425 resultados para velocity electrical conductivity


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O excesso de sais no solo e em águas utilizadas para irrigação podem provocar perdas significativas de crescimento e de produção em plantas cultivadas. Dentre algumas alternativas para redução dos efeitos negativos dos sais às plantas em áreas cultivadas, a utilização do biofertilizante fermentado vem sendo explorada no cultivo de hortaliças e frutíferas irrigadas com água salina. Nesse sentido, o trabalho teve como objetivo avaliar o comportamento do noni à salinidade da água de irrigação em substrato sem e com biofertilizante bovino. Os tratamentos foram distribuídos em blocos ao acaso, com quatro repetições, utilizando o arranjo fatorial 5 x 2, correspondente a cinco níveis de condutividade elétrica da água de irrigação (0,5; 1,5; 3,0; 4,5; 6,0 dS m-1), em substratos com e sem biofertilizante bovino. Foram avaliados: altura de plantas, diâmetro do caule, número de folhas, área foliar, matéria seca da parte aérea e consumo hídrico. Todas as variáveis avaliadas foram influenciadas negativamente pelo incremento de sais na água de irrigação, mas sempre com menor intensidade nos tratamentos com biofertilizante bovino. O biofertilizante não elimina, mas atenua os efeitos negativos dos sais às plantas de noni.

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O tratamento de esgotos sanitários e o seu posterior reúso, tornou-se uma alternativa viável para a irrigação, atividade que utiliza em torno de 70 % de toda a água consumida no planeta. Nesse sentido, o objetivo deste estudo foi monitorar durante todo o ciclo do trigo, os teores de Ferro e Manganês, bem como valores de pH e condutividade elétrica da água residuária utilizada para irrigação da cultura por gotejamento. A água residuária utilizada no estudo foi proveniente da Estação de Tratamento de Esgotos (ETE) da cidade de Botucatu-SP. No período de maio a outubro de 2011 a amostragem da água residuária foi realizada semanalmente, na saída da ETE. Foram determinados os seguintes parâmetros: Boro (B), Cobre (Cu), Ferro (Fe), Manganês (Mn) e Zinco (Zn), segundo metodologia adaptada de Malavolta et al. (1997). O pH e a condutividade elétrica (CE) foram determinados com auxilio de um pHmetro e condutivímetro, respectivamente. Não foi observado teores de Fe e Mn e valores de pH que comprometessem o sistema de irrigação, ou seja, que apresentasse alto potencial de risco de obstrução de tubulações e emissores (gotejamento). Os valores de CE indicam que a água residuária pode ser usada no solo, sempre que houver grau elevado de lixiviação, sem maior comprometimento das culturas.

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Pós-graduação em Agronomia (Agricultura) - FCA

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Pós-graduação em Agronomia (Energia na Agricultura) - FCA

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The aim of this study was to adapt the methodology of electrical conductivity (EC) test and determine the physiological quality of seeds of B. virgilioides. Seeds were separated into three batches according to tegument color (1-yellow, 2-orange, and 3-red/black). The EC test analyzed three quantities of seeds (25, 50 and 100), three volumes of water (25, 50 and 100 mL), and six times of seed imbibition (12, 24, 36, 48, 60 and 72), at 25 °C with 6 replications. Germination test was employed to compare the results. The EC test allowed the differentiation of batches in three levels of vigor - the same was observed in germination test: batch 1 presented the best seed vigor, followed by batches 2 and 3. The use of 25, 50 or 100 seeds imbibed in 50 mL of water for 24 hours is recommended.

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Physiological potential characterization of seed lots is usually performed by germination and vigor tests; however, the choice of a single test does not reflect such potential, once each test assesses seeds of differentiated mode. Multivariate techniques allow understanding structural dependence contained in each variable, as well as characterize groups of seed lots according to specific standards. The study aimed at evaluating variability among soybean seed lots and discriminate these lots by multivariate exploratory techniques as function of seed vigor. Experiment was performed with 20 soybean seed lots (10 lots cv. BRS Valiosa RR and 10 lots cv. M-SOY 7908 RR). Seed physiological potential was assessed by testing for: germination (standard, and under different water availability); vigor (accelerated aging and electrical conductivity); and field seedling emergence. Cluster analysis of seed lots, as well as Principal Component Analysis was performed using data obtained on all tests. Multivariate techniques allowed stratifying seed lots into two distinct groups. Principal Component Analysis showed that values obtained for variables: field seedling emergence, accelerated aging, and germination under different water availability were linked to BRS Valiosa RR; while to variables germination and electrical conductivity, were linked to M-SOY 7908 RR.

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The efficiency of vigor tests in assessing the physiological potential of seeds depends on their standardization for different species. In this context, the research aimed to study specific methodologies to evaluate the vigor of spinach seeds (Tetragonia tetragonoides). For this purpose, five lots of spinach seed cv. New Zealand were submitted to germination, first count of germination, seedling emergence in the field, accelerated aging (with and without use of saturated solution of NaCl at 41and 45 ºC for 24,48 and 72 hours), controlled deterioration (18,21 and 24% seed water content adjustments for 24 hours at 45 ºC) and electrical conductivity tests with variations inwater volume (25, 50 and 75 mL), seed quantity (25 and 50) and soaking period (1, 2, 4, 8,12, 16 and 24 hours) at 25 ºC. The first count test allowed obtaining preliminary information about seed vigor, and other tests in general showed similarity with seedling emergence in the field. Thus, it was concluded that traditional accelerated aging test 24 h /41 ºC and accelerated aging test with saturated salt solution for 24 h at 41 ºC and 45 ºC, and controlled deterioration test with 21% seed water content / 24 h / 45 ºC were all efficient for evaluating the physiological potential of spinach seeds.

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O objetivo deste trabalho foi avaliar os efeitos da adubação com fósforo e potássio na produção e na qualidade de sementes de soja. Foram realizados experimentos em dois anos agrícolas, em delineamento de blocos ao acaso, em arranjo fatorial 5x3, com cinco doses de fósforo (0, 40, 80, 120 e 160 kg ha‑1 de P2O5 como superfosfato triplo), três de potássio (0, 50 e 100 kg ha‑1 de K2O como cloreto de potássio) e quatro repetições. Foram avaliados: produtividade, número de sementes por planta, número de vagens por planta, peso de mil sementes, germinação, vigor (envelhecimento acelerado, condutividade elétrica e lixiviação de potássio), e teores de P e K na folha e na semente. A produtividade, o peso de mil sementes e a produção de vagens e de grãos por planta aumentaram linearmente com a adubação fosfatada. O aumento na produtividade foi de 17,6%, no primeiro ano, e de 39,7% no segundo. As doses de P, no entanto, não interferiram na germinação e no vigor das sementes. A adubação potássica não altera a produtividade nem a concentração de K nas sementes, mas pode melhorar a germinação, sem interferir no vigor.

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Pós-graduação em Agronomia (Agricultura) - FCA

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Pós-graduação em Agronomia (Energia na Agricultura) - FCA

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Pós-graduação em Engenharia Civil - FEIS

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The influence of tilapia cages on limnological characteristics of the Chavantes Reservoir, Paranapanema River, Brazil, was investigated in March and June 2007. Principal components analysis was used to compare the transparency; dissolved oxygen; temperature; total organic nitrogen, phosphorus, and dissolved solids; chlorophyll aand electrical conductivity of fish farm 1 (239.3m.t.), 2 (461.5m.t.) and areas without cages, in the lacustrine and river-reservoir transition regions. The variables differentiated the regions and areas with and without cages. In March, in the lacustrine region, there was a thermal and chemical stratification, and in the transition region, there was a temperature and oxygen reduction gradient between the surface and bottom that was also observed in June in fish farm 1. The higher transparency confirmed the increased light penetration in the lacustrine region. In the transition region, there were higher turbidity, total dissolved solid, and conductivity values that are likely related to allochthonous material flow and transport. In fish farms, lower oxygen and pH values indicate intense decomposition and respiration. The generally higher total dissolved solid and nutrient values, turbidity, and conductivity and the lower transparency in one or both fish farms indicate their contribution to eutrophication, demonstrating the need for careful monitoring.

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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In different crops, the seeds treatment with the use of fungicides and/or insecticides has been performed before the storage or in the seeding moment as a guarantee form of longer conservation period and adequate initial stand. However, it is not known if the various products used for the treatment interfere with test results of electrical conductivity of corn seeds. The experimental design was completely randomized and the analysis carried out in a factorial 5x5x2 with four replications. The treatments consisted of five cultivars of corn (DKB 390YG, DKB 185YG, 2B710, AGN-30A91HX and AL Bandeirante) treated with four insecticides (imidacloprid+thiodicarbe, thiamethoxam, fipronil, fipronil+piraclostrobin+thiophanate-methyl), and the control previously treated by the company with fungicides (fludioxonil+metalaxyl-M e captan) and insecticides (pirimiphos-methyl, deltamethrin e bifenthrin), analyzed in two different times (after treatment and at 35 days of storage). Seeds were subjected to tests of germination, electrical conductivity and water content. The results showed that the treatment of corn seeds with insecticides and fungicides doesn't interfere on the test results of electric conductivity, even if the analysis is made after 35 days of storage of seeds.

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Lithium ion conducting polymer electrolytes based on polyvinyl Alcohol (PVA-OH) complexed with salt Li2SO4 and different weight percent ratios of PEG(400) plasticizer have been prepared by solution cast technique using deionized water as solvent. The thermogravimetric analysis (TGA) showed that the thermal stability of the materials depended on the plasticizer content. The FTIR study confirmed the polymer salt complex formation. The modulus spectra indicated the non-Debye nature of the material; a dominant relaxation process is visible being associated with the dynamic glass transition, relaxation-a. The maximum of each peak is shifted to higher frequencies as the plasticizer increases due to an enhancement of dipolar mobility in the origin of cooperative motions. A power law frequency dependence of the real part of the electrical conductivity is observed, which is characteristic of the effects of ion-ion and/or ion-chain correlations in ion motion. This variation is well fitted to a Jonscher's expression.