Rough Rice Grains Research Articles

Weed control and rice response to microencapsulated acetochlor and a fenclorim seed treatment on a clay soil

AbstractRecent research has demonstrated the ability of a fenclorim seed treatment to reduce rice (Oryza sativa L.) injury to acetochlor. However, all studies were conducted on silt loam soils and have not evaluated rice tolerance or weed control on clay soils. Experiments were initiated in 2021 and 2022 at the Northeast Research and Extension Center near Keiser, AR, to determine rice response and the effectiveness of delayed‐preemergence (DPRE)‐applied microencapsulated (ME) acetochlor (1.1, 1.7, and 2.3 lb ai acre−1) when applied to a clay soil with and without a fenclorim seed treatment at 0 or 2.5 lb ai 1000‐lb−1 of seed. Averaged over the fenclorim seed treatment, acetochlor at 1.1 and 1.7 lb ai acre−1 caused similar injury levels to rice; however, barnyardgrass [Echinochloa crus‐galli (L.) P. Beauv.] control increased at 1.7 lb ai acre−1, eliciting 19% injury to rice and 82% barnyardgrass control at 28 days after emergence (DAE). Palmer amaranth (Amaranthus palmeri S. Watson) control ranged from 82% to 93%. Additionally, fenclorim did not influence barnyardgrass or Palmer amaranth control, but it did reduce rice injury and increase shoot density, plant height, and rough rice grain yield. At 14 and 28 DAE, fenclorim at 2.5 lb ai 1000‐lb−1 of seed (averaged over acetochlor rates) reduced visible rice injury from 61% to 13% and 40% to 8%, respectively. Results from this study indicate ME acetochlor could be successfully applied to rice grown on a clay soil when a fenclorim seed treatment is used, providing producers a new site of action for use in U.S. rice production.

Rice cultivar tolerance to florpyrauxifen-benzyl spray-applied vs. coated on urea

Abstract Complaints regarding the sensitivity of rice to florpyrauxifen-benzyl and off-target movement of the herbicide occurred following its commercial launch in 2018 in the midsouthern United States. These two concerns encouraged the exploration of an alternative application method for florpyrauxifen-benzyl in rice. A field study was conducted in 2020 and 2021 to determine if coating florpyrauxifen-benzyl on urea would reduce negative impacts of the herbicide to rice. Five commercial rice lines were evaluated: ‘Diamond’, ‘Titan’, ‘RT7321 FP’, ‘RT7521 FP’, and ‘XP753’. Florpyrauxifen-benzyl coated on urea at a 2× rate (60 g ai ha–1) reduced rice injury in one of five commercial rice lines in 2020 and four of five commercial rice lines in 2021, compared to spray applications at the same rate. In 2020, ‘RT7521 FP’ exhibited a 17-percentage point injury reduction when coating florpyrauxifen-benzyl on urea at a 2× rate vs. the same rate sprayed. In 2021, rice injury was reduced by 26, 10, and 27 percentage points in the commercial rice lines ‘Diamond’, ‘Titan’, and ‘XP753’, respectively, following coated urea vs. spray applications at 4 wk after treatment (WAT). ‘XP753’ exhibited reduced injury (15 percentage points) by coating florpyrauxifen-benzyl at a 1× rate (30 g ai ha–1) 4 WAT in 2021, and another, ‘Diamond’, had comparable groundcover to nontreated plots when florpyrauxifen-benzyl was coated on urea at a 1× rate rather than the reductions observed from the spray application at a 2× rate. Yield differences were a function of urea rate rather than application method, where in six out of ten instances greater rough rice grain yield occurred at the higher rate. Findings from this experiment indicate that coating florpyrauxifen-benzyl on urea can reduce the amount of injury observed, especially in areas of overlap where you would have a 2× rate.

Quizalofop-resistant rice response to quizalofop when exposed to low rates of glyphosate and imazethapyr

AbstractInjury to quizalofop-resistant rice was reported in some fields following postemergence applications of quizalofop. Glyphosate-resistant (GR) corn, cotton, and soybean, and imidazolinone-resistant rice are grown near quizalofop-resistant rice. Herbicide drift from glyphosate and imazethapyr and the resulting crop injury and potential yield loss is a cause of concern for producers. Field experiments conducted near Colt, and Keiser, AR, in 2021 evaluated whether low rates of glyphosate or imazethapyr interact with sequential quizalofop applications to exacerbate injury to quizalofop-resistant rice compared to quizalofop applications alone. Herbicide treatments consisted of a low rate of glyphosate (90 g ae ha−1) or imazethapyr (10.7 g ai ha−1) applied 10, 7, 4, and 0 d before the 2-leaf growth stage of rice, and glyphosate or imazethapyr, at the same rate and timings, followed by quizalofop at 120 g ai ha−1 applied to 2-leaf rice. All plots treated with quizalofop received a subsequent application of the same herbicide and rate at the 5-leaf rice stage. At 28 d after final treatment (DAFT), glyphosate followed by quizalofop the same day to 2-leaf rice caused 77% injury compared with 58% when glyphosate was applied alone, regardless of location. Glyphosate followed by quizalofop the same day reduced rough rice grain yield by 67% compared with 33% when glyphosate was applied alone to 2-leaf rice at the Colt location. Application of imazethapyr followed by quizalofop the same day to 2-leaf rice caused more injury (63% and 19% injury at the Colt and Keiser locations, respectively) than imazethapyr alone (42% and 7% injury at the Colt and Keiser locations, respectively) at 35 DAFT. Overall, glyphosate and imazethapyr followed by quizalofop applications worsened injury compared to glyphosate, imazethapyr, and quizalofop applications alone. As the interval between exposure to a low rate of glyphosate or imazethapyr and quizalofop decreases, the detrimental effect of herbicide on rice likewise increases.

Performance of different herbicides on pondweed (Potamogeton nodosus) in rice

AbstractPondweed is a rhizomatous perennial weed of aquatic habitats that recently adapted to rice ecosystems in northern Iran. Two field experiments were conducted at the Rice Research Institute of Iran to determine the impact of pondweed on rice yield and identify effective herbicides for pondweed control. The focus of the first study was to evaluate the herbicides commonly used in Iranian rice, including butachlor, pretilachlor, oxadiargyl, pendimethalin, thiobencarb, and bensulfuron-methyl. None of these herbicides effectively controlled pondweed, except bensulfuron, which reduced pondweed biomass by ≥95% and produced 26% higher rough rice grain yield than the nontreated plots. The second experiment evaluated the performance of acetolactate synthase–inhibiting herbicides on pondweed control, rough rice yield, and pondweed regrowth. Herbicide efficacy on pondweed varied from 36% to 100%. Five preemergence herbicides, bensulfuron at 45 g ai ha−1, flucetosulfuron at 30 g ai ha−1, triafamone plus ethoxysulfuron at 40 g ai ha−1, and metsulfuron-methyl at 15 g ai ha−1, provided ≥98% control of pondweed. Use of postemergence herbicides penoxsulam at 35 g ai ha−1, bispyribac-sodium at 30 g ai ha−1, and pyribenzoxim at 35 g ai ha−1provided 36%, 89%, and 93% pondweed control, respectively. Rough rice yields ranged from 107% to 124% in herbicide-treated plots compared with the nontreated plots. Soil-applied herbicide treatments produced higher (≥119%) yield than the hand-weeded control or foliar-applied herbicides. Pondweed regrowth was affected by herbicides and was variable. Soil-applied residual herbicides metazosulfuron, flucetosulfuron, and metsulfuron provided complete control of pondweed and prevented regrowth. In contrast, pondweed regrowth in other soil- and foliar-applied herbicide treatments occurred, indicating their lesser translocation to underground vegetative rhizomes. This study shows that although most sulfonylurea herbicides can control pondweed effectively to achieve high rough rice yield, only a few soil-applied herbicides were able to prevent pondweed regrowth.

Sensitivity of rice to low rates of glyphosate and glyphosate plus dicamba at multiple growth stages

AbstractOff‐target movement of glyphosate can be severely injurious to rice (Oryza sativa L.). Glyphosate is routinely mixed with dicamba and applied to crops with resistance to both herbicides, such as glyphosate‐ and dicamba‐resistant corn (Zea mays L.) and soybean [Glycine max (L.) Merr.] cultivars. This research was conducted to evaluate the effects of low rates of glyphosate and glyphosate plus dicamba on rice at multiple application timings. Separate field experiments were conducted and were repeated in 2018 and 2019 near Stuttgart, AR. The first experiment evaluated rice's response to glyphosate alone; a second experiment evaluated responses to glyphosate applied as a mixture with dicamba over several rice growth stages. The rates of glyphosate alone evaluated were 0.023, 0.047, 0.187, and 0.375 oz acid equivalent (ae) acre–1. Mixtures of glyphosate plus dicamba were evaluated at 0.050 plus 0.025, 0.2 plus 0.1, and 0.8 plus 0.4 oz ae acre–1, respectively. Visible injury to rice from glyphosate alone was never more than 3%, averaged over application timings. Unique symptomology and greater yield losses were observed for glyphosate mixed with dicamba. There was no reduction in rough rice grain yield after treatment with glyphosate alone. For the glyphosate plus dicamba experiment, no more than 13% injury occurred from any treatment. Rough rice grain yield was reduced by 21% relative to the nontreated control for the highest rate of glyphosate plus dicamba, averaged over application timings. Care should be taken to prevent off‐target movement of mixtures of glyphosate plus dicamba to neighboring rice.

Rice response to sublethal concentrations of paraquat, glyphosate, saflufenacil, and sodium chlorate at multiple late-season application timings as influenced by exposure

AbstractIn Mississippi, rice reproduction and ripening often overlaps with soybean maturation, creating potential for herbicide exposure onto rice from desiccants applied to soybeans. Six independent studies were conducted concurrently at the Delta Research and Extension Center in Stoneville, MS, from 2016 to 2018 to determine the response of rice to sublethal concentrations of soybean desiccants during rice reproductive and ripening growth stages. Studies included the desiccants paraquat, glyphosate, saflufenacil, sodium chlorate, paraquat + saflufenacil, and paraquat + sodium chlorate applied at a rate equal to 1/10th of Mississippi recommendations. Treatments were applied at five different rice growth stages, beginning at 50% heading––defined as 0 d after heading (DAH)––with subsequent applications at 1-wk intervals (0, 7, 14, 21, and 28 DAH), up to harvest. Injury was observed 7 d after application (DAA), with five of six desiccants at all application timings. No injury was observed with glyphosate application across all rating intervals. Rough rice grain yield following all glyphosate applications was reduced by >6%. In the studies evaluating paraquat, injury ranged from 5% to 18% at all evaluations, regardless of application timing. Rough rice grain yield was reduced >12% 0 to 21 DAH, following paraquat application. Similar trends were observed with paraquat + saflufenacil and paraquat + sodium chlorate, with rice exhibiting yield decreases >6% following an application 0 to 14 and 0 to 21 DAH, respectively. In studies evaluating saflufenacil and sodium chlorate, rough rice grain yield was >95% of the untreated across all application timings Yield component trends closely resembled reductions observed in rough rice grain yield. Reductions in head rice yield were >5% following applications of paraquat or paraquat + saflufenacil 0 to 14 and 0 to 21 DAH, respectively. Late-season exposure to sublethal concentrations of desiccant from 50% heading (0 DAH) to 28 DAH has an impact on rough rice grain yield, yield components, and head rice yield.

Changes in the quality of some improved rice grain varieties during storage

This research aimed to investigate the changes in the quality of some improved rice grain varieties during storage. In the rainy season of 2014/2015, 10 improved rice varieties, namely, Inpari 10, 13, 16, 20, 30, Sintanur, Ciherang, Mekongga, Situ Bagendit, and Situ Patenggang, were planted at the Sukamandi Research Station, Indonesian Center for Rice Research. The rough rice grains were harvested at optimum maturity, machine threshed, and dried with a box dryer’s aid at a temperature of 45°C for 10 hours until the water content was at 13-14%. Furthermore, they were packed in plastic sacks and stored at room temperature for six months (March-November 2015). At 0, 3, and 6 months of storage, the rice’s physical, milling, and physicochemical qualities were analyzed. The results showed that the quality of all the rice grain varieties equally decreased during the six months of storage while the average grain moisture content slightly increased by 13.7% (13.30-14.16%). In addition, the yield of unpolished, polished, and head rice slightly decreased. While the percentage of broken rice, groats, green/chalky, and yellowing/damage grains slightly increased. Additionally, the gel consistency and alkali digestion remained constant, while the amylose content, water absorption ratio, and volume expansion ratio slightly increased.

Heat and Mass Transfer on the Microwave Drying of Rough Rice Grains: An Experimental Analysis

This work aims to experimentally study the drying of agricultural products using microwaves, with particular reference to grains. Microwave drying experiments were carried out with paddy rice grains in natura (BRSMG Conai variety) for three levels of incident microwave power per mass of fresh grain (6.27, 14.63 and 22.99 W/g). Results of grain drying and heating kinetics are presented and analyzed. It was verified that the ideal average moisture content for grain storage and marketing, 15% (d.b.), occurred at 20 min (6.27 W/g), 13 min (14.63 W/g) and 7 min (22.99 W/g), and that the equilibrium moisture content of the samples reached 4.4%, 2.7% and 1.9%, at 310, 180 and 110 min, for each of the three power levels studied, respectively. The drying with the highest absorbed power caused discoloration of the grains at the end of the drying process.

Rice cultivar response to sublethal concentrations of glyphosate and paraquat late in the season

AbstractDifferential tolerance may be observed among rice cultivars with desiccant exposure events during rice reproduction and ripening. Five field studies were established at the Mississippi State University Delta Research and Extension Center in Stoneville, MS, to determine the effects of exposure to sublethal concentrations of common desiccants across multiple rice cultivars. Rice cultivars in the study were ‘CLXL745’, ‘XL753’, ‘CL163’, ‘Rex’, and ‘Jupiter’. Desiccant treatments included no desiccant, paraquat, or glyphosate and were applied at the 50% heading growth stage respective to cultivar. Differential injury estimates among cultivars and desiccant treatments was observed when glyphosate or paraquat was applied at 50% heading. Injury from glyphosate at 50% heading was nondetectable across all cultivars. However, injury following paraquat applications was >7% across all rating intervals and cultivars. Hybrid cultivars exhibited less injury with paraquat applications than the inbred cultivars in the study. Rice following exposure to glyphosate or paraquat at 50% heading growth stage produced rough rice grain yield decreases ranging from 0% to 20% and 9% to 21%, respectively. Rough rice grain yield decreases were observed across all cultivars following paraquat exposure, and all inbred cultivars following glyphosate exposure. Across desiccant treatment, head rice yield was reduced in three of five cultivars in the study. When pooled across cultivar, paraquat applications cause a head rice yield reduction of 10%, whereas rice yield following glyphosate application remained >95%. Although differential tolerance among cultivars to paraquat or glyphosate exposure was observed, impacts on grain quality coupled with yield reductions suggests extreme rice sensitivity to exposure to sublethal concentrations of these desiccants at the 50% heading growth stage.

Continuous and Intermittent Drying of Rough Rice: Effects on Process Effective Time and Effective Mass Diffusivity

The choice of the drying process plays a key role in reducing the costs of electricity consumption in the food industry. Thus, this study aimed to evaluate continuous and intermittent drying of rough rice, using empirical and diffusion models to describe the drying kinetics, considering only effective time of operation to compare and evaluate these processes. Experiments were carried out during the month of April 2018, in Campina Grande, Paraiba Brazil, and were conducted with continuous and intermittent drying of rough rice grains (about 20 g, each experiment) using a fixed-bed dryer with constant power, at temperatures of 50 and 70 °C. For the intermittent experiments, the intermittency ratio was α = 2/3 and the drying periods were 10 and 20 min, with intermittency periods of 20 and 40 min, respectively. Comparison between continuous and intermittent drying kinetics indicated reduction in the effective time of all intermittent drying experiments, reaching up to 32.2%, hence promoting energy saving. It was also found that a one-dimensional diffusion model with boundary condition of the first kind properly described all rough rice drying processes and that the effective mass diffusivity is higher in intermittent drying, compared to continuous drying at the same temperature.

Modeling and experimentation of continuous and intermittent drying of rough rice grains

Rice (Oryza sativa L.) is one of the most produced and consumed cereals in the world, being characterized as the main food of more than half of the world population, since it is source of energy, protein, vitamins and minerals. Freshly harvested rice from the field generally has a high moisture content to be stored safely and, therefore, a suitable drying process needs to be conducted to decrease the physical-chemical activity of the product and inhibit the associated microbial activities. In this work, experiments were carried out on the intermittent drying of rice grains, in order to evaluate the effects of different drying air temperatures (40, 50, 60 and 70 °C) and tempering times (30, 60, 120, 180 and 240 min). Intermittent drying was simulated by means of a new liquid diffusion model based on a prolate spheroid geometry. To validate the model, the solution was fitted to the experimental data for the drying air temperatures of 40 and 70 °C and tempering periods ranging from 0 to 180 min. The results show that, for all experiments of intermittent drying of rough rice, the effective operating time decreased compared to the continuous drying. In addition, intermittent drying produces lower temperature on the grain surface, which minimizes the thermal damages caused to the product during the process. Numerical simulations provide information on moisture distribution inside the rice grain during the periods of interruption in hot air application. After 15 min of drying at temperatures of 40 and 70 °C, followed by a 60-min pause at room temperature, it is possible to respectively reduce about 72 and 68% of the moisture content gradients inside the rice grain. With tempering of 180 min, it is possible to eliminate almost all moisture content gradients for the drying at 70 °C.

Effect of drying and milling modes on the quality of white rice of an Indonesian long grain rice cultivar.

Many studies have revealed the susceptibility of long grain rice to breaking during milling, while others have demonstrated the variation in the yield of head rice due to different rough rice drying methods. Thus, this study aims to determine appropriate drying and milling methods to improve the head rice yield and nutritional quality of long grain rice. A series of drying experiments were performed on rough paddy rice employing shallow bed, oven and sun drying methods. Then, the dried rough rice grains were milled with various dehusking (H), separation (S) and polishing (P) configurations to obtain white rice. The resulting batches of white rice were analyzed and compared in terms of head rice yield, broken rice yield, brewer yield, whiteness and nutritional quality. Milling configurations strongly affected the total, head rice, broken rice and brewer yields. The configuration of one dehusking, one separation and one polishing (H – S – P) resulted in the highest milling and head rice yields. Although the whiteness of the rice samples was significantly affected by the milling configuration, their values fell within an acceptable range preferred by consumers in Southeast Asia (39–47). The milling of dried rough rice obtained from shallow bed and sun drying using a concrete floor and white tarpaulin resulted in a comparable total (65%) and head rice yield (51%). However, the milling of rough rice dried using an oven and sun drying on black tarpaulin resulted in a slightly lower total yield (64.50%) and head rice yield (50.50%). The moisture, ash, protein and lipid contents of the white rice were significantly lower than those of manually dehulled rice, whereas the carbohydrate and amylose contents of the white rice were significantly higher. Application of shallow bed or sun drying on a concrete floor followed by milling with the H – S – P configuration produced the highest head rice yield with an acceptable whiteness and nutritional composition. These combined postharvest technologies are simple, efficient and economical for both small- and large-scale applications. Further research on consumer acceptance and on the nutritional and cooking qualities of the white rice obtained from these combined postharvest technologies is essential.

Rough Rice Grain Drying (BRSMG CONAI) at Temperatures of 60 and 80°C in Oven

Rice (Oryza sativa L.) is a greatly important socio-economic crop. Immediate threshing and drying of wet harvested grains, to reach 18–19% (w.b) moisture content, is a practical method used by individual farmers to slow deterioration and increase selling prices. However, rough rice grain is different from other grains because it has an outer cover shell (palea and lemma) and a bran layer. Thus, the heat and mass transfer processes that take place during grain drying are different from those of other cereal grains, so understanding the effect of different treatments, drying temperature, moisture content and the gradients in rice grains is essential to optimize the drying conditions. In this sense, the current study aims to analyze the moisture removal and its effects on the stress cracking and the number of brown rice grains (BRSMG CONAI variety) at the temperatures of 60 and 80°C.

Applying Liquid Diffusion Model for Continuous Drying of Rough Rice in Fixed Bed

Simulate the rice drying process at specific drying conditions is of great interest to optimize the process and ensure a better quality of the final product. In the present work, experimental drying procedures of rough rice grains (BRSMG CONAI variety) was reported and drying kinetic was obtained at temperature using 40°C. The results were compared with simulated data by means of the liquid diffusion model equilibrium boundary condition. The geometry used to represent the rice grain was prolate spheroid. For this purpose, the diffusion equation, written in cylindrical coordinates, and solved via Galerkin-based integral method considering the constant diffusion coefficient. A good agreement was observed between predicted and experimental data. It was also possible to observe that the highest moisture gradients occur at the tip of the grain, which is region more affected by thermal and hydric stresses. The studied model can be used to solve problems involving diffusion processes, such as: drying, wetting, heating and cooling, provided that the geometrical shape of the body is similar to prolate spheroid.

Transgenic cry1C⁎ gene rough rice line T1C-19 does not change the host preferences of the non-target stored product pest, Rhyzopertha dominica (Fabricius) (Coleoptera: Bostrichidae), and its parasitoid wasp, Anisopteromalus calandrae (Howard) (Hymenoptera: Pteromalidae)

Rough rice grains are often stored for extended periods before they are used or consumed. However, during storage, the rough rice is vulnerable to insect infestation, resulting in significant economic loss. Previous studies have shown that volatiles cues, physical characteristics, and taste chemicals on the grains could be the important key behavior factors for storage insect pests to locate the hosts and select oviposition sites. It is also well known that the transgenic Bt rough rice line T1C-19, which expresses a cry1C⁎ gene has a high resistance to Lepidoptera pests. However, there were no evidences to show the consequences of host preference for non-target insect pests after growing Bt transgenic rice. In this study, the potential key factors of Bt rough rice were investigated for their impacts on the behaviors of non-target pest lesser grain borer Rhyzopertha dominica, the main weevil pest of grain and its parasitic wasps Anisopteromalus calandrae, the natural enemy of the beetle. Both electronic nose and electronic tongue analyses showed that the parameters of Bt rough rice were analogous to those of the non-Bt rough rice. The volatile profiles of Bt and non-Bt rough rice examined by gas chromatographic mass spectrometry (GC–MS) were similar. For most volatile compounds, there were no significantly quantitative differences in compound quantities between Bt and non-Bt rough rice. The densities of sclereids and trichomes on the rough rice husk surface were statistically equal in Bt and non-Bt rough rice. The non-target pest, R. dominica, and its parasitoid wasp, A. calandrae, were attracted to both rough rice and could not distinguish the transgenic T1C-19 from the isogenic rough rice. These results demonstrated that Bt rough rice has no negative impacts on the host preference behaviors of non-target stored product pest R. dominica and its parasitoid A. calandrae.

DEVELOPMENT A MECHANICAL STIRRING UNIT FOR DRYING RICE GRAINS

The present study was carried out to develop and evaluate the performance of a mechanical stirring unit for rice crop after harvesting for drying to increase stirring efficiency and decrease both power and cost requirements. The aim of this study is to develop a mechanical stirring-unit for drying rough rice-grains after harvesting. The performance of the developed stirring unit was studied as a function of change in screw paddles speed of (120, 180 and 300 rpm ), paddle inclination angle of( zero, 15 and 30deg) with two paddle shapes (trapezoid and rectangle) and a unit wheel width of (4 and 10 cm). The developed unit performance was evaluated in terms of unit capacity, stirring efficiency and required power. The results showed that the screw trapezoid paddle with inclination angle of 300 decreased specific power by 15.79 % and 20.83 % by increasing paddle speed from 120 to 180 rpm and from 180 to 300 rpm, respectively. While, under the same conditions, stirring efficiency increased by 4.39 %, and volumetric capacity decreased by 8.8 % and 17.6 % under conditions of increasing inclination angle from zero to 150 and to 300, respectively at the same screw pitch of 20 cm with layer height of 7.0 cm. Total costs with the use of the developed stirring unit decreased by 48.2% comparing to the traditional method (by feet) according to hiring laborers with recent prices

Discriminant Analysis of Multiple Physicochemical Properties for Thai Rough Rice Varietal Authentication

Rough rice variety is a factor influencing milling and eating qualities. To accomplish the prediction of five Thai rough rice varieties with high accuracy, physicochemical properties of those varieties were investigated and used for discriminant analysis. The results indicated that dry weight of a hundred rough rice grains and the content of brown rice protein offered moderate accuracy of 65.38 and 55.38%, respectively, in varietal differentiation in the validation set. Better distinction could be achieved using multiple properties, namely, the hundred-grain weight, brown rice protein content, milled rice protein content, apparent amylose content, and alkali spreading value. The developed model performed the definite prediction with 84.9% explained variances in the first two functions and 100% accuracy.

Physico-mechanical properties of rough rice grain under different moisture conditions

This study was carried out to evaluate some physical and mechanical properties of three Hungarian rice varieties named Dáma, Janka and M488 under different moisture levels to be a useful data for modelling the moisture changes in rough rice storage bins. Rough rice grains were conditioned to moisture contents of 12, 18, 24, and 30% (w.b.). Five mechanical expressions named rupture force (Fr), maximum stress (σmax), grain deformation (D), energy (E) and toughness (T) were extracted from stress–strain curve for all tested varieties as a function of moisture content. Also, some physical properties such as bulk density, true density, porosity and some morphological features of grain were determined as a function of moisture content for tested rough rice grain. The results revealed that the measured physical and mechanical properties are significantly effected by moisture contents for the three tested rice varieties. In general, when the moisture content increased, the rupture force and maximum stress decreased for all investigated grains. However, the deformation, energy and toughness firstly decreased with moisture content increase and after that increased with further increase of moisture content for all rice varieties. On the other hand, the bulk density, true density and porosity do not have a specific trend with increasing moisture content. Moreover, there was a significant difference among the selected rice varieties in terms of their bulk density and porosity at the same moisture content range.

Non-linear modelling and control of a conveyor-belt grain dryer utilizing neuro-fuzzy systems

The grain drying process is characterized by its complex and non-linear nature. As a result, conventional control system design cannot handle this process appropriately. This work presents an intelligent control system for the grain drying process, utilizing the capabilities of the adaptive neuro-fuzzy inference system (ANFIS) to model and control this process. In this context, a laboratory-scale conveyor-belt grain dryer was specifically designed and constructed for this study. Utilizing this dryer, a real-time experiment was conducted to dry paddy (rough rice) grains. Then, the input–output data collected from this experiment were presented to an ANFIS network to develop a control-oriented dryer model. As the main controller, a simplified proportional–integral–derivative (PID)-like ANFIS controller is utilized to control the drying process. A real-coded genetic algorithm (GA) is used to train this controller and to find its scaling factors. From the robustness tests and a comparative study with a genetically tuned conventional PID controller, the simplified ANFIS controller has proved its remarkable ability in controlling the grain drying process represented by the developed ANFIS model.

A NATURAL CONVECTION SOLAR DRYER FOR ROUGH RICE

A solar drying system was constructed and tested to dry rough rice grains for seeding under Zagazig city prevailing weather conditions. The system consists of two integrated units, a solar collector with total area of 1.8 m2 attached to a drying chamber. The system is classified as a natural convection indirect passive cabinet type without any moving parts. The study parameters included varying the air inlet area from 244 to 732 cm2, testing three levels of initial moisture contents (20, 22, and 25% w.b.), and two different grain layer thicknesses of 5 and 10 cm. The system was operated from 8 AM to 5 PM under Zagazig local conditions (Latitude 30.5° N) for 2 weeks during the rice harvesting season of 2009. The results showed that the smallest air inlet area of 244 cm2 gave the highest collector thermal efficiency, the highest temperature difference between ambient air and heated air inside the collector, and highest drying rate. Also the initial moisture content of 20% w.b. gave the highest drying rate and fastest drying time. Same results were found using layer thickness of 5 cm. So the combination of 244 cm2 air inlet area, 5 cm layer thickness, and 20% initial moisture content is recommended for the best thermal performance and highest drying rate.