Protein Content Of Rice Grains Research Articles

Protein content prediction of rice grains based on hyperspectral imaging

This study utilized hyperspectral imaging technology combined with mathematical modeling methods to predict the protein content of rice grains. Firstly, the Kjeldahl method was used to determine the protein content of rice grains, and different preprocessing techniques were applied to the spectral information. Then, a prediction model for rice grain protein content was developed by combining the spectral data with the protein content. After performing multiplicative scatter correction (MSC) preprocessing and selecting feature wavelengths based on successive projections algorithm (SPA), the multivariate linear regression (MLR) model showed the best prediction performance, with a calibration set R2C of 0.9393, a validation set R2V of 0.8998, an RMSEV of 0.1725, and an RPD of 3.16. Finally, the quantitative protein content model was mapped pixel by pixel to visualize the distribution of rice protein, providing possibilities for non-destructive protein content detection.

Heterosis, character association and path analysis for grain protein content in rice (Oryza sativa L.)

Heterosis, character association and path analysis for grain protein content in rice (Oryza sativa L.)

Grain quality and yield response of rice to application of plant growth-promoting bacteria and amino acids

To investigate the effects of foliar application of plant growth-promoting bacteria (PGPB) and amino acids (AAs) on grain yield, nutrient concentrations and protein content of rice grain, a field experiment was conducted as a split-plot in a randomized complete block design with three replications during 2019-2020. The experimental treatments included the PGPB at five levels (control, P. agglomerans strain O4 (PGPB1), P. putida strain P13 + P. agglomerans strain P5 (PGPB2), P. koreensis strain S14 + P. vancouverensis strain S19 (PGPB3), and PGPB1 + PGPB2 + PGPB3 (PGPB4) as main plots and AAs at four levels (control, methionine, lysine, and methionine + lysine) as sub-plots. The results indicated that PGPB significantly enhanced the grain yield, protein content and nutrient uptake in rice grains when compared with control plants. However, the plants treated with co-application of PGPB strains (PGPB4) showed higher yield, higher protein accumulation and greater nutrients uptake such as N, P, K and Fe compared with individual application of PGPB strains and untreated plants. Among the separate application of PGPB strains, rice plants treated with PGPB1 with capability to N-fixing had the potential for enhance yield and improve protein and nutrients accumulation. The combined foliar application of AAs had greatest impact in increasing yield and improving rice grain quality in terms of protein content and uptake of nutrients, especially N, Ca and Fe in grain. Overall, our results suggest that co-applications of PGPB strains (PGPB4) and using a mixture of two AAs (methionine + lysine) may find value as plant growth-promoting for increasing rice yield and quality.

Produktivitas dan Kandungan Protein Beras Mutan M6 Hasil Iradiasi Sinar Gamma pada Benih Padi Varietas Mentik Susu

<p>Mentik Susu is a popular rice germplasm in Indonesia. Due to field constraints in Mentik Susu rice cultivation, farmers switched to better varieties with higher yields. Farmers switch to superior types with high yields due to high plant posture, long harvest life, and low yields. Rice plants usually have a protein content of 4-5% per gram while without given radiation. It will be expected that after receiving gamma rays, the protein content in mutant plants will increase up to 7-8% per gram. The aim of this research was to evaluate the productivity and protein content of rice grain of 35 mutant strains of rices that could be developed into new varieties. The research took place at the Tegalgondo Rice Seed Garden Agricultural Land between June to October 2020. This research used Randomized Complete Block Design method with a single factor. Each treatment was repeated three times. The data obtained was analyzed with analysis of variance and followed with Duncan’s Multiple Range Test at a 5% level if any significant influences. The results of this research showed productivity of 35 Mentik Susu rice lines ranged from 4.28 to 6.69 ha<sup>-1</sup>, with either a high protein content ranging from 5-8% per gram and intermediate high yield potential strains G63T11-B6-T27(1), G15T5-14-B5-T60, G15T5-14-B5-T46, G11T22-19-B1-T48, G15T5-14-B3-T36, M-MS2-G15T3-2-5 -T27, M-MS2-G18T7-4-12-T13, M-MS2-G18T7-4-9-T12. These strains might be cultivated as potential candidates for new high-yielding varieties, which would then be evaluated for higher yields or multilocation tests before becoming published as new varieties.</p>

Screening and Validation of Rice OsAAP6 Interaction Protein

The protein content of rice seeds is an extremely important quality trait, but its genetic basis and molecular regulatory mechanism are still unclear. This study focuses on a positive regulatory gene OsAAP6 of grain protein content in rice. Proteins that interact with OsAAP6 were screened using yeast two hybrid experiments, and validated using in vivo point-to-point experiments and bimolecular fluorescence complementarity tests (BiFC). The main results are as follows: 98 positive colonies that may interact with OsAAP6 were screened from a rice cDNA library using yeast two hybrid technology. After sequencing and analysis, 40 proteins that may interact with OsAAP6 were ultimately obtained. Through comparative analysis, three proteins (Pyruvate phosphate dikinase (PPDR), WRKY, and GreA) were selected from these 40 proteins that may interact with each other. In vivo point-to-point experiments in yeast and bimolecular fluorescence complementarity (BiFC) experiments in rice were used to further verify that PPDK, WRKY, and GreA can interact with OsAAP6 protein, respectively. Therefore, the results of this study will provide important clues for further revealing the molecular mechanism by which the OsAAP6 gene regulates grain protein content.

Variation in nitrogen partitioning and reproductive stage nitrogen remobilization determines nitrogen grain production efficiency (NUEg) in diverse rice genotypes under varying nitrogen supply.

Nitrogen (N) is an important macronutrient needed for grain yield, grain N and grain protein content in rice. Grain yield and quality are significantly determined by N availability. In this study, to understand the mechanisms associated with reproductive stage N remobilization and N partitioning to grain 2 years of field experiments were conducted with 30 diverse rice genotypes during 2019-Kharif and 2020-Kharif seasons. The experiments were conducted with two different N treatments; N deficient (N0-no external N application, available soil N; 2019-234.15 kgha-1, 2020-225.79 kgha-1) and N sufficient (N120-120 kgha-1 external N application, available soil N; 2019-363.77 kgha-1, 2020-367.95 kgha-1). N application increased the NDVI value, biomass accumulation, grain yield, harvest index and grain N accumulation. Post-anthesis N uptake and N remobilization from vegetative tissues to grain are critical for grain yield and N harvest index. Rice genotypes, Kalinga-1, BAM-4234, IR-8384-B-B102-3, Sahbhagi Dhan, BVD-109 and Nerica-L-42 showed a higher rate of N remobilization under N sufficient conditions. But, under N deficiency, rice genotypes-83929-B-B-291-3-1-1, BVD-109, IR-8384-B-B102-3 and BAM-4234 performed well showing higher N remobilization efficiency. The total amount of N remobilization was recorded to be high in the N120 treatment. The harvest index was higher in N120 during both the cropping seasons. RANBIR BASMATI, BAM-832, APO, BAM-247, IR-64, Vandana, and Nerica-L-44 were more efficient in N grain production efficiency under N deficient conditions. From this study, it is evident that higher grain N accumulation is not always associated with higher yield. IR-83929-B-B-291-3-1-1, Kalinga-1, APO, Pusa Basmati-1, and Nerica-L-44 performed well for different N use efficiency component traits under both N deficient (N0) and N sufficient (N120) conditions. Identifying genotypes/donors for N use efficiency-component traits is crucial in improving the fertilizer N recovery rate and site specific N management.

The genetic basis of grain protein content in rice by genome-wide association analysis.

The online version contains supplementary material available at 10.1007/s11032-022-01347-z.

Response of Phytic Acid to Nitrogen Application and Its Relation to Protein Content in Rice Grain

Nitrogen (N) fertilization has been recognized as improving the grain beneficial micronutrients, including Zn and Fe, in rice. However, only a few studies have explicitly focused on N-induced variation in anti-nutritional components such as phytic acid (PA), PA synthesis-related gene expression, and variation in grain protein fractions. Therefore, in this study, two culture systems (hydroponic and detached panicle culture systems) were used to elucidate the influence of N application on PA concentration and its relation to the grain protein fractions, such as albumin, globulin, prolamin, and glutelin, and total protein in rice. Results showed that N application generally decreased the grain PA concentration in brown rice and down-regulated the PA synthesis-related genes in the lipid-independent pathway. In contrast, total grain protein and its fractions concentrations increased significantly. For grain positional distribution, PA and protein concentration were generally higher in the aleurone fraction than in the milled rice, regardless of N application. However, higher N application decreased the PA in both aleurone fraction and milled rice, while increased the grain protein fractions mainly in milled rice. These findings imply that N application could substantially improve the rice nutrition by reducing the PA while increasing the protein concentration. Hence, these findings may provide critical bases for rice nutritional improvement through optimal N management.

Identification of growth‐related indicators affecting the appearance and protein content of rice grains

AbstractTo facilitate the stable production of rice (Oryza sativa L.) in a changing climate, it is imperative to establish optimal N application rate via growth diagnosis. In this study, field experiments were conducted to identify useful indicators of white‐back grains and protein content of rice. During the reproductive stages in 2018 and 2019, we applied N at different rates and recorded the soil and plant analyzer development (SPAD) readings and normalized difference vegetation index (NDVI) measurements. The white‐back grain percentage and grain protein content were more strongly correlated with SPAD readings and NDVI during the reproductive stage when the 2018 and 2019 data were combined than with the separate data for each year. In the combined 2018 and 2019 data, SPAD readings were the most dominant factor affecting white‐back grain percentage at 4–2 wk before heading, whereas NDVI was the most dominant factor at 1 wk before heading. Similarly, in the combined 2018 and 2019 data, SPAD readings were the most dominant factors for grain protein content on all measurement days, and NDVI was one of the dominant factors at 1 wk before heading. These results suggest that SPAD readings at 4–2 wk before heading and SPAD readings and NDVI at 1 wk before heading are useful indicators for determining the optimal N application rates during the reproductive stage to reduce the occurrence of white‐back grains and to regulate the grain protein content.

Patterns of physiological parameters and nitrogen partitioning in flag leaf explain differential grain protein content in rice

The grain protein content (GPC) in rice is low, and more efforts with agronomic and molecular approaches were performed to increase them. However, the rice research focusing on the plant physiological behaviour that modulates the phenomenon of grain protein filling is very scarce. This work contains physiological parameters related to photosynthetic activity in the flag leaf in the grain filling period and N partitioning assays of high (Nutriar) and traditional (Camba) GPC cultivars. Results indicated a higher photosynthetic capacity, a better capacity to provide CO2 to the chloroplast and a healthier PSII structure in Camba relative to Nutriar. Chlorophyll fluorescence parameters decreased more steeply over time in the high protein variety, and a strong negative correlation was observed between GPC and PSII structure parameters. N content in the flag leaf at anthesis showed lower values and higher remobilisation during the grain filling period in Nutriar compared to Camba. The results of this work suggested that the inactivation of some PSII structures in higher GPC cultivars is associated with N remobilisation and would contribute to an increase in the free N available to be translocated to the grain.

Laboratory shortwave infrared reflectance spectroscopy for estimating grain protein content in rice and wheat

ABSTRACT Grain protein content (GPC), as an important agronomic indicator of nutritional value, is commonly used for optimized cultivation, classified harvesting, and quality grading. Previous studies on the spectroscopic estimation of GPC were often conducted at the canopy level with vegetation indices (VIs) derived from the visible and near-infrared (VNIR) bands, which are apart from the absorption features of protein predominately located in the shortwave infrared (SWIR) region. Since those absorption features are mostly masked by water for living plants, the causal relationships between sensitive spectral bands and protein absorption features are poorly understood. Recently, continuous wavelet spectral analysis has been commonly applied to the spectroscopic estimation of vegetation parameters in the way of extracting the optimal wavelet feature (denoted as WF λ,S, λ is the shifting factor in wavelength and S is the scaling factor in the power number of two) or the red-edge position. This study proposed the wavelet-based SWIR edge position (SWEP) for estimating the GPC in cereal crops through extending the red edge position extraction technique to laboratory SWIR reflectance spectroscopy. The performance of SWEPs and WFs was evaluated in coefficient of determination (R 2), root mean squared error (RMSE) and relative RMSE (RRMSE) with experimental data over field trials. Our results demonstrated that the protein absorption features in the SWIR region could be enhanced using wavelet-based methods towards accurate estimation of the GPC across rice and wheat crops. The optimal features WF1510,4 (R 2 = 0.96) and WF1610,5 (R 2 = 0.93) exhibited similar performance for GPC estimation as compared to normalized difference protein indices (NDPIs) on calibration data, but the latter NDPI models had much poorer performance on independent validation data (NDPI1745,1780: R 2 = 0.35, RMSE = 1.83%, RRMSE = 21.70%; NDPI2080,2160: R 2 = 0.57, RMSE = 1.48%, RRMSE = 17.55%). The GPC could be estimated with high accuracies on both calibration (R 2 = 0.94) and validation (R 2 = 0.92, RMSE = 0.64%, RRMSE = 7.59%) using the SWEP extracted from the 1450–1650 nm range at Scale 5. Given their close predictive performance, the wavelet-based SWEP was less affected by the degradation of spectral resolution in the input data than the WF. The application of SWEPs could help us better understand the spectroscopy mechanism of GPC estimation from grain reflectance spectra. It also suggests that not just the commonly used red edges but also the insufficiently exploited SWIR edges are important in the entire spectral domain for quantifying vegetation properties.

Comparative analysis on grain quality and yield of different panicle weight indica-japonica hybrid rice (Oryza sativa L.) cultivars

Indica-japonica hybrid rice (Oryza sativa L.) cultivars showed high yield potential and poor tasting quality when compared with common japonica rice cultivars. Large panicle is a prominent factor of high yield for indica-japonica hybrid rice cultivars, and the panicle weight varies greatly among different indica-japonica hybrid rice cultivars. It is important to research on yield and grain quality of different panicle weight indica-japonica hybrid rice cultivars. In this study, two different panicle types indica-japonica hybrid cultivars were used to research on the relation of yield and grain quality. The yields of two heavy panicle weights indica-japonica hybrid cultivars were significantly higher than that of two medium panicle weight rice cultivars. The cooking and eating quality and starch properties of different panicle type cultivars were evaluated. Yongyou 6715 (medium panicle) and Yongyou 1852 (heavy panicle) got the relatively higher cooking and eating quality. Rice cultivars with medium panicle weight had more large starch granules and higher relative crystallinity than cultivars with heavy panicle weight. Transition temperature and retrogradation enthalpy (ΔHret) of medium panicle type cultivars were significantly higher than that of heavy panicle type cultivars. There was no significant difference in amylose content among different panicle type cultivars. Protein content of heavy panicle type cultivar was higher than that of medium panicle type cultivar, and protein content is the main factor affect cooking and eating quality in this study. The cultivar Yongyou 6715 got the highest taste value with the lowest protein content. Thus, it is suggested that the emphasis on improving rice cooking and eating quality of indica-japonica hybrid rice cultivars is how to reduce the protein content in rice grain. According to the results of this study, medium panicle type with high grain weight is the desired panicle type for high quality indica-japonica hybrid rice breeding.

Rice Flour: A Promising Food Material for Nutrition and Global Health.

Hunger and malnutrition, especially children, are still global issues today. Rice is a staple food for more than half of the world population and important nutritional source of not only carbohydrate but also protein. In recent aging societies, protein-energy malnutrition in elderly people emerges also as a social issue. Malnutrition in elderly people raises the risk of falling into age-related chronic diseases. Nutritional care can prevent elderly people from such age-related diseases. Rice and rice flour would be good foodstuff for preparation of diet suitable for and preferred by elderly people. Protein content of rice grains, like the other cereal grains, is less than 10% by weight, which is a little lower than meat and cheese, but higher than dairy milk and yoghurt. Nutritional quality of rice proteins is higher than the other cereal grains. Such relatively higher nutritional quality of rice proteins could be due to high copies of glutelin genes evolved from an ancestral gene common to soybean glycinin and resultant high content of legume-type seed storage proteins. Recently, rice flour became to be utilized for various processed food. The rice seed proteins as well as starch are accumulated in specific organelles termed protein bodies and amyloplast in the cells of endosperm and aleurone layer. By milling rice grains to flour particles consisting of protein and starch nanoparticles, processing characteristics of rice starch and proteins could be changed. To develop rice-based processed food for prevention of malnutrition, rice flour particles from various different rice sources could be blended for desired nutritional composition without spoiling the value of product food.

Detection of stable QTLs for grain protein content in rice (Oryza sativa L.) employing high throughput phenotyping and genotyping platforms

Lack of appropriate donors, non-utilization of high throughput phenotyping and genotyping platforms with high genotype × environment interaction restrained identification of robust QTLs for grain protein content (GPC) in rice. In the present investigation a BC3F4 mapping population was developed using grain protein donor, ARC10075 and high-yielding cultivar Naveen and 190 lines were genotyped using 40 K Affimetrix custom SNP array with the objective to identify stable QTLs for protein content. Three of the identified QTLs, one for GPC (qGPC1.1) and the other two for single grain protein content (qSGPC2.1, qSGPC7.1) were stable over the environments explaining 13%, 14% and 7.8% of the phenotypic variances, respectively. Stability and repeatability of these additive QTLs were supported by the synergistic additive effects of multi-environmental-QTLs. One epistatic-QTL, independent of the main effect QTL was detected over the environment for SGPC. A few functional genes governing seed storage protein were hypothesised inside these identified QTLs. The qGPC1.1 was validated by NIR Spectroscopy-based high throughput phenotyping in BC3F5 population. Higher glutelin content was estimated in high-protein lines with the introgression of qGPC1.1 in telomeric region of short arm of chromosome 1. This was supported by the postulation of probable candidate gene inside this QTL region encoding glutelin family proteins.

Tos17 insertion in NADH-dependent glutamate synthase genes leads to an increase in grain protein content in rice

Nutrition from cereal grains sustains human life, and the protein content of rice grains is an important source for humans. Recent forward genetics studies pointed out the significant contribution of NADH-dependent glutamate synthase (NADH-GOGAT) to increased grain protein content in durum wheat. The aim of this work was to investigate the contribution of the two NADH-GOGAT enzymes in rice, NADH-GOGAT1, and NADH-GOGAT2, to rice grain protein content, using a reverse genetics approach. The grain protein content and free amino acid concentration were determined in Tos17 insertion mutants of the structural gene of each protein. We found a significant increase in protein content in the NADH-GOGAT2 mutant and an increase in free amino acid concentration in both the NADH-GOGAT1 and the NADH-GOGAT2 mutants. These results provide the first nutritional characterization of the NADH-GOGAT mutants. Rice containing increased protein and amino acid concentrations may have potential to contribute to improved rice nutrition. Since previous field analysis had indicated a 40% yield reduction in each of the mutants, future work should focus on improving the yield of the mutants.

Effects of open-field warming during grain-filling stage on grain quality of two japonica rice cultivars in lower reaches of Yangtze River delta

To evaluate the actual and comprehensive response of rice grain quality to global warming in lower reaches of Yangtze River delta, a 3-year open-field warming experiment was conducted with two japonica rice cultivars using Free-air temperature enhancement (FATE) facility. Ningjing3 and Wuyunjing24 were planted under two temperature regimes (NT: natural temperature; ET: elevated temperature) during grain-filling. FATE facility increased rice canopy temperature by 2.7 °C (daytime 1.5 °C/nighttime 3.9 °C), 2.0 °C (daytime 1.6 °C/nighttime 2.5 °C) and 3.4 °C (daytime 2.0 °C/nighttime 4.9 °C) in 2012, 2013 and 2014, respectively. Compared with NT, head rice rate, occurrence of perfect grains, amylose content, setback and consistency were decreased by ET, while occurrence of chalky grains, breakdown, cool paste viscosity, pasting temperature were increased under ET. Response of different chalky types to warming were unstable among cultivars and years. Based on Wu-Gilbert model, we found that the relative activity of starch branching enzyme (SBE) to starch synthase (SS) was decreased by ET, which may contribute to longer average amylopectin chain length. ET increased protein content of rice grain but performed no influence on the relative proportion of amino acids. These results revealed that low-amplitude warming during grain-filling could deteriorate rice milling, appearance and cooking quality, but improved its nutritional quality.

Biofertilizer as a Supplement of Chemical Fertilizer for Yield Maximization of Rice

Biofertilizer performs major role in crop production. A study was conducted to determine the effect of bio-organic fertilizer with reduced chemical fertilizer for rice yield maximization. The treatments were (i) control (without fertilizer), (ii) N, P, K at recommended rate i.e. 100% (120, 30, 60 kg ha -1 ), (iii) N and P (75%), and K (recommended rate) with biofertilizer (5 t ha -1 ) and (iv) N and P (50%), and K (recommended rate) with biofertilizer (10 t ha -1 ). Results showed that N and P (50%) with biofertilizer (10 t ha -1 ) increased the number of tillers (29), panicle length (28 cm), weight of 1000 grain (21.31 g), and produced the highest grain yield (7.26 t ha -1 ). There was no significant difference found among the N, P (75%) with biofertilizer (5 t ha -1 ) and N, P (50%) with biofertilizer (10 t ha -1 ) treatments for plant height, number of panicle plant -1 and harvest index (%). The application of biofertilizer with beneficial microbes improved the leaf chlorophyll, plant nutrient uptake and grain protein content in rice. Hence, the use of chemical N and P fertilizer can be minimized by 50 percent and improve rice yield with the supplement of 5 ton ha -1 of bio-organic fertilizer.

Hubungan Produksi dan Kandungan Protein Padi Populasi F3 Hasil Persilangan G39 x Milky Rice dan G39 x Ciherang

Rice is one of the commodity that is very important as a staple food for more than 95% of the population in Indonesia. Rice production should be increase continously in line with the increasing population of Indonesia. Therefore, it is important to improve the quality and quantity of the production of rice. Improvement in terms of quality through development of rice with high protein content, beside of its production. Protein content in rice grain be important because it serves as an essential nutrient that can be used in the growth and cell recovery. This research be conducted in the village Sokawera, district Baturaden, Banyumas Regency. The material used is a population of F3 results of crossing with G39 x Milky Rice and G39 x Ciherang. The results showed the highest protein content in population of crossing G39 x Milky Rice is amount 13.42%. and a crossing G39 x Ciherang is amount 13.05%. The value of the correlation of protein content with component output is -0.36. There is no relations between production rice and its protein content.

Determination of chemical, insoluble dietary fibre, neutral-detergent fibre and in vitro digestibility in rice types commercialized in Czech markets

This study aimed to characterize non-traditional types of rice imported to the Czech Republic. Several chemical parameters of rice types were evaluated, and easy procedures for determination of insoluble dietary fibre, neutral-detergent fibre and the in vitro digestibility were suggested. Twelve imported rice types commonly available in the Czech market were purchased and subjected to analyses. Dry matter, ash, crude oil, starch and protein were determined in all samples of rice types. Additionally, in vitro organic matter digestibility, dry matter digestibility, dietary and neutral-detergent fibre contents were determined too. The highest amount of dietary fibre was detected in red (3.49%) and basmati natural rice (3.26%) (P<0.05) and the highest content of neutral-detergent fibre was found in red (8.22%), red jasmine (7.61%) and brown jasmine rice (7.98%) (P<0.05). While the best digestibility was assessed in parboiled (97.51%), parboiled with Indian (97.79%), lilac (96.12%) and milky round-grained rice (96.25%) (P<0.05), the poorest digestibility was found in Thaibonnet natural (77.82%) and basmati natural rice (87.48%) (P<0.05). High values of dry matter digestibility and organic matter digestibility are in relation with low amounts of dietary and neutral-detergent fibre and also with higher starch and protein content of rice grains.

English

This study aimed to evaluate the agronomic efficiency and grain quality of rice cultivars to nitrogen application in upland conditions with supplemental sprinkler irrigation. The experiment was carried out in 2012/13 at Jaboticabal-SP on a randomized block and split plots design with four replications. The plots were composed of twelve rice cultivars (BRS Aroma, BRS Monarca, BRS Primavera, BRS Sertaneja, BRSMG Curinga, Caiapo, CIRAD 141, Guarani, IAC 165, IAC 201, IAC 202, and IAC 25), and two levels of nitrogen application (0 and 100 kg N ha -1 ) in topdress at the R 1 stage (panicle differentiation) as subplots. The N application intensifies the degree of lodging, mainly at Caiapo, Guarani, IAC 165, IAC 201 and IAC 25 cultivars. The N application affects the number of sterile spikelets per panicle, mainly in CIRAD 141, BRS Sertaneja, IAC 202, and BRS Aroma cultivars. Caiapo cultivar shows higher grain yield and agronomic efficiency in function of N application, followed by BRS Monarca, BRSMG Curinga, IAC 165, and IAC 202. Although Caiapo, CIRAD 141, Guarani, IAC 165, IAC 202, and IAC 25 cultivars present better results, all the others cultivars also present acceptable values of milling yield, without N application effects. The grain protein content in rice is increased by the N topdressing application.