The mombin tree (Spondias mombin L.) is found in almost all regions of Brazil. Fresh and processed mombin fruits are increasingly demanded by the market. The objective of this work was to evaluate the post-harvest characteristics of mombin fruits coated with cassava starch and PVC film. Fruits from the mombin cultivar Lagoa-Redonda were harvested at physiological maturity in Limoeiro do Norte, State of Ceará, transported to the Chemistry Laboratory of the Ceará Federal Institute, Limoeiro do Norte campus, and stored for 8 days at 29.7°C and 59% of relative humidity. A completely randomized experimental design in a 3x5 factorial arrangement was used, with three coating types (control, cassava starch at 3%, and cassava starch at 3% combined with PVC film) and five storage times (0, 2, 4, 6 and 8 days), four replicates and five fruits per plot. The fruit skin color, external appearance, soluble solids (SS), titratable acidity (TA), SS/TA ratio and weight loss were evaluated. The PVC film was effective in maintaining the fruit external appearance and decreasing weight loss. The use of cassava starch was not as efficient as the PVC film for conserving mombin fruits. The post-harvest life of fruits was 8 days for those treated with cassava starch or cassava starch combined with PVC film, and 6 days for the control.

RESUMO A cajazeira é encontrada em quase todas as Regiões do Brasil vem apresentando crescente demanda de frutos in natura e produtos processados. Este trabalho teve como objetivo avaliar o comportamento pós-colheita de frutos de cajá recobertos com fécula de mandioca e filme PVC. Para realização deste trabalho utilizaram-se frutos da cajazeira do genótipo ‘Lagoa Redonda’ colhidos em Limoeiro do Norte-CE em maturação fisiológica. Em seguida, os frutos foram transportados ao Laboratório de Química do IFCE Campus Limoeiro do Norte e armazenados por 8 dias a 29,7 ºC e 59% de UR. O delineamento experimental foi o inteiramente casualizado em esquema fatorial 3 x 5, com três tipos de revestimento (controle, fécula de mandioca a 3 % e fécula de mandioca a 3 % associada ao filme de PVC) e cinco tempos de armazenamento (0,2, 4, 6 e 8 dias), com quatro repetições de cinco frutos por parcela. Avaliou-se a coloração da casca, aparência externa, teores de sólidos solúveis e de acidez titulável, relação SS/AT e a perda de massa. O uso do filme plástico foi eficiente na conservação da aparência externa e controle da perda de massa. O uso da fécula de mandioca não se mostrou tão eficiente quanto o filme plástico na conservação de cajás. A vida útil pós -colheita dos frutos foi de 8 dias para os tratados com fécula de mandioca ou fécula de mandioca associada ao PVC e de 6 dias para o controle. | ABSTRACT The mombin tree (Spondias mombin L.) is found in almost all regions of Brazil. Fresh and processed mombin fruits are increasingly demanded by the market. The objective of this work was to evaluate the post-harvest characteristics of mombin fruits coated with cassava starch and PVC film. Fruits from the mombin cultivar Lagoa-Redonda were harvested at physiological maturity in Limoeiro do Norte, State of Ceará, transported to the Chemistry Laboratory of the Ceará Federal Institute, Limoeiro do Norte campus, and stored for 8 days at 29.7°C and 59% of relative humidity. A completely randomized experimental design in a 3x5 factorial arrangement was used, with three coating types (control, cassava starch at 3%, and cassava starch at 3% combined with PVC film) and five storage times (0, 2, 4, 6 and 8 days), four replicates and five fruits per plot. The fruit skin color, external appearance, soluble solids (SS), titratable acidity (TA), SS/TA ratio and weight loss were evaluated. The PVC film was effective in maintaining the fruit external appearance and decreasing weight loss. The use of cassava starch was not as efficient as the PVC film for conserving mombin fruits. The post-harvest life of fruits was 8 days for those treated with cassava starch or cassava starch combined with PVC film, and 6 days for the control.

Changes in row spacing may result in changes in crop and weed behavior and crop-weed competition. A study was performed to determine the periods of weed presence and weed control in cotton sown with 0.76 m spacing between planting rows. Cotton cultivar FM 993 was sown on 01/08/2010 with the aim of reaching a density of 190,000 seeds ha-1. Treatments with either weed presence or weed control during the first 0, 5, 10, 15, 22, 29, 36, 43, 50, 57, 64, 71, and 190 days of cultivation were established to determine the period prior to weed interference (PPI), total period of interference prevention (TPIP) and critical period of weed control (CPWC). The weed species with high relative importance were Amaranthus retroflexus, Bidens pilosa, Eleusine indica, Digitaria horizontalis, Alternanthera tenella, and Commelina benghalensis. Considering a maximum yield loss of 5%, the PPI was established 11 days after cotton emergence (DAE), the TPWC at 46 DAE, and the CPWC between 11 and 46 DAE, for a total duration of 35 days. Considering a maximum acceptable yield loss equal to the standard deviation for the weed-free treatment, the PPI was established at 6 DAE, the TPWC at 55 DAE, and the CPWC between 6 and 55 DAE for a total duration of 49 days.

RESUMO Alterações no espaçamento de semeadura podem gerar modificações no comportamento da cultura, das plantas daninhas e nas relações de competição entre ambas. Um experimento foi desenvolvido para determinar os períodos de convivência e controle das plantas daninhas no algodoeiro, semeado em espaçamento de 0,76 m entre linhas. A semeadura do cultivar FM 993 foi realizada no dia 08/01/2010 buscando-se atingir uma densidade de 190 mil sementes ha-1. Para determinar os períodos de convivência, período anterior a interferência (PAI), período total de prevenção da interferência (PTPI) e período crítico de prevenção à interferência (PCPI), foram analisados os períodos de 0; 5; 10; 15; 22; 29; 36; 43; 50; 57; 64; 71 e 190 dias de convivência ou de controle inicial das plantas daninhas. As plantas daninhas de maior importância relativa foram Amaranthus retroflexus, Bidens pilosa, Eleusine indica, Digitaria horizontalis, Alternanthera tenella e Commelina benghalensis. Admitindo-se a perda máxima de 5% em relação a produtividade, o PAI foi de 11 dias após a emergência após a emergência (DAE), o PTPI foi de 46 DAE e o PCPI de 35 dias, entre 11 e 46 DAE. A tolerância equivalente ao desvio padrão da média do tratamento no limpo resultou no PAI de 6 DAE, PTPI de 55 DAE e PCPI com duração de 49 dias, entre 6 e 55 DAE. | ABSTRACT Changes in row spacing may result in changes in crop and weed behavior and crop-weed competition. A study was performed to determine the periods of weed presence and weed control in cotton sown with 0.76 m spacing between planting rows. Cotton cultivar FM 993 was sown on 01/08/2010 with the aim of reaching a density of 190,000 seeds ha-1. Treatments with either weed presence or weed control during the first 0, 5, 10, 15, 22, 29, 36, 43, 50, 57, 64, 71, and 190 days of cultivation were established to determine the period prior to weed interference (PPI), total period of interference prevention (TPIP) and critical period of weed control (CPWC). The weed species with high relative importance were Amaranthus retroflexus, Bidens pilosa, Eleusine indica, Digitaria horizontalis, Alternanthera tenella, and Commelina benghalensis. Considering a maximum yield loss of 5%, the PPI was established 11 days after cotton emergence (DAE), the TPWC at 46 DAE, and the CPWC between 11 and 46 DAE, for a total duration of 35 days. Considering a maximum acceptable yield loss equal to the standard deviation for the weed-free treatment, the PPI was established at 6 DAE, the TPWC at 55 DAE, and the CPWC between 6 and 55 DAE for a total duration of 49 days

ABSTRACT The characterization of litterfall in forest and agroforest systems is important to better understand the cycling of nutrients, however, few studies on litterfall of fruit trees, such as banana, are found. Therefore, the objective of this work was assess the production and decomposition and chemically characterize the litterfall of banana genotypes cropped in a dystrophic typical Red-Yellow Latossol, with weak A horizon, medium texture in a hypo-xerophytic Caatinga in the Southwest of Bahia, Brazil. A completely randomized experimental design was used, with twelve treatments (genotypes) and five replications. The genotypes Preciosa, Pacovan-Ken and Maravilha presented the greatest dry weight. The genotype Fhia18 showed the longest half-life of litterfall decomposition. The banana genotypes Preciosa, Maravilha and Pacovan-Ken produce the greatest contents of litterfall, and their chemical characterization shows the descending order Ca>N>Mg>K>S>P for macronutrients and Fe>Mn>B>Zn>Cu for micronutrients. The banana genotypes PV-79-34, Garantida, Pacovan, JV-42-135, Prata-Anã, Pacovan-Ken, Preciosa and Maravilha present the lowest number of days for decomposition of the litterfall accumulated. | RESUMO A caracterização da serapilheira em sistemas florestais e agroflorestais mostra-se importante no entendimento da ciclagem de nutrientes, no entanto, estudos em frutíferas, como a bananeira, ainda são escassos. Objetivou-se determinar a produção, decomposição e caracterização química da serapilheira em genótipos de bananeira no Sudoeste Baiano em Latossolo Vermelho Amarelo distrófico típico, com horizonte A fraco, textura média, fase caatinga hipoxerófila. O delineamento experimental utilizado foi inteiramente casualizado, constituído de doze tratamentos (genótipos) e cinco repetições. Os genótipos Preciosa, Pacovan-Ken e Maravilha, apresentaram as maiores produções de massa seca. Para decomposição de 50 % da massa seca da serapilheira, observou-se que o genótipo Fhia18 apresentou o maior tempo de decomposição. Os genótipos Preciosa, Maravilha e Pacovan-Ken apresentam maiores produções de serapilheira com caracterização química em ordem crescente para os macronutrientes Ca>N>Mg>K>S>P e micronutrientes Fe>Mn>B>Zn>Cu. Os genótipos PV-79-34, Garantida, Pacovan, JV-42-135, Prata-Anã, Pacovan-Ken, Preciosa, Maravilha apresenta menores números de dias para decomposição da serapilheira acumulada.

The characterization of litterfall in forest and agroforest systems is important to better understand the cycling of nutrients, however, few studies on litterfall of fruit trees, such as banana, are found. Therefore, the objective of this work was assess the production and decomposition and chemically characterize the litterfall of banana genotypes cropped in a dystrophic typical Red-Yellow Latossol, with weak A horizon, medium texture in a hypo-xerophytic Caatinga in the Southwest of Bahia, Brazil. A completely randomized experimental design was used, with twelve treatments (genotypes) and five replications. The genotypes Preciosa, Pacovan-Ken and Maravilha presented the greatest dry weight. The genotype Fhia18 showed the longest half-life of litterfall decomposition. The banana genotypes Preciosa, Maravilha and Pacovan-Ken produce the greatest contents of litterfall, and their chemical characterization shows the descending order Ca>N>Mg>K>S>P for macronutrients and Fe>Mn>B>Zn>Cu for micronutrients. The banana genotypes PV-79-34, Garantida, Pacovan, JV-42-135, Prata-Anã, Pacovan-Ken, Preciosa and Maravilha present the lowest number of days for decomposition of the litterfall accumulated.

ABSTRACT The objective of this work was to evaluate the growth and yield of cowpea grains in different intercropping systems with millet, in wet and dry seasons. The experiments were performed in the experimental field of the Department of Plant Science of the Federal Rural University of Rio de Janeiro, Brazil, using a randomized block design with three replications and five treatments: T1- sole crop of millet; T2- sole crop of cowpea; T3- intercrop of millet (1 row) and cowpea (1 row) with 0.5 m between rows (1Mx1C-0.50); T4 - intercrop of millet (1 row) and cowpea (1 row) with 0.75 m between rows (1Mx1C-0.75); and T5 - intercrop of millet (1 row) and cowpea (2 rows) with 0.5 m between rows (1Mx2C-0.50). The cowpea shoot dry weight, root dry weight, number and dry weight of nodules, grain yield and 1000-grain weight, and the millet fresh weight, shoot dry weight, grain yield and 1000-grain weight were evaluated. The land-use efficiency index (LUE) showed significant differences in yield between the sole crop of cowpea and the intercropping system, with greater grain weight in the intercrop 1Mx2C-0.50. On the other hand, the intercrop 1Mx1C-0.75 was not recommended for the study conditions. | RESUMO O objetivo do trabalho foi avaliar o crescimento e a produtividade de grãos do feijão-caupi nos diferentes sistemas de consórcio com o milheto, na época das águas e da seca. Os experimentos foram conduzidos no campo experimental do Departamento de Fitotecnia, da Universidade Federal Rural do Rio de Janeiro, em delineamento em blocos ao acaso, com três repetições e cinco tratamentos: T1- cultura solteira de milheto; T2- cultura solteira de feijão-caupi; T3- consórcio com uma linha de milheto e uma de feijão-caupi espaçadas de 0,5m (1M x 1C-0,50); T4- consórcio com uma linha de milheto e uma de feijão-caupi espaçadas de 0,75m (1M x 1C-0,75); e T5- consórcio com uma linha de milheto e duas de feijão-caupi espaçadas de 0,5m (1M x 2C-0,50). No feijão-caupi, avaliou-se a massa seca da parte aérea, massa seca de raiz, o número e massa seca de nódulos, a produtividade de grãos e a massa de 1000 grãos; enquanto no milheto, avaliou-se a massa verde, a massa seca da parte aérea, a produtividade de grãos e a massa de 1000 grãos. Pela comparação do índice de equivalência de área (IEA), se verificou diferenças significativas na produção de feijão-caupi por área explorada, no sistema consorciado em relação ao cultivo solteiro, com a maior massa de grãos no consórcio 1M x 2C-0,50, em relação aos outros. Por outro lado, o consórcio 1M x 1C-0,75 não é recomendável para o local.

The objective of this work was to evaluate the growth and yield of cowpea grains in different intercropping systems with millet, in wet and dry seasons. The experiments were performed in the experimental field of the Department of Plant Science of the Federal Rural University of Rio de Janeiro, Brazil, using a randomized block design with three replications and five treatments: T1- sole crop of millet; T2- sole crop of cowpea; T3- intercrop of millet (1 row) and cowpea (1 row) with 0.5 m between rows (1Mx1C-0.50); T4 - intercrop of millet (1 row) and cowpea (1 row) with 0.75 m between rows (1Mx1C-0.75); and T5 - intercrop of millet (1 row) and cowpea (2 rows) with 0.5 m between rows (1Mx2C-0.50). The cowpea shoot dry weight, root dry weight, number and dry weight of nodules, grain yield and 1000-grain weight, and the millet fresh weight, shoot dry weight, grain yield and 1000-grain weight were evaluated. The land-use efficiency index (LUE) showed significant differences in yield between the sole crop of cowpea and the intercropping system, with greater grain weight in the intercrop 1Mx2C-0.50. On the other hand, the intercrop 1Mx1C-0.75 was not recommended for the study conditions.

RESUMO Objetivou-se caracterizar morfologicamente 15 cultivares de bananeiras em dois estádios de maturação. Determinaram-se as características físicas e químicas dos frutos na fase pré-climatérica e após o amadurecimento. Também avaliou-se as plantas quanto a altura e diâmetro do pseudocaule, comprimento do pecíolo e do limbo, largura do limbo e relação comprimento/largura do limbo. A cultivar Ouro apresentou os frutos com menor diâmetro, comprimento total, comercial e massa fresca nos dois estádios, além da polpa mais firme quando verde. A cultivar Caru-Roxa apresentou maior massa fresca dos frutos e da polpa e a ‘Terrinha’, a maior porcentagem de matéria seca nas polpas verde e madura. As cultivares Maçã e a Ouro proporcionaram maior relação polpa/casca na polpa verde. Houve redução da massa fresca e da espessura da casca e acréscimo da matéria seca da casca madura em relação à casca verde. A casca da ‘Marmelo’ apresentou a maior massa fresca nos dois estádios. As cultivares Marmelo e a Maçã apresentaram maior porcentagem de matéria seca em ambos os estádios de maturação da casca. A polpa verde apresentou baixo teor de sólidos solúveis. Houve acréscimo na acidez titulável na polpa com o amadurecimento. A altura média das plantas variou de 2,25 a 6,15 m. As cultivares com maior diâmetro do pseudocaule foram também os mais altos, com exceção da ‘Prata-Anã’ e da ‘Prata-Graúda’. A cultivar e o estádio de maturação influenciaram todas as características avaliadas nos frutos, com exceção dos comprimentos total e comercial, que não variaram com o amadurecimento dos frutos. | ABSTRACT The objective of this work was to morphologically characterize 15 banana cultivars and assess the physical and chemical characteristics of their fruits at two maturation stages, unripe (pre-climacteric) and ripening. The plants were evaluated regarding their pseudostem height and diameter, petiole length, leaf blade length, width and length-to-width ratio. The cultivar Ouro had fruits with lower diameter, total length, market weight and fresh weight at both stages, and also firmer pulp when they were unripe. The cultivar Caru-Roxa had higher fresh fruit and pulp weights, and the cultivar Terrinha had the highest percentage of pulp dry weight percentage in unripe and ripe fruits. The cultivars Maçã and Ouro had higher pulp-to-peel ratio in unripe fruits. The ripe peels had lower fresh weight and thickness and higher dry weight percentage compared to unripe peels. The fruit peel of the cultivar Marmelo had the highest fresh weight at both stages. The cultivars Marmelo and Maçã had higher percentage of peel dry weight percentage at both stages. The unripe pulp had lower soluble solids. The titratable acidity in the pulp increased with ripening. The average plant height ranged from 2.25 to 6.15 m. The cultivars that had the largest pseudostem diameters had also the highest heights, except the Prata-Anã and Prata-Graúda. The cultivar and maturity stage influenced all the characteristics evaluated in fruits, except the total and market lengths, which did not vary with the ripening of fruits.

The objective of this work was to morphologically characterize 15 banana cultivars and assess the physical and chemical characteristics of their fruits at two maturation stages, unripe (pre-climacteric) and ripening. The plants were evaluated regarding their pseudostem height and diameter, petiole length, leaf blade length, width and length-to-width ratio. The cultivar Ouro had fruits with lower diameter, total length, market weight and fresh weight at both stages, and also firmer pulp when they were unripe. The cultivar Caru-Roxa had higher fresh fruit and pulp weights, and the cultivar Terrinha had the highest percentage of pulp dry weight percentage in unripe and ripe fruits. The cultivars Maçã and Ouro had higher pulp-to-peel ratio in unripe fruits. The ripe peels had lower fresh weight and thickness and higher dry weight percentage compared to unripe peels. The fruit peel of the cultivar Marmelo had the highest fresh weight at both stages. The cultivars Marmelo and Maçã had higher percentage of peel dry weight percentage at both stages. The unripe pulp had lower soluble solids. The titratable acidity in the pulp increased with ripening. The average plant height ranged from 2.25 to 6.15 m. The cultivars that had the largest pseudostem diameters had also the highest heights, except the Prata-Anã and Prata-Graúda. The cultivar and maturity stage influenced all the characteristics evaluated in fruits, except the total and market lengths, which did not vary with the ripening of fruits.

RESUMO A salinidade e a sodicidade dos solos são problemas mundiais porque promovem a degradação das propriedades físicas, químicas e biológicas dos solos e comprometem a capacidade produtiva das áreas agrícolas. Uma das tentativas de redução do problema é a aplicação de corretivos inorgânicos ou insumos orgânicos associados com plantas tolerantes aos sais. Pelo exposto, o trabalho objetiva avaliar o efeito de insumos orgânicos na rebrota de cepas de nim (Azadirachta indica) após o corte no crescimento das plantas em solo salino - sódico. Os tratamentos foram arranjados em blocos ao acaso, com quatro repetições em esquema fatorial 3 × 5, referentes aos insumos orgânicos - esterco bovino, biofertilizante bovino comum (partes iguais de água e esterco fresco de bovino) e biofertilizante enriquecido quimicamente (componentes do biofertilizante comum associados a gesso, melaço de cana - de - açúcar e leite de vaca), aplicados uma única vez, após a lavagem do solo, dois dias antes da semeadura das sementes, aos níveis de 0, 3, 6, 9 e 12 % do volume do substrato. Exceto no diâmetro caulinar, o esterco bovino foi mais eficiente que os biofertilizantes no crescimento em altura e rendimento em biomassa das plantas de nim após o corte, principalmente nos tratamentos em níveis acima de 6 %. Os insumos orgânicos apesar de elevarem a salinidade e a sodicidade do solo no intervalo do final da lavagem até o corte das plantas, estimularam o crescimento biométrico e a formação de biomassa do nim em solo salino sódico. | ABSTRACT Soil salinity and sodicity are global problems since both promote the physical, chemical and biological degradation of soil, jeopardising the productive capacity of agricultural fields. Inorganic correctives or organic inputs are applied as an attempt to reduce the problem, alongside the use of salt -tolerant plants. This study aimed at evaluating the effects of organic inputs on the growth of neem (Azadirachta indica) strains in saline-sodic soil after cutting. Treatments were arranged in a randomised block design, with four replicates in a 3 × 5 factorial. Organic inputs - bovine manure, common bovine biofertilizer (equal parts of water and fresh bovine manure) and chemically enriched biofertilizer (common biofertilizer components combined with plaster, sugarcane molasses and cow’s milk) - were applied only once, after soil washing, two days prior to seeding, at the levels of 0, 3, 6, 9 and 12% of the substrate volume. Except effects on the stem diameter, the most efficient input was bovine manure, with strong effects on the height increase and biomass yield of neem plants after cutting, especially in treatments at a level greater than 6%. The organic inputs, despite increasing the soil salinity and sodicity in the interval between washing and cutting, stimulated biometric growth and biomass formation in saline-sodic soil.

Soil salinity and sodicity are global problems since both promote the physical, chemical and biological degradation of soil, jeopardising the productive capacity of agricultural fields. Inorganic correctives or organic inputs are applied as an attempt to reduce the problem, alongside the use of salt-tolerant plants. This study aimed at evaluating the effects of organic inputs on the growth of neem (Azadirachta indica) strains in saline-sodic soil after cutting. Treatments were arranged in a randomised block design, with four replicates in a 3 × 5 factorial. Organic inputs — bovine manure, common bovine biofertilizer (equal parts of water and fresh bovine manure) and chemically enriched biofertilizer (common biofertilizer components combined with plaster, sugarcane molasses and cow’s milk) — were applied only once, after soil washing, two days prior to seeding, at the levels of 0, 3, 6, 9 and 12% of the substrate volume. Except effects on the stem diameter, the most efficient input was bovine manure, with strong effects on the height increase and biomass yield of neem plants after cutting, especially in treatments at a level greater than 6%. The organic inputs, despite increasing the soil salinity and sodicity in the interval between washing and cutting, stimulated biometric growth and biomass formation in saline-sodic soil.

ABSTRACT This study aimed to assess the foam-mat drying kinetics of mango pulp (cv. Keitt) adding 1% Emustab® and 1% Super Liga Neutra®, for a whipping time of 20 minutes, dried in a forced -air convection oven at different temperatures (50, 60 and 70oC) and foam layer thicknesses (0.5, 1.0 and 1.5 cm). Drying kinetic data were used to build drying curves and then fit to Page, Henderson, Henderson and Pabis, Logarithmic and two-term Exponential models. Both temperature and foam layer thickness influenced drying time, which reached the shortest value at the highest temperature and smallest thickness. The Page model provided the best fit to the experimental drying curve data. | RESUMO Este trabalho foi realizado com o objetivo de avaliar a cinética de secagem em camada de espuma da polpa de manga cv. Keitt, com a incorporação de 1% de Emustab® e 1% de Super Liga Neutra®, para um tempo de batimento de 20 min, desidratada em estufa com circulação forçada de ar em diferentes temperaturas (50; 60 e 70 oC) e espessuras de camada de espuma (0,5; 1,0 e 1,5 cm). A partir dos dados obtidos durante a cinética de secagem foram construídas as curvas de secagem e ajustados os modelos de Page, Henderson, Henderson e Pabis, Logarítmico e Exponencial de dois termos. Verificou-se que a temperatura de secagem e a espessura da camada de espuma influenciaram no tempo de secagem, com os menores tempos de secagem observados na maior temperatura e na menor espessura. O modelo de Page foi o que melhor se ajustou aos dados experimentais das curvas de secagem.

This study aimed to assess the foam-mat drying kinetics of mango pulp (cv. Keitt) adding 1% Emustab® and 1% Super Liga Neutra®, for a whipping time of 20 minutes, dried in a forced-air convection oven at different temperatures (50, 60 and 70oC) and foam layer thicknesses (0.5, 1.0 and 1.5 cm). Drying kinetic data were used to build drying curves and then fit to Page, Henderson, Henderson and Pabis, Logarithmic and two-term Exponential models. Both temperature and foam layer thickness influenced drying time, which reached the shortest value at the highest temperature and smallest thickness. The Page model provided the best fit to the experimental drying curve data.

ABSTRACT Stream water quality is dependent on many factors, including the source and quantity of the streamflow and the types of geology and soil along the path of the stream. This study aims to evaluate the origin and the mechanisms controlling the input of ions that effect surface water quality in the sub -basin of the Rio das Cobras, Rio Grande do Norte state, Northeastern Brazil. Thirteen ponds were identified for study: three in the main river and ten in the tributaries between, thus covering the whole area and lithology of the sub -basin. The samples were collected at two different times (late dry and rainy periods) in the hydrological years 2009 and 2010, equating to total of four collection times. We analyzed the spatial and seasonal behavior of water quality in the sub-basin, using Piper diagrams, and analyzed the source of the ions using Guibbs diagram and molar ratios. With respect to ions, we found that water predominate in 82% sodium and 76% bicarbonate water (cations and anions, respectively). The main salinity control mechanism was related to the interaction of the colloidal particles (minerals and organic sediment) with the ions dissolved in water. Based on the analysis of nitrates and nitrites there was no evidence of contamination from anthropogenic sources. | RESUMO A qualidade da água de um rio dependente de vários fatores, incluindo a origem e quantidade de escoamento e a formação geologia dos solos ao longo do fluxo. Objetivou-se avaliar a origem e os mecanismos controladores da entrada dos íons e, consequentemente, da qualidade da água na sub-bacia do rio das Cobras, RN. Foram selecionados 13 açudes, sendo 3 no rio principal e 10 entre os afluentes, abrangendo toda a área e litologias da sub-bacia. As amostras foram coletadas em duas épocas distintas (final dos períodos secos e chuvosos) nos anos hidrológicos de 2009 e 2010, totalizando 4 momentos de coleta. Analisou-se o comportamento espacial e sazonal da qualidade da água na sub-bacia utilizando o diagrama de Piper e a origem dos íons pelo diagrama de Gibbs e razão molar. Constatou-se que em relação aos íons, predominam águas sódicas em 82% e águas bicarbonatadas 76% (cátions e ânions), respectivamente. Os resultados obtidos sugerem que o principal mecanismo controlador da salindiade está relacionado a interação das partículas coloidais (sedimentos orgânicos e minerais) com os íons dissolvidos na água. Também não se observou indícios de contaminação antrópica na área, tendo por base a análise de nitratos e nitritos.

Stream water quality is dependent on many factors, including the source and quantity of the streamflow and the types of geology and soil along the path of the stream. This study aims to evaluate the origin and the mechanisms controlling the input of ions that effect surface water quality in the sub-basin of the Rio das Cobras, Rio Grande do Norte state, Northeastern Brazil. Thirteen ponds were identified for study: three in the main river and ten in the tributaries between, thus covering the whole area and lithology of the sub-basin. The samples were collected at two different times (late dry and rainy periods) in the hydrological years 2009 and 2010, equating to total of four collection times. We analyzed the spatial and seasonal behavior of water quality in the sub-basin, using Piper diagrams, and analyzed the source of the ions using Guibbs diagram and molar ratios. With respect to ions, we found that water predominate in 82% sodium and 76% bicarbonate water (cations and anions, respectively). The main salinity control mechanism was related to the interaction of the colloidal particles (minerals and organic sediment) with the ions dissolved in water. Based on the analysis of nitrates and nitrites there was no evidence of contamination from anthropogenic sources.

ABSTRACT Cowpea has great socioeconomic importance in the northeastern part of Pará state. However, in order to provide suitable irrigation management during the dry period this region requires solid information regarding water demand by regional crops. This research aims to determine the water demand, the crop coefficient (Kc) and the uncoupling factor during the different development stages of cowpea in the northeast of Pará. The crop evapotranspiration (ETc) was measured by drainage lysimeters. This information was coupled to the reference evapotranspiration (ETo) to obtain the crop coefficients, which were used to adjust the model function of accumulated degree-days and the leaf area index (LAI). The uncoupling factor was estimated to indicate the factors that control evapotranspiration. The ETc values reached a cumulative total of 267.73 mm ± 10.21 mm during the cowpea cycle. The average value of the uncoupling factor was 0.66. This indicates that the cowpea crop does not fully uncouple from the atmosphere underneath the climatic conditions in northeast Pará. The cowpea Kc values presented averages of 0.8, 1.4 and 0.8 in the vegetative phase, reproductive phase and final stage, respectively. The Gaussian model showed an excellent fit for the estimation of Kc values based on accumulated degree days and the LAI. These amounts differ from others found in the literature. Therefore, it reinforces the necessity for an assessment of crop coefficients under local conditions and for the employment of more precise methods. | RESUMO O feijão caupi possui grande importância sócioeconômica para o nordeste paraense, porém, a região necessita de informações seguras quanto demanda hídrica, para promover um manejo adequado de irrigação no período considerado mais seco do ano. Assim, o objetivo da pesquisa foi determinar a demanda hídrica, coeficiente da cultura (Kc) e fator de desacoplamento nos diferentes estádios de desenvolvimento do feijão caupi no nordeste paraense. Com a evapotranspiração da cultura (ETc), obtida por meio de lisímetros de drenagem, e a evapotranspiração de referência (ETo) foram obtidos os coeficientes de cultura (Kc), utilizados posteriormente, para ajustar modelos em função dos graus dias acumulados (GD) e índice de área foliar (IAF), o fator de desacoplamento foi estimado para indicar os fatores que estão governando a evapotranspiração. Os valores de ETc atingiram um total acumulado, durante o ciclo do feijão caupi, de 267,73 mm ± 10,21 mm. O valor médio do fator de desacoplamento foi 0,66 indicando que a cultura do feijão-caupi não desacopla totalmente da atmosfera nas condições climáticas do nordeste paraense. O Kc do feijão caupi apresentou valor médio de 0,8, 1,4 e 0,8 na fase vegetativa, fase reprodutiva e estádio final, respectivamente. O modelo Gaussiano apresentou ótimo ajuste para a estimativa dos valores Kc em função dos graus-dia acumulados e do IAF. Tais valores se diferenciam de alguns encontrados na literatura, o que reforça a necessidade de estudos relacionados a consumo hídrico, assim como coeficiente de cultura, em condições locais e por métodos precisos.

Cowpea has great socioeconomic importance in the northeastern part of Pará state. However, in order to provide suitable irrigation management during the dry period this region requires solid information regarding water demand by regional crops. This research aims to determine the water demand, the crop coefficient (Kc) and the uncoupling factor during the different development stages of cowpea in the northeast of Pará. The crop evapotranspiration (ETc) was measured by drainage lysimeters. This information was coupled to the reference evapotranspiration (ETo) to obtain the crop coefficients, which were used to adjust the model function of accumulated degree-days and the leaf area index (LAI). The uncoupling factor was estimated to indicate the factors that control evapotranspiration. The ETc values reached a cumulative total of 267.73 mm ± 10.21 mm during the cowpea cycle. The average value of the uncoupling factor was 0.66. This indicates that the cowpea crop does not fully uncouple from the atmosphere underneath the climatic conditions in northeast Pará. The cowpea Kc values presented averages of 0.8, 1.4 and 0.8 in the vegetative phase, reproductive phase and final stage, respectively. The Gaussian model showed an excellent fit for the estimation of Kc values based on accumulated degree days and the LAI. These amounts differ from others found in the literature. Therefore, it reinforces the necessity for an assessment of crop coefficients under local conditions and for the employment of more precise methods.