• Korean journal of food and cookery science
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• v.2 no.2
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• pp.32-42
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• 1986

Two Tongil type rice varieties and two Japonica rice varieties were prepared and experimented to investigate the effect of physicochemical properties on rice palatibility. Obtained results are as follows; (1) Width and thickness of unhunlled and unpolished grains of Tongil type rices were shorter than those of Japonica type rices and the length of the former was much longer than the latter. (2) Protein contents of Tonsil type varieties were greater than Japonica ones and amylose contents of the former is less than the latter. Alkali digestibility of them showed no significant differences. These means that the qualities of Tongil rices are not less than Japonica ones. (3) Sensory evaluation test showed that Japonica type rices are more excellent than Tongil types in expansion, glutinosity, flavour and taste while the former is inferior to the letter in gloss. (4) Preconceived ideas on the shape of rice seemed to affect most on its palatability.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.48 no.3
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• pp.216-223
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• 2003

This study was conducted to investigate the varietal differences in leaf senescence and the relationship between leaf senescence and photosynthesis during ripening stage of rice. During grain filling period, leaf senescence was evaluated by SPAD readings (an indirect indicator of chlorophyll content) for 3 rice varieties (SNU-SG1, Hwaseongbyeo, Nampungbyeo). SPAD value of flag leaf and 2nd leaf of SNU-SG1 were much higher than the other varieties and the leaves of SNU-SG1 also showed a tendency of delayed senescence as compared to the other varieties. Photosynthesis at light saturation (Pmax) of flag, 2nd and 3rd leaf in SNU-SG1 during grain filling period were much higher than Hwaseongbyeo and Nampungbyeo. The Pmax of the flag leaf in SNU-SG1 was especially higher over 20% than the other varieties. It was due to its higher mesophyll conductance and stomatal conductance as compared to the other varieties. Pmax, stomatal conductance and mesophyll conductance had positive correlation with SPAD value and nitrogen concentration of leaves. In conclusion, the stay green characteristics of SNU-SG1 would contribute to increasing the grain yield through the improved photosynthesis during grain filling.

• Journal of Biosystems Engineering
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• v.3 no.2
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• pp.62-68
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• 1978

Equilibrium moisture content of rough rice is an important factor because it has a close relationship to storage and drying problems. Determination of the EMC for 10 different varieties of rough rice were made in atmospheres of various constant humidities at three different constant temperatures. In addition , some physical properties were also measured for two different levels of moisture content of the samples. The results may be summarized as follows ; 1. Several physical properties of ten different varieties of rough were measured. Significant difference of the properties was appeared between the varieties in which the difference was pronounced in the dimensions of the varieties. Also, all the dimensions were increased as the moisture content of the rough rice was increased from 14 % to 16%. 2. Significant difference of the equilibrium moisture content was also appeared between some of the varieties in which the equilibrium moisture content of Josaengtongil and Minehikari was 24.26% while that of the others was in the range between 18 to 19% at the conditions of relative humidity of 84% and temperature of 47℃ , respectively. Similar pattern was also observed in other conditions. 3. The values of the constant of Henderson's equation were calculated from the data obtained but they are believed to be useful until more precise and complete data are obtained. There was a good agreement between the calculated and experimental results.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.29 no.2
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• pp.109-113
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• 1984

This study was conducted to get basic information about yield capacity and major agronomic characteristics of rice varieties with large grain. The results obtained are as follows; Between grain weight and grain components such as length, width and thickness showed highly positive correlation. The relationship between grain length and grain shape (Length/Width) was clear (r=0.5707${\ast}\;{\ast}$). 1, 000 grain weight of 14 rice varieties with large grain was negatively correlated with number of spikelets per panicle, number of panicles per hill, ripening ratio, total dry matter, grain yield and harvest index, but less clear. The relationship between grain weight of 14 rice varieties with large grain and growth duration was less clear (r=0.440). 1, 000 grain weight of 20 rice varieties differing in grain size showed a highly positive correlation with chalkiness of rice kernel (r=0.8477${\ast}\;{\ast}$).

• KOREAN JOURNAL OF CROP SCIENCE
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• v.65 no.1
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• pp.1-21
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• 2020

Association mapping is widely used in rice and other crops to identify genes underlying important agronomic traits. Most association mapping studies use diversity panels comprising accessions with various geographical origins to exploit their wide genetic variation. While locally adapted breeding lines are rarely used in association mapping owing to limited genetic diversity, genes/alleles identified from elite germplasm are practically valuable as they can be directly utilized in breeding programs. In this study, we analyzed genetic diversity of 179 rice varieties (161 japonica and 18 Tongil-type) released in Korea from 1970 to 2006 using 192 microsatellite markers evenly distributed across the genome. The 161 japonica rice varieties were genetically very close to each other with limited diversity as they were developed mainly through elite-by-elite crosses to meet the specific local demands for high quality japonica rice in Korea. Despite the narrow genetic background, abundant phenotypic variation was observed in heading time, culm length, and amylose and protein content in the 161 japonica rice varieties. Using these varieties in association mapping, we identified six, seven, ten, and four loci significantly associated with heading time, culm length, and amylose and protein content, respectively. The sums of allelic effects of these loci showed highly significant positive correlation with the observed phenotypic values for each trait, indicating that the allelic variation at these loci can be useful when designing cross combinations and predicting progeny performance in local breeding programs.

• Plant Breeding and Biotechnology
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• v.6 no.4
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• pp.381-390
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• 2018

Percentage of aerenchyma area has been closely linked with amounts of methane emitted by rice. A diversity panel of 39 global rice varieties were examined to determine genetic variation for root transverse section (RTS), aerenchyma area, and % aerenchyma. RTS and aerenchyma area showed a strong positive correlation while there existed no significant correlation between RTS area and % aerenchyma. Five varieties previously shown to differ in methane emissions under field conditions were found to encompass the variation found in the diversity panel for RTS and aerenchyma area. These five varieties were evaluated in a greenhouse study to determine the relationship of RTS, aerenchyma area, and % aerenchyma with methane emissions. Methane emissions at physiological maturity were the highest for 'Rondo', followed by 'Jupiter', while 'Sabine', 'Francis' and 'CLXL745' emitted the least. The same varietal rank, 'Rondo' being the largest and 'CLXL745' the smallest, was observed with RTS and aerenchyma areas. RTS and aerenchyma area were significantly correlated with methane emissions, r = 0.61 and r = 0.57, respectively (P < 0.001); however, there was no relationship with % aerenchyma. Our results demonstrated that varieties with a larger root area also developed a larger aerenchyma area, which serves as a gas conduit, and as a result, methane emissions were increased. This study suggests that root transverse section area could be used as a means of selecting germplasm with reduced $CH_4$ emissions.

• Journal of Biosystems Engineering
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• v.3 no.1
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• pp.47-63
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• 1978

This study was conducted to obtain a basic information necessary to assess present rice milling technology in Korea The profiles for milling plants was analyzed by survey work.For the private custom-work mills, which process about 80 percent of domestic rice consumption ,their actual milling test for the identical samples as used for filed mills was conducted. Two rice varieties Japonica and Tongil-type were associated with the experiments. The results are summarized as follows: 1. Analyses for private custom-work mills showed their general aspects as; about 91 percent of the mills belonged to an individual owner ship ; more than 93 percent of the mills was established earlier than 1950 ; about 80 percent of the mills was powered with electric motor; mills having less than two employees were about 75 percent; about 45 percent of the mills provided for warehouse in storing customers cereal grains. 2. The polishers installed in 1,255mills within the surveyed area (7 counties) have been supplied by 44 different domestic manufacturers ;in but about 60 percent of which was supplied by 6major manufacturers. The polishers could be classified into two categories in terms of principles of their polishing actions ;jet-pearler and friction types. About 51 percent of the mills was equipped with the former which has been recognized as giving greater milling recovery than the friction types. 3. Reason for owners of private mills to supplement new machines was due mainly to pgrading their mills to meet the requirements that established by the Government. However, about 60 percent of the mill owners intended to replace with new pearler by their own needs to meet with new high yielding varieties. 4. Processing systems of each previate rice mills surveyed could be classified into three categories, depending upon whether the systems posessed such components as precleaner and paddy separator or not. Only 36.7 percent of mills was installed with both precleanr ad paddy seperrator, 5.0 percent of mills did have neither percleaner nor paddy seperator, and rest of them equipped only one of the two. Hence,it is needed for about 63% of rice miils to be supplemented with these basic facilities to meet with the requirements for the standaized system. 5. Actual milling capacity measured at each field rice mills was shown a wide variation, having range from about 190 to 1,210 kg/hr. The percentages of mills classified according to daily milling capacity based on this hourly capacity were 24.3% for the capacity less than 3 M/T a day; 20.0% for 3-4 M/T; 15.6% for 4-5 M/T; 6.7% for 5-6 M/T; 22.3% for 6-7 M/T; and 11.0% for more than 7 M/T a day. 6. Actual amount of rice processed was about 310 M/T a year in average. About 42% of total milled rice was processed during October to Decembear, which formed a peak demand period for rice mills. The amount of rice milled during January to May was relatively small, but it had still a large amount compared to that during June to September. 7. Utilization rate of milling facility, i. e., percentage of the actual amount of milled rice to the capacity of rice mills, was about 18% on the year round average, about 41% in the peak demand season, and about 10% during June to September. Average number of operating days for mills surveyed was about 250 days a year, and about 21 days a month. 8. Moisture contents of paddy at the time of field mill tests were ranged 14.5% to 19.5% for both Japonica and Tong-i] varieties, majority of paddy grains having moisture level much higher than 1530. To aviod potential reduction of milling recovery while milling and deterioration of milled rice while storage due to these high grain mJisture contents, it may be very important for farmers holding rice to dry by an artificial drying method. 9. Milling recovery of JapJnica varieties in rice mills was 75.0% in average and it was widely ranged from 69.0% to 78.0 % according to mills. Potential increase in milJing recovery of Japonica variety with improvement of mill facilities was estimated to about 1.9%. On the other hand, milling recovery of Tong-il varieties in the field mill tests was 69.8% in average and it ranged from 62% to 77 %, which is much wider than that of Japonica varieties. It is noticed that the average milling recovery of Tong-il variety of 69.8% was much less than that of the Japonica-type. It was estimated th3.t up to about 5.0% of milling recovery for Tong-il variety could be improved by improving the present lo'.ver graded milling technology. 10. Head rice recoveries, as a factor of representing the quality of commercial goods, of Japonica and Tong-il varieties were 65.9% and 53.8% in average, and they were widely ranged from 52% to 73% and from 44% to 65% , respectively. It was assessed that head rice recovery of Japonica varieties can be improved up 3.3% and that of Tong-il varieties by 7.0% by improving mill components and systems.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.30 no.1
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• pp.26-32
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• 1985

Ten recommended rice varieties were cultivated in paddy area affected by air-pollutants and in normal area to select varieties adaptable to air-pollution environment. Rice plants grown in pollution site showed higher contents of total sulfur and fluorine in leaf through the whole growing period compared with those in non-pollution site, and rice leaves destroyed by air-pollutants were found only in pollution site. Rice grain yield and four yield components of ten rice varieties grown in pollution site were lower than those in normal area. Five rice varieties among ten were selected as adaptable to air-pollution environment, based on their yielding potential in pollution site and grain yield ratio between two sites. Rice varieties adaptable to pollution showed little variation of percent ripened grains and number of panicles per hill between two sites. Chlorophyll content in flag leaf of rice plants grown in pollution area was lower than in non-pollution area. No relationship was found between grain yield ratio (pollution/non-pollution site) of ten varieties and total sulfur content ratio, fluorine content ratio, chlorophyll content ratio between two sites, and percent destroyed leaf in pollution site, respectively. This result suggest that varietal adaptability to air-pollution environment is not related with the amount of pollutants absorbed, but with the degree of response to pollutants.

• Korean Journal of Food Science and Technology
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• v.42 no.2
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• pp.175-182
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• 2010

Differences in physiochemical characteristics of row waxy rice, steeped in optimum steeping conditions ($31.5^{\circ}C$, 9 days) were investigated along with the relationship between these properties and the quality characteristics of Gangjung made from ten different varieties of waxy rice in order to identify the optimal waxy rice variety for making Gangjung. The moisture content of ten waxy rice varieties was increased, but protein and ash contents were decreased during steeping. Mineral analysis, showed that the Fe, Mg, Ca, Na and K contents of all samples were decreased during steeping. Regarding the gelatinization behavior of the ten waxy rice varieties, the peak viscosity and breakdown were increased with the exception of Backjinju and Backjinju-1 during steeping. Shinsunchalbyeo was the most adaptable waxy rice variety for making Gangjung, as its tested scores for expansion ratio and crispness were higher than other waxy rice varieties. The textural properties of Gangjung made from Backjinju and Backjinju-1 had the highest levels of hardness and showed the lowest expansion ratios. Therefore, Backjinju and Backjinju-1 are considered the worst varieties for making Gangjung.

• Korean journal of food and cookery science
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• v.28 no.5
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• pp.541-547
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• 2012

This study was performed to compare the processing aptitudes of the rice muffins produced from the seven rice varieties, including Goami, Goami 2, Deuraechan, Baegjinju, Seolgaeng, Haiami and Hanareum, along with the use of hydroxypropyl methylcelluloses (HPMCs) as a replacement for the egg white. The water binding capacity of rice flours was significantly higher than that of wheat flour, but its fat binding capacity was lower than that of wheat flour (p<0.05). In the viscosity of the batter, Goami and Baegjinju were lower than that of the wheat flour. There was no significant difference in the specific gravity of Seolgaeng and the batter of wheat flour. The pH of all varieties except Goami 2 was higher than batter of wheat flour(p<0.05). Haiami flour produced higher muffin volume and specific volume compared with the wheat flour muffin. The textural characteristics, the muffins produced by Haiami and Hanareum flours had significantly lower hardness than the wheat flour muffin after 30 hours. All rice varieties except Gaomi 2 showed no significant difference compared to the wheat flour muffin in color, taste and texture (p<0.05). Furthermore, flavor of muffins produced from the Seolgaeng, Haiami and Hanareum flours tested higher than the wheat flour muffin. It was concluded that the rice varieties of Seolgaeng, Goami, Haiami and Hanareum were considered to be the most suitable rice cultivars for the rice muffins.