The objective of this work was to assess the effect of vegetation on the runoff coefficients of a Caatinga dry tropical forest before and after thinning. Thus, an experiment was conducted with evaluations in three hydrological years (2008, 2011 and 2013) in Iguatu, State of Ceará, Brazil. In 2008, the vegetation consisted of a 30-year regenerating Caatinga forest. The vegetation was subjected to thinning in 2009, 2011 and 2013, removing trees with less than 10-cm diameter at breast height. Hydrological responses were evaluated as a function of daily precipitation water depths, based on cumulative frequency distribution, by dividing precipitation events into three classes (CP) (CP≤30, 30<CP≤50 and CP>50 mm). Significant differences between runoff coefficients before and after vegetation thinning were assessed through the Student's t-test (p<0.01). Before thinning (2008), CP≤30 mm showed the highest runoff coefficient, differing statistically (p<0.01) from the other years. The results of precipitation events of great magnitude (CP>50 mm) indicate that the runoff is greatly dependent on rainfall characteristics and soil moisture conditions. The greater development of herbaceous vegetation due to thinning reduced the surface runoff.

RESUMO Tendo como objetivo responder ao questionamento de como o raleamento da cobertura vegetal de uma floresta tropical seca, caatinga, pode interferir no coeficiente de escoamento superficial, desenvolveu-se este estudo em três anos hidrológicos (2008, 2011 e 2013). O experimento foi conduzido no município de Iguatu no estado do Ceará, Brasil. No ano de 2008 a cobertura vegetal era caatinga em regeneração há 30 anos. A vegetação foi submetida ao manejo de raleamento em 2009, 2011 e 2013, eliminando-se as árvores com diâmetro inferior a 10 cm a altura do peito. Para investigar a resposta hidrológica em função da altura pluviométrica diária, tendo-se por base a distribuição de frequência acumulada, os eventos foram divididos em três classes pluviométricas (CP): CP ≤ 30 mm, 30 < CP ≤ 50 mm e CP > 50 mm. Para identificar se os coeficientes de escoamento gerados antes e após o raleamento da vegetação apresentavam diferenças significativas, aplicou-se o teste “t” de Student ao nível de 1%. Antes do raleamento (2008), a CP ≤ 30 mm registrou o maior percentual do coeficiente de escoamento diferindo estatisticamente ao nível de 1% de significância dos outros anos. Para eventos de grande magnitude (CP > 50 mm), os resultados apontam que o escoamento apresenta uma maior dependência das características da chuva e das condições de umidade do solo. O maior desenvolvimento do estrato herbáceo devido ao raleamento resultou em uma redução do fluxo do escoamento superficial. | ABSTRACT The objective of this work was to assess the effect of vegetation on the runoff coefficients of a Caatinga dry tropical forest before and after thinning. Thus, an experiment was conducted with evaluations in three hydrological years (2008, 2011 and 2013) in Iguatu, State of Ceará, Brazil. In 2008, the vegetation consisted of a 30-year regenerating Caatinga forest. The vegetation was subjected to thinning in 2009, 2011 and 2013, removing trees with less than 10-cm diameter at breast height. Hydrological responses were evaluated as a function of daily precipitation water depths, based on cumulative frequency distribution, by dividing precipitation events into three classes (CP) (CP≤30, 30<CP≤50 and CP>50 mm). Significant differences between runoff coefficients before and after vegetation thinning were assessed through the Student's t-test (p<0.01). Before thinning (2008), CP≤30 mm showed the highest runoff coefficient, differing statistically (p<0.01) from the other years. The results of precipitation events of great magnitude (CP>50 mm) indicate that the runoff is greatly dependent on rainfall characteristics and soil moisture conditions. The greater development of herbaceous vegetation due to thinning reduced the surface runoff.

Changes in the agricultural environment can be determined by providing microbiological indicators of the soil since the soil microorganisms are sensitive to variations in the environment. In this way, the impact of herbicides of long residual effect on the rhizospheric soil microorganisms of sugarcane cultivars was evaluated. The cultivars of sugarcane (SP 81-3250 and RB 867515) were treated with four herbicides (tebuthiuron, diuron, ametryn and mixture of diuron + and hexazinone) applied in pre-emergence. The herbicides were applied seven days after the planting of the gems. At 30, 60 and 90 days after the application, the soil rhizosphere was collected in each treatment to determine the CO2 evolution of the soil (C-CO2), microbial biomass carbon (MBC), metabolic quotient (qCO2), solubility potential of inorganic phosphorus P (PSFI) and percentage of roots colonized by mycorrhizal fungi Arbuscular. No changes were observed in the microbial activity of the sugarcane rhizosphere at 30 days after application of the herbicides (DAA). However, at 90 DAA, all herbicides negatively affected the activity of the rhizospheric microorganisms of sugarcane. The metabolic activity of rhizosphere in soil cultivated with RB 867515 was less affected by herbicides.

ABSTRACT Changes in the agricultural environment can be determined by providing microbiological indicators of the soil since the soil microorganisms are sensitive to variations in the environment. In this way, the impact of herbicides of long residual effect on the rhizospheric soil microorganisms of sugarcane cultivars was evaluated. The cultivars of sugarcane (SP 81-3250 and RB 867515) were treated with four herbicides (tebuthiuron, diuron, ametryn and mixture of diuron + and hexazinone) applied in pre-emergence. The herbicides were applied seven days after the planting of the gems. At 30, 60 and 90 days after the application, the soil rhizosphere was collected in each treatment to determine the CO2 evolution of the soil (C-CO2), microbial biomass carbon (MBC), metabolic quotient (qCO2), solubility potential of inorganic phosphorus P (PSFI) and percentage of roots colonized by mycorrhizal fungi Arbuscular. No changes were observed in the microbial activity of the sugarcane rhizosphere at 30 days after application of the herbicides (DAA). However, at 90 DAA, all herbicides negatively affected the activity of the rhizospheric microorganisms of sugarcane. The metabolic activity of rhizosphere in soil cultivated with RB 867515 was less affected by herbicides. | RESUMO Alterações no ambiente agrícola podem ser determinadas por meio indicadores microbiológicos do solo, uma vez que a microbiota do solo é sensível às modificações do ambiente. Desta forma, avaliou-se o impacto de herbicidas de longo efeito residual sobre a microbiota rizosférica de cultivares de cana-de-açúcar. As cultivares de cana-de-açúcar SP 81-3250 e RB 867515 foram tratadas com quatro herbicidas (tebuthiuron, diuron, ametryn e a mistura diuron + hexazinone) aplicados em pré-emergência. Os herbicidas foram aplicados sete dias após o plantio das gemas. Aos 30, 60 e 90 dias após a aplicação, o solo rizosferico de cada tratamento foi coletado para determinar a evolução de CO2 no solo (C-CO2), o carbono da biomassa microbiana (MBC), o quociente metabólico (qCO2), o potencial de solubilização de P inorgânico (PSFI) e a percentagem de raízes colonizadas por fungos micorrízicos arbusculares. Não foram observadas alterações na atividade microbiana da rizosfera da cana-de-açúcar aos 30 dias após a aplicação dos herbicidas (DAA). No entanto, aos 90 DAA todos os herbicidas afetaram negativamente a atividade dos micro-organismos rizosféricos da cana-de-açúcar. A atividade metabólica da rizosfera em solo cultivado com a RB 867515 foi menos afetada pelos herbicidas.

Irrigation with saline water is a worldwide necessity an excess of salts in water or in soil causes growth inhibition, and negatively affects the productivity of many crops. Application of nitrogen fertilizers may be a way of mitigating the effects of salts on plants. The aim of this study was to evaluate the accumulation of biomass and the chlorophyll pigment content in jackfruit seedlings irrigated with water of increasing salinity level in soil with nitrogen sources. The treatments were distributed in randomized blocks with four replicates and three plants per plot, arranged in a 5 × 3 factorial scheme, related to electrical conductivity levels of the irrigation water of 0.3, 1.0, 2.0, 3.0 and 4.0 dS m-1, in soil without nitrogen, with ammonium sulfate and with urea, in a split application 60 and 75 days after sowing. An increase in the salinity of the water increased the salinity levels of soil, which was intensified by a dose of 150 mg of N, mainly when applied in the form of ammonium sulfate, inhibiting dry matter production and chlorophyll content in jackfruit seedlings. The greatest reductions in chlorophyll a and b content occurred in jackfruit seedlings irrigated with water of 4.0 dS m-1 conductivity in the soil without nitrogen fertilization. Urea is the most suitable nitrogen source for the production of seedlings under conditions of high salinity.

RESUMO A irrigação com água salina é uma necessidade mundial e o excesso de sais da água ou do solo, causa inibição no crescimento e no rendimento da grande maioria das plantas cultivadas. Nesse contexto, os fertilizantes nitrogenados podem constituir alternativa para a mitigação dos efeitos dos sais sobre as plantas. Com isso, objetivou-se avaliar o acúmulo de biomassa e o índice de pigmentos clorofiláticos em mudas de jaqueira irrigadas com água de salinidades crescentes no solo com fontes de nitrogênio. Os tratamentos foram distribuídos em blocos casualizados com quatro repetições e com três plantas por parcela, arranjados em fatorial 5 × 3, relativo aos níveis de condutividade elétrica da água de irrigação de 0,3; 1,0; 2,0; 3,0 e 4,0 dS m-1, no solo sem nitrogênio, com sulfato de amônio e com ureia aplicados parceladamente aos 60 e 75 dias após a semeadura. O aumento da salinidade da água elevou a salinidade do solo, a qual foi intensificada pela dose de 150 mg de N, principalmente quando aplicada na forma de sulfato de amônio, ao ponto de inibir a formação de massa da matéria seca e os teores de clorofila em mudas de jaqueira. As maiores reduções no índice de clorofila a e b foram nas mudas de jaqueira irrigadas com água de 4,0 dS m-1 no solo sem adubação nitrogenada. A ureia é a fonte nitrogenada mais indicada para produção de mudas em condições de elevada salinidade. | ABSTRACT Irrigation with saline water is a worldwide necessity an excess of salts in water or in soil causes growth inhibition, and negatively affects the productivity of many crops. Application of nitrogen fertilizers may be a way of mitigating the effects of salts on plants. The aim of this study was to evaluate the accumulation of biomass and the chlorophyll pigment content in jackfruit seedlings irrigated with water of increasing salinity level in soil with nitrogen sources. The treatments were distributed in randomized blocks with four replicates and three plants per plot, arranged in a 5 × 3 factorial scheme, related to electrical conductivity levels of the irrigation water of 0.3, 1.0, 2.0, 3.0 and 4.0 dS m-1, in soil without nitrogen, with ammonium sulfate and with urea, in a split application 60 and 75 days after sowing. An increase in the salinity of the water increased the salinity levels of soil, which was intensified by a dose of 150 mg of N, mainly when applied in the form of ammonium sulfate, inhibiting dry matter production and chlorophyll content in jackfruit seedlings. The greatest reductions in chlorophyll a and b content occurred in jackfruit seedlings irrigated with water of 4.0 dS m-1 conductivity in the soil without nitrogen fertilization. Urea is the most suitable nitrogen source for the production of seedlings under conditions of high salinity.

This study aimed to determine the doses of maximum agronomic and economic efficiency as a function of different amounts of roostertree Calotropis procera (Ait.) R.Br. biomass added to the soil, that results in the maximum yield of green grains of cowpea in the semi-arid of Rio Grande do Norte state, Brazil. The experiment was conducted at the “Rafael Fernandes” Experimental Farm of the Universidade Federal Rural do Semi-Árido (UFERSA), Alagoinha, RN, from August to November 2013. In the experiment was used a randomized completely block design with 5 replicates. The treatments consisted of 20, 35, 50, and 65 t ha-1 (on a dry matter basis) of roostertree biomass added to the soil. The evaluated characteristics were: number of green pods per m2, productivity and dry mass of green pods, number of green grains per pod, weight of 100 green grains, and dry mass of green grains. The following economic indicators were determined: gross and net incomes, production operational costs, rate of return, and profit margin. The maximum agronomic efficiency of the yield of cowpea green grain was reached at the yield of 3.05 t ha-1, using 61.0 t ha-1 of roostertree biomass in the soil. The maximum economic efficiency yielded a net income of R$ 8,701.42, at the production of 3.02 t ha-1 green grains with 53.57 t ha-1 of roostertree biomass added to the soil. The use of roostertree as a green manure presents technical-economic feasibility in cowpea cultivation for green grains in the semi-arid conditions of Rio Grande do Norte.

ABSTRACT This study aimed to determine the doses of maximum agronomic and economic efficiency as a function of different amounts of roostertree [Calotropis procera (Ait.) R.Br.] biomass added to the soil, that results in the maximum yield of green grains of cowpea in the semi-arid of Rio Grande do Norte state, Brazil. The experiment was conducted at the “Rafael Fernandes” Experimental Farm of the Universidade Federal Rural do Semi-Árido (UFERSA), Alagoinha, RN, from August to November 2013. In the experiment was used a randomized completely block design with 5 replicates. The treatments consisted of 20, 35, 50, and 65 t ha-1 (on a dry matter basis) of roostertree biomass added to the soil. The evaluated characteristics were: number of green pods per m2, productivity and dry mass of green pods, number of green grains per pod, weight of 100 green grains, and dry mass of green grains. The following economic indicators were determined: gross and net incomes, production operational costs, rate of return, and profit margin. The maximum agronomic efficiency of the yield of cowpea green grain was reached at the yield of 3.05 t ha-1, using 61.0 t ha-1 of roostertree biomass in the soil. The maximum economic efficiency yielded a net income of R$ 8,701.42, at the production of 3.02 t ha-1 green grains with 53.57 t ha-1 of roostertree biomass added to the soil. The use of roostertree as a green manure presents technical-economic feasibility in cowpea cultivation for green grains in the semi-arid conditions of Rio Grande do Norte. | RESUMO Este estudo teve como objetivo determinar as doses de eficiência agronômica e econômica máximas em função de diferentes quantidades de biomassa de flor-de-seda [Calotropis procera (Ait.) R.Br.] adicionadas ao solo, que resultem no rendimento máximo de grãos verdes de feijão caupi no semiárido do estado do Rio Grande Norte, Brasil. O experimento foi conduzido na Fazenda Experimental "Rafael Fernandes" da Universidade Federal Rural do Semi-Árido (UFERSA), Alagoinha, RN, no período de agosto a novembro de 2013. No experimento foi usado um delineamento de blocos completos casualizados com cinco repetições. Os tratamentos consistiram de 20, 35, 50 e 65 t ha-1 (em base seca) de biomassa de flor-de-seda adicionada ao solo. As características avaliadas foram: número de vagens verdes por m2, produtividade e massa seca de vagens verdes, número de grãos verdes por vagem, peso de 100 grãos verdes e massa seca de grãos verdes. Os seguintes indicadores econômicos foram determinados: rendas bruta e líquida, custos operacionais de produção, taxa de retorno e índice de lucratividade. A eficiência agronômica máxima do rendimento de grãos verdes de feijão-caupi foi alcançada com o rendimento de 3,05 t ha-1, utilizando-se 61,0 t ha-1 de biomassa de flor-de-seda incorporada ao solo. A eficiência econômica máxima produziu uma renda liquida de R$ 8.701,42, no rendimento de grãos verdes de 3.02 t ha-1 com 53,57 t ha-1 de biomassa de flor-de-seda adicionada ao solo. O uso da flor-de-seda como adubo verde apresenta viabilidade técnico-econômica no cultivo do feijão-caupi para grãos verdes nas condições semiáridas do Rio Grande do Norte.

Brackish waters represent great potential for profitable agricultural production; however, productive usage depends on the adoption of proper cultural practices as well as a culture tolerant of salinity, which can require some restrictions related to soil and crop production. Given the lack of information pertaining to hydroponic melon culture, the objective of this study was to investigate physiological changes promoted by the use of brackish water in the preparation of the nutrient solution for melon (Cucumis melo L., cv. AF 015) growth in coconut fiber substrate under greenhouse conditions in Mossoró-RN, a semiarid region of Brazil. The experimental design was completely randomized, with 12 treatments arranged in a 4 x 3 factorial scheme, with 4 salt concentration levels (1.1 - control, 2.5, 4.0 and 5.5 dS m-1) and 3 exposition times (vegetative growth: 10-30 days after transplanting, DAT; flowering: 31 to 50 DAT; and fruiting and ripening: 51-70 DAT, which are the assessment phases of physiological maturation). Increasing salt concentrations in the nutrient solution reduced photosynthetic efficiency, stomatal conductance and transpiration, but increased the intercellular CO2 concentration in melon plants. A salt concentration in the low to intermediate range (2.5 dS m-1) resulted in the best water use efficiency by melon crops.

RESUMO A água salobra pode representar um grande potencial para a produção agrícola rentável, com base na adoção de práticas culturais adequadas e tolerância das culturas à salinidade, contrapondo aos problemas produtivos e de solo que normalmente ocasionam. Devido à escassez de informações sobre o cultivo hidropônico de melão, o presente estudo teve o objetivo de investigar as alterações fisiológicas provocadas pelo uso de água salobra no preparo da solução nutritiva para o cultivo de melão (Cucumis melo L., cv. AF 015) em ambiente protegido e em substrato de fibra de coco, em Mossoró-RN, região semiárido do Brasil. O delineamento experimental utilizado foi o inteiramente casualizado, com 12 tratamentos arranjados em esquema fatorial 4 x 3, sendo 4 níveis de concentração de sais (1,1 dS m-1 - controle, 2,5, 4,0 e 5,5 dS m-1) e 3 fases de desenvolvimento (vegetativo: 10-30 dias após o transplantio, DAT; floração: 31-50 DAT e frutificação: 51-70 DAT, que representam as fases de avaliação da maturação fisiológica) com três repetições. O aumento da concentração de sal da solução nutritiva reduziu a eficiência da fotossíntese, da condutância estomática e da transpiração e aumentou a concentração intracelular de CO2 em plantas de melão. A melhor eficiência do uso da água pela cultura do melão cultivada em fibra de coco foi alcançada na solução nutritiva com concentração de 2.5 dS m-1. | ABSTRACT Brackish waters represent great potential for profitable agricultural production; however, productive usage depends on the adoption of proper cultural practices as well as a culture tolerant of salinity, which can require some restrictions related to soil and crop production. Given the lack of information pertaining to hydroponic melon culture, the objective of this study was to investigate physiological changes promoted by the use of brackish water in the preparation of the nutrient solution for melon (Cucumis melo L., cv. AF 015) growth in coconut fiber substrate under greenhouse conditions in Mossoró-RN, a semiarid region of Brazil. The experimental design was completely randomized, with 12 treatments arranged in a 4 x 3 factorial scheme, with 4 salt concentration levels (1.1 - control, 2.5, 4.0 and 5.5 dS m-1) and 3 exposition times (vegetative growth: 10-30 days after transplanting, DAT; flowering: 31 to 50 DAT; and fruiting and ripening: 51-70 DAT, which are the assessment phases of physiological maturation). Increasing salt concentrations in the nutrient solution reduced photosynthetic efficiency, stomatal conductance and transpiration, but increased the intercellular CO2 concentration in melon plants. A salt concentration in the low to intermediate range (2.5 dS m-1) resulted in the best water use efficiency by melon crops.

Cowpea is one of the major food crops in Northeast Brazil, where it is commonly cultivated in the semi-arid regions with limited water availability. It is important to study the elicitors associated with cowpea to mitigate any deleterious effects of abiotic stress on the initial establishment of this crop. In this study, we aimed to evaluate the morphophysiological changes in cowpea cultivars under osmotic stress with seeds soaked in salicylic acid. The germination test was conducted in B.O.D germination chambers. The seeds of three cowpea cultivars: BRS Tumucumaque, BRS Aracê, and BRS Guariba, were germinated at five osmotic potentials (0.0; -0.2; -0.4; -0.6, and -0.8 MPa) after three pre-treatments: pre-soaking in deionized water, pre-soaking in salicylic acid, and without pre-soaking. The following parameters were evaluated: germination, germination speed index, seedling height, total phytomass, contents of chlorophyll ‘a’ and ‘b’, carotenoid content, electrolyte leakage, water content, and proline content. Our results indicate that salicylic acid promotes reduction in the harmful effects of abiotic stress, which is reflected in the increase in germination percentage, seedling height, and chlorophyll and carotenoid content as well as in the adjustment of electrolyte leakage and increase in proline content under induced water stress conditions. The cultivar BRS Guariba proved to be more tolerant to water deficit during germination and initial growth stages, when the seeds were treated with salicylic acid (1 mM).

ABSTRACT Cowpea is one of the major food crops in Northeast Brazil, where it is commonly cultivated in the semi-arid regions with limited water availability. It is important to study the elicitors associated with cowpea to mitigate any deleterious effects of abiotic stress on the initial establishment of this crop. In this study, we aimed to evaluate the morphophysiological changes in cowpea cultivars under osmotic stress with seeds soaked in salicylic acid. The germination test was conducted in B.O.D germination chambers. The seeds of three cowpea cultivars: BRS Tumucumaque, BRS Aracê, and BRS Guariba, were germinated at five osmotic potentials (0.0; -0.2; -0.4; -0.6, and -0.8 MPa) after three pre-treatments: pre-soaking in deionized water, pre-soaking in salicylic acid, and without pre-soaking. The following parameters were evaluated: germination, germination speed index, seedling height, total phytomass, contents of chlorophyll ‘a’ and ‘b’, carotenoid content, electrolyte leakage, water content, and proline content. Our results indicate that salicylic acid promotes reduction in the harmful effects of abiotic stress, which is reflected in the increase in germination percentage, seedling height, and chlorophyll and carotenoid content as well as in the adjustment of electrolyte leakage and increase in proline content under induced water stress conditions. The cultivar BRS Guariba proved to be more tolerant to water deficit during germination and initial growth stages, when the seeds were treated with salicylic acid (1 mM). | RESUMO O feijão-caupi é uma das principais culturas alimentares no Nordeste do Brasil, onde é geralmente cultivada nas regiões semiáridas com pouca disponibilidade de água. É importante estudar os elicitores associados ao caupi para mitigar os efeitos deletérios do estresse abiótico no estabelecimento inicial desta cultura. Neste estudo, buscaram-se avaliar as alterações morfofisiológicas em cultivares de caupi sob estresse osmótico com sementes embebidas em ácido salicílico. O teste de germinação foi realizado em câmaras de germinação B.O.D. As sementes de três cultivares de caupi: BRS Tumucumaque, BRS Aracê e BRS Guariba foram germinadas em cinco potenciais osmóticos (0,0; -0,2; -0,4; -0,6 e -0,8 MPa) após três pré-tratamentos: pré-imersão em Água desionizada, pré-imersão em ácido salicílico e sem pré-imersão. Foram avaliados os seguintes parâmetros: germinação, índice de velocidade de germinação, altura da plântula, fitometria total, conteúdo de clorofila 'a' e 'b', conteúdo de carotenóides, vazamento eletrolítico, teor de água e conteúdo de prolina. Os resultados indicam que o ácido salicílico promove a redução dos efeitos nocivos do estresse abiótico, o que se reflete no aumento da porcentagem de germinação, altura da plântula e teor de clorofila e carotenóides, bem como no ajuste do vazamento eletrolítico e aumento do teor de prolina sob condições de estresse hídrico. A cultivar BRS Guariba mostrou-se mais tolerante ao déficit de água durante a germinação e estágios de crescimento inicial, quando as sementes foram tratadas com ácido salicílico (1 mM).

New hybrid onions that are more productive are currently being cultivated. Information on growth and nutrient accumulation must thus be updated to assist in the refinement of existing recommendations, enabling the better exploitation of the productive potential of these new genotypes. We determined the growth of plants and the accumulation and export of nutrients of the short-day onion ‘Soberana’ established by direct seeding. The experimental design was a randomized block with four replicates and the treatments were evaluation times. Leaf number, tissue dry weight, nutrient accumulation, and the maximum daily rate of accumulation were evaluated throughout the growing cycle. The order of nutrient accumulation was (g plant-1) K (0.72) > Ca (0.38) > N (0.32) > S (0.14) > P (0.08) > Mg (0.06) and (mg plant-1) Fe (2.26) > Mn (1.43) > Cu (0.93) > Zn (0.91) > B (0.85). Macronutrient demand was highest between 61 and 148 days after sowing (DAS), and micronutrient demand was highest between 70 and 148 DAS.

ABSTRACT New hybrid onions that are more productive are currently being cultivated. Information on growth and nutrient accumulation must thus be updated to assist in the refinement of existing recommendations, enabling the better exploitation of the productive potential of these new genotypes. We determined the growth of plants and the accumulation and export of nutrients of the short-day onion ‘Soberana’ established by direct seeding. The experimental design was a randomized block with four replicates and the treatments were evaluation times. Leaf number, tissue dry weight, nutrient accumulation, and the maximum daily rate of accumulation were evaluated throughout the growing cycle. The order of nutrient accumulation was (g plant-1) K (0.72) > Ca (0.38) > N (0.32) > S (0.14) > P (0.08) > Mg (0.06) and (mg plant-1) Fe (2.26) > Mn (1.43) > Cu (0.93) > Zn (0.91) > B (0.85). Macronutrient demand was highest between 61 and 148 days after sowing (DAS), and micronutrient demand was highest between 70 and 148 DAS. | RESUMO Novos híbridos de cebola mais produtivos estão sendo cultivados atualmente. Assim, informações sobre o crescimento e absorção de nutrientes devem ser atualizadas para auxiliar no refinamento das recomendações existentes, possibilitando melhor explorar o potencial produtivo desses novos genótipos. Objetivou-se com o trabalho determinar o crescimento, acúmulo e exportação de nutrientes do híbrido de cebola Soberana no sistema de semeadura direta. O delineamento experimental foi o de blocos casualizados, com quatro repetições, onde os tratamentos foram épocas de avaliação. Avaliou-se o número de folhas, massa seca, acúmulo de nutrientes e a taxa máxima de acumulo diário. A sequência de acúmulo de nutrientes foi (g planta-1): K (0,72) > Ca (0,38) > N (0,32) > S (0,14) > P (0,08) > Mg (0,06) e (mg planta-1) Fe (2,26) > Mn (1,43) > Cu (0,93) > Zn (0,91) > B (0,85). A exigência máxima dos macronutrientes ocorreu entre 61 e 148 dias após a semeadura (DAS) e dos micronutrientes entre 70 e 148 DAS.

Safflower crops is usually intended for production of seeds to oil extraction. The objective of this work was to evaluate the chlorophyll index, biometric characteristics and water use efficiency of safflower plants grown under different nitrogen and potassium rates and controlled soil water tension. The experiment was conducted in a greenhouse, in pots containing 8 dm3 of a Oxisol. A complete randomized block experimental design in a 5x5 factorial arrangement was used, with four replications, consisting of five nitrogen rates (0, 60, 120, 180 and 240 mg dm-3) and five potassium rates (0, 50, 100, 150 and 200 mg dm-3). The safflower number of leaves, stem diameter, chlorophyll index, number of capitula, shoot, root and total dry weights, water consumption and water use efficiency were evaluated. Data were subjected to analysis of variance (F test) at 5% of probability and to polynomial regression. The nitrogen and potassium fertilization, as independent factors, affected the safflower plants. The chlorophyll index, biometric characteristics and water use efficiency of safflower showed better responses under nitrogen rates of 82 to 168 mg dm-3. The responses of chlorophyll index, biometric characteristics and water use efficiency of safflower increased 10 to 60% with potassium fertilization.

ABSTRACT Safflower crops is usually intended for production of seeds to oil extraction. The objective of this work was to evaluate the chlorophyll index, biometric characteristics and water use efficiency of safflower plants grown under different nitrogen and potassium rates and controlled soil water tension. The experiment was conducted in a greenhouse, in pots containing 8 dm3 of a Oxisol. A complete randomized block experimental design in a 5x5 factorial arrangement was used, with four replications, consisting of five nitrogen rates (0, 60, 120, 180 and 240 mg dm-3) and five potassium rates (0, 50, 100, 150 and 200 mg dm-3). The safflower number of leaves, stem diameter, chlorophyll index, number of capitula, shoot, root and total dry weights, water consumption and water use efficiency were evaluated. Data were subjected to analysis of variance (F test) at 5% of probability and to polynomial regression. The nitrogen and potassium fertilization, as independent factors, affected the safflower plants. The chlorophyll index, biometric characteristics and water use efficiency of safflower showed better responses under nitrogen rates of 82 to 168 mg dm-3. The responses of chlorophyll index, biometric characteristics and water use efficiency of safflower increased 10 to 60% with potassium fertilization. | RESUMO O cártamo destina-se à produção de grãos para a obtenção de óleo vegetal. Objetivou-se avaliar o índice de clorofila, as características biométricas e a eficiência no uso da água de plantas de cártamo sob doses de nitrogênio e potássio. O experimento foi conduzido em casa de vegetação, em vasos contendo 8 dm3 de um Latossolo Vermelho. O delineamento experimental foi blocos casualizados, com esquema fatorial 5x5 correspondente a cinco doses de nitrogênio (0, 60, 120, 180 e 240 mg dm-3) e cinco doses de potássio (0, 50, 100, 150 e 200 mg dm-3), com quatro repetições. Avaliou-se o número de folhas, diâmetro de caule, índice de clorofila, número de capítulos, massa seca da parte aérea, massa seca de raízes, massa seca total, consumo de água e eficiência no uso da água. Os dados foram submetidos a 5% de probabilidade de erro a análise de variância pelo teste F e regressão polinomial. O índice de clorofila, as características biométricas e a eficiência no uso da água das plantas de cártamo apresentaram melhores respostas nas doses de nitrogênio entre 82 a 168 mg dm-3. A adubação potássica nas plantas de cártamo proporcionou respostas crescentes com incrementos de 10 a 60% para o índice de clorofila, nas características biométricas e na eficiência de uso da água. As respostas a adubação com nitrogênio e potássio no cártamo ocorrem com efeito isolado.

Plasma technology is a fast, cost-effective, and pollution-free method that can be used in place of conventional methods to overcome seed dormancy. The goal of the present study was to determine the effect of different application times of atmospheric plasma on soaking and germination of Hybanthus calceolaria seeds in order to accelerate these processes. Helium plasma jet produced by dielectric barrier discharge was used to treat H. calceolaria seeds with applications of 1, 5, and 10 minutes. The treated seeds were characterized considering their weight variation during soaking, changes in electrical conductivity, and pH. It was found that germination depended on the plasma application time. The treatment of H. calceolaria seeds with atmospheric plasma for 1 minute provided 3.5 times greater germination in comparison to untreated seeds. Atmospheric plasma technology obtained by dielectric barrier discharge had potential of being used as a germination accelerant in H. calceolaria seeds. The treatment of H. calceolaria seeds using atmospheric plasma for 1 minute favored germination.

ABSTRACT Plasma technology is a fast, cost-effective, and pollution-free method that can be used in place of conventional methods to overcome seed dormancy. The goal of the present study was to determine the effect of different application times of atmospheric plasma on soaking and germination of Hybanthus calceolaria seeds in order to accelerate these processes. Helium plasma jet produced by dielectric barrier discharge was used to treat H. calceolaria seeds with applications of 1, 5, and 10 minutes. The treated seeds were characterized considering their weight variation during soaking, changes in electrical conductivity, and pH. It was found that germination depended on the plasma application time. The treatment of H. calceolaria seeds with atmospheric plasma for 1 minute provided 3.5 times greater germination in comparison to untreated seeds. Atmospheric plasma technology obtained by dielectric barrier discharge had potential of being used as a germination accelerant in H. calceolaria seeds. The treatment of H. calceolaria seeds using atmospheric plasma for 1 minute favored germination. | RESUMO A tecnologia de plasma constitui-se em um método rápido, econômico e livre de poluição que pode ser utilizada na superação de dormência de sementes em substituição aos métodos convencionais. O objetivo com esse estudo foi verificar o efeito do tempo de aplicação de plasma atmosférico sobre a embebição e germinação de sementes de Hybanthus calceolaria visando à aceleração destes processos. Jato de plasma de gás hélio, produzido por descarga em barreira dielétrica (DBD), foi utilizado para tratar as sementes de H. calceolaria por 1, 5 e 10 minutos de aplicação. As sementes tratadas foram caracterizadas quanto à variação de peso durante a embebição, variações da condutividade elétrica e pH. Verificou-se que a germinação depende do tempo de aplicação do plasma. O tratamento de sementes de H. calceolaria com plasma atmosférico por 1 min. proporcionou incremento na germinação de 3,5 vezes em comparação com as não tratadas. A tecnologia de plasma atmosférico, obtido por barreira dielétrica, apresenta potencial de utilização como acelerador da germinação de sementes de H. calceolaria. O tratamento de sementes de H. calceolaria à plasma atmosférico durante 1 minuto favorece a germinação.

Information about the response of onion to different potassium doses may contribute to optimizing the use of fertilizers and, consequently, make the activity more profitable and environmentally sustainable. In this context, the aim of this study was to evaluate the effects of doses of potassium on onion yields. Two field experiments were carried out in the periods of September to December 2012 and April to July 2013. The experimental design used was completely randomized blocks with four replications. The treatments corresponded to the potassium doses (0, 36, 72, 108, 144 and 180 kg ha-1 of K2O). Potassium fertilization promoted an increase in the content of K in the leaf, commercial and total yield, with the maximum obtained in the dose of 180 kg ha-1 of K2O. The maximum overall and commercial yields were respectively 54.69 and 54.12 t ha-1 in the experiment of September to December 2012 and 47.39 and 46.39 t ha-1 in that of April to July 2013.

ABSTRACT Information about the response of onion to different potassium doses may contribute to optimizing the use of fertilizers and, consequently, make the activity more profitable and environmentally sustainable. In this context, the aim of this study was to evaluate the effects of doses of potassium on onion yields. Two field experiments were carried out in the periods of September to December 2012 and April to July 2013. The experimental design used was completely randomized blocks with four replications. The treatments corresponded to the potassium doses (0, 36, 72, 108, 144 and 180 kg ha-1 of K2O). Potassium fertilization promoted an increase in the content of K in the leaf, commercial and total yield, with the maximum obtained in the dose of 180 kg ha-1 of K2O. The maximum overall and commercial yields were respectively 54.69 and 54.12 t ha-1 in the experiment of September to December 2012 and 47.39 and 46.39 t ha-1 in that of April to July 2013. | RESUMO Informações sobre a reposta da cebola a diferentes doses de potássio podem contribuir para a otimização do uso de fertilizantes e, consequentemente, tornar a atividade mais rentável e ambientalmente sustentável. Nesse contexto, o objetivo do trabalho foi avaliar os efeitos de doses de potássio na produtividade da cebola. Para isso dois experimentos de campo foram realizados nos períodos de setembro a dezembro de 2012 e abril a julho de 2013 O delineamento experimental foi em blocos casualizados completos com quatro repetições. Os tratamentos corresponderam às doses de potássio (0, 36, 72, 108, 144 e 180 kg ha-1 de K2O). A adubação potássica promoveu aumento do teor de K na folha, produtividade comercial total, com o máximo obtido na dose de 180 kg ha-1 de K2O. As produtividades máximas totais e comerciais foram respectivamente de 54,69 e 54,12 t ha-1 no experimento de setembro a dezembro de 2012 e 47,39 e 46,39 t ha-1 de abril a julho de 2013.