• KOREAN JOURNAL OF CROP SCIENCE
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• v.35 no.6
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• pp.512-517
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• 1990

This experiment was conducted to evaluate the tillering behavior of low- and high-tillering rice plants, IR58. a high-tillering cultivar with small panicles showed not only higher tiller number but also earlier tillering, faster tillering rate and longer tillering duration than IR25588. a low-tillering cultivar with large panicles, Tillering ability of IR25588 was only 59% that of IR58, Percent effective tillers was higher in IR25588(85%) than in IR58 (67%), Tillering response to wider spacing was higher in a high-tillering cultivar than in a low-tillering cultivar, Grain yield response to closer spacing (close spacing adaptability) was higher in a low-tillering cultivar than in a high-tillering cultivar.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.52 no.4
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• pp.439-446
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• 2007

We carried out this experiment on the purpose to investigate the quality properties of aseptic-packaged cooked rice by cultivars in 2006. Brown rice was milled for white rice to 89.6% weight of it. Based on cluster analysis of acceptance of sensory evaluation, eleven rice cultivars of 29 cultivars had superior palatability. Whiteness(r=0.42, p<5%), lightness(r=0.39, p<5%), Toyo value(r=0.35, p<10%), and moisture content(r=0.33, p<10%) of milled rice were correlated positively with acceptability. Protein content(r=-0.40, p<5%), expansion rate(r=-0.68, p<1%) and water absorption rate(r=-0.42, p<5%) of milled rice, and yellowness(r=-0.45, p<5%) of aseptic-packaged cooked rice were negatively correlated. In sensory evaluation, correlation coefficients of taste and texture with acceptability were higher than those of appearance and flavor. During storage, hardness and cohesiveness of aseptic-packaged cooked rice before reheating were increased and decreased, but those after reheating had no difference based on storage period and cultivar. On the contrary, whiteness of reheated aseptic-packaged cooked rice with no distinct differences before reheating was decreased during storage. There were no significant differences of texture property, color characteristics and moisture contents by cultivar during storage.

• Korean Journal of Breeding Science
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• v.51 no.4
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• pp.504-514
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• 2019

'Yechan' is a high grain quality mid-late maturing rice cultivar with lodging tolerance and multiple disease resistance. It was a derived from a cross between 'Hopum' and 'Iksan537' (cultivar name 'Haepum'). 'Hopum' is a high grain quality mid-late maturing rice cultivar with strong lodging tolerance and 'Haepum' is a high grain quality medium maturing rice cultivar with multiple disease resistance. To shorten the breeding period, another culture method was applied to the F₁ plants. 'Yechan' was selected through the pedigree method, yield trials, and local adaptability tests, with a high selection pressure for grain quality, lodging, and disease resistance. The heading date of 'Yechan' was August 14, one day later than that of 'Nampyeong'. 'Yechan' is a cultivar tolerant to lodging and it has short culms. It has multiple disease resistance against rice blast, rice stripe virus, and bacterial blight, including the K3a race, the most virulent race in Korea. The yield of 'Yechan' was similar to that of 'Nampyeong'. 'Yechan' showed excellent grain appearance, superior taste when cooked, and enhanced milling performance; thus, we concluded that it could contribute to the improvement of Korean japonica rice cultivar quality. 'Yechan', a high grain quality mid-late maturing rice cultivar with lodging tolerance and multiple disease resistance, would be suitable for cultivation in the southern plain area in Korea and has been utilized in the breeding programs aimed at enhancing the grain quality and stability for the cultivation of Korean japonica rice (Registration No. 7647).

• Korean Journal of Food Science and Technology
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• v.51 no.5
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• pp.432-437
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• 2019

The objective of this study was to determine the molecular/crystalline structures and phase transition properties of starches isolated from six rice cultivars grown in Korea. Apparent amylose content was highest in starch obtained from the Saemimyeon cultivar (30.8%) and lowest in that obtained from the Sheonhyangheukmi cultivar (20.3%). Starch from the Saemimyeon cultivar had a lower proportion of short chains (DP 6-12) and a the higher proportion of long chains (DP${\geq}37$) than that seen in other rice starches. Saemimyeon had relatively higher pasting temperature ($86.5^{\circ}C$), gelatinization temperature ($72.1^{\circ}C$) and gelatinization enthalpy (14.2 J/g) than these values found for other rice starches. The onset temperature and enthalpy for ice crystallization of rice starch ranged from $-27.1{\sim}-20.2^{\circ}C$ and 241.1~264.8 J/g, respectively. The ice melting enthalpy measured in excess water (67% water content) of rice starches was 282.4~310.1 J/g. Among the rice starches examined, starch obtained from Sheonhyangheukmi, with the lowest amylose content, showed the lowest glass transition temperature (${T_g}^{\prime}$).

• Proceedings of the Korean Society of Crop Science Conference
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• 2022.10a
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• pp.59-59
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• 2022

The transplanting date of rice affects grain yield and quality, and it is changed by the environment during cultivation. Thus, it is important to provide the optimal transplanting dates for rice growers under global warming environment. In this study, transplanting date experiments with thirty-day-old seedlings of three cultivars (early, mid, and mid-late maturity) were conducted at the National Institute of Crop Science in Suwon from 2018 to 2021 to determine the optimal transplanting dates for and quantify the effect of planting dates on yield and quality. Transplanting date was strongly associated with culitvar across every year. Clear relationships between transplanting date and head rice yield in early and mid-late maturing rice varieties were observed, and the highest head rice yields were observed during transplantings in mid and late June for early maturing cultivar and mid June for mid-late maturing cultivar. It is obvious that the optimal rice transplanting dates have been shifted and are better later than the optimal transplanting dates in 2002-2004. Days to heading was also strongly associated with the transplanting date and cultivar with 89% of the variation explained. Days to heading was reduced in the later transplanting dates. Grain yield was strongly associate with biomass production during ripening(R²=0.85), however translocated biomass from leaf and stem showed little association with grain yield. The results from this study reconfirmed the importance of shifting optimal transplanting dates to maximize head rice yield for the Mid-plain area in South Korea.

• Proceedings of the Korean Society of Crop Science Conference
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• 2022.10a
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• pp.145-145
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• 2022

South Korea greenhouse gas emissions have increased year by year, resulting in a total emission of 727.6 million tons of CO₂ eq in 2018, a 2.5% increase compared to 2017. Among them, the agricultural sector emitted 21.2 million tons of CO₂ eq., accounting for 2.9% of the total. Among the greenhouse gases emitted from the agricultural sector, a particularly problematic is methane gas emitted from rice paddies. Methane is one of the important greenhouse gases with a global warming potential (GWP) that is about 21 times higher than that of carbon dioxide due to its high infrared absorption capacity despite its relatively short remaining atmospheric period. Since the pattern of methane generation varies depending on the rice variety and ecological type, research related to this is necessary for accurate emission calculation and development of reduction technology. Accordingly, a study was conducted to find out the changes in greenhouse gas emission according to rice varieties and ecology types. As for the rice eco-type cultivar, early maturing cultivar (Haedamssal) and medium-late rice cultivar (Saeilmi) were used. Haedamssal was transplanted on May 25 and June 25, and Saeilmi was transplanted on June 10 and June 25. The amount of methane generated according to the growing day showed a tendency to increase as the planting period was earlier. The difference between varieties was that Haedamssal showed higher methane production than Saeilmi. The total CH₄ flux in the saeilmi was 18.7 kg·h^-1(Jun 10 transplanting), 12.4 kg·h^-1(Jun 25 transplanting) during rice cultivation. Lower methane emission was observed in Saeilmi than in Haedam rice. In addition, the earlier the planting period, the higher the methane emission. This study is the result of the first year of research, and it is planned to investigate the amount of greenhouse gas emission between double cropping and single cropping using wheat cultivation after harvest for each ecological type.

• Proceedings of the Korean Society of Crop Science Conference
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• 2022.10a
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• pp.281-281
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• 2022

Rice is a staple crop used by more than 50% of the world's population. However, in rapidly changing climates such as abnormal high temperatures and typhoons, the food security of rice is greatly threatened. Plant factories have the advantage of being able to grow crops regardless of climate change, so they can be a response to climate change. However, in plant factories, crops are grown by placing the culture bed vertically, so shorter crops are more efficient. Therefore, in order to search for genes related to the height of rice, QTL analysis was performed by investigating the plant height of Cheongcheong/Nagdong doubled haploids from 2017 to 2021. Plant height of rice investigated for five years showed a normal distribution, meaning that genes related to rice height are quantitative traits. As a result of QTL analysis, a total of 12 QTLs were detected, and QTLs overlapped for 5 years in RM12285-RM212 on chromosome 1. Also, The QTLs of plant height detected in 2019 has a LOD score of 17.64 in RM12285-RM212 region of chromosome 1. As a result of QTL analysis, 44 height-related genes were searched from the detected chromosomes, and among them, Os01g0757200 in RM 12285-RM212 on chromosome 1 region, named OsGA2ox3q1, were selected as genes related to the height of rice. The relative gene expression level of OsGA2ox3q1 was highly expressed in cultivar with short culm lines, and was low expressed in cultivar with long culm lines. OsGA2ox3q1 can be used to breed semi-dwarf cultivar in rice more efficiently.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.13-13
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• 2017

By the progress of genome sequencing, infrastructures for marker-assisted breeding (MAB) of rice came to be established. Fine mapping and gene isolation have been conducted using the breeding materials derived from natural variations and artificial mutants. Such genetic analysis by the genome-wide dense markers provided us the knowledge about the many genes controlling important traits. We identified several genes or quantitative trait loci (QTL) for heading date, blast resistance, eating quality, high-temperature stress tolerance, and so on. NILs of each gene controlling heading date contribute to elongate the rice harvest period. Determination of precise gene location of blast resistance gene pi21, allowed us to overcome linkage drag, co-introduction of undesirable eating quality. We could also breed the first practical rice cultivar in Japan with a brown planthopper resistance gene bph11 in the genetic back-ground of an elite cultivar. Discovery of major and minor QTLs for good eating quality allowed us to fine-tune of eating quality according to the rice planting area or usage of rice grain. Many rice cultivars have bred efficiently by MAB for several traits, or by marker-assisted backcross breeding through chromosome segment substitution lines (CSSLs) using genetically diverse accessions. We are also systematically supporting the crop breeding of other sectors by MAB or by providing resources such as CSSLs. It is possible to pyramid many genes for important traits by using MAB, but is still difficult to improve the yielding ability. We are performing a Genomic Selection (GS) for improvement of rice biomass and grain yield. We are also trying to apply the genome editing technology for high yield rice breeding.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.329-329
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• 2017

The study was conducted to investigate the effects of different harvesting time on pasting properties of starch in three colored rices. Seven major parameters of starch pasting properties, peak viscosity (PKV), hot pasting viscosity (HPV), cool pasting viscosity (CPV), setback (CPV minus PKV), breakdown (PKV minus HPV), peak time, and pasting time were determined by Rapid Visco Analyzer. The peak viscosity, hot viscosity, cool viscosity and peak time were influenced by different harvesting times. Pasting time was delayed slightly with prolonged harvesting time in all rice cultivars. Pasting temperature in each rice cultivar differed from each harvesting time, and pasting temperature of the two rice cultivars, Hongjinju and Joseongheugchal, showed the highest at the 40 days after heading and then it decreased at the final harvesting time. With the delay of the harvesting time, peak viscosity, hot viscosity, cool viscosity, setback value and pasting temperature did not exhibit a regular trend depending on their genetic characteristics. Branch chain length distribution of amylopectin was demonstrated a distinct difference among these colored rices. In changes of amylopectin branch chain-length distribution, the amylopectin structure of Hongjinju rice cultivar as affected by different harvesting time, the shortest chain length of amylopectin in rice starch harvested at 20 days after heading was characterized by the significant increase in A chains with $DP{\geq}12$ and remarked decrease in long chains $37{\leq}DP$ compared to that of 30, 40, and 50 days after heading. In particular, when harvesting time is delayed the distribution percentage of short chain (A chains with $DP{\geq}12$) was increased except for the rice which harvested 20 days after heading. The similar results were also observed in Sintoheugmi rice cultivar like that of Hongjinju rice cultivar. Otherwise, distribution percentage of the shortest chain length of amylopectin in rice starch harvested at 20 days after heading was characterized by the significant decrease in A chains with $DP{\geq}12$ and remarked increase in B chains $13{\leq}DP{\geq}24$ compared to that of 30, 40, and 50 days after heading.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.10-10
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• 2017

Rice consumption has been continuously decreasing as the eating habits of Koreans have become westernized and diversified. The per capita annual rice consumption in Korea has dropped sharply from 136.4 kg in 1970 to 61.9 kg in 2016. The Korean government, therefore, has been trying to promote rice consumption by invigorating the processed food industry using rice flour. To facilitate the market for processed rice foods, it is essential to develop proper milling technology in terms of flour particle size and damaged starch content to produce high quality rice flour at competitive cost. Dry milling and wet milling are the two major processes used to produce rice flour. Although the dry milling process is relatively simple with a lower production cost, damaged starch content increases because of the high grain hardness of rice. In wet milling, the quality of rice flour is improved by reducing flour particle size as well as damaged starch content through soaking procedures. However, the production costs are high because of the additional expenses associated with the disposal of waste water, sterilization and drying of the wet flour. Recently developed technologies such as jet milling and cryogenic milling also require expensive investment and production. Therefore, developing new rice cultivars with dry milling adaptability as well as good processing properties is an important goal of rice breeding in Korea. 'Suweon 542' is a floury endosperm mutant line derived from sodium azide treatment on a high-yield, early maturing, and non-glutinous japonica rice cultivar, 'Namil'. Compared with the wild type, after dry milling process, the grain hardness of 'Suweon 542' was significantly lower because of its round and loosely packed starch granules. Also, the flour of 'Suweon 542' had significantly smaller particles and less damaged starch than 'Namil' and other rice cultivars and its particle size distribution was similar to a commercial wheat cultivar. Recently, through collaborations with nine universities and food companies, a total of 21 kinds of processed prototypes, using the dry milling flour of 'Suweon 542', were evaluated. In the production of major rice processing products, there was no significant quality difference between the flours prepared by wet milling and dry milling. Although the amount of water added to the dough was slightly increased, it was confirmed that the recipe applying the wet flour could be used without significant change. To efficiently transfer the floury endosperm characteristics of 'Suweon 542' to other commercial rice cultivars, it is essential to develop DNA marker tightly linked to the target gene. Association analysis using 70 genome-wide SSR markers and 94 F2 plants derived from 'Suweon 542'/'Milyang 23' showed that markers on chromosome 5 explained a large portion of the variation in floury grains percentage (FGP). Further analysis with an increased number of SSR markers revealed that the floury endosperm of 'Suweon 542' was directed by a major recessive locus, flo7(t), located in the 19.33-19.86 Mbp region of chromosome 5, with RM18639 explaining 92.2% of FGP variation in the F2 population. Through further physical mapping, a co-segregate and co-dominant DNA marker with the locus, flo7(t) was successfully developed, by which, thereby, breeding efficiency of rice cultivars having proper dry milling adaptability with high yield potential or useful functional materials would be improved. 'Suweon 542' maintained the early maturity of the wild type, Namil, which can be used in rice-wheat double cropping systems in Korea not only for improved arable land but also for sharing flour production facilities. In addition to the high susceptibility against major rice diseases, nevertheless, another possible drawback of 'Suweon 542' is the high rate of viviparous under prolonged rainfall during the harvesting season. To overcome susceptibility and vivipary of 'Suweon 542', the progeny lines, derived from the crosses 'Suweon 542' and 'Jopyeong', an early maturing rice cultivar with multiple resistance against rice blast, bacterial blight, and rice strip virus, and 'Heugjinju', a anthocyanin pigment containing black rice cultivar, were intensively evaluated. As the outputs, three dry milling suitable rice elite lines, 'Jeonju614', 'Jeonju615', and 'Jeonju616' were developed.