• KOREAN JOURNAL OF CROP SCIENCE
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• v.43 no.4
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• pp.250-253
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• 1998

Somaclonal variation was observed in the field on doubled haploid plants derived from single pollen of a rice cultivar "Hwaseongbyeo". The variations of seven quantitative traits including plant height and one qualitative trait (pubescence) in 436 lines ($R_2$ generation) were analyzed. The number of lines which fell beyond the boundaries of the 95% confidence intervals of the check variety, Hwaseongbyeo was checked for each quantitative trait, and of those fertility showed the highest variation frequency (85.6%), followed by plant height (77.5%), flag leaf length (66.5%), grains per panicle (42.2%), days to heading (34.5%), panicle length (30.7%) and panicles per hill (22.7%). And the variations of quantitative traits except days to flowering appeared to move in the negative direction compared to "Hwaseongbyeo". Variability within lines was also observed for quantitative and qualitative traits. Twenty-nine $R_2$ lines (7%) segregated for pubescence and 130 $R_2$ lines (30%) showed variation with regard to fertility. This suggests that mutations usually occur before diploidization. Twenty-nine $R_2$ lines representing a wide spectrum of variation were chosen for RAPD analysis. The number of lines showing DNA polymorphism compared to Hwaseongbyeo ranged 0 from to 10 according to the primer used and this seems to indicate that specific loci have highly mutable genomic site.utable genomic site.

• Korean Journal of Plant Resources
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• v.30 no.3
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• pp.318-322
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• 2017

The study was carried out to determine the changes of growth characteristics, anthocyanidin, and brown rice yield grown at coast and inland areas apart from the east coastline of Gyeongsangbuk-do province. Number of spikelets per panicle was much more increased in inland area. Regional difference in number of spikelets per panicle was observed in Jeongjinju cultivar. Among these red rice cultivars, the highest brown rice yield was Jeongjinju rice cultivar having 702 kg in inland area and 692 ㎏ in coast area, respectively. Anthocyanidin content ranged 524 to $610{\mu}g/g$ dry weight basis. Cyanidin content was 11.4 to 14.0 times higher than that of delphinidin under coast and inland area. Anthocyanidin content was higher in rice cultivar grown at coast area. Highest head brown rice rate was only observed in Geonganghongmi to 95.2 at coast area and 95.4 inland area. In considering brown rice yield and pigment content, Hongjinju rice cultivar was recommended in optimal pigment rice cultivar in eastern coast of Gyeongsangbuk-do Province.

• The Plant Pathology Journal
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• v.17 no.6
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• pp.376.4-377
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• 2001

• KOREAN JOURNAL OF CROP SCIENCE
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• v.61 no.4
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• pp.235-241
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• 2016

Three different transplanting dates for two rice cultivars grown in Daegu, Republic of Korea, were examined to identify the changes in growth, rice quality, and characteristics of amylopectin. An early transplanting date caused a reduction in the number of panicles in both rice cultivars compared to that in the optimal and late transplanting dates. The 1000-grain weight in the two rice cultivars was significantly increased in the late transplanting date. The rice cultivar tolerant to high temperatures, Donganbyeo, exhibited the lowest milky grain rate in the late transplanting date. The highest rate of head grain was observed in the late transplanting date in both rice cultivars. Regarding the pattern of pasting properties, peak viscosity increased with delayed transplanting dates. With respect to changes in the amylopectin branch-chain length distribution, the amylopectin structure of the translucent Dongan rice cultivar transplanted on April 25 was characterized by a significant increase in A chains with DP > 12, and a decrease in long chains $DP{\geq}37$ compared to that transplanted on June 25. In contrast, the amylopectin structure of the chalky Dongan rice cultivar transplanted on April 25 exhibited further decrease in 13 < DP < 19 than that transplanted on June 25. In the Ungwang rice cultivar, the amylopectin structure of the translucent Ungwang rice cultivar transplanted on April 25 and June 25 was characterized by a significant decrease in the lengths of total amylopectin chains. Furthermore, the amylopectin structure of the chalky Ungwangbyeo rice cultivar transplanted on April 25 was characterized by a significant increase in 7 < DP < 30, while a significant decrease was observed in that transplanted on June 25. These results indicate that the amylopectin structure is altered by different transplanting dates depending on the characteristics of the rice cultivar.

• Journal of the Korean Society of International Agriculture
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• v.31 no.4
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• pp.428-436
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• 2019

As the main objective of rice breeding programs, rice eating quality is one of critical factors directly determining the market price and the consumer preference. However, the genetic complexity of eating quality and the difficulty in accurate evaluation often constrain improvement of the eating quality in rice breeding programs. In addition, given that the rice eating quality of current cultivars has already reached some high-level, diversifying of genetic resources are demanded more than ever to improve the rice eating quality. In this study, we developed a recombinant inbred lines (RILs) population derive from Wandoaengmi6, a japonica-type Korean weedy rice with high eating quality and a high degree of glossiness of cooked rice. Year-to-year correlations between the traits in three years were shown normal distribution for major agronomic traits and physicochemical characteristics. After evaluating tested traits related to eating quality procedure, a total of ten lines were ultimately selected from the population. Increasement of the taste of cooked rice (TA) and the overall eating quality (OE) were confirmed in the selected lines, which are caused by alleles derived from Wandoaengmi6 without any linkage drag. These results indicate that the utility of wide genomic resources in Korean landrace could be of application in various rice breeding programs and countermeasure to contribute to properly response to climate change.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.53 no.4
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• pp.421-426
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• 2008

Freshly harvested seed of Chinese milk vetch (Astragalus sinicus L.; CMV) was strongly dormant because of hardseedness. Seeds of freshly harvested germinated only 8% while clipping the seed coat completely overcome the innate dormancy, which indicates inhibition of germination of the seed is mainly due to seed coat (87%). The dormant (intact) hard seeds did not imbibe water whereas the non-dormant (clipped) seeds took up rapidly. In natural environment condition, the hard seed coat dormancy was broken only after 5 months after seed harvest. To break such a strong seed coat dormancy, the chemical and heat treatments were effective. Concentrated sulfuric acid was more effective than dry heat and hot water treatments. Hot water treatment improved germination but the germination percentage was less than 41%. Treatments increased germination due to its effect on the seed coat integrity. A scanning electron microscope reveled that disruption of seed coat layers and subsequent development of numerous crack in the hilum region of the seed and on the seed coat surface of concentrated sulfuric acid treatment and formation of cracks in the dry heat treatments, respectively, were observed in the seed coat surface, which served as water entry points.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.68 no.4
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• pp.262-275
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• 2023

This study aimed to assess the preferences of African, American, and Asian panels, in comparison to a Korean panel, for various Korean rice varieties, including three japonica, two indica, and one Tongil-type, all developed by the Rural Development Administration in Korea. Regarding rice appearance, most panelists, except for the Koreans, favored long and slender rice varieties like 'Hanyeol', 'Hyangyeol', and 'Amissal'. In contrast, the Koreans preferred wider varieties like 'Sindongjin' and 'Deuraehyang'. Notably, the overseas panelists consistently favored rice varieties with high appearance quality in sensory evaluations of cooked rice. Both overseas and Korean panelists strongly preferred the indica rice variety 'Hanyeol' in terms of appearance quality and sensory evaluations. However, Korean rice varieties like 'Amissal' and 'Sindongjin' scored high in appearance quality with overseas panelists but received low ratings in sensory aspects, including shape, stickiness, and taste, compared to those for 'Hanyeol'. This suggests that considering sensory characteristics is important when exporting Korean rice varieties. Regarding taste characteristics preferred by the panelists derived from the correlation analysis between taste traits, Africans preferred rice with a smooth texture and no stickiness, especially favoring long-grain rice. Americans leaned towards rice with a slightly firm texture, some stickiness, and late aging characteristics. Asians preferred rice with a smooth texture, low stickiness, and long-grain varieties. In contrast, Koreans favored round rice with a glossy appearance, a slightly firm texture, late aging traits, and some stickiness. These research findings can serve as valuable data for the development of rice varieties for overseas markets and are expected to contribute to securing competitiveness in international markets.

• Proceedings of the Korean Society of Crop Science Conference
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• 2022.10a
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• pp.278-278
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• 2022

Recently, the yield potential of high yield Tongil-type rice varieties has greatly increased, reaching 817kg/10a(Geumgang No.1). Moreover, in order to promote rice consumption and strengthen the competitiveness of the rice processing industry, the R&D of high yield Tongil-type rice varieties for each processing purpose, such as rice noodles, grain feed and industrial materials, has been continuously carried out. However, because Tongil-type rice varieties or lines are generally very vulnerable to cold damage, cold tolerance test can be said to be absolutely necessary to improve the cultivation safety. This study is the result of the seedling and field cold tolerance characteristic tests carried out in 2021 of high yield Tongil-type rice breeding lines. For the cold tolerance characteristic test of seedlings, total 303 high yield rice breeding lines for processing were treated in cold water of 13℃ and irrigation depth of 4cm for 10 days from the third-leaf age, then it was evaluated by comparing the degree of discoloration and withering with the checked varieties(Boramchan, Hanahreum No.2). Also, for the test of field, total 186 high yield rice breeding lines for processing were treated in cold water of 17℃ by keeping pouring day and night from 30 days after transplanting to ripening stage, then it was evaluated by comparing the degree of discoloration, delay of heading, shortening rate of stem length and percent of fertile grain etc. with the checked varieties. And the cold tolerance evaluative criteria were classified as strong(1~3), medium(4~6) and weak(7~9) in overall cold tolerance. (Seedling test) As for the degree of cold tolerance of the check variety, 'Boramchan' and 'Hanahreum No.2' showed a response of 'medium' and 'weak', respectively. However, there was no 'strong' line in the high yield rice breeding lines, 2 lines showed a 'medium' response, and 301 lines showed a 'weak' response. Therefore, except for a few lines(0.7%), most lines(99.3%) showed a 'weak' response. (Field test) In terms of the overall cold tolerance of the check variety, both 'Boramchan' and 'Hanahreum No.2' showed a 'medium' response. Similarly, there was no 'strong' line in the case of high yield rice breeding lines, 20 lines showed a 'medium' response, and 166 lines showed a 'weak' response. Therefore, except for some(10.8%) lines, most(89.2%) lines showed a 'weak' response. From the above results, we selected about 100 individuals with less seed shattering and degeneration of the ear tip, and with a relatively high percent of fertile grain, and are continuing to select lines with improved cold tolerance in the F4~F5 group in this year. As such, most of the Tongil-type rice varieties have poor cold tolerance and thus have low cultivation safety at low temperatures. However, it is important to select improved lines through generational progress because there are some lines that still have a certain level of cold tolerance among them.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.48 no.1
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• pp.56-64
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• 2003

If a quantitative trait loci (QTL) marker identified in a population is applicable to different populations (marker universality), this will not only reduce the labor and cost in marker assisted selection (MAS), but accelerate the application of molecular markers to real breeding programs. Present study aims to evaluate the defined QTL related markers from a population to a different breeding population for the MAS. Four rice breeding populations were subjected to seventy-five simple sequence repeat (SSR) markers which were already identified for their polymorphism information content (PIC) in the parents of the crossings. Among them, eight markers were evaluated for their correlation between presence of marker alleles and phenotypic expression in breeding populations. A reasonable level of polymorphism for the mapped markers originated from any sources of rice accessions was observed between crosses of any sources (marker repeatability). However, correlation between presence of markers and expression of the traits in rice breeding populations was not significant except for minor portion of traits and markers examined (failure of marker universality). In the present study, various strategies were discussed to develop new markers with universality of breeding application.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.332-332
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• 2017

Rice ratooning is the cultural practices to produce easily second rice from the stubble left behind after the main-crop harvest. The main advantage of rice ratooning is that in areas where rice is the main crop, double crop of rice can be grown for additional returns. Three early ripened rice cultivars were tested for estimation their milled rice quality and starch characteristics from main and ratoon rice. The main crop was harvested at mass maturity, after which the tillers were mowed to stubbles of about 10 cm tall. And then it left without any further input until the ratooned plant was ready for harvest. Highly significant variations were detected in the milled rice quality between main and ratoon rice. Protein and amylose contents of ratoon rice were more increased than those of main rice. The Toyo value (gloss) of cooked rice of ratoon crop was measured also higher than that of main crop. It resulted from higher air temperature during grain ripening compared with that of ratoon crop. The mean temperature during ripened period of ratoon rice was favorable for optimal maturation for early ripened rice cultivars. Normalized chromatograms of branch chain length distribution of amylopectin are demonstrated a distinct difference between main and ratoon rice flour. Ratoon rice had higher amount of short chains than that of main crop rice starches. Microscopic examination of rice flours with scanning electron microscopy shows starch granule shapes affected by the cropping types, main and ratoon rice. It showed significant differences among rice starch granule shapes and in granule size between main and ratoon rice. Starch of ratoon rice had more neat and smaller granules than that of main rice.