This method is based on the ability of the element of interest to electrochemically accumulate on the surface and dissolve in the anode or cathode polarization at a certain potential, which is characteristic for each element. The peak height of the element recorded on voltammogram is proportional to the mass fraction of the element in the solution. The method for the determination of silicon dioxide weight ratio PND F The humidity of rice husk and dust GOST was determined by drying to constant weight.
The dust samples were collected by quartering. Drying was carried out to obtaining a difference of dust husk masses with a weighing bottle during two subsequent weighings of not more than 0.
The technological stages of the raw rice production and the characteristics of aspiration systems like air pollutants were considered in []. TSOL — for cleaning of dusty air coming from aspiration and pneumatic networks sawdust, weeds, grain dust and other impurities of particles larger than microns, and UBBC — the battery cyclone plant Figure 1 with a mm cyclone diameter.
The battery cyclone plant consists of four cyclones of conical-cylindrical shape. The cylindrical part of the cyclone includes inner and outer cylinders. The outer cylinder at the top is cut along the spiral line; a pipe is welded to it.
The inner cylinder is inserted into the outer one. Four cyclones are attached to the receiving hopper at the top. Dusty air is supplied in the cyclone through the inlet and its movement becomes a helical rotational one. By centrifugal force the dust particles press against the walls of the cyclone, lose speed and roll down into the collecting cone.
With the help of the lock closures unit, the collected dust is discharged to the dust pipe, and through the exhaust pipes of cyclones and setup box purified air is discharged from the cyclones in the air duct.
The dust is removed from the air during the air filtering through the fabric cross-linked as separate bags and embedded in a sealed filter case Figure 2. The design of the bag filter represents a collapsible cabinet, divided into sections by vertical partitions.
Each section has the cylindrically-shaped filter bags. The bags are stretched on a metal frame. The bags are periodically cleaned of dust deposited thereon as a result of their shaking through a special mechanism. Click here to View figure.
To determine the chemical composition of the waste generated during the processing of raw rice, the samples of husk, dust, detained by the group cyclone and dust, detained by a bag filter-cyclone, were selected Figure 3. The chemical composition of the rice dust and the husk is shown in Table 7. The rice husk contains a significant amount of silicon dioxide — Due to abrasive particles, ferrum is removed from gravity flow during grain movement; the fraction becomes heavy and is deposited in the cyclone under the centrifugal force.
Wetter particles stick together and become larger. Man-made emissions of heavy metals, which include ferrum, plumbum and copper, cause global pollution as a result of man-made dispersion.
Upon flushing of rice dust in stagnant basins, heavy metals increase its acidity and contribute to the intensification of CO 2 as a result of the microorganisms activity. In contrast, disposal of crop residues is a major problem in industrialized countries because of possible environmental pollution Oh et al. Crop residues are lignocellulosic material rich in energy, low in crude protein and poor in palatability. Ruminal microbial utilization of energy-rich cell walls of crop residues is hindered by the presence of nonpolysaccharide compounds such as lignin, phenolic acids and silica in some cereal straws Besle et al.
Extensive research has been done in the past to understand the role of lignin and phenolic acids in cell wall utilization by rumen microorganisms, the exact mechanism has yet to be fully elucidated. Research has sought to improve the nutritive value of poor quality crop residues by physical, chemical and enzymatic pre-treatments Jackson, ; Bar1 et al. Chemical treatment of poor quality roughages has been extensively studied and well documented Jackson, ; Fahey et al.
However, a potential environmental problem exists in long term usage of chemicals. Chemical pretreatment is expensive, corrosive and possibly toxic to workers. As an alternative to chemical treatments, the use of lignolytic white-rot fungi WRF for converting lignocellulosic materials to more digestible feedstuffs has been investigated. Many species of WRF have been screened on a variety of lignocellulosic substrates for their ability to improve the nutritional value of poor quality crop residues for use as a ruminant feedstuff Zadrazil, ; Reid, ; Fahey et al.
Of all substrates, biological treatment of wheat straw has been the most widely studied crop residue. Other studies, including ours, indicated selective degradation of substrates by WRF Rolz et al. As a result, successes as well as failures have been reported in terms of improvement in the quality of crop residues by WRF.
Rice straw differs considerably from other cereal straws such as barley, wheat aad oat in that it has a very high proportion of leaf: stem 60 vs. Fungus-substrate whole plants speci- ficity has been widely reported however, no information is available on fungus speci- ficity for plant parts. Screening of WRF for their ability to improve the quality of crop residues has been limited to chemical methods.
Structural methods, including scanning electron mi- croscopy SEM and transmission electron microscopy TEM , are effective in evaluat- ing digestion of specific cell types and have increased our understanding of the contribution of plant and ruminal microbial factors in digestion of forages Akin, The objectives of the present study were firstly to investigate the effect of different fungal species on botanical parts of rice straw for improved digestibility and secondly to determine chemical and structural alterations responsible for the improvement.
Materials and methods 2. Sample preparation Rice straw used in this experiment was baled and transported from Louisiana in Rice straw was hand-separated into leaf blade and stem plus sheath.
Since Cherney et al. Both leaf and stem fractions of rice straw were ground through a Wiley mill using a 9 mm screen prior to SSF. Representative samples of intact leaf blade and stem fractions were saved for microscopic evaluation. Rye spawn Rye spawn was used as the inoculum to introduce the WRF to the substrates. Rye spawn was defined as a pure vegetative growth of the fungus on sterilized rye Secale cereale L grain supplemented with hardwood sawdust.
Approximately 90 g rye and 15 g hardwood sawdust were placed in a ml flask with 1 g CaSO, and ml tap water. For a detailed procedure see Karunanandaa et al. Strains of WRF used in this study are presented in Table 1.
Solid state fermentation SF Fifty grams air dried of each substrate was placed in 1L Erlenmeyer flasks with ml tap water. The flasks were stoppered with cotton plugs to allow air exchange. Controls were identical samples that were not inoculated with rye spawn. Oven dried samples were weighed and ground through a 1 mm sieve using a laboratory UDY cyclone mill Ft. Chemical analyses were performed on ground samples and reported as a percent of dry matter of the decayed sample.
Neutral detergent solubles were calculated as the percentage of organic matter minus NDF. IVDMD was determined as a 48 h incubation followed by a 24 h acid pepsin digestion as described by Marten and Barnes The experimental design used in this study was a completely randomized design with 2 X 4 factorial arrangement of treatments with three replicates.
The two factors were morphological fractions leaf and stem of rice straw and fungi three species of WRF listed in Table 1 and the control. The major sources of variation were due to treatment effects of botanical fractions and fungi.
To prevent any unwanted microbial growth on leaf and stem, samples were gas sterilized as follows: leaf and stem samples were placed separately into two plastic containers and soaked over night with tap water and the excess water was poured off from the containers after 24 h-soaking. Then the plastic containers were wrapped with a plastic sheet including vials of ethylene oxide processed according to product instructions; Anprolene, H.
Anderson Products, Inc. The experimental design used in the microscopy study was similar to the earlier experiment described in this paper. Samples were inoculated with fungi 5 rye spawns per petridish and the petridishes were sealed with parafilm to prevent any contamination of samples. At the end of the incubation period, part of the samples were randomly selected and transferred into small bottles containing the glutaraldehyde fixative solution. The rest of the samples were incubated in the rumen by suspending in nylon bags 20 pieces per bag.
Nylon bags were incubated in the rumen for 24, 48, 72, and 96 h. At the end of incubation, bags were hand-washed in cold water and the samples were placed in fixative for further microscopic studies.
Samples were prepared for SEM as described by Akin et al. Results 3. Chemical composition of fingal decay ed material and IVDM D Chemical composition of control rice leaf and stem Table 2 revealed that rice leaf had higher concentrations of crude protein, silica, neutral detergent solubles and lower cell wall NDF content compared to stem 3.
The higher cell wall content found in rice stem compared to leaf was mainly due to the higher concentration of cellulose ND, Not detectable. Since the rice straw was rich in ash, mainly silica, ash-free NDF was determined on decayed samples. Values for NDF were reduced by about percentage units, but the relative difference between treatments remained similar.
Chemical composition of fungal decayed material is reported in Table 2. Fungal treatment in general significantly reduced the concentration of cell wall components. The silica content of fungal decayed material increased compared to the control indicating that WRF were unable to remove this element during decay.
During the process of fungal growth on substrates, structural carbohydrates are converted into cell solubles for fungal metabolism. In this study, cell solubles of fungal decayed rice leaf were increased by two fold compared to the control leaf indicating successful growth of all three fungi on rice leaf. However in rice stem, except with Ps, the difference in concentration of cell solubles of fungal decayed stem was not high, but statistically significant, from the control stem, suggesting that PC and Cs failed to grow on the stem fraction.
The organic matter content of fungal-decayed leaf is significantly lower compared to the control and ranged from 66 to Fungal selection of botanical parts of rice straw was determined based on the ability of the fungi to consume organic matter from the substrate during the 30 d of SSF. Organic matter OM loss was closely related to the appearance of fungal mass on the substrate at the end of 30 d of SSF. PC and Cs preferentially colonized rice leaf compared to stem, while Pleurotus sujor-caju Ps grew equally well on leaf and stem.
Losses in organic matter by fungi during the 30 d of SSF were primarily due to the consumption of carbohydrates which were mostly associated with the cell wall.
Therefore, OM loss included the losses in hemicellulose, cellulose and lignin Table 3. Almost half the amount of total lignin found in rice leaf was degraded by all three fungi during the 30 d of SSF. However, hemicellulose found in stem was degraded only by Ps, while the other two fungi degraded insignificant amounts of hemicellulose found in stem. Extensive degradation of cell wall components of rice leaf by PC and Cs, but the lack of breakdown of the same structural components in stem, indicates that the chemical organization within the rice leaf is available to these two fungi.
The mechanism for the disparity in growth of the fungi between leaf and stem is not known. Within rice leaf, PC indiscriminately degraded a greater proportion of hemicellulose and cellulose while the other two fungi selectively degraded hemicellulose and left the major cell wall carbohydrate, cellulose, intact.
The similar IVDMD for leaf and stem found in this study was mainly due to the higher concentra- tion of silica found in leaf compared to stem.
Within leaf, Cs and Ps improved the IVDMD equally, in contrast to stem digestibility, which was only improved by Ps, suggesting fungal specificity for the different botanical fractions. The r values were determined individually for leaf and stem because of the observed differences in the growth of fungus on leaf and stem; the mechanism especially for the inhibition of IVDMD of stem decayed by Cs and PC is not known.
However these two components failed to explain the major part of the variation found in IVDMD of the leaf fraction. The regression model, with stepwise option, selected hemicellulose and cellulose as the two variables to predict IVDMD of fungal decayed rice leaf with an R2 of.
A negative relationship of hemicellulose with IVDMD may suggest that the remaining hemicellulose, after fungal degradation, became more recalci- trant and resisted ruminal microbial degradation. M icroscopy of fungal decayed material Microscopic evaluation of tissues focused primarily on rice leaf, because the chemi- cal analyses of fungal decayed substrates revealed that most of the improvement in IVDMD was from the rice leaf fraction.
Control tissues as well as fungal-decayed tissues were evaluated before and after ruminal digestion by scanning electron mi- croscopy EM and transmission electron microscopy TEM. Microscopic evaluation of stem was limited to control tissues and stem decayed by Ps.
Scanning electron micrographs of rice leaf blade cross sections. A Control leaf not incubated rumt :n fluid. Tis:sues present are epidermis e , sclerenchyma s , phloem p , xylem x1 and mesophyll cm. Presl Ctll ce of bulli form cells b are also evident. Bar, 0. B Control leaf incubated for 72 h in sib 1. All tissu es are intact except phloem and minimal amounts of mesophyll tissues which were degraded. Bal ; 0. In-field rice straw management Learn different strategies to manage rice straw in the paddy soil such as open-field burning and incorporation.
Know their advantages and disadvantages, why they should be regulated, and why they must be properly practice. With developments in the technologies for its collection and utilization, rice straw is increasingly removed from the fields to be used for better purposes such as for mushroom and energy production and for cattle feed. Leaf Color Chart. Drying systems. Harvesting systems. Drying basics. Harvesting costs. Drying strategies. The Solar Bubble Dryer. Home Step-by-step production Postproduction By-products Rice straw.
What is rice straw? The proportions of the air-dried component tissues are shown in Figure 1 a. The quantity of node tissue was small and showed little variation between the plants, whilst the internode and leaf tissues comprised the bulk of the biomass and varied considerably. For comparison, Jacobs et al. The milled materials were chemically analyzed in this state without any treatments to remove any extractable substances and were thus representative of raw whole material. The amounts of rhamnose, fucose, arabinose, xylose, mannose, galactose, glucose, uronic acid as anhydro sugar equivalents and a range of functionally important cell wall phenolics including ferulic acid, a range of diferulic acids, coumaric acid and lignin are presented in Additional files 1 and 2 : Tables S1 and S2.
The analyses showed the expected distinct differences in tissue composition. The main sugars were glucose and xylose. Lignin corrected for ash content was highest in the internode, and lowest in the node, probably reflecting the requirement for the node to undergo controlled extension to address lodging disturbances. Uronic acid was present in all tissues, and will have been derived predominantly from glucuronic acid found in glucuronoarabinoxylans [ 8 ]. However some will have originated from galacturonic acid in the small quantities of pectic polysaccharides found particularly in the leaf tissues.
This was clearly indicated by the small but measurable levels of rhamnose, which was highest in leaf tissues and lowest in internode and ear tissues. Mannose was present at its highest levels in the node and internode compared with leaf tissue, and lower still in ear tissue.
These values reflect the predominance of lignocellulose or hemicellulose in the stem. It is possible that some mannose may have been derived from hydrolysis and reduction of any residual sucrose present in the tissues. Lignin was measured gravimetrically and corrected for ash in all tissues Additional files 1 and 3 : Table S1 and S3. There was considerable variation in content, which related to both tissue type and cultivar.
For comparison, Additional file 3 : Table S3 shows published values for cell wall sugars and lignin from whole wheat straw and constituent tissues from a number of studies over the last 25 years.
Such variation is consistent with that found in the compositions of component tissues of the six cvs reported in this study. Phenolic esters were analyzed across the four tissues in the six plant varieties for modelling. The distributions are shown in Additional file 2 : Table S2. The main phenolic ester was p-coumaric acid pCA which, in all the cultivars, was highest in the node tissues, ranging from 0.
In most cultivars, the leaf tissue exhibited the lowest level of pCA, ranging from 0. The distribution of pCA in the internode and ear tissues varied widely. The next most prominent phenolic ester was trans-ferulic acid FA. The levels differed considerably between the cultivars, but were distributed in a similar manner between the tissues. FA ranged from under 0. Small but significant levels of other phenolics were identified, including vanillic acid and vanillin.
For each cultivar, the standard errors for the phenolics data were quite noticeable Additional file 2 : Table S2. However, this was not due to experimental error, but due to strong variability between different replicate plants used in building the model. This contrasts with the sugars data which gave low variation between plants of a specific cultivar Additional file 1 : Table S1.
Figure 2 shows representative Fourier transform infrared attenuated total reflectance FTIR-ATR spectra of the separated tissue types from wheat straw internode and node, leaf, and ear spikelets. The varying chemical composition of the tissues was reflected in distinct variations between their FTIR spectra. These bands are generally attributed to lignin-like moieties, although this did not directly reflect differences in Klason ash-corrected lignin.
These spectral differences were consistent across lines, although band intensities varied between different samples. FTIR-ATR spectra of the four different tissues of wheat straw cv Avalon Averaged spectra from four plants, with five area-normalized replicate spectra each. Since whole wheat straw biomass is a mixture of these tissues, it would be reasonable to assume that the spectrum of the whole wheat is a linear combination of the component spectra the models were derived from tissues dissected from whole plants which had not been subjected to harvesting-related losses of loose and friable parts like leaves.
Hence a PLS model was created to quantify the relative amounts of these tissues in wheat straw biomass. Models made from the raw spectra performed reasonably well. However some of the hemicellulose sugars, notably xylose, exhibited a constant underestimation bias in test set predictions. This was successfully addressed by using first derivative spectra to eliminate nonlinear baseline effects.
In contrast, a fourth order polynomial spline baseline correction did not improve the predictions. Examples of correlations between measured and predicted values for tissue proportions are shown in Figure 3 a-d.
PLS model-predicted data versus actual data: a-d PLS predicted versus actual weight percentage of individual tissue types in whole plants from six different wheat cultivars square: Avalon, circle: Cadenza, Star: Charger, diamond: Paragon, plus: Robigus, cross: Savannah; average of four plants for each cv. PLS predicted versus actual contents plotted for e total sugars, f total phenolics and g corrected lignin in the calibration set samples listed in Table 1 , five technical replicate predictions for each sample averaged.
A total of 28 chemical constituents of the wheat straw were modelled using the calibration sample set listed in Table 1. Figure 3 e-g shows the calibration curves for total sugars, phenolics and lignin as examples.
Table 2 provides an overview of the input data, number of factors used and the error for all PLS models. The models for hemicellulosic and pectin components showed some variability. The error for the latter component meant that the fucose PLS model could not give a usable prediction. Para-coumaric acid pCA and FA made up the bulk of the phenolic compounds.
Such an error is not surprising in view of the level of variability between individual plants discussed above. The quality of modelling can be compared with that of other recent, relevant studies. However, although their study involved whole straw samples for triticale and wheat collected over two seasons at different locations in Canada, they used only two to three cultivars each, demonstrating inherently much less variation.
They explained the lower accuracy for smaller components by the low concentrations and relatively greater errors in their chemical analysis. In the present study our results have shown similar trends, with the minor components like mannose giving worse predictions than the predominant glucose and lignin.
The prediction errors in our models are similar to those of Liu et al. However, overfitting the calibration set would have made the prediction errors for independent samples worse. Averaging the input spectra did not increase the prediction accuracy because the replicate infrared spectra were already closely grouped, and very few spectra could be considered as outliers.
In addition, we observed a marked increase in accuracy when we reduced the number of different wheat lines in the calibration set, and individual lines tended to model extremely accurately.
Nevertheless, the aim of this study was to evaluate variation across a wide range of samples. Hence the models were developed with six wheat lines that had been preselected for high phenotypic variability in order to maximize the potential for downstream evaluation of field-grown cultivars below. A set of 90 field-grown wheat cultivars with a spread of genetic variation was grown over two seasons see Materials and Methods.
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