• Current Research on Agriculture and Life Sciences
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• v.15
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• pp.1-5
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• 1997

The purpose of this study was to determine the inheritance of chlorosis under low temperature at seedling stage of rice. The expression of chlorosis among 21 rice cultivars treated at $18^{\circ}C$ showed in one Tongil type cultivar, Milyang 23, and two Indica type cultivars, IR 36 and Dular. The sign of chlorosis was not appeared in all of the japonica type cultivars under the same treatment. The reduction of chlorophyll content under the low temperature was differed from varietal group and cultivars. The $F_2$ population from a cross between Toyohatamochi and Dular segregated 3:1 ratio for normal and white phenotypes of third leaf. From the result, it was suggested that the chlorosis was controlled by a single recessive gene. The chlorosis rice detected from this study will be used as a good material for the genetic study related to photosynthetic ability of rice.

• Korean Journal of Food Science and Technology
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• v.27 no.4
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• pp.631-634
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• 1995

Some structural characteristics of hot-water insoluble rice starch [3 varieties of Japonica type and 3 varieties of Tongil type(Japonica-Indica breeding type)]were investigated. The amylose contents of hot-water insoluble starches were 2.7-6.1%. The chain distributions of hot-water insoluble starches were composed of super long chain of above ${\overline{DP}}\;55$ (31.9-38.7%), B chain of ${\overline{DP}}\;40-50$ (12.3-18.0%) and A chain of ${\overline{DP}}\;10-20$ (48.5-50.4%). The chain distributions of hot-water insoluble starches and their ${\beta}-limit$ dextrin were difference between rice varieties and their were differ from those of amylopectin and their ${\beta}-limit$ dextrin. these result suggest that hot-water insolubility of rice starch was showed its characteristic on the varieties and it be responsible for the molecular structure of amylopectin.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.35 no.4
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• pp.309-314
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• 1990

A pot experiment was carried out to find the effects of chemicals and its application time on the sterility and other agronomic characters of rice. Two rice cultivars, Samgangbyeo, a Tongil type, and Chuchungbyeo, a japonica type rice were treated with maleic hydrazide (6000ppm), ethephon (6000ppm) and GA3 (10ppm) at five different growth stages. The application times of chemicals were comprised of two different stages of stem elongation and booting and panicle emerging stage. Grain sterility and panicle length were measured for panicles per pot. Culm length was measured for pot basis. MH induced complete grain sterility in rice, but caused severe plant damage (phytotoxicity) ; restricted spike emergence and drying out of plant leaves, sheath and panicles. Ethephon induced 50-60% grain sterility in rice with the least in plant damage. GA3 was not effective in inducing grain sterility in rice, but it increased culm length. The earlier application of chemicals, the higher sterility was induced. Both MH and ethephon reduced culm length and grain yield. Also observed was the varietal response in the occurrence of to chemicals Samgangbyeo showed the higher response to chemicals than Chuchungbyeo.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.65 no.3
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• pp.199-213
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• 2020

Grain size and shape are the two important components contributing to rice yield and quality. To analyze traits related to grain-shape, a total of 272 varieties derived from japonica, japonica black and Tongil-type rice accession in Korea were evaluated in this study. The traits, grain length (GL), grain width (GW), grain thickness (GT), length to width ratio (RLW), and 1000-grain weight (TGW) were measured and replicated 10 times. Genes (GW2, GS3, qGL3, qSW5, GS5, TGW6, GW7, and GW8) related to grain-shape were validated in the accessions using specific DNA marker sets. K-mean clustering of the accession based on phenotypic data revealed three groups: group 1 was classified by GW and GT and included most of japonica type, group 2 was classified by RLW and GL reached a medium size and possessed a half spindle-shaped type, and group 3 was classified by TGW, reached a long size and possessed a semi-round shape. In validation tests using the marker sets, both gw2 and tgw6 were validated in less than 1% of the tested accessions and two allelic types, qgl3 and gw8, were only verified in Tongil-type accessions. For GW8 and GW2, any different amplicons were not amplified in any japonica or Tongil-type accessions, respectively. In order to suggest the representative grain-shape gene combinations for each ecotype, the allelic combinations were evaluated by PCR analysis. Cj1 and 2 in japonica (Cj1-7), Cj_b1 and 2 in japonica-black (Cj_b1-3), and CT3 in Tongil-type (CT1-13) turned out to be the dominant combination in each ecotype, respectively. In addition, the results revealed that introgression of four genes (gw2, gs3, qSW5, and GS5) would expand the diversity of grain shape in Korean japonica varieties. The gene combinations information could be utilized practically to understand or enhance grain shape in japonica rice breeding program.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.56 no.2
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• pp.167-176
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• 2011

Brown planthopper (BPH) is a serious insect pest of rice crop throughout rice growing countries, and yield loss due to its infection can be up to 60%. This study aimed to evaluate efficiency of molecular markers for screening BPH resistance accessions among 86 aromatic rice germplasm Eighty-six accessions of aromatic rice germplasm included two accessions of Tongil type (bred in Korea), 28 accessions of japonica type and 56 accessions of indica type. We applied eight STS markers (pBPH9, pBPH19, pBPH20, pBPH21, AJ09-b, RG457L, RG457B, and 7312.T4A) which were linked to four of BPH resistance genes, Bph1, Bph13(t), Bph10, and Bph18(t) respectively. One japonica type accession, 415XIr352, and six indica type accessions possessed one or four positive bands when tested with four STS markers linked to Bph1 gene. One indica type aromatic rice, Basmati9-93, showed the target bands linked to the Bph10 gene. The other accessions did not show same fragments as the respective resistant lines. Bph13(t) is the most widely introduced resistance gene and only one accession showed positive bands implying that this accession might harbor Bph10 and Bph18(t) genes. Three aromatic accessions, Domsiah, Khao Dawk Mali 105 and 415XIr352 showed gene pyramiding of Bph1 and Bph13(t). Two indica aromatic rice, Ds 20 and Basmati 9-93, possessed at least two BPH resistance genes, Bph1, Bph18(t) and Bph13(t), Bph18(t), respectively. These results indicates that aromatic rice germplasm have narrow diversities of BPR resistance genes.

• Journal of Biosystems Engineering
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• v.7 no.1
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• pp.17-32
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• 1982

The binders introduced in Korea were originally designed to be used for Japonica-type varieties which have relatively long stem and are highly resistant to shattering. In order to use it for Tongil varieties which are short and easy to be shattered, mechanical modifications are necessary to reduce a grain loss incurred during binder operation. This study was intended to investigate analytically and experimentally the major sources of grain losses caused by three kinds of binders now introduced in Korea. Actual modification for each of three binders was done and experimentally compared to see if any improvement on grain loss was achieved. The results obtained in this study are summarized as follows; 1. It was required that the power transmission of binder should have a shifting mechanism so that velocities of pick-up and traveling units could be changed independently as desired according to the Japonica-type and Tongil varieties. In other words, the desired velocity of traveling unit should be obtained by shifting the transmission and the velocity of pick-up unit should be selected by reaping clutch according to the variety independent of the velocity of traveling unit as shown in Fig. 6. 2. To reduce grain loss it was desired that the moving parts of the pick-up unit should have the lowest possible velocities in harvesting Tongil varieties, unless the reduction of the speed be hindered the conveyance of the material. Based on the study, it was concluded that the velocities of pick-up unit be reduced by about 35% of those of the existing units. 3. It was found that the lug at the upper rotating section of pick-up case gave a severe impact on the ears of rice to increase grain loss. The optimum design of pick-up case to protect the ears from the protruding part of the lug was recommended by the result of analysis of the trajectory of the end-point of lug at the position. 4. It was proved analytically and experimentally that pick-up unit at the lower-rotating part was the other important source of grain loss in pick-up and divider assembly. In order to reduce a grain loss incurred by lugs at their lower-rotating section, it was suggested to improve it by (1) widening the space between right and left lower-rotating section, (2) shortening the length of lugs, (3) enlargement of the angle between the pick-up case and ground-level, and (4) attaching guard to right and left dividers so that the rotating lug could not give a high impact to the paddy hill. 5. Pick-up and divider assembly of the original binder of three models studied was modified according to the suggestions that were given by the preliminary study. Field test showed that the modified binders were able to reduce grain losses by about 0.4-0.7 percentage points compared to those without modification.

• Korean journal of applied entomology
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• v.22 no.1 s.54
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• pp.21-25
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• 1983

To develop forecasting methods of rice sheath blight caused by Rhizoctonia solani, two rice cultivars Jinheung (Japonica type) and Yushin (Tongil type) were used from 1976 to 1981. Severity of rice sheath blight disease at maturing stage was estimated by top lesion height, percentage of top lesion height vs. plant height in July and lesion index on September 11. The relationship between top lesion height on July 11 and degree of damage at maturing stage for a cultivar Yushin was represented by the equation of Y=4.64x-13.2, and $r=.840^{**}$, where Y is degree of damage by shea4h blight at maturing stage and x is top lesion height on July 11. Considering the percentage of infected hills/stems was rapidly increased from July 11 to August 1, the most effective period and time for fungicide spray were considered July 15 and July 25 or July 25 and August 5.

• Proceedings of the Korean Society of Crop Science Conference
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• 1996.10a
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• pp.28-29
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• 1996

• Proceedings of the Korean Society of Crop Science Conference
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• 1996.10a
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• pp.30-31
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• 1996

• Journal of Plant Biotechnology
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• v.30 no.4
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• pp.369-373
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• 2003

In spite of potential benefits of anther culture, low productivity of plant regeneration in some genotypes; e.g. tonsil and indica rice, is one of the major obstacles for practical use of anther culture. This study was conducted to improve cold shock method and carbohydrate source for increasing the efficiency of anther culture in rice. The most common carbon source, sucrose was replaced to maltose, which has two molecules of glucose. Maltose increased callus induction 1.4-to 1.8-fold higher in japonica rice, 3.2-to 11.6-fold in tongil types and 2.7-fold in indica rice IR50. Callus induction was increased from 0.2％ to 12.5％ in maltose medium compared to the medium supplemented with sucrose plus glucose in indica rice "Tetep". A simple procedure of vacuum packaging of panicles during cold shock treatment prolonged not only anther viability more than 15 days but also increased callus induction more than 2-fold compared to open-air storage (conventional method). Combining of above two methods, callus induction was increased 28 to 56％ in japonica, 13 to 33％ in tonsil type and 12 to 31％ in indica rice. Plant regeneration was increased 14 to 35％ in japonica, 10 to 20％ in tonsil and 4 to 15％ in indica rice, respectively.