Commercial Rice Production Research Articles

EXTENSION MODEL DEVELOPMENT OF COMMERCIAL RICE PRODUCTION IN SAVANNAKHET PROVINCE, LAOS

The government of Laos conducted the climate-friendly agribusiness value chains sector project in the year 2019 to encourage the improvement of competitiveness in rice production and to develop production according to meet the needs and production programs of the government. However, the number of farmers who participated in this project is an insignificant proportion compared to the number of total rice farmers. This study aims: 1) to find the problems and suggestions about commercial rice production, and 2) to develop an extension model for commercial rice production. Using a mixed methods research design, data were gathered from a) structured interviews (n = 177) and b) workshops with extension agents (n = 21). The data was analyzed using such statistics as frequency and percentage. The findings showed that most respondents were concerned with 16 problems and eight suggestions about commercial rice production. The extension model of commercial rice production comprised four main components: developing knowledge and understanding of the farmers; approaches for strengthening attitudes; encouraging the use of modern technology; and government supporting factors that could support commercial rice production. Therefore, all concerned organizations should set a clear policy to increase the capacity of the farmers and continue to develop the market system for increasing competitiveness that the farmers can sell their rice products at a satisfactory price as a result, farmers who do not participate in the commercial rice production extension project will turn to participate in the project more in the future.

Chinese sisal estates and smallholder land uses and livelihoods, Kilosa, Central Tanzania

The impacts of large-scale agribusiness, commonly associated with land grabbing, on smallholder livelihoods in Africa have been the subject of an expansive array of research that tends to focus on socioeconomic or environmental issues. This study examines the nexus of smallholder land-livelihood dynamics from 2000 to 2018 owing to the resurrection of fiber estates in the “sisal belt” of Kilosa, Tanzania. Here, Chinese firms have restored former colonial sisal estates, offering wage opportunities to neighboring communities, giving rise to commercial rice production among smallholders and incentivizing in-migration with its increasing demands for subsistence agricultural land. The combination of estate, subsistence, and rice cultivation has enhanced smallholder livelihoods on average, suggesting positive impacts of the fiber estates. These emerging conditions, however, have generated significant landscape changes, which foretell impacts on environmental services. These dynamics of land systems are revealed through the lens of remote sensing data, field surveys and observations, and SURE models.

Modeling Textural Properties of Cooked Germinated Brown Rice Using the near-Infrared Spectra of Whole Grain.

If a non-destructive and rapid technique to determine the textural properties of cooked germinated brown rice (GBR) was developed, it would hold immense potential for the enhancement of the quality control process in large-scale commercial rice production. We combined the Fourier transform near-infrared (NIR) spectral data of uncooked whole grain GBR with partial least squares (PLS) regression and an artificial neural network (ANN) for an evaluation of the textural properties of cooked germinated brown rice (GBR); in addition, data separation and spectral pretreatment methods were investigated. The ANN was outperformed in the evaluation of hardness by a back extrusion test of cooked GBR using the smoothing combined with the standard normal variate pretreated NIR spectra of 188 whole grain samples in the range of 4000-12,500 cm-1. The calibration sample set was separated from the prediction set by the Kennard-Stone method. The best ANN model for hardness, toughness, and adhesiveness provided R2, r2, RMSEC, RMSEP, Bias, and RPD values of 1.00, 0.94, 0.10 N, 0.77 N, 0.02 N, and 4.3; 1.00, 0.92, 1.40 Nmm, 9.98 Nmm, 1.6 Nmm, and 3.5; and 0.97, 0.91, 1.35 Nmm, 2.63 Nmm, -0.08 Nmm, and 3.4, respectively. The PLS regression of the 64-sample KDML GBR group and the 64-sample GBR group of various varieties provided the optimized models for the hardness of the former and the toughness of the latter. The hardness model was developed by using 5446.3-7506 and 4242.9-4605.4 cm-1, which included the amylose vibration band at 6834.0 cm-1, while the toughness model was from 6094.3 to 9403.8 cm-1 and included the 6834.0 and 8316.0 cm-1 vibration bands of amylose, which influenced the texture of the cooked rice. The PLS regression models for hardness and toughness had the r2 values of 0.85 and 0.82 and the RPDs of 2.9 and 2.4, respectively. The ANN model for the hardness, toughness, and adhesiveness of cooked GBR could be implemented for practical use in GBR production factories for product formulation and quality assurance and for further updating using more samples and several brands to obtain the robust models.

Induced resistance to rice sheath blight (Rhizoctonia solani Kühn) by β-amino-butyric acid conjugate of phenazine-1-carboxylic acid

Rice sheath blight caused by Rhizoctonia solani Kühn is a major fungal disease that plagues commercially grown rice. Occurring mainly in leaf sheaths and leaves, the disease leads to great losses in food production. β-amino-butyric acid (BABA) has been demonstrated to activate an induced resistance response and is a potent inducer of broad-spectrum disease resistance in different plant species. In this study, β-amino-butyric acid conjugate of phenazine-1-carboxylic acid (PCA) with prominent induced resistance to rice sheath blight was tested. The in vitro fungicidal activity, as well as in vivo efficacy, systemicity, induced resistance and defense enzyme activity of BABA conjugate of PCA against R. solani in rice seedlings was systematically evaluated. The results indicated that in vitro fungicidal activity of PCA-β-aminobutyric acid (4e) against R. solani was lower than that of PCA, but in vivo curative ability of 4e was the highest among all tested compounds. The systemicity tests in rice seedlings revealed that PCA did not possess phloem mobility, while 4e exhibited moderate phloem mobility but much lower thanα-amino-butyric acid conjugate of PCA (4d). In addition, Compound 4e showed the highest induced activity against rice sheath blight. The observed effects of defense enzymes help to explain this high level of induced activity. The current research results indicate that in rice seedlings, BABA conjugate of PCA induce observable resistance to rice sheath blight and exhibit moderate phloem mobility, which could be used as an induced resistance fungicide against rice sheath blight in commercial rice production. The BABA conjugate of PCA might provide a useful example of induced resistance to R. solani.

Regulation of 2-acetyl-1-pyrroline and grain quality in early-season indica fragrant rice by nitrogen and silicon fertilization under different plantation methods

Fragrant rice has a high market value, and it is a popular rice type among consumers owing to its pleasant flavor. Plantation methods, nitrogen (N) fertilizers, and silicon (Si) fertilizers can affect the grain yield and fragrance of fragrant rice. However, the core commercial rice production attributes, namely the head rice yield (HRY) and 2-acetyl-1-pyrroline (2-AP) content of fragrant rice, under various nitrogen and silicon (N-Si) fertilization levels and different plantation methods remain unknown. The field experiment in this study was performed in the early seasons of 2018 and 2019 with two popular indica fragrant rice cultivars (Yuxiangyouzhan and Xiangyaxiangzhan). They were grown under six N-Si fertilization treatments (combinations of two levels of Si fertilizer, 0 kg Si ha−1 (Si0) and 150 kg Si ha−1 (Si1), and three levels of N fertilizer, 0 kg N ha−1 (N0), 150 kg N ha−1 (N1), and 220 kg N ha−1 (N2)) and three plantation methods (artificial transplanting (AT), mechanical transplanting (MT), and mechanical direct-seeding (MD)). The results showed that the N-Si fertilization treatments and all the plantation methods significantly affected the HRY and 2-AP content and related parameters of the two different fragrant rice cultivars. Compared with the Si0N0 treatment, the N-Si fertilization treatments resulted in higher HRY and 2-AP contents. The rates of brown rice, milled rice, head rice, and chalky rice of the fragrant rice also improved with the N-Si fertilization treatments. The N-Si fertilization treatments increased the activities of N metabolism enzymes and the accumulation of N and Si in various parts of the fragrant rice, and affected their antioxidant response parameters. The key parameters for the HRY and 2-AP content were assessed by redundancy analysis. Furthermore, the structural equation model revealed that the Si and N accumulation levels indirectly affected the HRY by affecting the N metabolism enzyme activity, N use efficiency, and grain quality of fragrant rice. Moreover, high N and Si accumulation directly promoted the 2-AP content or affected the antioxidant response parameters and indirectly regulated 2-AP synthesis. The interactions of the MT method with the N-Si fertilization treatments varied in the fragrant rice cultivars in terms of the HRY and 2-AP content, whereas the MD method was beneficial to the 2-AP content in both fragrant rice cultivars under the N-Si fertilization treatments.

Factors influencing the practice of commercial rice production for food security in Vientiane capital, Laos

Rice is viewed as an indicator of food security and poverty reduction, but many rural areas of Laos still face rice insufficiency. Dealing with the problem requires transitioning from traditional farming to commercial production using modern techniques. This study aimed to investigate the factors influencing the adoption of commercial rice production for local food security and poverty reduction. The survey included 70 samples in the Namxouang irrigation development area of Vientiane Capital, Laos, using a questionnaire for secondary and primary data collection. Both descriptive and inferential statistics were employed to describe the collected data and analyze factors influencing commercial rice production. The findings revealed that 65.7%, 18.6%, and 15.7% of the respondents engaged in commercial, semi-commercial, and subsistence rice production, respectively. In addition, it also found that land size, labor costs, and machinery costs each had a significant positive relationship with the practice of commercial rice production at a statistical significance level of 0.01. At the same time, household size, media perception, and annual income had significant negative relationships with the practice of commercial rice production at significance levels of 0.01 and 0.05. Therefore, high-quality rice varieties, new rice production techniques, and rice production groups are needed to support farmers using the same technical practices to obtain similar yields. Moreover, regulations are required to control chemical use and manage paddy land. These changes would help achieve the government policy to promote smart farming and good agricultural practice for food security and poverty reduction.

Profitability of Actors in the Value Chain of Commercial Rice

This qualitative study explored the value chain of commercial rice in Nueva Vizcaya, Philippines. It presented the value chain map of commercial rice highlighting the profitability of each actor involved in the value chain, namely paddy rice farmers, primary traders, millers, retailers, and final traders (wholesalers and retailers). The findings revealed that the miller contributes the highest value-added cost to commercial rice production, accounting for approximately 40.39% of the total, followed closely by the farmers at 39.22%. The primary trader represented 10.93%, while the wholesaler and retailer contributed 6.72% and 2.07% respectively. Analysis of the percentage of profit to cost showed that farmers earned the highest percentage at 32.36%, followed by the retailer at 8.48%, the primary trader at 5.11%, the miller at 2.32%, and the wholesaler at 1.68%. However, when considering the operating cycle of each actor, it became apparent that the primary trader emerged as the highest-earning actor due to their shorter operating cycle compared to other actors in the value chain. Hence, venturing into paddy rice production, trading, milling, and wholesaling of commercial rice in Nueva Vizcaya is profitable, given the wide market demand for rice as a staple food. There is a viable opportunity to enhance profitability among the various actors in the value chain, particularly for farmers, by leveraging appropriate government support programs, specifically by maximizing the utilization of initiatives provided under the Rice Tariffication Law.

Response of Temperature-Related Rice Disaster to Different Warming Levels Under an RCP8.5 Emission Scenario in a Major Rice Production Region of China

Rice is the basic food for about 50% of the global population, and feeds two-thirds of the Chinese population. Under the influence of global change, extreme weather, and climate events increase in frequency, duration, and intensity, which affect food production substantially. In the medium-to-long term in the future, the impacts of climate change on food availability are likely to grow. In this work, we first define the rice damage indices and then use surface observation and regional climate downscaling results from the variable resolution model LMDZ4 driven by the six Coupled Model Intercomparison Project phase 5 (CMIP5) global climate models (GCMs) to describe the temporal-spatial characteristics and the future changes of the temperature-related rice damages in Northeast China and Central and East China, the major commercial rice production regions in China. Compared with the observation, LMDZ4 demonstrates its ability to reproduce the regional characteristics of both heat and chilling rice damages. Based on the future regional projections under the RCP8.5 pathway, future changes of rice damage under four temperature-rising categories of 1.5, 2, 3, and 4°C are estimated. In the two rice production regions, the future extent of heat-related damage for Northeast China is mostly limited to the western area, and the occurrence of heat damage generally increases with global warming levels, particularly when it is higher than 2°C. For Central and East China, the heat-related rice damage increases in both coverage and intensity. The region is also likely to have a faster increasing rate of heat damage than in Northeast China. When global warming reaches 3 and 4°C, the median heat-related damage spreads over almost the whole region of Central and East China. Moreover, the probability of regional-scale heavy level heat damage would be over 50% by the end of twenty-first century. On the other hand, the disastrous impact of a cold event affecting rice yield is reduced in both coverage and duration although the model projections over Northeast China show larger intermodel variability and uncertainty.

Does ENSO strongly affect rice yield and water application in Northeast China?

Northeast China (NEC) has recently become one of the largest commercial rice production regions in China. However, the increased production combined with increasingly frequent climate oscillations is severe competing for fresh water with the non-agricultural sectors in this region and is threatening national food security. In this study, the ORYZA (v3) crop model was used to estimate the rice yields and water applications under three management regimes, continuous flooded irrigation (CF), alternate wetting and drying (AWD), and rain-fed (RF), in the full nutrient supply and biotic-stress-free conditions in NEC from 1961 to 2016. The predicted average rice yields in these three production regimes were 12.7, 12.7 and 10.6 t ha−1. El Niño events reduced yields by 2.5% and 2.4% (P < 0.05) in the CF and AWD regimes, respectively, compared with those in Neutral years. The simulated total water application in the CF, AWD and RF regimes were 1437.3, 706.1 and 523.7 mm, respectively. The total water application decreased 50.9% and 63.6% in the AWD and RF regimes compared with the CF regime, respectively. El Niño events decreased water application by 1.7% and 1.2% in the CF and AWD, respectively (P < 0.05). In addition, the sea surface temperature (SST) impacts on rice yield varied among water management regimes in NEC. El Niño events decreased rice yield under CF and AWD, implying that El Niño may hammer rice production in NEC and impact China’s food security in the future. In addition, AWD management significantly decrease rice water application during both ENSO and non-ENSO years and is a water-saving technology for local government and producers to address the challenge of increasing water application from non-agriculture sectors.

Closing yield gaps in Colombian direct seeding rice systems: a stochastic frontier analysis

Rice is one of the most important crops in terms of harvested area and food security both globally and for Colombia. Improvement of technical efficiency levels in rice production in order to close yield gaps in a context in which rice demand increases, natural resources are depleted, and where there are growing expectations about both climate changes and trade agreements is likely the most important challenge that farmers confront. This research assessed the main management factors that limit both rice crop productivity and the likely drivers of non-optimal technical efficiency levels (a proxy for yield gaps). This study focused on both upland and irrigated direct seeding systems across a variety of environments in Colombia. Stochastic frontier models were used to integrate microeconomic theory and empirical regression analysis in conjunction with a large commercial rice production database developed by the Colombian rice growers’ federation (Fedearroz). A large variation was found in technical efficiency (from 40 to 95%) levels for both upland and irrigated systems, and major differences were obtained in the limiting factors of the two systems (e.g. seed availability, variety type, market accessibility, fertilizer type, and use rate). This suggests both substantial and varied opportunities for improvements in current technical efficiency levels. Across systems, the correct choice of variety was identified as a common key factorfor maximizing yield for a particular environment. For upland systems, optimal choices were F174 and F2000, whereas for irrigated rice F473 was found to produce the highest yield. Additionally, numerical analysis suggests a yield impact of ca. 0.18% for each 1% increase in the nitrogen application rate for upland systems. For irrigated rice, phosphorous rather than nitrogen application rates were found to be more important. Since our analysis is based on farm-scale commercial production data, we argue that once our results are brought to consensus with local extension agents, technicians and agronomists, then management recommendations for closing yield gaps can be used to improve rice productivity.

Evaluation of Rice Responses to the Blast Fungus Magnaporthe oryzae at Different Growth Stages.

Rice blast, caused by the fungus Magnaporthe oryzae, is the most damaging disease for rice worldwide. However, the reactions of rice to M. oryzae at different growth stages are largely unknown. In the present study, two temperate japonica rice cultivars, M-202 and Nipponbare, were inoculated synchronously at different vegetative growth stages, V1 to V10. Plants of M-202 at each stage from V1 to reproductive stage R8 were inoculated with M. oryzae race (isolate) IB-49 (ZN61) under controlled conditions. Disease reactions were recorded 7 days postinoculation by measuring the percentage of diseased area of all leaves, excluding the youngest leaf. The results showed that the plants were significantly susceptible at the V1 to V4 stages with a disease severity of 26.7 to 46.8% and disease index of 18.62 to 37.76 for M-202. At the V1 to V2 stages, the plants were significantly susceptible with a disease a severity of 28.6 to 39.3% and disease index of 23.65 to 29.82 for Nipponbare. Similar results were observed when plants of M-202 were inoculated at each growth stage with a disease severity of 29.7 to 60.6% and disease index of 21.93 to 59.25 from V1 to V4. Susceptibility decreased after the V5 stage (severity 4.6% and index 2.17) and became completely resistant at the V9 to V10 stages and after the reproductive stages, suggesting that plants have enhanced disease resistance at later growth stages. These findings are useful for managing rice blast disease in commercial rice production worldwide.

Inter-laboratory validation of an inexpensive streamlined method to measure inorganic arsenic in rice grain.

With the establishment by CODEX of a 200ng/g limit of inorganic arsenic (iAs) in polished rice grain, more analyses of iAs will be necessary to ensure compliance in regulatory and trade applications, to assess quality control in commercial rice production, and to conduct research involving iAs in rice crops. Although analytical methods using high-performance liquid chromatography-inductively coupled plasma-mass spectrometry (HPLC-ICP-MS) have been demonstrated for full speciation of As, this expensive and time-consuming approach is excessive when regulations are based only on iAs. We report a streamlined sample preparation and analysis of iAs in powdered rice based on heated extraction with 0.28M HNO3 followed by hydride generation (HG) under control of acidity and other simple conditions. Analysis of iAs is then conducted using flow-injection HG and inexpensive ICP-atomic emission spectroscopy (AES) or other detection means. A key innovation compared with previous methods was to increase the acidity of the reagent solution with 4M HCl (prior to reduction of As5+ to As3+), which minimized interferences from dimethylarsinic acid. An inter-laboratory method validation was conducted among 12 laboratories worldwide in the analysis of six shared blind duplicates and a NIST Standard Reference Material involving different types of rice and iAs levels. Also, four laboratories used the standard HPLC-ICP-MS method to analyze the samples. The results between the methods were not significantly different, and the Horwitz ratio averaged 0.52 for the new method, which meets official method validation criteria. Thus, the simpler, more versatile, and less expensive method may be used by laboratories for several purposes to accurately determine iAs in rice grain. Graphical abstract Comparison of iAs results from new and FDA methods.

Dietary Arsenic and Gut Microbiome Analysis

BACKGROUNDTypical exposure to inorganic arsenic (iAs) in food and water is linked to cancers, toxicity, and other health effects. The extent to which dietary iAs is metabolized to mono and dimethyl arsenicals (MMA and DMA) affects toxicity. Nutritional, genetic, and other factors determine iAs methylation, but recent experiments show that the gut microbiome also plays a role. In turn, iAs alters the composition of gut microbiota in mice. We evaluated the relationship of dietary iAs exposure to changes in gut microbiota in humans and mice and potential effects of gut microbiota on iAs methylation and toxicity.METHODSUsing a cross‐over design, a controlled dietary intervention study was conducted in human subjects and mice. Human subjects consumed a low‐As diet for 6 days, followed by 5 days on a high‐iAs diet that consisted of 3 servings per day of commercial rice products (110–250 μg/kg As). After establishing a baseline, mice were fed high‐iAs chow (138 μg/kg As) for 3 weeks, then low‐As chow (14 μg/kg As) for 1 week. Urine, blood, and stool samples were collected during and after each phase and samples were analyzed for total As and iAs metabolites. Fecal microbiota was analyzed using 16S rRNA amplicon profiling.RESULTSIn humans, high‐As diet was generally associated with an increase in Bacteroidaceae (from 40 to 54%) and decrease in Lachnospiraceae family from 25% to 18%. The high‐As diet resulted in a doubling of urinary As metabolites. Compared to the middle tertile of the urinary %DMA (DMA/sum of As metabolites), subjects in the highest tertile showed an increase in Bacteroidaceae (26% vs 51%) and decreases in Lachnospiraceae (26% vs 20%) and Ruminococcaceae (25% vs 15%). Those changes were correlated with the middle, not the highest tertile of total blood As. Alpha‐diversity increased on the high vs. low‐As diet in the highest tertile of blood total As. There were, however, no significant differences in Principal Coordinate Analysis (PCoA) analysis by diet or blood As. In mice fed high‐As chow, Bacteroidales S24‐7 group increased 1.54‐fold and Bacteroidaceae decreased 0.82‐fold. The highest vs. lowest tertile of %DMA was associated with a 1.4‐fold increase in Bacteroidales S24‐7 group bacteria in the mouse gut and decreases in most of the other major taxa. Contrary to human subjects, alpha diversity it was higher in mice fed low‐As chow, particularly in the highest tertile of urinary iAs excretion. The mouse microbiome showed a clear separation between mice on low‐ vs. high‐As chow in PCoA plots. The composition of bacterial flora in the guts of humans and mice overlapped, but relative abundances differed. Human subjects showed an increase in Bacteroidaceae during the high‐As diet, while in mice, Bacteroidaceae decreased sharply.CONCLUSIONThis is a preliminary assessment of the effects of dietary iAs on the mouse and human gut microbiome. High secondary methylation capacity (i.e., high %DMA) was associated with a large increase in the prevalence of Bacteroidaceae in the human gut and a large increase in Bacteroidales S24‐7 group in the mouse gut. The impact of alterations in gut microflora will require further investigation.Support or Funding InformationResearch Support: University of Arizona, Southwest Environmental Health Science Center (SWEHSC) Grant Number – P30 ES006694This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Accelerated molecular breeding of a novel P/TGMS line with broad-spectrum resistance to rice blast and bacterial blight in two-line hybrid rice

BackgroundBreeding two-line hybrid rice with disease resistance is an effective approach to stabilize rice yield in commercial rice production of China.ResultsWe improved the blast and bacterial blight resistance of Guangzhan63-4S, an elite photoperiod- and thermo-sensitive male sterile (P/TGMS) line widely used in two-line hybrid rice, by introducing the R genes Pi2 and Xa7 conferring resistance to rice blast and bacterial blight, respectively. Through the backcrossing and gene pyramiding breeding coupled with molecular marker-assisted selection, a new P/TGMS line Hua1228S carrying Pi2, Xa7, and tms5 was developed. Based on 200,000 SNP markers by next-generation sequencing, Hua1228S covered 87.6% of the recurrent genome, as well as 4.5% of the donor genome from VE6219 and 7.9% from YR7029–39. When infected with seven tested Xanthomonas oryzae pv. oryzae strains, Hua1228S conferred high resistance (0 level) to six bacterial blight strains. Moreover, Hua1228S showed broad-spectrum resistance to rice blast isolates with a high resistance frequency of 90.91%. High levels of resistance to leaf blast and neck blast were observed under heavy disease pressure in natural field. Importantly, Hua1228S showed identical fertility-sterility alteration pattern to Guangzhan63-4S. Thus, two hybrid combinations Hua Liangyou 2821 and Hua Liangyou 284 derived from Hua1228S exhibited enhanced resistance and higher yield compared with the control variety Feng Liangyou 4.ConclusionsThese results indicate that Hua1228S has tremendous potentiality to increase and stabilize the rice yield, through the introgression of two R genes by marker-assisted selection strategy.

Arsenic concentrations and speciation in Australian and imported rice and commercial rice products

Environmental contextIn countries where inhabitants are not exposed to arsenic-contaminated drinking water, food is the major source of potentially toxic inorganic arsenic. To complement the existing worldwide dataset on arsenic in rice, data are presented on Australian- and overseas-grown rice, and assessed in terms of possible risk. Only a diet comprising multiple serves of some rice products per day poses a potential risk to young children. AbstractArsenic concentrations and speciation measurements were determined for six varieties of Australian-grown rice (n = 130), imported rice (n = 53) and rice products (n = 56) from supermarkets. Total As, inorganic As and dimethylarsinic acid (DMA) concentrations in Australian rice ranged from 16 to 630 µg As kg−1 (mean ± s.d.: 220 ± 122 µg kg−1), 16 to 250 µg As kg−1 (92 ± 52 µg As kg−1) and &lt;5 to 432 µg As kg−1 (125 ± 109 µg As kg−1), respectively. Total As, inorganic As and DMA concentrations in imported rice ranged between 31 and 376 µg As kg−1 (130 ± 98 µg kg−1), 17 and 198 µg As kg−1 (73 ± 40 µg As kg−1) and &lt;5 and 327 µg As kg−1 (84 ± 92 µg As kg−1) respectively. Few samples exceeded the guidelines for inorganic As in polished rice. In rice products, total As, inorganic As and DMA concentrations ranged between 21 and 480 µg As kg−1 (160 ± 110 µg As kg−1), 20 and 255 µg As kg−1 (92 ± 78 µg As kg−1) and &lt;5 and 340 µg As kg−1 (65 ± 69 µg As kg−1) respectively. Sixteen samples exceeded the 100 µg kg−1 maximum for inorganic As concentration in rice foods for infants and young children. Ingestion of multiple serves of some rice products poses a potential risk. Environmental chemistry gaps, on processes influencing As occurrence in rice, are discussed.

Changes in Rice Grain Quality of Indica and Japonica Type Varieties Released in China from 2000 to 2014.

China is the first country to use heterosis successfully for commercial rice production. This study compared the main quality characteristics (head rice rate, chalky rice rate, chalkiness degree, gel consistency, amylose content, and length-to-width ratio) of 635 rice varieties (not including upland and glutinous rice) released from 2000 to 2014 to establish the quality status and offer suggestions for future rice breeding for grain quality in China. In the past 15 years, grain quality in japonica rice and indica hybrid rice has improved. In japonica rice, inbred varieties have increased head rice rates and decreased chalkiness degree over time, while hybrid rice varieties have decreased chalky rice rates and chalkiness degree. In indica hybrid rice, the chalkiness degree and amylose contents have decreased and gel consistency has increased. Improvements in grain quality in indica inbred rice have been limited, with some increases in head rice rate and decreases in chalky rice rate and amylose content. From 2010 to 2014, the percentage of indica varieties meeting the Grade III national standard of rice quality for different quality traits was low, especially for chalky rice rate and chalkiness degree. Japonica varieties have more superior grain quality than indica rice in terms of higher head rice rates and gel consistency, lower chalky rice rates and chalkiness degree, and lower amylose contents, which may explain why the Chinese prefer japonica rice. The japonica rice varieties, both hybrid and inbred, had similar grain qualities, but this varied in indica rice with the hybrid varieties having higher grain quality than inbred varieties due to significantly better head rice rates and lower chalkiness degree. For better quality rice in future, the chalky rice rate and chalkiness degree should be improved in japonica rice along with most of the quality traits in indica rice.

Farmers’ Perceptions of Rice Postharvest Losses in Eastern Uganda

Postharvest losses (PHLs) are a threat to efforts aimed at ensuring food and income security. This study aimed at contributing to the efforts to reduce PHLs through examining smallholder farmers’ perceptions about level of PHLs in Eastern Uganda. A descriptive cross sectional survey involved 83 farmers in focus group discussions and 150 individual household interviews. Principal component analysis and logistic regression were used to establish the determinants of farmers’ perceived ability to reduce PHLs. Results indicate that farmers perceive 66% of the losses occurred at the stages of harvesting, heaping and threshing through spillage. Quality deterioration was perceived to be highest at harvesting and drying. Farmers’ perceived ability to reduce PHLs was lowest at those stages where the losses were highest. This implies that the losses are likely to remain high unless farmers’ mindset about their control beliefs is enhanced. Farmers perceived ability to reduce PHLs is significantly influenced by potential for expansion of rice production, awareness of the modes through which losses occur and ways in which rice is used at household level and household characteristics. Any interventions to reduce PHLs should focus on mobilizing and coordinating farmers into commercial rice production and mind shift through intensifying sensitization.

Map-based cloning and characterization of the novel yellow-green leaf gene ys83 in rice (Oryza sativa)

Leaf-color mutants have been extensively studied in rice, and many corresponding genes have been identified up to now. However, leaf-color mutation mechanisms are diverse and still need further research through identification of novel genes. In the present paper, we isolated a leaf-color mutant, ys83, in rice (Oryza sativa). The mutant displayed a yellow-green leaf phenotype at seedling stage, and then slowly turned into light-green leaf from late tillering stage. In its yellow leaves, photosynthetic pigment contents significantly decreased and the chloroplast development was retarded. The mutant phenotype was controlled by a recessive mutation in a nuclear gene on the short arm of rice chromosome 2. Map-based cloning and sequencing analysis suggested that the candidate gene was YS83 (LOC_Os02g05890) encoding a protein containing 165 amino acid residues. Gene YS83 was expressed in a wide range of tissues, and its encoded protein was targeted to the chloroplast. In the mutant, a T-to-A substitution occurred in coding sequence of gene YS83, which caused a premature translation of its encoded product. By introduction of the wild-type gene, the ys83 mutant recovered to normal green-leaf phenotype. Taken together, we successfully identified a novel yellow-green leaf gene YS83. In addition, number of productive panicles per plant and number of spikelets per panicle only reduced by 6.7% and 7.6%, respectively, meanwhile its seed setting rate and 1000-grain weight (seed size) were not significantly affected in the mutant, so leaf-color mutant gene ys83 could be used as a trait marker gene in commercial hybrid rice production.

Methylmercury varies more than one order of magnitude in commercial European rice

Rice is known to accumulate methylmercury (MeHg) in the rice grains. MeHg as a neurotoxin impacts on the human central nervous systems and especially on the developing brain. In this exploratory study, 87 commercial rice products sold in Europe, including nine baby-rice products, were analyzed for total Hg and MeHg content. MeHg concentration in all rice products investigated range from 0.11 to 6.45μgkg−1 with an average value of 1.91±1.07μgkg−1 and baby-rice is not significantly different from other rice products. Total Hg ranges from 0.53 to 11.1μgkg−1 with an average of 3.04±2.07μgkg−1. MeHg concentrations in all rice products studied in this work would not exceed the provisional tolerable weekly intake (PTWI). 30% of all commercial market rice products exceeded 10% of the PTWI calculated for toddlers or 13% of products for adults with rice based diet.

냉동볶음밥 제조를 위한 품종별 쌀의 특성

Physicochemical properties of five commercial rice products were investigated in order to select the appropriate rice varieties for the preparation of frozen fried rice. Among the evaluated rice varieties, Onnuri (16.06%) had the highest amylose content, while Beakjinju (11.83%) had the lowest. The water absorption index ranged from 1.45 to 1.65 g/g. Regarding the Hunter’s color values, the L and a values of all rice varieties decreased while the b value increased with freezing-storage following the cooking process. The initial pasting temperature showed no significant differences among the five rice varieties. The highest viscosity (peak, trough, and final) and setback were found in the Sindongjin, while the lowest breakdown was found in the Baekjinju variety. Hardness, chewiness, and cohesiveness of all five cooked rice varieties decreased while their adhesiveness increased after freezing-storage. Under electron microscopy scanning, pores were observed inside the tissue of frozen cooked rices manufactured from Baekjinju and Hopum varieties, while substantially smooth tissue structure was observed in Sindognjin, Onnuri, and Ilmi rice varieties.