Effects of Thickness Fraction Process on Physicochemical Properties, Cooking Qualities, and Sensory Characteristics of Long-Grain Rice Samples

A process of removing thinner kernels of rough rice, i.e., thickness fraction process, has been suggested as a method for increasing milling yields in the rice industry. This study aimed at determining whether physicochemical properties, cooking qualities, and sensory characteristics of rice samples could be changed by the addition of a thickness fraction into the rice process stream. Each of four long-grain rice cultivar lots was assigned into two groups: unfractionated and thickness-fractionated. For the thickness-fractionated group, thin rice kernels (<1.9 mm) of rough rice were discarded from unfractionated rice samples. Unfractionated and thickness-fractionated rice samples were compared with respect to physicochemical properties, cooking qualities, and sensory characteristics. The results showed that the removal of such thin kernels decreased the breakage and chalkiness rates and increased head rice yields. Fractionated rice samples exhibited lower amylose contents and crude protein contents but higher gelatinization temperatures than unfractionated rice samples. While the optimum cooking duration and width–expansion ratios of thickness-fractionated rice samples were higher than those of unfractionated ones, there was a negligible impact of the thickness fraction process on sensory characteristics of long-grain rice samples. In conclusion, the thickness fraction process affects physicochemical properties and cooking qualities more than the sensory characteristics of rice samples.

SIMULATION OF RECIRCULATION TYPE DRYER USING PNEUMATIC CONVEYORS

Recirculating rice dryers are suitable for a large amount of loading capacity. It generally comprises two parts, the tempering section, a drying section, and the grains are dried intermittently until the final moisture content of the grains can be achieved. Wet grains are initially dried for about 11 minutes within the drying section of the dryer. The grains then are conveyed to the tempering section, stored for about 40 to 50 minutes. At every passes, about less than 2% (wb). The moisture content can be removed from the grains. The number of passes required to accomplish a drying process in a recirculation dryer depends on the initial moisture content and the amount of rough rice to be dried. The drying and tempering duration can be adjusted through a mechanical valve. The purpose of this study was to examine the performance of recirculating dryers equipped with pneumatic conveyors instead of bucket elevators to reduce electricity cost and heated using a proper blend between kerosene and jatropha oil. Several experimental runs were conducted under a constant drying temperature of 60℃ and were controlled by adjusting the fuel consumption rate. The experimental results showed that the drying efficiency was in the range of 22.2% to 31.1%, the specific energy consumption was between 3,475-4,785 MJ/kg H2O evaporated, fuel consumption at 0.95 to 1.15 liters/hr, and the drying rate was 0.9% per day. Using 465 kg of rough rice, the entire drying operation required 10 hours of drying time with 74.3% of head yield. The mathematical model used in this study also had indicated close agreement with experimental data.

Weather Forecast Based Rice Advisory Services in Bangladesh

Strengthening the early warning system to forecast extreme weather and provide action-oriented advisories may increase rice yield as well as enhance the income of the farmers through minimizing risks and losses, if proper use of the generated advisory is ensured. This study assessed the importance and impact of weather forecast based advisory service (WFBAS) in Bangladesh. Literature review and field experimental data were used in a sensitivity analysis to show the impact of WFBAS on rice production. Available literatures suggested that the weather based advisory service would enhance rice yield by around 6.7-10%, but the experimental findings revealed that yield advantage could be 21.48%. Besides, the adoption of this technology would reduce the cost of cultivation by 12%, whereas the aggregate impact would increase the farmers’ profit by 25%. In the sensitivity study, we considered the production and price of Aman and Boro seasons (actual and government procured prices for 2018-19) and assumed only 6.70% yield increase with 5% farmers adopting of WFBAS. As such, additional 0.172 million tons will be added to the national rough rice production and thus the nation will be benefited by 3143 million Bangladeshi taka (BDT) at the actual farmgate price and it would be 4478 million BDT at the government procured price. The return on one BDT investment in this technology would be 51-73 BDT based on actual and procured prices. The projection showed enhenced production of the rough rice at 0.119 million tons and 0.214 million tons by 2025 and 2030, on which the additional return would be BDT 2441 and BDT 5223 million at the projected actual farmgate price and BDT 3522 and BDT 6979 million at the projected Government procured price, respectively. Hence, the successful implementation of the WFBAS will help to develop resilient rice farming communities, minimize livelihood risk, reduce the cost of production, utilize resources efficienty, and enable the farmers to take maximum benefit from favorable weather conditions through improved agricultural extension services. Finally, the enhanced yield and loss reduction will help to achieve the target of Sustainable Development Goal (SDG) by 2030 through sustaining rice production in Bangladesh under changing climate. Bangladesh Rice J. 25 (1) : 51-74, 2021

Risk of Rice Cultivation under Current and Future Environment and Market

Risk is an inevitable feature of agriculture globally, and it might increase over time in the future. The study assesses the risk of rice cultivation in the three seasons under current and future conditions. The software programme @Risk version 7.6 was used to simulate the risk-return trade of rice cultivation in the three seasons in Bangladesh. The likelihood of having negative net income for the Aus (90%) and Boro (80%) rice was very high under the current market and environmental conditions. Besides, the chance of obtaining negative net income was notable for T. Aman (33%). Both the yield and price variation significantly contributed to the fluctuation of returns of rice production. However, with the current seasonal variation in yield, the probability of having negative net income for paddy rice was very low under the farmers’ expected price (Aman: 22.5 BDT kg-1, Boro: 25 BDT kg-1 and Aus: 24 BDT kg-1). The result indicates that only access to the fair price of the rough rice can ensure the economic sustainability of the rice production. Likewise, chances of having a negative net income of paddy rice in 2030 will be zero under the extrapolated yield (Aman: 5.3 kg ha-1, Boro: 6.3 kg ha-1 and Aus: 4.8 kg ha-1) and price (Aman: 31.75 BDT kg-1, Boro: 30.75 BDT kg-1 and Aus: 30 BDT kg-1). The findings indicate that rice cultivation in the three seasons will be economically sustainable, subject to achieving the expected genetic gain and ensuring access to the projected price. Thus, policy supports are needed to ensure farmers' access to a fair price, improve management practice, and strengthen research to enhance genetic gain for sustainable rice farming under future conditions. Bangladesh Rice J. 25 (1) : 101-110, 2021

Rice Response to Sub-Lethal Concentrations of Paraquat, Glyphosate, Saflufenacil, and Sodium Chlorate at Multiple Late-Season Application Timing as Influenced by Exposure

In Mississippi, rice reproduction and ripening often overlaps with soybean maturation creating potential for herbicide exposure from desiccants applied to soybeans onto rice. 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 sub-lethal 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 1/10 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 one week intervals (0, 7, 14, 21, and 28 DAH) up to harvest. Injury was observed 7 days 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 sub-lethal 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.

Rice Response to Sub-lethal Rates of Paraquat, Metribuzin, Fomesafen, and Cloransulam-methyl at Different Application Timings

Paraquat mixtures with residual herbicides before planting is a common treatment in Mississippi, and rice in proximity is susceptible to off-target movement of these applications. Four concurrent studies were conducted in Stoneville, MS, to characterize rice performance following exposure to a sub-lethal rate of paraquat, metribuzin, fomesafen, and cloransulam-methyl at different application timings. Applications were made to rice at spiking to one-leaf (VEPOST), two- to three-leaf (EPOST), three- to four-leaf (MPOST), 7 d postflood (PFLD), and panicle differentiation (PD) growth stages. Regardless of application timing, rice injury following exposure to paraquat was ≥ 45%. Delays in maturity were increased by 0.3 d d-1 following paraquat from emergence through PD. Dry weight, rough rice yield, panicle density, and germination were reduced 18.7 g, 131.5 kg ha-1, 5.6 m-2, and 0.3%, respectively, d-1 from paraquat at emergence through PD. By 28 d after treatment (DAT), metribuzin injured rice 3 to 6%, and that injury did not translate into a yield reduction. Regardless of application timing, rice injury following fomesafen ranged from 2 to 5% 28 DAT. Rice exposed to cloransulam-methyl EPOST exhibited greatest root and foliar injury 21 and 28 DAT, respectively. Additionally, yield was reduced to 6,540 kg ha-1 compared with 7,850 kg ha-1 in the nontreated when rice was exposed to cloransulam-methyl EPOST. Rice yield was negatively affected following paraquat applied any time after rice emergence. However, applications of paraquat to rice in early reproductive growth reduced rough rice yield and seed germination the greatest. Application timing is crucial in determining severity of rice injury. Early-season injury to rice following paraquat had less effect on yield compared with injury at later stages. Additionally, fields devoted to seed rice production are at risk for reduced seed germination if exposed to paraquat during early reproductive growth stages.