• KOREAN JOURNAL OF CROP SCIENCE
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• v.30 no.3
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• pp.236-244
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• 1985

To know the varietal differences of ethylene evolution, 55 rice varieties were tested at seedling stage. And, also, 6 rice varieties were tested the biosynthesis of ethylene production. The group of japonica varieties produced higher amount of ethylene than the indica and indica x japonica crossed varieties. The content of ACC in rice seedlings of japonica varieties was higher than in seedlings of indica and indica x japonica varieties. And, also, the conversion rate of mathionine and ACC to ethylene in seedling of japonica varieties was higher than in seedling of indica and indica x japonica varieties.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.230-230
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• 2017

About 200 rice varieties for irrigated and rainfed lowland ecosystems were released in the Philippines, which were bred for improving yield under favorable conditions. Root plasticity plays key roles in maintaining crop productivity under abiotic stressed conditions. We hypothesized that some of these varieties possess root plasticity traits in response to water stressed conditions. This study aimed to evaluate the root system development and dry matter production of 14 randomly selected rice varieties (6 irrigated lowland and 9 rainfed varieties) under progressive drought (PDR) and soil moisture fluctuations (SMF) stress conditions. Two experiments were done in rootbox and line source sprinkler systems (LSS). Each of the varieties was subjected to well-watered (WW), PDR and SMF conditions during vegetative stage in rootbox system while the same genotypes were subjected to different intensities of drought stress under LSS. Under rootbox system, PDR and SMF significantly reduced shoot dry matter production in all varieties relative to their WW controls. Among varieties, NSIC Rc238 (irrigated lowland) showed the least reduction in shoot dry weight (SDW) in both PDR (by 11.8%) and SMF (by 26.9%) conditions. Less reductions in SDW of NSICRc238 were partially attributed to the promotion of L-type lateral roots, thus increasing total lateral root length by 24.2% and 30.7% under PDR and SMF, respectively. In LSS, SDW of NSIC Rc238 under mild drought stress (16-21% soil moisture content (SMC) had 31.8% reduction relative to its WW control (${\geq}22%SMC$) and had lower sensitivity drought index. Compared with the IR64 susceptible check and NSIC Rc9 tolerant check, NSIC Rc238 had higher SDW by 90.8% and 38.6%, respectively. Furthermore, no rainfed lowland varieties included in the experiment performed well under different water stress treatments. The results implied that some other irrigated lowland rice varieties may also possess drought dehydration avoidance root plasticity traits under water-stressed growing environments.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.154-154
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• 2017

In accordance with the opening of the Korean rice market, this study was focused on establishment of database for discriminating the Korean rice varieties and imported brand rices using DNA markers. In this study, the SNP markers were developed using single nucleotide polymorphisms between the reference sequences of japonica and them of 40 brand rices which collected in Australia, China, Thailand, United States and Vietnam. The developed SNP markers were screened to a total of 360 rices including 320 Korean rice varieties and 40 imported brand rices. We selected polymorphic markers among Korean bred rive varieties and imported brand rices. The selected markers were classified into 3 grades. The markers of A grade produced DNA band in 360 rices of 30~40%, B grades produced in 40~60%, and C grades produced bands over 60% rices. First, we tried to set-up the discriminating system using the minimum SNP markers of A grade. Especially, a set of sixteen SNP markers could identify among Korean bred rice varieties and imported brand rices. Additionally, some SNP markers like NSb for Pib gene, JJ80-T for Pi5 and YL155/YL87 for Pita which linked to resistance genes to blast were used to fingerprinting system. These markers were set-up as multiplex set for enhancing the identification efficiency among rice varieties. Finally, the selected SNP markers would be used to the fluidigm assay to construct the database for elaborate discrimination of rice varieties.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.63 no.3
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• pp.210-218
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• 2018

This study was conducted to examine the influence of different transplanting dates on rice quality and starch properties (morphology and pasting properties) of rice varieties that may be used for the production of rice flour. Three rice flour varieties, 'Seolgaeng', 'Hangaru', and 'Milyang317', were transplanted on May 20, May 30, June 10, and June 20. The peak viscosity decreased with a delay in the transplanting date. However, the amylose content increased with a delay in the transplanting date, whereas that of protein decreased. Amylopectin short-branch chain content increased in the rice varieties that were transplanted on May 30. The morphology of the starch granule of the varieties was determined by SEM. No apparent external difference in the starch granules was observed for the different transplanting dates. These results indicate that the transplanting date influenced the amylopectin structure and pasting properties, which led to changes in the physicochemical characteristics of rice starch.

• Journal of Plant Biotechnology
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• v.44 no.3
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• pp.243-263
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• 2017

This study is to establish the varietal discrimination based on DNA profiling of different varieties of rice. We examined the genetic distance among Korean rice varieties using allele frequencies and a genetic diversity analysis with Simple Sequence Repeats (SSRs) markers. The analysis of the genetic diversity and genetic relationships of 243 Korean rice varieties was varied out using 20 SSRs markers. A total of 268 alleles were detected, ranging from 6 to 32, with an average of 13.45 alleles per locus, and and average of gene diversity (GD) of 0.556. Seven SSR markers were selected as key markers for discrimination among the Korean rice varieties. Concerning the results, 243 varieties (100%) were discriminated among by using acrylamide gel and fragment analyzer-based markers. In conclusion, this study provides useful basic data that can be utilized concerning Korean rice varieties breeding and development. In addition, we will have to manage and conserve as a valuable genetic resource, without losing the diversity of Korean rice varieties.

• Proceedings of the Korean Society of Crop Science Conference
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• 2022.10a
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• pp.201-201
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• 2022

Rice bakanae disease is a serious global threat in major rice-cultivating regions worldwide causing high yield loss. It is caused by the fungal pathogen Fusarium fujikuroi. Varying degree of resistance or susceptibility to bakanae disease had been reported among Korean japonica rice varieties. We developed a modified in vitro bakanae disease bioassay method and tested 31 Korean japonica rice varieties. Nampyeong and Samgwang varieties showed highest resistance while 14 varieties including Junam and Hopum were highly susceptible with 100% mortality rate. We carried out mapping QTLs for bakanae disease resistance with four F2:F3 populations derived from the crosses between Korean japonica rice varieties. The Kompetitive Allele-Specific PCR (KASP) markers developed in our laboratory based on the SNPs detected in Korean japonica rice varieties were used in genotyping F2 plants in the populations. We found four major QTLs on chromosome 1, 4, 6, and 9 with LOD scores of 21.4, 6.9, 6.0, and 60.3, respectively. In addition, we are doing map-based cloning of the QTLs on chromosome 1 and 9 which were found with Junam/Nampyeong F2:F3 population and Junam/Samgwang F2:F3 population, respectively. These QTLs will be very useful in developing bakanae disease resistant high quality rice varieties.

• Journal of the East Asian Society of Dietary Life
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• v.11 no.1
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• pp.11-18
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• 2001

The saccharification and sensory characteristics of Sikhe, Korean traditional beverage of saccharified rice, made from thirteen glutinous rice varieties and one of non-glutinous rice named I1pum were examined. During saccharification, Shinsunchalbyeo, Whasunchalbyeo, Yukdononhrimna 1 and Hangangchalbyeo showed the highest sweetness determined by refractometer. Yukdononhrimna 1 was good for the morphology and texture of cooked rice kernel during saccharification. There was interrelationship between contents of released reducing sugar and sweetness determined by refractometer during preparation of Sikhe. The overall acceptability determined by sensory evaluation of Sikhe made from Yukdonongrimna 1, was slightly higher than that of Sikhe made from Ilpum, the non-glutionous rice variety. Yukdononhrimna 1 was considered to the most suitable varieties of Sikhe.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.294-294
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• 2017

Rice (Oryza sativa L.) is one of the main agricultural crops in Asian countries, including Korea, and is considered as the most important staple food in the world. Rice is also processed into flour, which is consumed through various foods such as cake, noodle, bread, and confectionary. Rice flour quality is highly dependent on variety and milling conditions. Producing rice flour with fine particles is more difficult than wheat flour because of its grain hardness. The Korean rice varieties representing different amylose contents were selected for this study. The relationship between the morphological and starch characteristics of rice kernels and the appropriate varieties for producing good-quality, dry-milled rice flour were examined. The hardness of the rice kernels was determined by measuring the pressure at the grain breakage point. The damaged starch content of the rice flour was determined using a Megazyme starch damage assay kit. The particle-size distribution of the rice flour was measured as the volume-base distribution using a laser-diffraction particle size analyzer. The mean particle-size distribution of the dry-milled flour obtained was between $65.3{\sim}105.1{\mu}m$ among the rice varieties. The opaque, non-glutinous, Seolgaeng rice demonstrated a narrow peak at the fine size, whereas the entire particle-distribution range for other varieties was wide. Seolgaeng exhibited significantly lower damaged starch content of dry-milled flour than the other varieties (p < 0.05). Seolgaeng showed lowest in energy consumption on rice flour production with 200 mesh particle size. Accordingly, it is possible to produce dry-milled rice flour which is similar to wheat flour that would considerably reduce milling costs.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.39 no.2
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• pp.187-192
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• 1994

This study was conducted to investigate varietal difference in viviparous germinability at different days after heading and temperature conditions. Three Japonica rice varieties, Sobaekbyeo, Odaebyeo and Hwaseongbyeo, and Sare type rice variety, Jakwangdo, showed higher viviparous germination rate from 20 days after heading, while a Tongil type rice, ]ungwonbyeo, and a Indica varieyt, IR-20, showed still low viviparous germination at 40 days after heading. Viviparous germination rate of rice varieties observed at 4 and 10 days after incubation was greately increased with increasing temperature from 15$^{\circ}C$ to 3$0^{\circ}C$ , and germination rate less than 5% was observed at 4 days after incubating at 15$^{\circ}C$ in all rice varieties teased. Viviparous germination pattern of rice varieties was divided into two types. Three Japonica and Sare type rice varieties showed higher and faster in viviparous germination than a Tongil type and Indica rice verieties. Viviparous germination was delayed under day /night fluctuation of incubation temperature compared with day /night fluctuation of incubation temperature compared with day /night constant condition at the same average temperature. The optimum incubation temperature and duration to evaluate viviparous germinability of rice varieties were 25/15$^{\circ}C$ and 6 days, respectively.

• Food Science and Preservation
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• v.22 no.6
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• pp.823-830
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• 2015

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.