Electrical conductivity of soybean soaked seeds. I. Effect of genotype

During the period from October/92 to September/94 experiments were carried out at the Seed Laboratory, FCAV/UNESP, Jaboticabal, SP, Brazil, using soybean seeds of different genotypes in order to evaluate the effect of genotype on the electrical conductivity (bulk conductivity) of soaked seeds. Seed moisture content (105 ± 3°C, 24 h), standard germination (four 50-seed samples, paper towel, 30°C), and vigor-accelerated aging (42°C, 48 h) were first determined. Undamaged soybean seeds were soaked in deionized water (four 50-seed samples, 75 ml, 25°C, 24 h) and electrical conductivity (μmhos.cm+1.g+1) was measured. Significant differences in conductivity were observed among genotypes having the same pattern of germination and vigor. The results have showed that electrical conductivity can be significantly influenced by genotype.

Correlation of electrical conductivity and other vigor tests with field emergence of soybean seedlings

Seeds from six soybean cultivars (Cristalina, IAC 31-Foscarin, IAC-15, UFV-10, IAC-14 and IAS-5) and from five soybean cultivars (IAC 31-Foscarin, IAC-15, IAC-14, IAS-5 and Iguacu) were evaluated in 1993 and 1994, respectively, in terms of physiological seed quality by the mechanical damage (MD), standard germination (SG), accelerated aging (AA), electrical conductivity (EC), and seedling field emergence (FE) tests. Significant correlations were detected between SG, AA and EC and FE. However, in terms of the cultivar or the year, the degree of association among these parameters can change based on the environmental conditions of each year.

Potential use of the veris apparent EC sensor to predict soil texture under the semi-arid conditions of central Arizona

The operational details of the apparent electrical conductivity (ECa) sensor manufactured by Veris Technologies have been extensively documented in literature reports, but the geographical distribution of these research studies indicate a strong regional concentration in the US Mid-west and Southern states. The agricultural lands of these states diverge significantly to the soil conditions and water regime of irrigated land in the US South-western states such as Arizona where there is no previous research reports of the use of this particular sensor. The objectives of the present study were to analyze the performance of this sensor under the conditions of typical soils in irrigated farms of Central Arizona. We tested under static conditions the performance of the sensor on three soils of contrasting texture. Observations were collected as time series data as soil moisture changed from saturation to permanent wilting point. Observations were repeated at the hours of lowest and highest temperatures. In addition, this study included soil penetration resistance and salinity determinations. Preliminary results indicate that soil temperature of the upper layer caused the most dynamic change in the sensor output. The ECa curves of the three soil textures tested had well defined distinctive characteristics. Final multivariate analysis is pending.

Evaluation of electrical conductivity, pH and refractive index as physico-chemical parameters for quality control of Aveloz homeopathic solutions

Euphorbia tirucalli Lineu (Aveloz) belongs to the family Euphorbiaceae and is used in the treatment of cancer and warts. Some studies have reported that phorbol esters are the active principles responsible for the antitumor activity of Aveloz. The production of these molecules occurs in greater quantity in May, during the morning. This study aimed to evaluate whether the physico-chemical parameters of Aveloz homeopathic aqueous solutions such as pH, electrical conductivity and refractive index change due to storage time. Such parameters were measured regularly for 180 days. All solutions were prepared according to the method of grinding with lactose and subsequent dissolution in aqueous medium, as described in the Brazilian Homeopathic Pharmacopoeia, using as starting point the Aveloz latex collected in May. Homeopathic aqueous solutions containing only lactose were also prepared and evaluated as a control group. The potencies that were analyzed for electrical conductivity, pH and refractive index were: 4cH, 7cH, 9cH, 12cH, 14cH, 15cH, 29cH, 30cH. As a result, we found out that there was only statistical difference (p=0.035) in electrical conductivity between the homeopathic solutions containing Aveloz and the homeopathic solutions without Aveloz, when 15cH potency was compared. We also observed that the electrical conductivity increased with the aging of the solutions but is not directly related to the pH or the refractive index of the solutions, indicating that the aging process may alter the electrical conductivity of the homeopathic medicines. The presence of gas inside the glass that stores these solutions may affect the electrical conductivity measurements. Finally, no statistically significant difference was observed (p> 0.05) in the pH and refractive index.

Alterations in levels of NPK, electrical conductivity and pH of substrate, in cultivation of peppers

The objective of this work was to evaluate the chemical alterations of the substrate in the cultivation of pepper in coconut husk fiber, in a protected environment. Initially, 160 pepper plants ('Eppo') were divided into four blocks, where two pots per block were analyzed every 21 days after transplanting. The cultivation of pepper was carried out in plastic pots of 13 L, containing coconut husk fiber, and placed in double rows with a spacing of 0.5×0.8 m between single rows and 1.10 m between double rows. After removal of the plants from the pots, individual samples of substrate (approximately 1 L) were collected from each pot and dried at ambient temperature. Electrical conductivity (EC), pH, and levels of NH4 +-N, NO3 -, P and K were determined for all periods of the cultivation. These analyses were performed using the method of extraction 1:1.5 v/v. For the conditions which the experiment was conducted, there was an increase in substrate EC, as well as in the levels of nitrogen, phosphorus and potassium.

Nutritional status of the potted chrysanthemum relative to electrical conductivity and salt leaching

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Portable meters for nutritional assessment in plants of gerbera fertigated with electrical conductivity levels

Rapid tests to assess the nutritional status of plants gerbera can make easier the decision of any adjustments in the fertilization of the substrate. The study was conducted to evaluate nutritionally fertigated gerbera plants with increasing levels of electrical conductivity (EC), using portable meters nitrate and potassium, and chlorophyll. For this, two experiments were conducted. A randomized block design with five levels of EC (0.5, 2.0, 3.5, 5.0 and 6.5 dS m-1) and four replications was used. Cherry cultivar was used in the first experiment. In the second experiment, two cultivars (Cherry and Salmon Rose) were used. In the first experiment, the sap of the leaves was subjected to rapid testing of N-NO3- (equipment Cardy Horiba C -141). N-NO3- and K+ (C-131) were determined in the substrate solution. The intensity of the green leaf, in the second experiment was evaluated with portable Chlorophyll Meter. The N content in the indicator leaf in the first and N and K contents in the plant in the second experiment were determined. Rapid tests are presented as good indicators of the level of N-NO3- and K+ in plant tissue, with the advantages of convenience and speed of determination, facilitating monitoring of fertilization of the substrate by producers and technicians.

Electrical conductivity and pH of the substrate solution in gerbera cultivars under fertigation

The quality and the profitability on floriculture are intimately linked to the adequate plant nutrition. In the present research we aimed to evaluate the electrical conductivity (EC) and pH of the substrate solution on four different gerbera cultivars subjected to fertigation, with two nutritive solutions. The experiment was carried out in a greenhouse, from May to July 2006, on the Universidade Estadual Paulista, Botucatu, São Paulo state, Brazil. The experiment was carried out under an experimental design of random blocks, in 4×2 factorial arrangement, with four Gerbera cultivars (Cherry, Golden Yellow, Salmon Rose and Orange) and two nutritive solution concentrations: 0.92 and 1.76 dS m-1 EC) during the vegetative stage, and 1.07 and 2.04 dS m-1 during the reproductive stage (S1 and S2, respectively). The nutrients were applied through fertigation, manually performed every day. The EC and pH values of the substrate solution were evaluated weekly, using the 'pourthru' method. Orange and Cherry cultivars had, respectively, the highest and the lowest electrical conductivity of the substrate solution, and Cherry was the most efficient on the nutrient uptake. The solution S2 showed a trend to accumulate salts in the substrate, but without visual symptoms of plant toxicity, leading to the lowest pH values. The 'pourthru' method was efficient when compared to the 1:2 method and can be adopted for substrate solution analysis in gerbera culture.

Density, Refractive Index, Apparent Specific Volume, and Electrical Conductivity of Aqueous Solutions of Poly(ethylene glycol) 1500 at Different Temperatures

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Electrical conductivity of Ag-Na ion exchanged soda-lime glass

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

New method to assess the pozzolanic reactivity of mineral admixtures by means of pH and electrical conductivity measurements in lime:pozzolan suspensions

A very simple method based on electrical conductivity and pH measurements was proposed for assessing reactivity of pozzolans. Calcium hydroxide: pozzolan water suspensions were monitored by means of measurements of electrical conductivity and pH values. In these suspensions, Ca(OH)(2) in solid state was initially present, being them, thus, saturated in this reagent. Three testing temperatures were selected (40, 50 and 60 degrees C). In the experiments carried out, calcium hydroxide was suspended in deionized water for yielding a lime saturated suspension. The addition of siliceous pozzolan (two types of rice husk ash RHA and two types of densified silica fume DSF were tested) to the saturated lime suspension can produce the unsaturation of the system, depending on the testing time, testing temperature and reactivity of pozzolan. When unsaturation was reached, the loss of electrical conductivity was higher than 30% and the variation of pH was higher than 0.15 units. These threshold values were selected for characterizing the reactivity of pozzolans by means of a proposed template, classifying the pozzolan in three different reactivity levels.

Accelerated aging and electrical conductivity tests in crambe seeds

The aim of this study was to adapt the methodology of the accelerated aging and electrical conductivity tests for determination of physiological potential in crambe seeds. Six seed lots of crambe (cv. FMS Brilhante) were subjected to determination of moisture content, germination test, first count germination, emergence, and emergence speed index. For the accelerated aging test, the traditional methodology was used with water, and with a saturated potassium chloride and sodium chloride solution in three periods of exposure (24, 48, and 72 hours) at 41 degrees C; the electrical conductivity test was performed with four pre-soaking treatments (0, 2, 4, and 8 hours) and four soaking periods (4, 8, 16, and 24 hours) at 25 degrees C. The accelerated aging test with water for 72 hours and the electrical conductivity test with 2 hours of pre-soaking and assessment after 16 hours were effective for classification of the crambe seed lots in regard to physiological quality.

Influence of the deposition parameters on the morphology and electrical conductivity of PANI/PSS self-assembled films

The influence of deposition parameters, namely polymer concentration and pH of the deposition solution, cleaning, and drying steps on the morphology and electrical characteristics of polyaniline and sulfonated polystyrene (PANI/PSS) nanostructured films deposited by the self-assembly technique is evaluated by UV-Vis spectroscopy, optical and atomic force microscopy, and electrical resistance measurements. It is found that stirring the cleaning solution during the cleaning step is crucial for obtaining homogenous films. Stirring of the cleaning solution also influences the amount of PANI adsorbed in the films. In this regard, the drying process seems to be less critical since PANI amount and film thickness are similar in films dried with N-2 flow or with an absorbent tissue. It is observed, however, that drying with N-2 flow results in rougher films. As an additional point, an assessment of the influence of the deposition method (manual versus mechanical) on the film characteristics was carried out. A significant difference on the amount of PANI and film thickness between films prepared by different human operators and by a homemade mechanical device was observed. The variability in film thickness and PANI adsorbed amount is smaller in films mechanically assembled. (c) 2007 Elsevier B.V. All rights reserved.

On the electrical conductivity of Ti-implanted alumina

Ion implantation of metal species into insulators provides a tool for the formation of thin, electrically conducting, surface layers with experimenter-controlled resistivity. High energy implantation of Pt and Ti into alumina accelerator components has been successfully employed to control high voltage surface breakdown in a number of cases. In the work described here we have carried out some basic investigations related to the origin of this phenomenon. By comparison of the results of alumina implanted with Ti at 75 keV with the results of prior investigations of polymers implanted with Pt at 49 eV and Au at 67 eV, we describe a physical model of the effect based on percolation theory and estimate the percolation parameters for the Ti-alumina composite. We estimate that the percolation dose threshold is about 4 x 10(16) cm(-2) and the maximum dose for which the system remains an insulator-conductor composite is about 10 x 10(16) cm(-2). The saturation electrical conductivity is estimated to be about 50 S/m. We conclude that the observed electrical conductivity properties of Ti-implanted alumina can be satisfactorily described by percolation theory. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.3697900]

Electrical conductivity of silicate glasses with tetravalent cations substituting Si

The effects of substituting Si by M4+ cations in soda-lime silica glasses were analyzed by impedance spectroscopy in the frequency range of 1 Hz-1 MHz. The glass composition was (mol%) 22Na(2)O center dot 8CaO center dot 65SiO(2)center dot 5MO(2), M = Si, Ti, Ge, Zr, Sn, and Ce. Although the Na+ concentration in the glasses is constant, the Zr-containing glass exhibits the highest dc conductivity and the lowest activation energy, while the Ce-containing glass exhibits the lowest conductivity. The activation energies obtained experimentally agree with those obtained by a theoretical equation proposed by Anderson and Stuart. The differences in electrical conductivity presented by the several M-containing glasses are attributed to the effect that the M4+ ion has on the mobility of the diffusing Na+ ion. (C) 2012 Elsevier B.V. All rights reserved.