Protein Content Of Brown Rice Research Articles

Quantitative detection of crude protein in brown rice by near-infrared spectroscopy based on hybrid feature selection

It is important for rice breeding and quality evaluation to predict the protein content of brown rice rapidly and easily. In this study, near-infrared spectroscopy (NIRS) was utilized to establish a model for detecting crude protein content in brown rice based on 349 samples prepared from three kinds of brown rice, and the performance of the model was evaluated. Improved interval partial least squares (iPLS) was used to divide and screen different feature intervals after spectral preprocessing in this research. On this basis, competitive adaptive reweighted sampling (CARS) optimized the selected feature intervals, and finally 14 effective spectral features concentrated in 1160 nm–1338 nm were selected from 1050 features. The above hybrid feature selection has more advantages than the single selection. Support vector regression (SVR) calibration model was established, and partial least squares regression (PLSR) model commonly used in similar studies was selected as a comparison. The optimal spectral preprocessing method was selected according to the model prediction effect. The coefficient of determination (R2), R2 of cross-validation set (Rcv2), root mean square error of prediction (RMSEP), and relative percent difference (RPD) evaluated for the prediction model reached 0.9185, 0.8876, 0.2040% and 3.5194, respectively. The results showed that the designed method can be used for the rapid determination of the crude protein content of brown rice, providing a convenient, efficient and non-destructive method for related detection.

SSR marker-based study of the effects of genomic regions on Fe, Mn, Zn, and protein content in a rice diversity panel

Rice is one of the most important basic foods, especially in developing countries. However, rice production is negatively affected by drought and decreased water availability. Over the recent decades, aerobic rice has been considered as a promising approach to reduce water input. However, the rice genotypes suitable for aerobic rice should also be evaluated for other important characteristics such as grain micronutrient content. Studying the genetic variability of grain Fe, Mn, Zn, and protein content in aerobic rice genotypes compared to other rice varieties can be useful for improving nutritive value via plant breeding programs. In this study, 50 rice genotypes, including aerobic rice, Iranian-improved, and landrace varieties were studied for Fe, Mn, Zn, and protein content in brown rice and also for their association with 77 SSR markers. There was a significant diversity among the rice genotypes: 13.91–44.91 mg/kg for Fe, 5.85–35.93 mg/kg for Mn, 11.79–34.33 mg/kg for Zn, and 4.38–16.63% for protein. According to the cluster analysis, group (I) contained five Iranian landrace rice varieties (Champaboudar, Gharib, Alikazemi, Anbarbou, and Sangetarom) well-known for their eating and cooking quality and aroma; furthermore, 10 aerobic rice genotypes had the highest level of Fe and Zn content among other groups. According to the results some aerobic rice genotypes had high grain micronutrient values such as IR 82,639-B-B-103–4, which also had 16.63% protein content in the grain. Based on the results of association analysis, out of 55 random SSRs, 11 markers, and out of 22 linked SSRs, 17 markers were found to be associated with grain protein, Fe, Zn, and Mn in the present population. Out of 28 significant markers, RM488 associated with grain Fe, RM574 with Mn, and RM248 with Mn and Zn and the associated was detected in both the years. In addition, out of 11 newly detected SSR markers, five were substantially associated with rice grain quality traits. The markers, which are showing association, can be utilized to enhance the nutritional value of rice in plant breeding programs.

Methane and nitrous oxide emissions from paddy fields with no fertilizer use under continuous irrigation with treated municipal wastewater.

Treated wastewater (TWW) irrigation has been recommended as an environmentally friendly agricultural practice and has been applied in many countries for decades. The effects of wastewater irrigation on rice yield and quality, as well as on the environment, with particular focus on greenhouse gas emissions from paddy fields with municipal wastewater irrigation, have gained substantial attention. In this study, bench-scale experiments were conducted in two cultivation seasons where seedlings of Bekoaoba, a large-grain high-yield rice variety, were transplanted and irrigated with TWW without fertilization. A control experiment was performed to simulate the cultivation conditions of normal paddy fields. The study aimed to quantify the effects of TWW irrigation on rice yield and quality, in addition to CH4 and N2O emissions. The highest rice yield (10.4tha-1) and protein content in brown rice (13.8%) was achieved when the soil was repeatedly subjected to bottom-to-top TWW irrigation without any synthetic fertilizer. Bottom-to-top TWW irrigation decreased CH4 emissions by up to 95.6% when compared with tap water irrigation, whereas bottom-to-top and top-to-top TWW irrigation increased N2O emissions by 5 and 15 times, respectively. Bottom-to-top irrigation of TWW could be considered a promising solution for reducing greenhouse gas emissions as TWW irrigation resulted in a lower combined global warming potential than tap water irrigation. Further, bottom-to-top irrigation of TWW produced less CH4 and N2O than top-to-top irrigation.

肥効調節型肥料の窒素溶出パターンが全量側条施肥による水稲「あきたこまち」の生育・収量と玄米タンパク質含有率に及ぼす影響

肥効調節型肥料の窒素溶出パターンが全量側条施肥による水稲「あきたこまち」の生育・収量と玄米タンパク質含有率に及ぼす影響

Zinc (Zn) application methods influences Zn and iron (Fe) bioavailability in brown rice

In this study, we evaluated the possibility of increasing Zn and Fe bioavailability in twenty-six popularly grown rice cultivars by external application of Zn through soil and/or foliar means. A field experiment was conducted in an Inceptisol applying Zn through soil and/or foliar means and the harvested whole grains were processed to brown rice and subsequently analysed for Zn, Fe, phytic acid and crude protein contents. Native Zn concentration in the brown rice of those tested cultivars varied from 22.9 to 79.7 with a mean of 40.3 mg kg−1. Zn concentration in brown rice increased to the tune of 17 and 95% upon Zn application through soil and soil + foliar, respectively, over the control across the tested cultivars. Zn application further caused a decrease in the phytic acid/Zn molar ratio to the magnitude of 64.0 and 23.0% upon soil + foliar and sole soil application, respectively. The decrease in phytate/Zn molar ratio was higher in high yielding varieties followed by local varieties, aromatics and hybrids and thus increased the bioavailability of Zn in brown rice. An antagonistic effect was also observed on the iron content in brown rice upon application of Zn. The decrease in iron concentration in brown rice was higher with soil + foliar application than with only soil application of Zn. Zn application through soil + foliar over basal application could be a useful strategy to produce Zn dense grains and to reduce the phytate/Zn and phytate/Fe molar ratios and thus enhancing their bioavailability. Application of Zn fertilizers can also enhance crude protein content in brown rice.

Mapping and Validation of QTLs for the Amino Acid and Total Protein Content in Brown Rice.

Highly nutritious rice production will be benefited with the improvement of amino acid content (AAC) and protein content (PC). The identification of quantitative trait loci (QTLs) associated with the PC and AAC of rice grains could provide a basis for improving the nutritional value of rice grains. Here, we conducted QTL analyses using recombinant inbred lines from the cross between indica (Milyang 23 or M23) and japonica (Tong 88-7 or T887) rice varieties, afterward employing genotyping-by-sequencing to obtain a high-density genetic map. A total of 17 and 3 QTLs were detected for AAC and PC, respectively. Among them, two QTLs associated with more than 10 AACs, qAAC6.1 and qAAC7.1, were identified for the first time in this study. Each favorable allele that increased the AAC of the two QTLs was derived from M23 and T887, respectively. Allelic combination of qAAC6.1M23 and qAAC7.1T887 showed significantly higher content of associated amino acids (AAs) than other allelic combinations. Near-isogenic line (NIL) possessing qAAC7.1T887 with M23 genetic background had significantly higher AACs than both parents. These results indicate that the pyramiding of QTLs would be useful in developing brown rice with a high AA and protein content.

Rice Cultivation without Synthetic Fertilizers and Performance of Microbial Fuel Cells (MFCs) under Continuous Irrigation with Treated Wastewater

To obtain a high rice yield and quality for animal feed without synthetic fertilizers, an experiment with bench-scale apparatus was conducted by applying continuous irrigation with treated municipal wastewater (TWW). Uniform rice seedlings of a high-yield variety (Oryza sativa L., cv. Bekoaoba) were transplanted in five treatments to examine different TWW irrigation directions (“bottom-to-top” and “top-to-top” irrigation) and fertilization practices (with and without P-synthetic fertilizers) as well as one control that simulated the irrigation and fertilization management of normal paddy fields. The highest rice yield (14.1 t ha−1), shoot dry mass (12.9 t ha−1), and protein content in brown rice (14.6%) were achieved using bottom-to-top irrigation, although synthetic fertilizers were not applied. In addition, this subsurface irrigation system could contribute to environmental protection by removing 85–90% of nitrogen from TWW more effectively than the top-to-top irrigation, which showed a removal efficiency of approximately 63%. No accumulation of heavy metals (Fe, Mn, Cu, Zn, Cd, Ni, Pb, Cr, and As) in the paddy soils was observed after TWW irrigation for five months, and the contents of these metals in the harvested brown rice were lower than the permissible limits recommended by international standards. A microbial fuel cell system (MFC) was installed in the cultivation system using graphite-felt electrodes to test the capacity of electricity generation; however, the electricity output was much lower than that reported in normal paddy fields. Bottom-to-top irrigation with TWW can be considered a potential practice to meet both water and nutrient demand for rice cultivation in order to achieve a very high yield and nutritional quality of cultivated rice without necessitating the application of synthetic fertilizers.

High yield and nutritional quality of rice for animal feed achieved by continuous irrigation with treated municipal wastewater

Two consecutive pilot-scale experiments were conducted to investigate the potential reuse of treated municipal wastewater (TWW) as an irrigation source for cultivating forage rice (Oryza sativa L., cv. Bekoaoba) through examining our newly developed continuous irrigation systems, namely surface and subirrigation. Although only P-fertilizer was applied in 2016 and no fertilizer was supplemented in the 2017 season, the obtained yields were comparable to that recorded from normal paddy fields (7.3 t ha−1). The yields of the subirrigation plots (9.1 and 7.5 t ha−1) were significantly higher than those of the surface irrigation plots (7.5 and 7.1 t ha−1) in 2016 and 2017, respectively. There was no significant difference in the protein content of brown rice between the two fields, and this content (11.6–13%) was significantly higher than that (8.8%) recorded in normal paddy fields. This indicates our harvested rice was more favorable for animal husbandry since it can reduce the use of costly protein feed such as imported soymeal. Accumulation of heavy metals was not found in either paddy soil or brown rice after the two experiments. An effective N removal efficiency of the examined irrigation systems along with the reduced usage of chemical fertilizers could contribute to a substantial decrease in nutrients discharged from the wastewater treatment plants into surface water bodies. This study conveys the high feasibility of continuous irrigation with TWW to achieve high production and good nutritional quality of rice for animal feeding, which could promote an effective reuse of TWW in forage rice cultivation and enhance the self-sufficient feed ratio for sustainable dairy farming in Japan.

Estimation of rice protein content before harvest using ground-based hyperspectral imaging and region of interest analysis

Protein content, which represents rice taste quality, must be estimated in order to create a harvesting plan as well as next year’s basal dressing fertilizer application plan. Ground-based hyperspectral imaging with high resolution (1 × 1 mm per pixel) was used for estimating the protein content of brown rice before harvest. This paper compares the estimation accuracy of rice protein content estimation models generated from the mean reflectances of five regions of interest (ROIs): the overall target area, dark area (less illuminated parts of the rice plants), canopy area (leaves, yellow leaves, and ears), leaf area, and ear and yellow leaf area. The size of the target sampling area was 0.85 × 0.85 m. An R + G + B histogram and a GNDVI–NDVI image were used to separate the target area into the individual ROIs. The values of the coefficient of determination R 2 and the root mean square error of prediction (RMSE) were similar for each model: R 2 ranged from 0.83 to 0.86 and RMSE ranged from 0.27 to 0.30% for all models except for the dark area model, where R 2 = 0.76 and RMSE = 0.35%. There were no significant differences in the magnitude of the estimation error among all models. This result indicates that it is not necessary to obtain an image with a ground resolution that is greater than 0.85 × 0.85 m per pixel to estimate rice protein content before harvest. This result should provide useful information when deciding the altitude of platforms for imaging rice fields.

19 玄米タンパク質含有率が食味官能評価に与える影響(日本作物学会関東支部第100回講演会)

19 玄米タンパク質含有率が食味官能評価に与える影響(日本作物学会関東支部第100回講演会)

Predictive models for yield and protein content of brown rice using support vector machine

Rice production in Japan is facing problems of yield and quality instability owing to recent climate changes, aging of farmers, and a decrease in the farmer population. Thus, it is becoming important to develop an improved rice production technology that utilizes collected data about rice production rather than relying on the conventional technology that is based on the experience and knowledge of individual farmers. We developed predictive models for yield and protein content of brown rice that can provide useful knowledge to support farmer’s management decision-making, utilizing data sets from 47 paddy fields where rice was produced under various environments and management styles. Support vector machines (SVMs) were applied to build the predictive models based on explanatory variables representing the growth and nutrition conditions after the heading stage and the meteorological environment after the late spikelet initiation stage. The models achieved quantitative accuracy that was within approximately 1tha−1 in yield for 85.1% of the total data sets and within 0.8% in protein content for 76.6% of the total data sets, respectively. Further, patterns of explanatory variables classified in three classes of yield and protein content, which were visualized by the predictive models, were reasonable in terms of knowledge of crop science. We found that the predictive models using SVMs had the potential to describe a relation between yield or protein content and multiple explanatory variables that reflected diverse rice production in actual fields, and could provide useful knowledge for decision-making of topdressing and basal fertilization.

발아현미의 이화학적 특성

This study evaluated the physicochemical properties of brown rice (BR) and germinated brown rice (GBR) in Korea. The protein content of BR was significantly higher than that of GBR. The amylose content of BR and GBR ranged from 17.42 to 18.48% and from 17.50 to 19.69%, respectively. The GBR contained higher -aminobutyric acid (GABA) content than that of BR. In an RVA examination, pasting temperatures of BR and GBR were . Texture analysis test showed that GBR Yeonghojinmi had the lowest hardness and highest stickiness. In conclusion, this study showed that compared to BR, GBR has a much softer texture, improved eating quality and increased GABA content.

발아에 따른 현미의 품질 변화

본 연구는 국내 주요 벼 품종들중 일부 품종들에 대하여 현미와 발아현미에 대한 품질 특성에 대해 비교 분석하였다. 발아율은 95.0% 이상이었으며 단백질 함량은 현미 미광이 9.85%로서 가장 높았다. 아밀로스 함량 분석결과 현미보다 발아현미에서 높았으며 알칼리 붕괴도(ADV)는 품종 및 발아에 따라 다양하게 나타났다. 아밀로펙틴은 단쇄비율이 높을수록 밥맛이 좋은 것으로 알려져 있는데 삼광벼가 현미와 발아현미에서 각각 다른 품종들에 비하여 유의적으로 높음을 알 수 있었다. RVA 측정결과, 호화온도는 거의 비슷한 온도(<TEX>$67.93-68.05^{\circ}C$</TEX>)였으며 최고점도는 현미 삼광이 167.92 RVU로 가장 높은 수치를 보였다. 강하점도의 경우 발아현미 미광이 5.28 RVU로 가장 낮게 측정되어 가공시 안정도가 높을 것으로 사료되며 치반점도는 현미 미광이 14.34 RVU로서 조사되어진 품종들중 가장 높은 것으로 나타났다. 식감 측정결과 경도(hardness)는 발아현미 하이아미밥이 54.14로서 가장 낮은 값을 나타내었고 끈기(toughness)는 발아현미밥보다 현미밥에서 높았다. 찰기(stickiness)에서는 발아현미 삼광밥에서 51.45로서 가장 높은 값을 나타내었으며 부착성(adhesiveness)은 발아현미밥이 현미밥에 비하여 높은 값을 나타내었다. 따라서 본 연구에서는 주요 벼 품종들의 현미에 대하여 발아 전과 후의 품질 특성을 종합적으로 비교·분석한 결과, 식미가 우수한 최고품질 벼 품종인 삼광과 하이아미의 현미에서 발아 후 식감이 부드러워지고 찰기가 증대되어 밥맛이 향상되어 이는 발아현미 가공용으로 유망할 것으로 사료된다. 그리고 이와 같은 발아현미용 적합품종은 앞으로 국내 현미산업 활성화에 기여할 것으로 생각된다. The objective of this study was to evaluate quality properties, including amylose, alkali digestion value (ADV), and amylogram, of brown rice and germinated brown rice of some cultivars in Korea for rice processing products. The protein content of brown rice was significantly higher than those of germinated brown rice. The amylose content of the samples ranged from 17.09 to 18.85%. Alkali digestion value (ADV) of brown rice and germinated brown rice were described as a grade of 2-5 and 4-7, respectively. In a rapid visco analyzer (RVA) examination, pasting temperature of brown rice and germinated brown rice was <TEX>$67.93-68.05^{\circ}C$</TEX>. In addition, the pasting characteristics of brown rice were significantly higher than those of germinated brown rice. A texture analysis test showed that germinated brown rice Haiami had the lowest hardness and germinated brown rice Samkwang had the highest adhesiveness.

Evaluation of an analytical method to identify determinants of rice yield components and protein content

Modern information technologies have facilitated the collection of data to assess various aspects of rice production such as yield, quality, soil properties and growth conditions. Currently, farmers can identify any variation of these indicators within a field, between fields or with other farmers. However, a comprehensive analytical method to identify the determinants of variability has not been developed, and the data collected are not efficiently utilized to diagnose and improve the production skills of farmers. Our study focused on the development of an analytical method that can identify the determinants of rice yield and quality. The analytical method used applied cluster analysis (Ward method) to assess the data from 82 paddy fields where rice is produced in various environments and with various management styles. Initially, the 82 paddy fields were classified into 11 clusters based on five indicators of yield components and rice quality; number of panicles, number of spikelets, percentage of ripened grains, 1000-grain weight (GW) and protein content of brown rice. Then, 9 of 11 clusters (two clusters were excluded due to insufficient data to form a cluster) were divided into four groups based on yield capacity. As a result, common characteristics of fertilizer application, meteorological environment and growth conditions were extracted from each cluster. Furthermore, determinants of yield components and protein content were efficiently identified based on the common characteristics extracted.

Investigating Error Sources in Remote Sensing of Protein Content of Brown Rice Towards Operational Applications on a Regional Scale

近年，全国の米産地では，リモートセンシングで推定した玄米タンパク含有率 （以下，玄米タンパクと呼ぶ） を活用して，栽培指導や区分集荷が試みられるようになってきた．しかし，特に本州以南では推定精度が不十分で実用化が進んでいない場合が多い．本研究では推定精度および実用性の向上を目的として，青森県津軽中央地域の水田地帯100 km2を対象に航空機ハイパースペクトルで複数年の観測実験を行い，玄米タンパク推定の誤差要因をNDSI （正規化分光反射指数） を用いて分析した．地上で調査した葉色と玄米タンパクは，年次を通して密接な関係があった．しかし，反射スペクトルからの推定力の傾向は，葉色と玄米タンパクで違いがみられた．観測時の葉色に対しては赤と緑の双方の波長で推定力が高いが，収穫時の玄米タンパクに対しては赤の波長では大きく劣った．これは赤の波長が生育ステージの変化に対する感受性が強いことに起因している．この影響を分析するため，生育ステージの変動を施肥条件と田植時期の違いによる部分に分割したモデルを提示した．施肥条件は玄米タンパクと強く関係するのに対し，田植時期はほぼ無関係である．そのため，田植時期に起因する生育ステージの変動が大きい場合は，玄米タンパクの推定精度が低下しやすい．また，観測時期が早いほど，田植時期に起因する変動の影響が相対的に大きくなることも精度低下の一因となる．したがって，玄米タンパクの推定には，従来のNDVI （=NDSI［赤，近赤外］） に替わり，NDSI［緑，近赤外］ を用いることで，生育ステージによる影響が緩和され，精度の低下を軽減できる．

등숙기 온도변이가 중만생종 벼의 쌀 품질과 식미치에 미치는 영향

2006~2007년까지 2개년에 걸쳐 전국 8개도 27개 지역 28개 시험구에서 재배한 시료를 바탕으로 등숙기 온도가 벼의 등숙형질에 미치는 영향을 분석하고 식미치 향상에 적합한 등숙온도를 추적한 결과는 다음과 같다. 1. 출수기~출수 후 30일까지의 평균기온이 출수 후 40일까지의 평균기온 보다 벼의 등숙정도를 나타내는 현미 천립중과 식미치 변이를 더 잘 설명할 수 있었다. 2. 시험에 사용된 중만생종 벼 품종들은 출수기~출수 후 30일까지의 평균기온이 <TEX>$21^{\circ}C$</TEX> 이하일 경우에는 저온으로 등숙이 불량하였고 <TEX>$22^{\circ}C$</TEX> 전후에서 현미천립중이 최고를 나타내었으며 그 이상의 온도에서는 온도가 올라갈수록 현미천립중이 감소하였다. 3. 현미천립중이 최대가 되는 출수기~출수 후 30일까지 평균기온은 <TEX>$22.2^{\circ}C$</TEX>, 식미치가 가장 높았던 평균기온도 <TEX>$22.2^{\circ}C$</TEX>로 같은 경향을 나타내었다. 4. 출수기~출수 후 30일까지 평균기온이 증가할수록 현미단백질 함량은 증가하였고 현미천립중이 증가할수록 현미단백질 함량은 감소하였으며, 현미천립중이 증가하면 식미치가 증가하였고 현미단백질이 증가하면 식미치가 감소하였다. 5. 식미치가 최고를 나타내는 출수기~출수 후 30일까지의 평균기온은 남평벼에서 <TEX>$22.1^{\circ}C$</TEX>, 일품벼와 주남벼에서는 <TEX>$22.5^{\circ}C$</TEX>였지만 동진1호는 <TEX>$23.1^{\circ}C$</TEX>로 다소 높았다. 6. 출수기~출수 후 30일까지 평균기온이 <TEX>$21^{\circ}C$</TEX> 이상인 경우 온도가 높아질수록 현미단백질 함량은 유의하게 증가하였고, 현미천립중과 현미단백질 함량과의 관계는 부의 유의성을 나타내었다. 7. 식미치는 현미천립중과 정의 유의성을 보였고 현미단백질 함량과는 부의 유의성을 나타내었다. This experiment was conducted to clarify the effect of the temperature for grain filling duration on quality and taste of cooked rice cultivated in different region in Korea. In 2006 and 2007, 4 mid-late maturing group of rice varieties (Nampyeongbyeo, Ilpumbyeo, Junambyeo and Dongjin 1) were cultivated in 28 experimental plots of 27 different regions located in 8 provinces. The taste of cooked rice were positively correlated with 1,000 grain weight but negatively correlated with protein content of brown rice. Mean temperature for 30 days from heading was more closely correlated with grain filling and tastes of cooked rice than those for 40 days. Though, the optimum mean temperature for the best taste of cooked rice for 30 days after heading was 22.1 to <TEX>$23.1^{\circ}C$</TEX> depending on varieties, in general, 1,000 grain weight and cooked rice taste were the highest in the mean temperature of <TEX>$22.2^{\circ}C$</TEX> for 30 days from heading. But grains were poorly ripened in case of the mean temperature lower than <TEX>$21.0^{\circ}C$</TEX> for 30 days after heading. Therefore, for the better taste of cooked rice in Korea, the developing new rice varieties and cultivation method should be focused to adjust the mean temperature within <TEX>$22-23^{\circ}C$</TEX> during the period of 30 days after heading.

Study on Protein Components and Microstructure of the Japonica Restorer Line M119 with High Protein Content

A japonica restorer line (named m119) with extremely high protein content was bred successfully, whose protein content (wet base) reached 13.30%±0.19% in brown rice. SDS-PAGE analysis showed that the proportion of glutelin to total protein content increased to 71.77% in m119 compared with CK. The fracture of m119 grain was rough compared with CK, which might bring about negative influence to cooking and eating quality. However, there was no significant difference of endosperm cell in size, shape and distribution compared with CK. The increase of protein content in brown rice was neither proportion nor synchronization; The axis of japonica rice grain was nearly at the center and close to the ventral part of the grain fracture observed by confocal laser scanning microscopy, which was associated with the distribution of vascular bundles transporting nutrition to the grain. The proportion of smooth to rough surface in soaked grain fracture had certain correlation with protein content and cooking and eating quality.

Near-Infrared Spectrometer for a Head-Feeding Combine for Measuring Rice Protein Content

We have developed a near-infrared (NIR) spectrometer mountable on a head-feeding combine for measuring rice protein in real time while harvesting. The developed sensor employs reflectance optics instead of the more usual transmittance optics because (1) it operates under severe vibration and dust conditions; (2) it performs measurements in high moisture contents, low fluidity of rough rice; and (3) because of low light transmittance due to absorption by husks. The light source was a tungsten halogen lamp, with a diffusion cylinder installed so that uniform light would illuminate the sample. An Si-CCD measured the spectrum from 740 nm to 1140 nm with a post-dispersive grating. We made a calibration curve of brown rice protein from a spectrum of rough rice examined in a laboratory. The calibration curve accuracy was r= 0.87 and SECV (Standard Error of Cross-Validation) =0.47%. In the adopted measurement method, the sensor loaded the rough rice into a wide sample chamber by gravity and analyzed the loaded grain at the bottom using a reflected signal. The developed sensor was able to measure the protein content of brown rice from spectra of rough rice taken under severe conditions, e.g., a high-vibration, high-dust harvesting environment. In addition to the protein content, the rice weight and moisture content could be displayed on the monitoring terminal in real time. The accuracy of the protein content measurements in these field examinations was r=0.65 and SEP (Standard Error of Prediction) =0.22%. The SEP was far better than the SECV of the calibration, but the protein content fell in a narrow range in the field examination. Thus, we concluded that the actual accuracy was the same as the calibration.

Estimation of Rice Protein Content Using Ground-Based Hyperspectral Remote Sensing

Ground-based hyperspectral remote sensing was applied to rice plants a week before harvesting in order to estimate the protein content of brown rice. When the accuracy was predicted through a full cross-validation, a 2007 model was estimated with R2 = 0.626, RMSEP = 0.311%, REP = 3.95% and a 2008 model was estimated with R2 = 0.819, RMSEP = 0.188%, and REP = 2.68%. When one model was used for prediction using the other year's data, the prediction error increased twice or more because the tendencies of the regression coefficients were different between the 2007 and 2008 models. When model prediction accuracy using two years' data was calculated by full cross-validation, R2, RMSEP, and REP were 0.850, 0.247% and 3.32%, respectively.

Assessment of N topdressing rate at panicle initiation stage with chlorophyll meter-based diagnosis in rice

This study was conducted to determine N topdressing rate at panicle initiation stage by using chlorophyll meter (SPAD-502)-based N nutritional diagnosis in rice plant for high quality production of the Chucheongbyeo variety. Field experiments were carried for 3 years from 2003 to 2005 in Gyeonggi, Hwaseong. To confirm the method of measuring the leaf color with SPAD-502, leaf position of rice plant and measuring point on the leaf were studied. And the proper period to examine the leaf color and growth characteristics of rice plants was suggested at panicle initiation stage, from the results of the correlation between SPAD value and both content of chlorophyll and nitrogen in rice leaves. The multiply value of plant height, number of tillers per m2 and SPAD value could explain well the effect of nitrogen fertilization on the growth of rice plants, and was used to determine an equation for on-site determination of nitrogen fertilization rate for Chucheongbyeo variety at the panicle initiation stage. Nitrogen fertilization increased number of tillers and rice yields, and affected the increase in protein content in rice grain resulting in loss of quality, such as taste value, and decreased the percentages of both ripened and whole rice grains. Based on the response surface statistical methodology using the SAS program, the relationship equation among protein content of brown rice (PROT), plant growth value (plant height × number of tillers × SPAD value, PGV), and nitrogen fertilization rate at the panicle formation stage (NF) was developed. That is, PROT (%) = 7.379403 − (5.27E-7) a − 0.013291 b + (3.025355E-13) a2 + (3.222997E-8) ab + (6.781E-05) b2, where a means PGV and b is NF (%), and the equation’s coefficient of determination (R2) was 0.967. From this equation, to recommend the optimum N fertilization rate at panicle initiation stage easily to produce high quality rice of Chucheongbyeo variety, which contains the target protein content of brown rice.