Archive for June, 2013

Basics of Wastewater and Sewage Treatment – MyronLMeters.com

Posted by 10 Jun, 2013

TweetWastewater is treated in 3 phases: primary (solid removal), secondary (bacterial decomposition), and tertiary (extra filtration). fig. 1 Origins of Sewage Sewage is generated by residential and industrial establishments. It includes household waste liquid from toilets, baths, showers, kitchens, sinks, and so forth that is disposed of via sewers. In many areas, sewage also includes […]

Wastewater is treated in 3 phases: primary (solid removal), secondary (bacterial decomposition), and tertiary (extra filtration).

fig. 1

Origins of Sewage

Sewage is generated by residential and industrial establishments. It includes household waste liquid from toilets, baths, showers, kitchens, sinks, and so forth that is disposed of via sewers. In many areas, sewage also includes liquid waste from industry and commerce. The separation and draining of household waste into greywater and blackwater is becoming more common in the developed world. Greywater is water generated from domestic activities such as laundry, dishwashing, and bathing, and can be reused more readily. Blackwater comes from toilets and contains human waste.

Sewage may include stormwater runoff. Sewerage systems capable of handling storm water are known as combined sewer systems. This design was common when urban sewerage systems were first developed, in the late 19th and early 20th centuries.  Combined sewers require much larger and more expensive treatment facilities than sanitary sewers. Heavy volumes of storm runoff may overwhelm the sewage treatment system, causing a spill or overflow. Sanitary sewers are typically much smaller than combined sewers, and they are not designed to transport stormwater. Backups of raw sewage can occur if excessive infiltration/inflow (dilution by stormwater and/or groundwater) is allowed into a sanitary sewer system. Communities that have urbanized in the mid-20th century or later generally have built separate systems for sewage (sanitary sewers) and stormwater, because precipitation causes widely varying flows, reducing sewage treatment plant efficiency.

As rainfall travels over roofs and the ground, it may pick up various contaminants including soil particles and other sediment, heavy metals, organic compounds, animal waste, and oil and grease. (See urban runoff.)[5] Some jurisdictions require stormwater to receive some level of treatment before being discharged directly into waterways. Examples of treatment processes used for stormwater include retention basins, wetlands, buried vaults with various kinds of media filters, and vortex separators (to remove coarse solids).

Sewage treatment is done in three stages: primary, secondary and tertiary treatment (Figure 1).

Primary Treatment
In primary treatment, sewage is stored in a basin where solids (sludge) can settle to the bottom and oil and lighter substances can rise to the top. These layers are then removed and then the remaining liquid can be sent to secondary treatment. Sewage sludge is treated in a separate process called sludge digestion.

Secondary Treatment
Secondary treatment removes dissolved and suspended biological matter, often using microorganisms in a controlled environment. Most secondary treatment systems use aerobic bacteria, which consume the organic components of the sewage (sugar, fat, and so on). Some systems use fixed film systems, where the bacteria grow on filters, and the water passes through them. Suspended growth systems use “activated” sludge, where decomposing bacteria are mixed directly into the sewage. Because oxygen is critical to bacterial growth, the sewage is often mixed with air to facilitate decomposition.

Tertiary Treatment
Tertiary treatment (sometimes called “effluent polishing”) is used to further clean water when it is being discharged into a sensitive ecosystem. Several methods can be used to further disinfect sewage beyond primary and secondary treatment. Sand filtration, where water is passed through a sand filter, can be used to remove particulate matter. Wastewater may still have high levels of nutrients such as nitrogen and phosphorus. These can disrupt the nutrient balance of aquatic ecosystems and cause algae blooms and excessive weed growth. Phosphorus can be removed biologically in a process called enhanced biological phosphorus removal. In this process, specific bacteria, called polyphosphate accumulate organisms that store phosphate in their tissue. When the biomass accumulated in these bacteria is separated from the treated water, these biosolids have a high fertilizer value. Nitrogen can also be removed using nitrifying bacteria. Lagooning is another method for removing nutrients and waste from sewage. Water is stored in a lagoon and native plants, bacteria, algae, and small zooplankton filter nutrients and small particles from the water.

Sludge Digestion & Disposal
Sewage sludge scraped off the bottom of the settling tank during primary treatment is treated separately from wastewater. Sludge can be disposed of in several ways. First, it can be digested using bacteria; bacterial digestion can sometimes produce methane biogas, which can be used to generate electricity. Sludge can also be incinerated, or condensed, heated to disinfect it, and reused as fertilizer.

When a liquid sludge is produced, further treatment may be required to make it suitable for final disposal. Sewage sludge scraped off the bottom of the settling tank during primary treatment is treated separately from wastewater. Sludge can be disposed of in several ways. First, it can be digested using bacteria; bacterial digestion can sometimes produce methane biogas, which can be used to generate electricity. Sludge can also be incinerated, or condensed, heated to disinfect it, and reused as fertilizer.

Typically, sludges are thickened (dewatered) to reduce the volumes transported off-site for disposal. There is no process which completely eliminates the need to dispose of biosolids. There is, however, an additional step some cities are taking to superheat sludge and convert it into small pelletized granules that are high in nitrogen and other organic materials. In New York City, for example, several sewage treatment plants have dewatering facilities that use large centrifuges along with the addition of chemicals such as polymer to further remove liquid from the sludge. The removed fluid, called “centrate,” is typically reintroduced into the wastewater process. The product which is left is called “cake,” and that is picked up by companies which turn it into fertilizer pellets. This product is then sold to local farmers and turf farms as a soil amendment or fertilizer, reducing the amount of space required to dispose of sludge in landfills. Much sludge originating from commercial or industrial areas is contaminated with toxic materials that are released into the sewers from the industrial processes. Elevated concentrations of such materials may make the sludge unsuitable for agricultural use and it may then have to be incinerated or disposed of to landfill.

Notably, throughout the development of excreta, wastewater, wastewater sludge and biosolids management – from the least developed to the most developed countries – there are in­evitable public concerns about how best to manage this “waste” that is also a resource. Putting biosolids to their best uses in each local situation is the goal of most of the programs discussed in the following reports. That is the goal of many sanitation and water quality experts. But the general public has other goals: avoiding the waste and the odors it can produce.There is a natural aversion to fecal matter and anything associated with it. Conflicts arise when experts propose recycling this “waste,” usually in a treated and tested form commonly called “biosolids,” back to soils in communities.

Managing excreta and wastewater sludge to produce recyclable biosolids involves many technical challenges. But equally significant are these social, cultural, and political challenges. Funding is required to build infrastructure – and, around the world, the public is the source of funding, either through taxes or sewer usage fees. In order for proper sanitation to be built and operated, complex community sanitation agencies with support from state, provincial, and national governments are needed.

Wastewater quality indicators are laboratory tests to assess suitability of wastewater for disposal or re-use. Tests selected and desired test results vary with the intended use or discharge location. Tests measure physical, chemical, and biological characteristics of the wastewater.

Physical characteristics

Temperature
Aquatic organisms cannot survive outside of specific temperature ranges. Irrigation runoff and water cooling of power stations may elevate temperatures above the acceptable range for some species. Temperature may be measured with a calibrated thermometer.

Solids
Solid material in wastewater may be dissolved, suspended, or settleable. Total dissolved solids or TDS (sometimes called filtrable residue) is measured as the mass of residue remaining when a measured volume of filtered water is evaporated. The mass of dried solids remaining on the filter is called total suspended solids (TSS) or nonfiltrable residue. Settleable solids are measured as the visible volume accumulated at the bottom of an Imhoff cone after water has settled for one hour. Turbidity is a measure of the light scattering ability of suspended matter in the water. Salinity measures water density or conductivity changes caused by dissolved materials.

Chemical characteristics
Virtually any chemical may be found in water, but routine testing is commonly limited to a few chemical elements of unique significance.

Hydrogen
Water ionizes into hydronium (H3O) cations and hydroxyl (OH) anions. The concentration of ionized hydrogen (as protonated water) is expressed as pH.

Oxygen
Most aquatic habitats are occupied by fish or other animals requiring certain minimum dissolved oxygen concentrations to survive. Dissolved oxygen concentrations may be measured directly in wastewater, but the amount of oxygen potentially required by other chemicals in the wastewater is termed an oxygen demand. Dissolved or suspended oxidizable organic material in wastewater will be used as a food source. Finely divided material is readily available to microorganisms whose populations will increase to digest the amount of food available. Digestion of this food requires oxygen, so the oxygen content of the water will ultimately be decreased by the amount required to digest the dissolved or suspended food. Oxygen concentrations may fall below the minimum required by aquatic animals if the rate of oxygen utilization exceeds replacement by atmospheric oxygen.

The reaction for biochemical oxidation may be written as:
Oxidizable material + bacteria + nutrient + O2 → CO2 + H2O + oxidized inorganics such as NO3 or SO4
Oxygen consumption by reducing chemicals such as sulfides and nitrites is typified as follows:

S– + 2 O2 → SO4–
NO2- + ½ O2 → NO3-

Since all natural waterways contain bacteria and nutrient, almost any waste compounds introduced into such waterways will initiate biochemical reactions (such as shown above). Those biochemical reactions create what is measured in the laboratory as the biochemical oxygen demand (BOD).

Oxidizable chemicals (such as reducing chemicals) introduced into a natural water will similarly initiate chemical reactions (such as shown above). Those chemical reactions create what is measured in the laboratory as the chemical oxygen demand (COD).

Both the BOD and COD tests are a measure of the relative oxygen-depletion effect of a waste contaminant. Both have been widely adopted as a measure of pollution effect. The BOD test measures the oxygen demand of biodegradable pollutants whereas the COD test measures the oxygen demand of biogradable pollutants plus the oxygen demand of non-biodegradable oxidizable pollutants.

The so-called 5-day BOD measures the amount of oxygen consumed by biochemical oxidation of waste contaminants in a 5-day period. The total amount of oxygen consumed when the biochemical reaction is allowed to proceed to completion is called the Ultimate BOD. The Ultimate BOD is too time consuming, so the 5-day BOD has almost universally been adopted as a measure of relative pollution effect.
There are also many different COD tests. Perhaps, the most common is the 4-hour COD.

There is no generalized correlation between the 5-day BOD and the Ultimate BOD. Likewise, there is no generalized correlation between BOD and COD. It is possible to develop such correlations for a specific waste contaminant in a specific wastewater stream, but such correlations cannot be generalized for use with any other waste contaminants or wastewater streams.

The laboratory test procedures for the determining the above oxygen demands are detailed in the following sections of the “Standard Methods For the Examination Of Water and Wastewater” available at www.standardmethods.org:

5-day BOD and Ultimate BOD: Sections 5210B and 5210C
COD: Section 5220

Nitrogen
Nitrogen is an important nutrient for plant and animal growth. Atmospheric nitrogen is less biologically available than dissolved nitrogen in the form of ammonia and nitrates. Availability of dissolved nitrogen may contribute to algal blooms. Ammonia and organic forms of nitrogen are often measured as Total Kjeldahl Nitrogen, and analysis for inorganic forms of nitrogen may be performed for more accurate estimates of total nitrogen content.

Chlorine
Chlorine has been widely used for bleaching, as a disinfectant, and for biofouling prevention in water cooling systems. Remaining concentrations of oxidizing hypochlorous acid and hypochlorite ions may be measured as chlorine residual to estimate effectiveness of disinfection or to demonstrate safety for discharge to aquatic ecosystems.

Biological characteristics
Water may be tested by a bioassay comparing survival of an aquatic test species in the wastewater in comparison to water from some other source. Water may also be evaluated to determine the approximate biological population of the wastewater. Pathogenic micro-organisms using water as a means of moving from one host to another may be present in sewage. Coliform index measures the population of an organism commonly found in the intestines of warm-blooded animals as an indicator of the possible presence of other intestinal pathogens.

Myron L Meters is the premier online retailer of the Myron L meters preferred by water professionals, like the Ultrameter III 9PTKA.

Information shared via Attribution-ShareAlike 3.0 Unported (CC BY-SA 3.0), original material found here:

https://www.boundless.com/microbiology/industrial-microbiology/wastewater-treatment-and-water-purification/wastewater-and-sewage-treatment/

https://en.wikipedia.org/wiki/Sewage_treatment

http://www.iwawaterwiki.org/xwiki/bin/view/Articles/GLOBALATLASOFEXCRETAWASTEWATERSLUDGEANDBIOSOLIDSMANAGEMENTMOVINGFORWARDTHESUSTAINABLEANDWELCOMEUSESOFAGLOBALRESOURCE

 

Categories : Case Studies & Application Stories, Science and Industry Updates

Electrical Conductivity Testing Applied to the Assessment of Freshly Collected Kielmeyera coriacea Mart. Seeds: MyronLMeters.com

Posted by 4 Jun, 2013

Tweet  MyronLMeters.com brings you the latest in conductivity measurement research like the article below.  Please click here for accurate, reliable, conductivity meters. Abstract Assessment of seed vigor has long been an important tool of seed quality control programs. The conductivity test is a promising method for assessment of seed vigor, but proper protocols for its […]

 

MyronLMeters.com brings you the latest in conductivity measurement research like the article below.  Please click here for accurate, reliable, conductivity meters.

Abstract

Assessment of seed vigor has long been an important tool of seed quality control programs. The conductivity test is a promising method for assessment of seed vigor, but proper protocols for its execution have yet to be established. The objective of this study was to assess the efficiency of electrical conductivity (EC) testing as a means of assessing the viability of freshly collected Kielmeyera Coriacea Mart. seeds. The test was performed on individual seeds rather than in a bulk configuration. Seeds were soaked for different periods (30 min, 90 min, 120 min., 180 min, and 240 min) at a constant temperature of 25°C. Conductivity was then measured with a benchtop EC meter.

1. Introduction

Seeds are the primary factor of the seedling production process, despite their minor contribution to the end cost of each seedling. In order to estimate the success rate of seedling production, it is essential that seed characteristics such as vigor and germinability be known [1].

The importance of knowing the characteristics of Brazilian forest species to safer and more objective management of seedling production cannot be overstated. However, such studies are scarce, particularly in light of the vast number of species with this potential [2]. Given the intensity of anthropogenic pressure and the importance of rehabilitating disrupted or degraded environments, in-depth research of forest species is warranted.

Routine methods used for determination of seed quality and viability include germination testing and the tetrazolium test. Methods such as measurement of soak solution pH, electrical conductivity, and potassium content of leachate, all based on the permeability of the cell membrane system, are increasingly being employed in the assessment of seed vigor, as they are reliable and fast and can thus speed the decision making process.

Electrical conductivity testing, as applied to forest seeds, has yet to be standardized. Studies conducted thus far have focused on assessment of seed soaking times, which may range from 4 to 48 hours. Even at 48 hours, the conductivity test is considered a rapid technique as compared to the germination test, which, despite its status as a widespread and firmly established method, can take anywhere from 30 to 360 days to yield results (depending on species), and is limited by factors such as dormant seeds.

The total concentration of electrolytes leached by seeds during soaking has long been assessed indirectly, mostly through the conductivity test, which takes advantage of the fact that inorganic ions make up a substantial portion of these electrolytes [3–5].

Rapid assessment of seed quality allows for preemptive decision-making during harvest, processing, sale and storage operations, thus optimizing use of financial resources throughout these processes.

K. coriacea Mart. is a species of the Clusiaceae (Guttiferae) family popularly known in Brazil as pau-santo (Portuguese for “holy wood”), due to its properties as a medicinal and melliferous plant and as a source of cork. In traditional Brazilian medicine, the leaves are used as an emollient and antitumor agent, and the resin as a tonic and in the treatment of toothache and various infections. The fruits are used in regional crafts and flower arrangements. Even if the dye is of the leaves and bark. The trunk provides cork [6].

K. coriaceae specimens grow to approximately 4 meters in height. The flowering period extends from January to April and the fruiting period from May to September, and seed collection can take place from September onwards. Leaves are alternate, simple, oval to elliptical, coriaceous, and clustered at the end of the branches, and feature highly visible, pink midribs. A white to off-white latex is secreted in small amounts upon removal of leaves. Flowers are white to pale pink in color, large, fragrant, with many yellow stamens and are borne in short clusters near the apex of the branches. Seedling production requires that seeds be sown shortly after collection.

In the fruit are found 60 to 80 seeds with anemochoric. The seed varies from round to oblong, winged at the ends, light brown color, has integument thin and fragile, with smooth texture, the sizes range from 4.3 to 5.6 cm long, 1.3 to 1.9 cm wide, and 0.2 to 0.5 centimeter thick. The individual weight of the seeds ranges from. 112 to.128 grams. Nursery radicle emission occurred at 7 days and the germination rate was 90%. Germination occurs within 7 to 10 days. The species is slow growing, both in the field and in a nursery setting [7].

The present study sought to assess the applicability of the conductivity test to freshly collected K. coriacea Mart. seeds by determining the optimal soak time for performance of the test and comparing results obtained with this method against those obtained by tetrazolium and germination testing of seeds from the same batch.

2. Materials and Methods

2.1. Seed Collection

Seeds were collected in the cerrado sensu stricto, in SCA (Clean Water Farm), area of study at the University of Brasília (UNB) in August 2010, matrixes marked with the aid of GPS, after the period of physiological maturation of the seeds. The collection of fruits was directly from the tree, with the help of trimmer, then the seeds were processed and stored in paper bags at room temperature in the laboratory.

2.2. Conductivity Test

The development of tests to evaluate the physiological quality of seeds, as well as the standardization of these is essential for the establishment of an efficient quality control [8]. One of the main requirements for the seed vigor refers to obtain reliable results in a relatively short period of time, allowing the speed of decision making especially as regards the operations of collection, processing, and marketing [9]. The literature indicates that rapid tests are most studied early events related to the deterioration of the sequence proposed by Delouche and Baskin [10] as the degradation of cell membranes and reduced activity, and biosynthetic respiratory [9]. The measurement of electrical conductivity through the electrolyte amount released by soaking seeds in water has been applied by the individual method where each seed is a sample or more often, a sample of seed representative of a population (mass method). For this case, the results represent the average conductivity of a group of seeds, may a small amount of dead seeds affect the conductivity of a batch with many high-quality seed generating a read underestimated. To minimize this problem, we recommend choosing the seeds, excluding the damaged seeds.

The electrical conductivity is based on the principle that the deterioration process is the leaching of the cells of seeds soaked in water due to loss of integrity of cellular systems. Thus, low conductivity means a high-quality seed and high conductivity, that is, greater output seed leachate, suggests that less force [11].

The electrical conductivity is not yet widely used in Brazil, its use is restricted to activities related to research (Krzyzanowski et al., 1991). There are common jobs using this test to determine the physiological quality of tree seeds. However, it is a promising vigor test for possible standardization of the methodology, at least within a species. However, it is a promising vigor test for possible standardization of the methodology, at least within a species. However, there are factors which influence the conductivity values as the size, the initial water content, temperature and time of soaking, the number of seeds per sample, and genotype [12].

Five treatments were carried out to test the efficiency of the conductivity test as a means of evaluating the viability of freshly collected K. coriacea Mart. seeds.

Five runs of 20 seeds were tested for each treatment. Seeds were individually placed into containers holding 50 mL of distilled water and left to soak for 30, 90, 120, 180, and 240 minutes in a germination chamber set to a constant temperature of 25°C. The minimum time taken for the soaking of 30 minutes was adopted by the same authors and Amaral and peske [13], Fernandes et al. [14], and Matos [1] who concluded that the period of 30 minutes of soaking is more effective to estimate the germination of the seeds. After each period, the conductivity of the soak solution was immediately tested with a benchtop EC meter precise to +/−1% (Quimis). Readings were expressed as μS·cm−1/g−1 seed [15].

Data thus obtained were subjected to analysis of variance with partitioning into orthogonal polynomials for analysis of the effect of soaking times on electrical conductivity.

2.3. Tetrazolium Test

The tetrazolium test, also known as biochemical test for vitality, is a technique used to estimate the viability and seed germination. A fundamental condition for ensuring the efficiency of the test is the direct contact of the tetrazolium solution with the tissues of the seed to be tested. Due to the impermeability of the coats of most forest tree seeds, it is necessary to adopt a previous preparation of the seeds that were tested. This preparation is based on facilitating entry of the solution in the seed. Among the preparations that precede the test we have cutting the seed coat, seed coat removal, scarification by sandpaper scarification by soaking in hot water and water [16]. In the previous preparation of the seeds, factors such as concentration of the solution or even the time of the staining solution can affect the efficiency of the test in the evaluation of seed quality. The time required for the development of appropriate color according to the Rules for Seed Analysis [16] varies depending on each species, can be between 30 and 240 minutes.

The tetrazolium test has been widely used in seeds of various species due to the speed and efficiency in the characterization of the viability and vigor, and the possibility of damage to the same distinction, assisting in the process of quality control from the steps of harvest storage (GRIS et al, 2007).

The tetrazolium test was also applied to freshly collected K. coriacea Mart. seeds, for a total of three runs and 20 seeds. Seeds were soaked in a 0.5% solution of 2,3,5-triphenyl-2H-tetrazolium for 24 hours in a germination chamber set to a constant temperature of 25°C. After each run, seeds were washed, bisected, and the half-containing the embryonic axis placed under a stereo viewer for examination of staining patterns [17].

2.4. Germination Test

The standard germination test is the official procedure to evaluate the ability of seeds to produce normal seedlings under favorable conditions in the field, but does not always reveal differences in quality and performance among seed lots, which can manifest in storage or in the field [18].

During the germination test optimum conditions are provided and controlled for seeds to encourage the resumption of metabolic activity which will result in the seedlings. The main objective of the germination test is the information about the quality of seeds, which is used in the identification of lots for storage and sowing [19].

Freshly collected K. coriacea Mart. seeds were placed in a germination chamber at a constant temperature of 25°C (Treatment 1) or an alternating temperature of 20–30°C (Treatment 2), on a standard cycle of 8 hours of light and 16 hours of dark. Each test consisted of five runs and was performed on 20 seeds.

Germination was defined as emergence of at least 2.0 mm of the primary root [20]. Assessment was conducted daily, and emergence was observed between day 6 and day 7. At the end of the 14-day test period, the germination percentage was calculated on the basis of radicle emergence [21].

Capture

3. Results

3.1. Conductivity Test

Different soaking times were not associated with any significant differences in conductivity results in K. coriacea Mart. seeds (Table 1).

Table 1: Conductivity ranges of freshly collected Kielmeyera coriacea Mart. seeds after soaking for different periods.
Seeds with a leachate conductivity range of 7–17.99 μS·cm·g were considered nonviable, confirming the hypothesis behind conductivity testing, which is the nonviable seeds that have higher soaking solution conductivity values (Table 2).

Table 2: Percentage of viable Kielmeyera coriacea Mart. seeds according to EC range.
Analysis of variance revealed a low coefficient of variation (20.26%), which suggests good experimental control (Table 3).

Table 3: Analysis of variance of various soaking times for electrical conductivity testing of Kielmeyera coriacea Mart. seeds.
After analysis of variance, the correlation between the soaking time and electrical conductivity variables was assessed. The cubic model yielded

Capture

which is indicative of a positive correlation between the study variables.

The following equation was obtained on the basis of the cubic model:

Capture

 

Analysis of a plot of the above function in the GeoGebra 2007 software package shows that variation in electrical conductivity as a function of soaking time is minor and approaches a constant, which is consistent with the study results, in which changes in soaking time had no influence on conductivity (Figure 1).

378139.fig.001
Figure 1: Leachate conductivity as a function of soaking time in Kielmeyera coriaceaMart. seeds.

Matos [1] reported that a 30-minute soak was enough for assessment of Anadenanthera falcata, Copaifera langsdorffii, and Enterolobium contortisiliquum seeds by the soaking solution pH method—that is, the amount of matter leached after this period sufficed for measurement.

Although the principle of conductivity is the same used for the test pH of exudate, the soaking time needed to analyze the differential seeds through the conductivity may be explained by the fact that this technique is quantitative, while pH in the art exudate analyzes are qualitative. In other words to the technique of pH values of the exudate it is important to detect the acidity of imbibition while on the electrical conductivity we draw a comparison between the analyzed values to separate viable from nonviable samples. To determine a value of electrical conductivity as a reference to determine viable seeds are to be considered the values obtained for fresh seeds and seeds stored.

The thickness of the K. coriacea Mart. seed coat may also have affected the soaking procedure; this species has very thin seed coats, which makes soaking a very fast process.

These results are consistent with those reported by Rodrigues [22], who subjected stored K. coriaceaMart. seeds to the conductivity test and found that 90 minutes is an appropriate soaking time for analysis.

Therefore, it can be inferred that for seed Kielmeyera coriacea Mart. the soaking time of 90 minutes can be applied to obtain satisfactory results.

3.2. Tetrazolium Test

Table 4 shows the results of tetrazolium testing of K. coriacea Mart. seeds in our sample. The mean viability rate was 96.6%. The testing procedure was based on Brazilian Ministry of Agriculture recommendations [17].

tab4
Table 4: Tetrazolium testing of Kielmeyera coriacea Mart. seeds.

The results of the tetrazolium test were quite similar to those obtained with the conductivity method, thus confirming the efficiency of the latter method as a means for assessing the viability of K. coriaceaMart. seeds.

3.3. Germination Test

The germination test results of freshly collected K. coriacea Mart. seeds are shown in Table 5. Regardless of temperature, both test batches exhibited good viability, and no seed dormancy was detected.

tab5
Table 5: Germination test results of Kielmeyera coriacea Mart. seeds.

Radicle emergence was observed between day 7 and day 9 of the test, according to the analysis criteria proposed by Labouriau [21].

These findings are consistent with those of Melo et al., [23] who reported high and relatively rapid germination rates for K. coriacea seeds kept at 25°C on paper towels, with emergence of a perfect radicle on the 7th day of assessment.

4. Conclusions

The electrical conductivity can be used as an indicator of seed viability and presents two advantages: to provide rapid and reliable results and the technique is not destructive and can use the seeds after the conductivity test, so they can be used to produce seedlings.

The present study showed that different soaking times had no effect on the results of conductivity testing of freshly collected K. coriacea Mart. seeds, suggesting that the amount of leached matter was never below the threshold required for adequate testing.

Electrical conductivity testing proved to be a feasible option for viability testing of K. coriacea Mart. seeds, as the results obtained with conductivity testing were confirmed by germination testing and by the tetrazolium test.

References

  1. J. M. M. Matos, Evaluation of pH test on exudate check feasibility of forest seeds, dissertation, University of Brasília, Brasília, Brazil, 2009.
  2. F. Poggiani, S. Bruni, and E. S. Q. Barbos, “Effect of shading on seedling growth of three species forest,” in National conference on native plants, vol. 2, pp. 564–569, Institute of Forestry, 1992.
  3. M. B. Mcdonald Jr. and D. O. Wilson, “ASA-610 ability to detect changes in soybean seed quality,” Journal of Seed Technology, vol. 5, no. 1, pp. 56–66, 1980.
  4. S. Matthews and A. Powell, “A eletrical conductivity test,” in Handbook of Vigor Test Methods, D. A. Perry, Ed., pp. 37–42, International Seed Testing Associaty, Zurich, Switzerland, 1981.
  5. J. Son Mark, W. R. Singh, A. D. C. Novembre, and H. M. C. P. Chamma, “Comparative studies to evaluate dem’etodos physiological quality of soybean seeds, with emphasis the electrical conductivity test,” Brazilian Journal of Agricultural Research, vol. 25, no. 12, pp. 1805–1815, 1990.
  6. S. R. Singh, A. P. Silva, C. B. Munhoz, et al., Guide of Cerrado Plants Used in the Chapada Veadeiros, WWF-Brazil, Brasilia, Brazil, 2001.
  7. J. M. Felfili, C. W. Fagg, J. C. S. Silva, et al., Plants of the APA Gama Cabeça de Veado: Species, ecosystems and recovery, University of Brasilia, Brasília, Department of Engineering Forest, Brasília, Brazil, 2002.
  8. M. F. B. Muniz, et al., “Comparison of methods for evaluating the physiological and health quality of melon seeds,” Journal of Seeds, Pellets, vol. 26, no. 2, pp. 144–149, 2004.
  9. D. C. F. S. Dias and J. Marcos Filho, “Electrical conductivity to assess seed vigor of soybean (Glycine max (L.) Merrill),” Scientia Agricola, vol. 53, no. 1, Article ID article id, pp. 31–42, 1996.View at Publisher · View at Google Scholar
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  11. R. D. Vieira and F. C. Krzyzanowski, “Electrical conductivity test,” in Seed Vigor: Concepts and Tests, F. C. Krzyzanowski, R. D. Vieira, and J. B. França Neto, Eds., pp. 4.1–4.26, Abrates, London, UK, 1999.
  12. R. D. Vieira, “Electrical conductivity test,” in Seed Vigor Tests, R. D. Vieira and N. M. Carvalho, Eds., p. 103, FUNEP, Jaboticabal, Brazil, 1994.
  13. A. S. Amaral and S. T. Peske, “Exudate pH to estimate, in 30 minutes seed viability of soybeans,”Journal of seeds, vol. 6, no. 3, pp. 85–92, 1984.
  14. E. J. Fernandes, R. Sader, and N. M. Carvalho, “seed viability beans (Phaseolus vulgaris L.) estimated by the pH of the exudate,” in Congress Brazil’s Seeds, Gramado, Brazil, 1987.
  15. F. C. Krzyzanowski and R. D. Vieira, “Electrical conductivity test,” in Seed Vigor: Concepts and Tests, F. C. Krzyzanowski, R. D. Vieira, and J. B. France Neto, Eds., pp. 4.1–4.26, Abrates, London, UK, 1999.
  16. Ministry of Agriculture, Livestock and Supply, Rule for seed testing, SNPA/DNPV/CLAV, Brasilia, Brazil, 1992.
  17. Ministry of Agriculture, Livestock and Supply, Rule for seed testing, SNPA/DNPV/CLAV, Brasilia, Brazil, 2009.
  18. N. M. Carvalho and J. Nakagawa, Seeds: Science, Technology and Production, FUNEP, Jaboticabal, Brazil, 2000.
  19. Pina-Rodrigues, et al., “Quality test,” in Germination from Basic to Applied, A. Ferreira and G. F. Borghetti, Eds., pp. 283–297, 2004.
  20. A. G. Ferreira and F. Borghetti, from basic to Germination applied, Artmed, Porto Alegre, Brazil, 2004.
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Research article by: Kennya Mara Oliveira Ramos,1 Juliana M. M. Matos,1 Rosana C. C. Martins,1 and Ildeu S. Martins2

1Seed Technology Laboratory of Forestry, Department of Forestry, University of Brasilia, CP 04357, 70919970 Campus Asa Norte, DF, Brazil
2Department of Forestry, University of Brasilia, CP 04357, 70919970 Campus Asa Norte, DF, Brazil

Received 17 December 2011; Accepted 14 February 2012

Academic Editors: A. Berville, C. Gisbert, J. Hatfield, and Y. Ito

Copyright © 2012 Kennya Mara Oliveira Ramos et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

 

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