• Korean Journal of Agricultural Science
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• v.8 no.2
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• pp.224-230
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• 1981

Threshing forces of seven varieties, that is, three Japonica type varieties-Irri 348, Irri 345, and Milyang 15, and four Indica type varieties-Milyang 23, Irri 342, Suweon 294 and Suweon 287-, which have been cultivated in the standard fertilization field being at Chungnam Provincial Office of Rural Development, Youseong, Chungnam-do, they were measured every other day in the period from September 28 to October 20 which were included the proper harves ting time. Also the threshing forces were checked in three-dimensional directions. Relationships between threshing forces and moisture contents of the unthreshed rice were examined in the laboratory as dried in the natural condition. The results of this study were as follows; 1. The mean threshing force of Japonica type varieties was about 1969r. and that of Indica type varieties was about 113gr. when external force was loaded in the direction parallel to the grain. 2. The threshing force bent to the grain was about 9.8through 28.2gr. equal to 7 through 21 percent to the threshing force parallel to the grain in Indica type varieties meanwhile about 59.8 through 115.0gr equal to 33 through 50 percent in Japonica type varieties. 3. Under the warmer temperature than $0^{\circ}C$, the change of threshing forces was not great in this experimental period on the harvesting dates. 4. The threshing force decreased s lightly as moisture content decreased in natural drying under the shade after cutting. 5. The threshing force of the lower portion was a little biger than that of the upper portion in an ear.

• Korean Journal of Breeding Science
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• v.49 no.3
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• pp.180-189
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• 2017

Genetically modified (GM) crops have been developed worldwide through the recombinant DNA technology and commercialized by global agricultural companies. Until now, GM crops have not been cultivated commercially in Korea. Commercialization of GM crops requires a compulsory assessment of environmental risk associated with the release of GM crops. This study was conducted to evaluate the frequency of pollen mediated gene flow from Bt transgenic rice (Agb0101) to japonica non-GM rice (Nakdongbyeo), indica non-GM rice (IR36), and weedy rice (R55). A total of 729,917, 596,318 and 230,635 seeds were collected from Nakdongbyeo, IR36, and R55, respectively, which were planted around Agb0101. Selection of the hybrids was determined by repeated spraying of herbicide and Cry1Ac1 immunostrip assay. Finally, the hybrids were confirmed by PCR analysis using specific primer. The hybrids were found in all non-GM rice and out-crossing ranged from 0.0005% at IR36 to 0.0027% at Nakdongbyeo. All of hybrids were located within 1.2 m distance from the Agb0101 rice plot. The meteorological elements including rainfall and temperature during rice flowering time were found to be important factors to determine rice out-crossing rate. Consideration should be taken for many factors like the meteorological elements of field and physiological condition of crop to set up the safety management guideline to prevention of GM crops gene flow.

• Korean Journal of Agricultural Science
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• v.7 no.2
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• pp.145-155
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• 1980

An engineering design of the machines and equipment for processing grain as well as an understanding of processing itself need the knowledge of thermal properties of grain. Thermal properties of grain are thermal conductivity, thermal diffusivity and specific heat. Knowledge of any two and the bulk density of grain enables the third to be calculated. Several workers have investigated these properties, with special emphasis on thermal conductivity and diffusivity. However, some information is available on the specific heat of rough rice and barley but it is available only for a foreign variety of grain and for as a function of moisture content only. The objectives of this study were to develop a model for the specific heat of rough rice and barley which were a staple products in Korea as a function of initial temperature, moisture content and porosity of grain with cooling curve method, and to analyze the effect of these factors on the specific heat of rough rice and barley. The results of this study are summarized as follows; 1. The specific heat was $1.8209-2.7041kJ/kg\;^{\circ}K$ for Naked barley, 1.8862-2.5625 k.l/kg K for Covered barley, $1.5167-2.3779kJ/kg\;^{\circ}K$ for Japonica rice and $1.5260-2.3981kJ/kg\;^{\circ}K$ for Indica rice. 2. The model for the specific heat of rough rice and barley as a function of initial temperature, moisture content and porosity of grain was developed. 3. Specific heat of rough rice was decreased with initial temperature, but specific heat of barley was increased with initial temperature. 4. On the whole specific heat of sample grain was increased with moisture content of grain. 5. Specific heat of the grain was found to decrease with porosity except Indica rice.

• Molecules and Cells
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• v.26 no.2
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• pp.146-151
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• 2008

The brown planthopper (BPH) is a major insect pest in rice, and damages these plants by sucking phloem-sap and transmitting viral diseases. Many BPH resistance genes have been identified in indica varieties and wild rice accessions, but none has yet been cloned. In the present study we report fine mapping of the region containing the Bph1 locus, which enabled us to perform marker-aided selection (MAS). We used 273 F8 recombinant inbred lines (RILs) derived from a cross between Cheongcheongbyeo, an indica type variety harboring Bph1 from Mudgo, and Hwayeongbyeo, a BPH susceptible japonica variety. By random amplification of polymorphic DNA (RAPD) analysis using 656 random 10-mer primers, three RAPD markers (OPH09, OPA10 and OPA15) linked to Bph1 were identified and converted to SCAR (sequence characterized amplified region) markers. These markers were found to be contained in two BAC clones derived from chromosome 12: OPH09 on OSJNBa0011B18, and both OPA10 and OPA15 on OSJNBa0040E10. By sequence analysis of ten additional BAC clones evenly distributed between OSJNBa0011B18 and OSJNBa0040E10, we developed 15 STS markers. Of these, pBPH4 and pBPH14 flanked Bph1 at distances of 0.2 cM and 0.8 cM, respectively. The STS markers pBPH9, pBPH19, pBPH20, and pBPH21 co-segregated with Bph1. These markers were shown to be very useful for marker-assisted selection (MAS) in breeding populations of 32 F6 RILs from a cross between Andabyeo and IR71190, and 32 F5 RILs from a cross between Andabyeo and Suwon452.

• Korean Journal of Agricultural and Forest Meteorology
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• v.2 no.2
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• pp.41-46
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• 2000

This experiment was carried out to find out the responses of the growth characteristics to various air temperature in a high yielding indica/japonica rice cultivar, 'Dasanbyeo'. Five different transplanting dates with 30 day-old seedlings were tried to induce various environmental conditions, starting from 10th May to 19th June in the interval of 10 days at National Crop Experiment Station, in 1998. Planting densities with different plants per hill but same hill spacing were tested. The daily mean air temperature during 30 days after transplanting was 19.0, 20,8, 21.9, 24.4 and 25.2$^{\circ}C$ when transplanted on the 10th May, the 20th May, the 30th May, the 9th June and 19th June, respectively. The number of tillers per hill at 30 days after transplanting was affected by the daily mean air temperature during 30 days after transplanting. The higher the daily mean air temperature, the more tillers per hill at 30 days after transplanting were. The growth duration from transplanting to heading was greatly changed according to the transplanting dates. It was shortened as the transplanting date was delayed until transplanted on the 9th June, but it was prolonged when transplanted on the 19th June compared to that of the 9th June. The number of panicles per hill increased with the increase of the transplanted plants per hill up to 7 plants per hill. The number of panicle per unit area was closely related to the number of tillers per unit area at maximum tillering stage. It was found that the average effective temperature during first 10 tiller formation related to the days to the tenth tiller formation with the relationship of y = 1.071x$^2$ - 37.307x + 342.38($R^2$ = 0.9823).

• Applied Biological Chemistry
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• v.38 no.6
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• pp.554-562
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• 1995

Effect of the modification of rice protein by protease and 2-mercaptoethanol on physicochemical and gelatinization properties was investigated for the three cultuvars of rice. Total amylose contents of Chucheongbyeo(japonica type), Chosengtongilbyeo(tongil type, indica x japonica) and IR 36 (indica type) were in the range of $20{\sim}25%$. Total amylose and insoluble amylose content of IR 36 were higher than the others. The differential scanning calorimetric and X-ray diffraction results revealed higher relative crystallinity of IR 36 than the others. Water uptake was increased and amylographic viscosity was significantly decreased by 2-mercaptoethanol treatment. Amylographic viscosity was significantly decreased and hot water-soluble carbohydrate content was increased by protease treatment. The proportions of high molecular weight of soluble carbohydrate fractionated by gel filtration chromatography were increased by protease treatment. These effects were most significant in IR 36. This results suggested that starch gelatinization be accelerated by alteration of the protein with protease and reducing agent.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.33 no.1
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• pp.5-11
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• 1988

Varietal differences of grain filling duration and rate are generally recognized in rice (Oryza sativa L.). But the differences of grain filling characteristics between the parts within a panicle might be present since it takes 6-8 days to finish anthesis in a panicle. To elucidate this, 6 Japonica and 6 Japonica/Indica varieties were grown under three nitrogen levels at the Experimental Farm of Chungbuk National University in 1986, and grain filling characteristics of top, middle and bottom parts of a panicle were analyzed. Rice grain filling duration could be divided into 3 phases, i.e., Lag phase(LP) of 5 days after heading. Linear increasing period (LIP) of 5-20 days after heading and Late filling period (LFP) thereafter. Grain weight difference between the panicle parts was greater during LIP in all the varieties and was decreased during LFP. The difference was greater in Japonica/Indica varieties. Samgangbyeo and Seomjinbyeo had the shortest and the longest grain filling durations with 22.6 and 37.1 days, respectively. In average, grain filling duration of the bottom part of a panicle was 1-2 days shorter than that of top or middle part. The differences were negligible in Daecheongbyeo, Taebaegbyeo and Milyang 23, while it was greater in Tongil with 4.9 days. Grain filling rates were ranged from 0.612 to 1.097 mgㆍgrain$^{-1}$ㆍday$^{-1}$ㆍMilyang 23 showed the lowest rate with 0.612-0.682 mgㆍgrain$^{-1}$ㆍday$^{-1}$, while the rates of Baegyangbyeo, Yongmoonbyeo, Samgangbyeo, Nongbaeg and Daeseongbyeo were about 1 mgㆍgrain$^{-1}$ㆍday$^{-1}$ㆍGrain filling rate of bottom part of a panicle was lower than that of top or middle part. The difference was samll in Nongbaeg and Daeseongbyeo, while it was the greatest in Tongil with 0.222 mgㆍgrain$^{-1}$ㆍday$^{-1}$. Grain filling duration and rate were not afftected by nitrogen level, but varietal and spatial differences of grain filling characteristics were highly significant. However, the spatial difference of grain filling rates within a variety was not significant. Grain filling characteristics of each part of a panicle were significantly correlated (r=0.7207-0.9879) with those of a whole panicle.

• Korean Journal of Weed Science
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• v.13 no.2
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• pp.159-163
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• 1993

This research was conducted at the Crop Experiment Station to determine the changes of weed flora under direct seeded rice cultivation in dry paddy field from 1989 to 1992 and to establish an effective weed control strategy in direct seeded rice cultivation. With the continuous rice growing under direct seeded rice cultivation in dry paddy field, there were more occurrence in grasses and annual weeds while broadleaf and perennial weeds were diminished. The predominant weeds were aquatic weeds such as Eleocharis kuroguwai, Echinochloa crusgalli, and Monochoria vaginalis in machine transplanted rice paddy field while there were predominant of semi aquatic weed species such as E. crusgalli, Digitaria sanguinalis, Bidens tripartita, Aeschynomene indica, and Arthraxon hispidus in continuous direct seeded rice cultivation in dry paddy condition. Based on the vegetative analysis of weeds in terms of simpson index and community dominance, there was more distribution of weed species in direct seeded rice cultivation on dry paddy condition while only distributed with 1-2 weed species in machine transplanted rice paddy field. In similarity coefficient, there was a gradual increase up to 67% of weeds with the continuous direct seeded rice cultivation in dry paddy condition for 4 years starting from 41% of similarity coefficient.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.48 no.4
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• pp.316-321
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• 2003

Analysis of breeding gains in grain yield has been intensively conducted in wheat, barley, oat, maize, and soybean. Such information is limited in rice. The objective of this study was to compare the breeding gains and cultural gains contributed to yield gains of Korean rice varieties since early 1900s. Two sets of yield data were used for analysis; the historical yield data of 1908 for old japonica cultivars, and present yield data in the years from 1996 to 1998 for the six cultivars, consisting of previous two old cultivars and four contemporary cultivars. The old cultivars were two native cultivars, Jodongi and Damageum, while contemporary cultivars were two premium quality japonica cultivars, Hwaseongbyeo and Dongjinbyeo, and two Tongil-type cultivars, high yielding cultivars developed from indica/japonica hybridization, Milyang23 and Dasanbyeo. The yield differences of old cultivars between the experiments in 1908 and the experiments from 1996 to 1998 were estimated as cultural gains (1.84 tons $\textrm{ha}^{-1}$) due to the improvement of cultivation technology. Yield differences between the old cultivars and contemporary cultivars were considered total yield gains during the periods. These were 2.51 tons $\textrm{ha}^{-1}$ for japonica cultivars and 3.81 tons $\textrm{ha}^{-1}$ for Tongil-type cultivars. From these data, the genetic gain of 0.67 tons $\textrm{ha}^{-1}$ and 1.97 tons $\textrm{ha}^{-1}$ were estimated for japonica cultivars and Tongil-type cultivars respectively. The ratio between cultural gain and genetic gain appeared to be 2.7:1 for japonica cultivars and 1:1 for Tongil-type cultivars. This analysis clearly showed the higher genetic contribution in Tongil-type cultivars than in japonica cultivars, suggesting a guideline to be used when planning new yield improvement programs. Additional implication has emerged when a better yield response to modem cultivation technology was found in one of the old cultivars, suggesting the combined improvement between breeding and cultural improvement is necessary for attaining the maximum yield capacity of a crop.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.33 no.2
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• pp.201-204
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• 1988

To find out the relationship between the eco-physiological characteristics and wind damage of rice leaves by typhoon 'Thelma' occurred at young panicle formation stage of rice plant, the study was carried out. The rate of dead leaves by wind damage in Indica X Japonica varieties were higher than that in Jap. varieties. Ind. X Jap. varieties which had erect and broader leaves had the higher number of silicified cell, moisture loss and stomatal aperture in leaves. And the wind damage were positvely correlated with the characteristics such as the number of silicified cell (r=0.7546$\^$*/), rate of moisture loss (r=0.8343$\^$**/) and stomatal aperture (r=0.8460$\^$**/) of rice leaf blade etc.