the Cerrado and Pantanal biomes, including surface and subsurface horizons, was used. PTF-1 considers clay, organic matter, coarse sand, and microporosity; PTF-2 clay, total sand, and organic matter; and PTF-3 only microporosity. The estimated FC values were correlated to soil moisture values measured at different soil water potentials (0, 6, 10, 33, 100, 300, and 1500 kPa) to verify which potential corresponded to estimated FC. The data were subjected to regression analysis and Mann-Whitney rank-sum test to compare predicted and measured values and to principal component analysis (PCA). The analysis of the full dataset indicated that there was a strong correlation (R 0.84­0.91; R2 0.71­0.82; RMSE 0.07­0.09) between estimated FC and soil water retention measured at potentials of 10 kPa and 33 kPa. FC estimated by PTF-3 correlated better with water holding capacity at 6 kPa. When the PTFs were reapplied to homogeneous soil groups (identified by PCA analysis), the correlation between predicted and measured FC was decreased.

Considerando a importância da retenção de água no solo para fins agronômicos e ambientais, objetivou-se com este trabalho avaliar três funções de pedotransferência (FP) para estimativa da capacidade de campo (CC) com base em atributos de solo facilmente determinados. Uma coleção de 17 solos dos biomas Cerrado e Pantanal, incluindo amostras superficiais e subsuperficiais, foram utilizadas. FP 1 considera o conteúdo de argila, matéria orgânica, areia grossa e microporosidade. FP 2 considera argila, areia total e matéria orgânica. A FP 3 leva em consideração apenas microporosidade. Os valores estimados de CC foram correlacionados aos valores de umidade obtidos em diferentes potenciais (0, 6, 10, 33, 100, 300, and 1500 kPa) com o intuito de verificar qual potencial corresponde à CC estimada. Os dados foram submetidos à análise de regressão, ao teste Mann-Whitney rank-sum para comparar valores medidos e estimados e realizada análise de componentes principais (PCA). Considerando todo o conjunto de dados, foi obtida uma forte correlação (R 0.84­0.91; R2 0.71­0.82; RMSE 0.07­0.09) entre CC estimada e a umidade do solo obtida nos potenciais de 10 kPa e 33 kPa. A CC estimada pela FP 3 correlacionou melhor com a retenção de água no potencial de 6 kPa. Quando as FP's foram reaplicadas em grupos de solos homogêneos (identificados pela PCA), a correlação entre valores estimados e medidos diminuiu.

Survival of Pochonia chlamydosporia on the soil surface after different exposure intervals at ambient conditions / Supervivencia de Pochonia chlamydosporia en la superficie del suelo después de diferentes intervalos de exposición a condiciones ambientales

Background. Exposure of the nematophagous fungus Pochonia chlamydosporia to solar radiation and elevated temperatures before being incorporated into the soil can reduce its survival and efficiency as biocontrol agent. Aims. A field experiment was carried out to assess the effect of the exposure period on the viability of P. chlamydosporia applied on the soil surface. Methods. A commercial bionematicide based on P. chlamydosporia was sprayed on soil, and soil samples were collected before and at 0, 30, 60, 90, 120, and 150 min after fungal application. Relative humidity (RH), the irradiance (IR), air temperature (AT), and soil temperature (ST) were recorded. The number of P. chlamydosporia colony forming units (CFUs) was evaluated after 20 days of incubation. Results. P. chlamydosporia survival decreased over the time of exposure on the soil surface. Overall, the number of CFUs decreased by more than 90% at 150min after application. Exposure to RH ≥61%, ST and AT between 25-35°C and 19-29°C, and IR between 1172 and 2126μmol of photons m−2s−1 induced a negative exponential effect on the survival of the fungus over the time. Conclusions. Exposure to climatic conditions on the soil surface reduces P. chlamydosporia viability (AU)

Antecedentes. La exposición del hongo nematófago Pochonia chlamydosporia a la radiación solar y la temperatura elevada antes de ser incorporado al suelo puede reducir su supervivencia y eficiencia como agente de biocontrol. Objetivos. Se realizó un experimento de campo para evaluar el efecto del período de exposición a condiciones ambientales sobre la viabilidad de P. chlamydosporia en la superficie del suelo. Métodos. Se pulverizó sobre el suelo un bionematicida comercial hecho a base de P. chlamydosporia y se recogieron muestras de suelo antes y después de 0, 30, 60, 90, 120 y 150min tras la aplicación del hongo. Se registraron la humedad relativa (HR), la irradiación (IR), la temperatura del aire (TA) y la temperatura del suelo (TS). Se evaluó el número de unidades formadoras de colonias (UFC) de P. chlamydosporia después de 20 días de incubación. Resultados. La supervivencia de P. chlamydosporia disminuyó durante el tiempo de exposición en la superficie del suelo. En general, el número de UFC disminuyó en más de un 90% a los 150min después de la aplicación. La exposición a HR≥61%, TS y TA entre 25-35°C y 19-29°C, e IR entre 1.172 y 2.126μmol de fotones m−2 s−1 indujo un efecto exponencial negativo en la supervivencia del hongo. Conclusiones. La exposición a las condiciones climáticas en la superficie del suelo reduce la viabilidad de P. chlamydosporia (AU)

Temperature and humidity of soil covered with perennial herbaceous legumes in the semiarid region of Minas Gerais, Brazil / Temperatura e umidade do solo coberto com leguminosas herbáceas perenes na região semi-árida do Estado de Minas Gerais, Brasil

Agricultural sustainability of areas in semiarid region, is directly related to soil management, emphasizing especially the continuous coverage strategy. In this sense, this study aimed to evaluate the influence of perennial legumes on soil coverage, temperature and moisture in the semiarid region of Minas Gerais, Brazil. The study used a randomized blocks experimental, with 9 m2, design and treatments consisted of bare soil cultivated with the following legumes: tropical kudzu (Pueraria phaseoloides), calopo (Calopogonium mucunoides), perennial peanut (Arachis pintoi), perennial soybean (Glycine wightii) and stylosanthes Campo Grande (mixture of Stylosanthes capitata and Stylosanthes macrocephala), with four replications. Soil coverage, temperature and moisture rates were evaluated. Due to the soil protection provided by the biomass production, the use and management of cover plants in semiarid region of Minas Gerais contributed to the temperature reduction and to the conservation of soil moisture, both essential for the agricultural production in this region. Calopo, tropical kudzu and perennial peanut provided greater soil coverage and, consequently, they provided greater reduction in temperature and higher moisture retention in soil. In more advanced stages of the cycle, the perennial soybean also provided good soil coverage, temperature reduction and moisture retention in the soil.

A sustentabilidade agrícola das áreas na região semiárida está diretamente relacionada ao manejo do solo, ressaltando-se principalmente a estratégia de cobertura contínua. Neste sentido, esse trabalho foi realizado com o objetivo de avaliar a influência de leguminosas perenes sobre a cobertura, temperatura e umidade do solo no semiárido mineiro, Brasil. O delineamento experimental foi o de blocos ao acaso, e os tratamentos constituídos pelo solo descoberto e cultivado com as leguminosas: cudzu tropical (Pueraria phaseoloides), calopogônio (Calopogonium mucunoides), amendoim forrageiro (Arachis pintoi), soja perene (Glycine wightii) e estilosantes campo grande (mistura de Stylosanthes capitata e Stylosanthes macrocephala), com quatro repetições. Foram avaliados taxa de cobertura, temperatura e umidade do solo. Pela proteção ao solo proporcionada pela produção de biomassa, o uso e manejo de plantas de cobertura no semiárido mineiro contribuíram para a amenização da temperatura e a conservação da umidade do solo, essenciais para a produção agrícola nesta região. Calopogônio, cudzu tropical e amendoim forrageiro proporcionaram maior cobertura do solo e consequentemente promoveram maior redução da temperatura e maior retenção de umidade no solo. Em estágio mais avançado de ciclo, a soja perene também proporcionou boa cobertura de solo, redução da temperatura e retenção de umidade no solo.

Productividad del hongo nativo cortinarius austroturmalis en bosques de nothofagus siempreverde y caducifolio de las reservas nacionales altos de lircay y los ruiles de la VII región, Chile / Productivity of the native mushroom cortinarius austroturmalis in evergreen and deciduous nothofagus forests of the national reserves altos de lircay and los ruiles of the VII region, Chile

Los bosques de Nothofagus de la zona mediterránea de Chile, que incluye la VII Región, están constituidos por especies caducifolias y siempreverdes, las cuales se encuentran asociadas a diversos hongos ectomicorrícicos dentro de los que destaca el hongo nativo Cortinarius austroturmalis Moser & Horak (Agaricales, Basidiomycota). Este hongo constituye un Producto Forestal No Maderero (PFNM) poco conocido, cuya productividad no ha sido determinada, lo que implica que la población rural cercana a las Reservas Nacionales Altos de Lircay y Los Ruiles de la VII Región, no lo identifique como un hongo apto para el consumo humano y, por consiguiente, no lo coseche. El objetivo de esta investigación fue conocer la productividad de basidiomas del hongo nativo Cortinarius austroturmalis asociado a especies de Nothofagus siempreverdes y caducifolias en las Reservas Nacionales Altos de Lircay y Los Ruiles de la VII Región. Las hipótesis propuestas fueron: 1) La productividad de basidiomas de Cortinarius austroturmalis en la Reserva Nacional Los Ruiles es mayor que en la Reserva Nacional Altos de Lircay, 2) La productividad de basidiomas de Cortinarius austroturmalis asociados a especies de Nothofagus siempreverdes es mayor que la productividad de este hongo asociado a especies de Nothofagus caducifolias en ambas reservas estudiadas.

Nothofagus forests in the Mediterranean region of Chile, including VII Region consist of deciduous and evergreen species, which are associated with different ectomycorrhizal fungi within which highlights the native mushroom Cortinarius austroturmalis Moser & Horak (Agaricales, Basidiomycota). This fungus is a Non-Wood Forest Product (NWFP) obscure, whose productivity has not been determined, implying that close to the National Reserves Altos de Lircay and Los Ruiles, VII Region, rural population does not identify it a fungus suitable for human consumption and therefore not harvested. The objective of this research was to determine the productivity of fruit body of the native mushroom Cortinarius austroturmalis associated with Nothofagus species of evergreen and deciduous in the National Reserves Altos de Lircay and Los Ruiles, VII Region. The proposed hypotheses were: 1) Productivity of Cortinarius austroturmalis in the National Reserve Los Ruiles is higher than in the National Reserve Altos de Lircay, 2) Productivity of Cortinarius austroturmalis associated with Nothofagus species evergreen is greater than the productivity of this fungus associated with deciduous Nothofagus species in both reserves studied.

Frações de fósforo e simbiose micorrízica em floresta secundária em resposta a disponibilidade de água e nutrientes na Amazônia oriental / Soil phosphorus fractions and mycorrhizal symbiosis in response to the availability of moisture and nutrients at a secondary forest in eastern Amazonia

The availability of soil nutrients (especially phosphorus) and soil water strongly influence mycorrhizal symbiosis in forest ecosystems. The aim of this study was to evaluate the impact of litter removal and increased soil moisture availability on the spore density and mycorrhizal colonization of apogeotropic and non-apogeotropic roots of a secondary forest stand in eastern Amazonia. We determined the percentage of mycorrhizal colonization of apogeotropic and non-apogeotropic (0-10 cm soil depth) fine roots (diameter 2 mm), spore density, glomalin concentration, and soil phosphorus availability. Litter removal did not reduce soil phosphorus availability. The spore density was not affected by litter removal. In general, the variables varied on a seasonal basis, except the mycorrizal colonization of non-apogetropic roots and glomalin concentration, but were not affected by irrigation. Mechanical damage to the apogeotropic root system, inherent to the fortnightly litter removal, may have contributed to decrease mycorrhizal colonization of both apogeotropic and non-apogeotropic roots and, consequently, soil glomalin. Our results suggest that the reduction of soil cover may have negative impact over the fungus-plant symbiosis.

A disponibilidade de nutrientes, especialmente fósforo, e de água no solo influenciam fortemente a simbiose micorrízica em ecossistemas florestais. O objetivo do estudo foi avaliar o impacto da remoção de serapilheira e do aumento da disponibilidade de água no solo sobre a densidade de esporos e a colonização micorrízica em raízes apogeotrópicas e não-apogeotrópicas em floresta secundária na Amazônia oriental. Foram analisadas a porcentagem de colonização micorrízica de raízes finas (diâmetro ≤ 2 mm) apogeotrópicas e não-apogeotrópicas (presentes na camada de 0-10 cm do solo), a densidade de esporos, o teor de glomalina e a disponibilidade de fósforo no solo. A remoção de serapilheira não reduziu a disponibilidade de fósforo no solo. A densidade de esporos também não foi afetada pela remoção de serapilheira. De forma geral, as variáveis estudadas variaram sazonalmente, com exceção da colonização micorrízica em raízes não-apogeotrópicas e do teor de glomalina, mas não foram afetadas pela alteração na disponibilidade de água no solo decorrente da irrigação. Danos mecânicos ao sistema radicular apogeotrópico, inerentes à remoção quinzenal da serapilheira, devem ter contribuído para reduzir a colonização micorrízica em raízes apogeotrópicas e não-apogeotrópicas e, consequentemente, o teor de glomalina no solo. Os resultados deste estudo sugerem que a redução da cobertura do solo pode impactar negativamente a simbiose fungo-planta.

Chemical and physical attributes and calcium, magnesium, potassium, and phosphorus in the soil of murundu fields in Brazil / Atributos químicos, físicos e estoque de cálcio, magnésio, potássio e fósforo em solos de campos de murundus no Brasil

Fields of murundus (FM) are wetlands that provide numerous ecosystem services. The objectives of this study were to evaluate the chemical [organic carbon (OC), P, K+, Ca2+, Mg2+, Al3+ and H+Al] and physical [texture and bulk density (Bd)] soil attributes and calculate the organic matter (OM) and nutrient stock (P, Ca, Mg, and K) in soils of FM located in the Guapore River basin in Mato Grosso. Thirty-six sampling points were selected, and soil samples were collected from two environments: the murundu and plain area surrounding (PAS). At each sampling point, mini trenches of 0.5 × 0.5 × 0.4 m were opened and disturbed and undisturbed soil samples were collected at depths of 0-0.1, 0.1-0.2, and 0.2-0.4 m. In the Principal Component Analysis the variables H+Al (49%) and OM (4%) were associated with the F1 component and sand content (47%) with the F2 component. The FM had lower pH values and higher concentrations of K+, P, and H+Al than PAS at all depths (p < 0.05). Additionally, FM stocked up to 433, 360, 205, and 11 kg ha-1 of Ca, Mg, K, and P, respectively, for up to a depth of 0.2 m. The murundu stored two times more K and three times more P than that in the PAS. Our results show that the FM has high sand content and Bd greater than 1.5 Mg m-3, high acidity, low OC content, and low nutrient concentrations. Thus, special care must be taken to preserve FM such that human intervention does not trigger environmental imbalances.

Campos de murundus (CM) são áreas úmidas que prestam inúmeros serviços ecossistêmicos. Os objetivos desse estudo foram avaliar atributos químicos [carbono orgânico (CO), P, K+, Ca2+, Mg2+, Al3+ e H+Al] e físicos [textura e densidade do solo (Ds)] e calcular os teores de matéria orgânica (MO) e estoques dos nutrientes P, Ca, K e Mg em solos de CM localizados na bacia do Rio Guaporé em Mato Grosso. Foram selecionados 36 pontos de amostragem e coletadas amostras de solo em dois ambientes: murundu e área plana circunvizinha (APC). Em cada ponto foram abertas minitrincheiras de 0,5 × 0,5 × 0,4 m e coletadas amostras de solo deformadas e indeformadas nas profundidades de 0-0,1; 0,1-0,2; e 0,2-0,4 m. Na Análise de Componentes Principais as variáveis H+Al (49%) e MO (4%) foram associados com o componente F1 e o teor de areia (47%) com o componente F2. O murundu apresenta menor pH e maiores teores de K+, P e H+Al que a APC em ambas profundidades (p < 0,05). Até 0,2 m esses CM estocam 433; 360; 205; e 11 kg ha-1 de Ca, Mg, K e P, respectivamente. No entanto, o murundu estoca duas vezes mais K e três vezes mais P que a APC. Estes CM apresentam altos teores de areia, Ds superior a 1,5 Mg m-3, elevada acidez, baixo teor de CO e pobreza em nutrientes. Dessa forma, necessitam de cuidados especiais para que a intervenção antrópica não desencadeie desequilíbrios ambientais.

Acurácia e calibração de uma sonda de capacitância em um neossolo quartzarênico cultivado com caju / Accuracy and calibration of a capacitance probe in a typic quartzipisamment cultivated with cashews

A umidade do solo determinada à base de peso ou volume é um método destrutivo e não pode ser automatizado. Nesse contexto, objetivou-se avaliar a acurácia de uma sonda de capacitância (modelo Diviner 2000®) para medição da umidade em profundidade em um Neossolo Quartizarênico Órtico êutrico cultivado com caju. Para isso, a sonda foi calibrada com base na umidade volumétrica a cada 0,1 m até 0,3 m de profundidade. Verificou-se que: (i) a equação de calibração explicou significativamente 70% da umidade do solo, no intervalo mínimo e máximo de 0,0294 a 0,2418 m3 m-3, respectivamente; (ii) com base nos resultados do índice de concordância de Willmott (0,7817), do índice de desempenho de Camargo-Sentelhas (0,6557) a sonda substituiu "medianamente" a umidade real do solo, provavelmente devido as limitações verificadas no solo do presente trabalho, e do ponto de vista de economia de água aplicada via irrigação não é adequado, pois considerando a média da porosidade total do solo de 0,3533 m3 m-3 obteve-se variação de 7 m3 m-3 pelo teste de Bland-Altman, que representa 19,86% do total de poros, valor acima dos 5% de erro comum usado em experimentos agronômicos.

Soil moisture, when determined based on the weight or volume of samples is a destructive method and can not be automated. In this context, the objective was to evaluate the accuracy of a capacitance probe (Diviner 2000 ® model) for measuring moisture in depth in a Typic Quartzipisamment cultivated with cashew. For this, the probe is calibrated on the basis of the moisture measurements every 0.1 m to 0.3 m. It was found that: (i) the calibration equation explained significantly 70% soil moisture, in the minimum and maximum range from 0.0294 to 0.2418 m3 m-3, respectively; (ii) based on the results of the concordance Willmott Index (0.7817), the performance Camargo-Sentelhas index (0.6557), the probe replaced "moderately" real soil moisture, probably due to the limitations observed in the soil of this work, and from the standpoint of economy of water applied by irrigation, is not adequate, because taking the average of the total porosity of 0.3533 m3 m-3, obtained variation of 7 m3 m-3 pelo teste de Bland- Altman, by Bland-Altman, who represents 19.86% of the total porosity, value above 5% error commonly used in agronomic experiments.

Baixa umidade do solo na eficácia de herbicidas aplicados em pré-emergência / Low soil moisture in effectiveness of pre-emergence herbicide application

O objetivo do presente estudo foi avaliar o efeito da baixa umidade do solo na eficácia da aplicação dos herbicidas clomazone + ametrina, sulfentrazone e tebuthiuron em pré-emergência, submetidos à aplicação de lâminas de chuva em diferentes intervalos de tempo após sua aplicação, no controle de plantas de B. pilosa, C. echinatus e U. plantaginea. O experimento foi conduzido em vasos com capacidade de 2,5L, em condição de casa-de-vegetação, e o delineamento experimental utilizado foi o inteiramente casualizado, com quatro repetições, disposto em um esquema fatorial 3x5 (três herbicidas e cinco intervalos de chuva). Os herbicidas aplicados em pré-emergência foram clomazone+ametrina (Sinerge EC) a 5,0 L p.c. ha-1, sulfentrazone (Boral 500 SC) a 1,2 L p.c. ha-1 e tebuthiuron (Combine SC) a 2,0 L p.c. ha-1, e as lâminas de chuva de 20 mm foram aplicadas sobre os vasos em cinco intervalos de tempo após a aplicação dos herbicidas (0h, 4h, 8h, 12h e 24h). Foram realizadas avaliações visuais de controle nas plantas que emergiram aos 14 e 21 dias após a aplicação dos tratamentos e a porcentagem de emergência das plantas foi calculada. A aplicação dos três herbicidas em solo muito seco, seguida de chuvas em até 24 horas após a aplicação, permitiu a emergência de plantas de C. echinatus, reduziu a emergência das plantas de B. pilosa, mas ao final das avaliações controlou eficazmente estas duas especies e as plantas de U. plantaginea.

The aim of this study was to evaluate the effect of low soil moisture on the efficacy of applying herbicides ametryn + clomazone, sulfentrazone and tebuthiuron in pre-emergence application submitted to simulated rainfalls at different time intervals after application in control of B. pilosa, C. echinatus and U. plantaginea plants. The experiment was carried out in pots with a capacity of 2.5 L in green-house conditions and experimental design was completely randomized with four replications, arranged in a 3x5 factorial (three herbicides and five rains intervals). The herbicides clomazone + ametryn (Sinerge EC) 5.0 L commercial product (cp) ha-1, sulfentrazone (Boral 500 SC) 1.2 L cp ha-1 and tebuthiuron (combine SC) 2.0 L cp ha-1 were applied in pre-emergence and the precipitation of 20 mm were applied under de pots in five time intervals after the herbicide application (0h, 4h, 8h, 12h and 24hours). Visual evaluations of plants control that emerged plants were realized at 14 and 21 days after treatment application and the plant emergence percentage was calculated. The application of these three herbicides in dry soil then rain within 24 hours after application provided C. echinatus plants emergence, reduced B. pilosa emergency but in the end of the experiment effectively controlled these two species and U. plantaginea plants.

Influência do substrato sobre crescimento, reprodução e mortalidade de Rumina decollata (Linnaeus, 1758) (Mollusca, Subulinidae) e da umidade sobre a eclosão da espécie / Influence of substrate on growth, reproduction and mortality, of Rumina decollate (Linnaeus, 1758) (Mollusca, Subulinidae) and humidity on the species hatching

Rumina decollata (Linnaeus, 1758) é um molusco terrestre, exótico, com hábito alimentar onívoro, considerado predador de lesmas e caracóis. O conhecimento do ciclo de vida e desenvolvimento são de grande relevância para avaliar mecanismos de controle de espécies introduzidas, tendo este trabalho o objetivo de verificar a influência de substratos e da umidade sobre aspectos da biologia e eclosão de R. decollata. Para cada grupo experimental foram analisados os seguintes parâmetros: desenvolvimento, alimentação, taxa de reprodução, maturidade reprodutiva, número de ovos e a influência da umidade e restrição hídrica sobre a eclosão dos jovens. A maior taxa de reprodução entre adultos ocorreu em terra vegetal e areia e entre jovens em argila e terra vegetal. A taxa de mortalidade para jovens foi alta em areia, pouco significativa em argila e não ocorreu em terra vegetal. O substrato não influenciou nas médias de crescimento, com a maturidade reprodutiva atingida aos 109 dias de vida. Nos substratos de areia e argila umedecidos, a eclosão apresentou-se baixa e em condições de restrição hídrica os ovos não se mantiveram viáveis. O substrato de terra vegetal foi mais favorável à eclosão de jovens e também à conservação dos ovos em estádio estacionário, em condições adversas de restrição hídrica. Neste estudo foi evidenciada a existência de relação entre o substrato e a umidade, e os parâmetros reprodutivos de Rumina decollata.

Rumina decollata (Linnaeus, 1758) is an exotic, land molluscs, with omnivorous feeding habits, considered a predator to slugs and snails. The knowledge of the cycle of life and development are of great relevance to assess the control mechanisms of introduced species, having this paper the goal of verifying the influence of substrata and humidity over the aspects of biology and hatching of R. decollate. For every experimental group the following parameters were observed: development, d=feeding, reproduction rate, reproductive maturity, number of eggs and the influence of humidity and hydric restriction over the hatching of the young ones. The largest reproduction rate among adults took place on humus and sand ground and among the young ones on clay and humus ground. The mortality rate for the young ones was high on sand, of little significance in clay and did not take place on humus ground. The substrate did not influence the average growth, with reproductive maturity being reached at 109 days of life. In the humidified sand and clay ground, the hatching was low in conditions of hydric restriction and the eggs were not kept viable. The humus substrate was more favorable to the hatching of the young ones and also to the keeping of the eggs in stationary stage, in adverse hydric restriction conditions. In this study the relationship between substrate and humidity was demonstrated, and the reproductive parameters of the Rumina decollata.

Hydrotime model can describe the response of common bean (Phaseolus vulgaris L) seeds to temperature and reduced water potential / O modelo 'hydrotime' pode descrever a resposta de sementes de feijão comum (Phaseolus vulgaris L) à temperatura e potenciais de água reduzidos

Germination parameters of the response to temperature and water potential from four common bean (Phaseolus vulgaris) lines based on thermal-time and hydrotime concepts were estimated to verify to what extent they can predict germination under different thermal and water conditions. The cultivars IPR Uirapuru and IAPAR 81 (drought-tolerant), and Grauna and Carioca (not tolerant) were used. The isothermal assays were performed in a temperature gradient block, and the assays with different osmotic potentials (PEG 6000) were performed in germination chambers. Seeds from drought-tolerant cultivars spent less time to germinate at supra-optimum temperatures than non-tolerant ones, and the cultivar Uirapuru (drought-tolerant) germinated faster in response to reduced Ψ and low temperatures. The parameter Ψb(50) did not discriminate between drought-tolerant and non-tolerant lines at the infra-optimum temperature range, but it can be used to identify drought-tolerant lines at high temperatures. In general, the hydrotime model reproduced the actual germination data relatively well, chiefly at higher temperatures. This study evidenced that the hydrotime model can be used to describe the germination of common bean seeds under reduced water potentials, and as a screening tool for drought-tolerant bean genotypes.

Neste trabalho foram determinados alguns parâmetros térmicos e hídricos da germinação de quatro cultivares de feijão comum (Phaseolus vulgaris), com base nos modelos graus.dia (thermal-time) e psi.dia (hydrotime), testando-se sua adequação em descrever a germinação em diferentes condições de temperatura e água. Foram analisadas as cultivares IPR Uirapuru e IAPAR 81 (tolerantes à seca), e Grauna e Carioca (não-tolerantes). Os ensaios isotérmicos foram realizados em bloco termogradiente, enquanto que os experimentos com diferentes potenciais osmóticos (PEG 6000) foram realizados em câmaras de germinação. Sementes das cultivares tolerantes à seca germinaram mais rapidamente do que as não-tolerantes em temperaturas supraótimas, sendo que a cultivar Uirapuru (tolerante à seca) germinou mais rápido do que as demais em resposta ao Ψ reduzido e temperaturas baixas. O parâmetro Ψb(50) não discriminou entre cultivares tolerantes e não-tolerantes à seca na faixa térmica infraótima, embora ele possa ser usado para identificar cultivares tolerantes em temperaturas supraótimas. Em geral, o modelo hydrotime descreveu bem o comportamento germinativo, principalmente em temperaturas altas. Este trabalho mostra que o modelo pode ser usado para descrever a germinação de feijão comum em potenciais de água reduzidos, e como ferramenta para identificar genótipos de feijoeiro tolerantes à seca.

Hongos fitopatógenos asociados a la enfermedad de muerte regresiva y pudrición del fuste de Pachaco (Schizolobium parahybum) en el trópico húmedo ecuatoriano / Fungi pathogens associated disease dieback and stem rot of Pachaco (Schizolobium parahybum) in the Ecuadorian humed tropics

La enfermedad de muerte regresiva y pudrición del fuste de Pachaco (Schizolobium parahybum Vell Blake) fue detectada inicialmente 1988, matando árboles jóvenes en la zona central del Trópico Húmedo Ecuatoriano, desde entonces, cada año, miles de árboles mueren por esta causa. En el año 2002 se realizó la presente investigación que abarcó tres rodales de distintas edades, ubicados en provincias diferentes, planteándose los siguientes objetivos: describir la sintomatología de la enfermedad, su incidencia en las zonas de estudio e identificar los microorganismos asociados a árboles de S. parahybum enfermos. La enfermedad mostró una sintomatología compleja, empezando con una marchitez vascular y perdida de coloración verde oscura de las hojas hasta tornarse cloróticas. Las heridas no cicatrizadas mostraron una pudrición circular que afecta la corteza y el xilema, emanando fluidos de color amarillo claro a café oscuro, con fuerte olor a materia orgánica en descomposición. En la provincia de Los Ríos (rodal mayor a 25 años) se encontró la mayor incidencia de la enfermedad (55 por ciento), seguido de las provincias Esmeraldas (rodal de 8 años) y Santo Domingo de Los Tsáchilas (rodal de 4 años) con 29 y 24 por ciento, respectivamente. De árboles enfermos se aislaron e identificaron cinco hongos, tres a nivel de género: Macrophoma sp., Fusarium sp. y Graphium sp. y dos a nivel de especies: Ceratocystis paradoxa (Dade) y C. moniliformis (Hedgc.). Las pruebas de patogenicidad demostraron que C. paradoxa, Macrophoma sp. y C. moniliformis provocaron los mayores valores de volumen aparente de necrosis con 5.40, 3.55 y 3.48 cm3respectivamente.

Dieback disease and stem rot of Pachaco (Schizolobium parahybum Vell Blake) was detected initially in 1988, killing young trees in the Ecuadorian Humed Tropics, since then, thousands of trees are dying annually. The present investigation was made in 2002, where were included three rodales of different ages, located in different provinces. The aim for this research was describe the symptoms its incidence in the zones of study and identifying the associated microorganisms affecting S. parahybum. The disease showed complex symtoms, beginning with a wither of dark, green coloration of the leaves until becoming clorotics. The healed wounds did not show a circular root that affects the crust and xylem, of where emanates fluid of clear yellow color to dark coffee, with strong smell to organic matter in decomposition. In Los Ríos province (rodal more than 25 years old) the greater incidence of the disease was 55 percent, followed by he provinces of Esmeraldas (rodal of 8 years old) and Santo Domingo de Los Tsáchilas (rodal of 4 years old) with 29 and 24 percent respectively. Of ill trees five fungi isolated themselves and identified, three at sort level: Macrophoma sp., Fusarium sp. and Graphium sp. and two at level of species: Ceratocystis paradoxa (Dade) and C. Moniliformis (Hedgc.). The pathogenicity tests demonstrated that C. paradoxa, Macrophoma sp. and C. moniliformis caused the higher values of apparent volume of necrosis with 5.40, 3.55 and 3.48 cm3 respectively.

Microbial degradation of sulfentrazone in a Brazilian rhodic hapludox soil

Sulfentrazone is amongst the most widely used herbicides for treating the main crops in the State of São Paulo, Brazil, but few studies are available on the biotransformation of this compound in Brazilian soils. Soil samples of Rhodic Hapludox soil were supplemented with sulfentrazone (0.7 µg active ingredient (a.i.) g-1 soil) and maintained at 27ºC. The soil moisture content was corrected to 30, 70 or 100 percent water holding capacity (WHC) and maintained constant until the end of the experimental period. Herbicide-free soil samples were used as controls. Another experiment was carried out using soil samples maintained at a constant moisture content of 70 percent WHC, supplemented or otherwise with the herbicide, and submitted to different temperatures of 15, 30 and 40º C. In both experiments, aliquots were removed after various incubation periods for the quantitative analysis of sulfentrazone residues by gas chromatography. Herbicide-degrading microorganisms were isolated and identified. After 120 days a significant effect on herbicide degradation was observed for the factor of temperature, degradation being higher at 30 and 40º C. A half-life of 91.6 days was estimated at 27º C and 70 percent WHC. The soil moisture content did not significantly affect sulfentrazone degradation and the microorganisms identified as potential sulfentrazone degraders were Nocardia brasiliensis and Penicillium sp. The present study enhanced the prospects for future studies on the bio-prospecting for microbial populations related to the degradation of sulfentrazone, and may also contribute to the development of strategies for the bioremediation of sulfentrazone-polluted soils.

Germinação de sementes de Cynometra bauhiniifolia Benthan (jutairana) em função do dessecamento e da manutenção sob condição úmida / Germination of Cynometra bauhiniifolia Benthan (jutairana) seeds in terms of desiccation and maintenance under humid conditions

Jutairana (Cynometra bauhiniifolia) é uma espécie, normalmente, encontrada nas margens de rios, lagos e igarapés, que atualmente vem sendo utilizada na arborização urbana da cidade de Manaus (AM). Este trabalho teve por objetivo avaliar a viabilidade e o vigor de sementes de Cynometra bauhiniifolia em função da secagem e da manutenção em água de frutos e sementes. Foram desenvolvidos dois ensaios independentes. No primeiro, avaliou-se o efeito do período de secagem (0 a 10 dias), ou do grau de umidade, sobre a germinação e o vigor das sementes, em experimento inteiramente casualizado. No outro, avaliou-se a germinação e o vigor das sementes em função do acondicionamento de frutos, ou de sementes, em água ou ambiente natural, durante o período de 30 dias. Neste, o delineamento foi inteiramente ao acaso, em esquema fatorial 2 (condição da semente: no fruto ou isolada) x 2 (ambiente de condicionamento: na água e em ambiente natural) x 7 (período de acondicionamento: 0, 5, 10, 15, 20, 25 e 30 dias). As sementes de Cynometra bauhiniifolia são dispersas com alto grau de umidade (54,1 por cento) e perdem a viabilidade quando desidratadas. O teor de água crítico situou-se entre 46,6 por cento e 41,4 por cento, enquanto o grau de umidade letal ficou entre 28,2 por cento e <23,9 por cento, o que são características típicas de sementes recalcitrantes. O condicionamento dos frutos e das sementes em água, com aeração, foi satisfatório para a manutenção da viabilidade das sementes por um período de 30 dias.

Jutairana (Cynometra bauhiniifolia) is a species normally found in river banks, lakes and streams, and is currently being usedfor urban tree planting in the city of Manaus(AM), because of its visual and, or, aesthetic appearance. The object of this study was to evaluate the viability and the vigor of Cynometra bauhinnifolia seeds in terms of drying and maintenanceof fruits and seeds in water. This wasundertaken in two independent experiments. In the first, the effect of the drying period (0 to 10 days), or of moisture content in thegermination and vigor of seeds, wasevaluated in an entirely randomized experiment, with 11 treatments and 4 repetitions. In the other,seed germination and vigor was evaluatedin terms of fruit or seed conservation in water or in natural environment, during one month. In this, the delineation was entirely randomized, in factorial 2 (condition of the seed: in the fruit or isolated) X 2 (surrounding of conditioning) X 7 (period of conservation: 0, 5, 10, 15, 20, 25 and 30 days), with four repetitions. The Cynometra bauhinnifolia seeds were dispersed with high moisture content (54,1 percent) and their viability decreased when dehydrated. The critical moisture content was 46,6 percent to 41,4 percent, while the lethal moisture content was between 28,6 percent and <23,9 percent, which is a typical characteristic of recalcitrant seeds. The conditioning of fruits, or seeds, in aerated water was satisfactory for the maintenance of theseed viability for 30 days.

Diversity of the nitrite reductase gene nirS in the sediment of a free-water surface constructed wetland

The diversity of the nitrite reductase gene nirS was studied in the bulk sediment of a free-water surface constructed wetland (FWS-CW) located next to the Empuriabrava wastewater treatment plant (WWTP), in Castelló d'Empúries (Girona, NE Spain). The study period extended from the inception of the treatment wetland, in June 1998, until March 1999 and comprised periods of relatively high nitrate and ammonium concentrations at the influent and low nitrate-removal efficiencies. To evaluate nirS diversity, partial gene sequences were obtained by cloning of the respective PCR products. Rarefaction curves based on DOTUR analyses of the deduced amino-acid sequences predicted a greater diversity of nirS genes in samples containing higher ammonium concentrations. Estimated Shannon-Weaver indices of the four cloned samples showed a positive relationship with the N-NH4 +/N-NO3 - ratios measured at the FWS-CW inlet. Identities between the deduced amino-acid sequences and those previously deposited in public databases ranged from 72 to 97%. Phylogenetic analysis based on these deduced sequences grouped 165 nirS clones in seven main clusters according to high similarity indices. Up to 60% of the clones clustered together in a highly homogeneous group with little homologies to any sequence retrieved from cultured representatives. Moreover, prevailing environmental conditions appeared to select for particular denitrifying populations, e.g., with respect to ammonium load and nitrogen removal efficiencies. This observation is of particular interest for the management of treatment wetlands, in which only slight variations in the theoretical denitrification potential of the system can occur (AU)

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