• KOREAN JOURNAL OF CROP SCIENCE
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• v.33 no.4
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• pp.412-419
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• 1988

Cold-induced sterility is a problem of rice (Oryza sativa L.) production in temperate regions and high elevation tropics. The present study was conducted to measure combining ability, determine character associations. and to evaluate effectiveness of F$_2$selection for tolerance to this type of cold injury. The F$_1$, F$_2$, F$_3$ and reciprocal backcross F$_1$ populations of a nine-parent diallel were grown at Davis, California. a relatively cool location for rice. Additive genetic variance was predominant but some non -additive genetic variance existed for cold tolerance. Good general combining ability (GCA) was generally associated with the cold tolerant parents, 'M-201', and 'L-201', and poor GCA with the most susceptible parent. 7703008. Sterility was positively correlated with late heading. negatively with mature plant height. and negatively with spikelet number. Of the three agronomic characters, heading date had the greatest influence on sterility. Selection of F$_2$'s in seven crosses involving M-101, the most cold-tolerant parent, was effective for increasing cold tolerance. Realized heritability estimates for cold tolerance averaged 0.53, and observed selection response for cold-induced sterility averaged -9.4 percentage points.

• Korean Journal of Agricultural Science
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• v.4 no.1
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• pp.21-25
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• 1977

This experiment was conducted to estimate the effect of defoliation on the weight of 1,000 kernels, the rate of ripened grains and the weight of an ear of Yusin and Mylang No. 15 after heading. The resnlts obtained were as follows : 1. The weight of 1,000 kenels, the rate of ripend grains and the weight of an ear were significantly decreased by various defoliation. But there was not found significant difference in 1,000 kernel weight of Mylang No. 15 between each treatment of defoliation. 2. When lower leaves were remained, the weight of 1,000 kernels, the rate of ripened grains and the weight of an ear were more influence than when higher leaves were remained. And the same results were obtained when two leaves were remained at the different leaf position. In order words, when leaf remained was combined with leaf positioned at upper area, the weight of 1,000 kernels, the rate of ripened grains and the weight of an ear were higher than when the leaf was combined with lower leaves. 3. Even though Yusin was early heading variety and subjected to defoliation later than Mylang No. 15 in terms of total physiological maturity the response to defoliation was higher than that of Mylang No. 15 in the rate of ripened grains and ear weight. The exception was found for the 1,000 kernel weight. The result obtained indicated that leaves of Yusin influence more the weight of 1,000 kernels, the rate of ripened grains and the weight of an ear to the later stage than that of Mylang No. 15.

• Journal of Life Science
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• v.17 no.12
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• pp.1649-1653
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• 2007

High temperature stresses have caused growth inhibition and delayed heading in highland cultivation Chinese cabbage during summer in Korea. We have studied high temperature stress responses in the terms of changes of inorganic components and proteins by proteomic analyses. Insufficiencies of nitrogen and phosphorus have affected growth rate and calcium deficiency has caused blunted heading. Proteins extracted from Brassica seedling grown at the altitude of 600m and 900m in the Mount Jilun were extracted and analysed by 2-dimentional polyacrylamide gel electrophoresis. Profiles of protein expression was then analyzed by 2-dimentional gel analyses. Protein spots showing different expression level were picked using the spot handling workstation and subjected to MALDI-TOF MS. Total 48 protein spots were analyzed by MALDI-TOF MS and 30 proteins spots out of 48 were identified by peptide mass fingerprinting analyses. Fourteen proteins were up-regulated in extracts from the altitude of 900m and they were identified as oxygen-evolving proteins, rubisco activase and ATPase etc. Sixteen proteins were up-regulated in extracts from the altitude of 600m and they were identified as glutathione S-transferase(1, 28kD cold induced- and 24 kD auxin-binding proteins) and salt-stress induced protein etc. These stress-induced proteins were related to the mediated protective mechanism against oxidative damage during various stresses. The results indicated that physiological phenomenon in response to high temperature stresses might be resulted by complex and multiple array of responses with drought, heat, oxidative, salt, and cold by high temperature.

• Korean Journal of Weed Science
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• v.9 no.2
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• pp.141-148
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• 1989

Echinochloa species collected from 13 places of Korea appeared to be morphologically very different. They were classified by Yabuno's seed morphology method into two species such as Echinochloa oryzicola and Echinochloa crus-galli which have two varieties such E. crus-galli var, cuss-galli and var, praticola. Among them, E. oryzicola was morphologically similar to Oryza sativa, but it had small leaf length with straight from, no awn, late heading and little interspecific variance. As compared with E. oryzicola, E. eras-galli var. crus-galli, and var, praticola showed a great variance exerting so difficulty in classifing them morphologically, particularly a great variance in leaf length, tiller number and grain size. E. oryzicola species showed the more sensitive response to butachor and thiobencarb herbicides than E. eras-galli var. praticola and var. eras-galli. However, E. eras-galli var. praticola was themore sensitive one to pretilachloa herbicide than such as E. oryzicola and E. eras-galli var. eras-galli, indicating that Echinochloa species might have a selective response to the annual herbicides tested.

• Research in Plant Disease
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• v.24 no.4
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• pp.313-320
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• 2018

Fusarium infection rate of the paddy rice grain after harvest seemed to be influenced by the average temperature from late July (before heading) to the end of September (during ripening). In case of 2010 and 2013 in which average temperature of the same period was similar, Fusarium infection was related to cumulative precipitation, cumulative precipitation days, and precipitation durations over two days. The distribution ratio of Fusarium species complex isolated from paddy rice grains after harvest was 57% in 2010 and 45% in 2013 for Fusarium graminearum species complex (FGSC), 35% and 50% for Fusarium incarnatum-equiseti species complex, and 8% and 5% for Fusarium fujikuroi species complex (FFSC). The distribution ratios of FGSC and FFSC were higher in 2010 than 2013. Among the total 26 promoted rice varieties, the 'Mihyang' showed resistant response against the natural infection with Fusarium species belonging to FGSC and the varieties of 'Nampyeong', 'Hi-ami'and 'Younghojinmi' showed resistant response against the natural infection with overall Fusarium pathogens. Majority of the promoted rice varieties could not be classified for resistance or susceptibility. These results are valuable as basic data to determine the resistance and susceptibility of rice variety against Fusarium spp. infection in the field.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.67 no.2
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• pp.77-84
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• 2022

This study aimed to evaluate the growth, yield, and grain quality characteristics of rice varieties that were subjected to water stress during the tillering stage. We also sought to identify whether water stress could be indicated via the plants' response to chlorophyll fluorescence. In this study, we induced water stress by intentionally cutting off water for 30 days, starting 15 days after transplanting the rice varieties to a greenhouse. We analyzed nine rice varieties, including Ilpum, which is the most frequently cultivated variety in Gyeongsangbuk-do, South Korea. The control group was planted in a paddy field where irrigation was entirely dependent on rainfall. Our results revealed that the heading stage of the nine studied varieties occurred approximately ten days earlier in the rain shelter than in the field. Moreover, the rice yield, head rice rate, and palatability score decreased by 18.6%, 17.1%, and 8.3%, respectively, while protein content increased by 20.2% compared with the control group. The Saenuri and Haimi varieties showed the lowest reduction in yield under the water stress conditions, while the Daebo and Samkwang varieties showed the highest reduction in yield. The chlorophyll fluorescence response after re-irrigation was measured between July 30^th and August 17^th. The ratio of variable fluorescence to maximum chlorophyll fluorescence (F_V/F_M) values failed to recover to their baseline values, resulting in either no change or a reduction in fluorescent response, even after re-irrigation of Daebo and Samkwang varieties. These results can be utilized as empirical data for drought-affected farms to select resistant varieties that can respond to spring drought in the southern plains of Gyeongsangbuk-do.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.37 no.3
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• pp.257-263
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• 1992

Immature embryos were tested for investigating the effect of cold treatment duration and GA$_3$ concentration on the vernalization response in barley. Immature embryos were cultured on B$_{5}$ medium with GA$_3$ for 5 days, and were transplanted under 20/15$^{\circ}C$ temperature after cold treatment. Germination rate and shoot length were increased more in 20-day-old embryos than those in 13-day-old ones but germination day was decreased. Addition of 1 or 10 ppm of GA$_3$ to B5 medium was effective on the growth of immature embryos. The higher GA$_3$ concentration was, the shorter time from embryo culture to flag leaf emergence and heading was. The earlist flag leaf emergence and heading were showed on treatment of 1 or 10 ppm of GA$_3$, but GA$_3$ did not completely replace vernalization. The days to flag leaf emergence of immature embryo-cultured barley with cold treatment for two and three weeks was shortened by 3 and 18 days at 1 ppm GA$_3$, and 16 and 20 days at 10 ppm GA$_3$, respectively, when compared to 0 ppm GA$_3$ culture with cold treatment for three weeks. It was at 10 ppm GA$_3$ with 3 weeks cold treatment that showed the lowest culm length, spike length and number of grain per spike. GA$_3$ concentration was not correlated significantly with each character in 1 week cold treatment, but was significant with each character in 2 weeks. In 3 weeks cold treatment, it was except for days to heading. Correlation between cold treatment duration and culm length was negative in 0 ppm GA$_3$. In 1 or 10 ppm of GA$_3$, all characters had highly negative correlation with cold treatment duration.n.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.30 no.4
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• pp.460-470
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• 1985

Experiments were carried out to evaluate the standard gravity in determining potential kernel size and to determine the effective sampling way by analyzing intra - and inter - plant variations for some source and sink characters using eleven semi-dwarf indica and three japonica cultivars including four semi-dwarf indica nearisogenic lines. Also, additional experiments were conducted to understand yearly variation and variety x year interaction effects for ten characters related to source and sink and to characterize the varietal difference of pre- and post-heading self-competition employing three parental varieties and their F$\sub$5/ progenies in 1982 and 1983. It is desirable to determine the potential kernel size by average kernel wight of rice grains showing above 1.15 specific gravity. There was significant difference in leaf area per tiller, spikelets and sink capacity per panicle among vigorous, intermediate and inferior tillers classified by differentiated order and vigorousness. Although it was difficult to find out any significant difference in grain-fill ratio, ratio of perfectly ripened grain, potential kernel size and sink/source ratio between vigorous and intermediate tillers, there was big difference between them and inferior one. The coefficients of variation within each tiller-group for some characters related to source and sink were larger with the order of vigorous tillers < intermediate one '||'&'||'lt; inferior one, and the average heritability of all characters, evaluated by the ratio of varietal variance (equation omitted) to total variance (equation omitted), were higher with the order of inferior tillers '||'&'||'lt; intemediate one '||'&'||'lt; superior one. Therefore, it is desirable to sample the vigorous tillers to represent the varietal difference of these traits. '82-'83 year variations of three parental cultivars were significant for all traits except for leaf area/tiller, panicles/hill, leaf area index and rough rice yield. The characters showing highly significant variance of variety x year interaction were growth duration from transplanting to heading, leaf area/tiller, sink/source ratio, sink capacity/panicle and grain yield. Generalized yearly response of three parental varieties (Suweon 264, Raegyeong, IR1317-70-l) and their F$\sub$5/ progenies on the 1st and 2nd principal components extracted from ten source and sink characters generally exhibited reduction in both source and sink. However, there were diverse variety x year interactions such as progenies showing similar reaction with their parents and intermediate or recombinational yearly response with little or considerable yearly movement on the four-dimensional planes of the two upper principal components between 1982 and 1983. Sink characters revealing highly significant border effect were grain-fill ratio, spikelets and sink capacity per panicle. Among them the latter two especially showed significant variety x border effect interaction. Self-competition characterized by relative weakness of inside plant's sink characters compared to the border one was more severe during the reproductive stage before heading than maturing stage. Though the larger sink capacity per panicle generally disclosed the severer self-competition, some lines (like Suweon 264) revealed severe self-competition with small sink capacity while a few others showed tender self-competition in spite of big sink capacity per panicle.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2002.10b
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• pp.115-116
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• 2002

This study was carried out as one of efforts to overcome difficulties in air bearing design due to low stiffness and low damping. Hydrodynamic effects on hydrodynamic stiffness of a fluid film in a high speed air bearing with tow-row air sources are investigated. The hydrodynamic effects by the high speed over DN 1,000,000 and eccentricity of a proceeding which are not considered in conventional design of an air bearing need to be reconsidered. The hydrodynamic effects, which dominantly influence on the load capacity of air bearing, are caused mainly by proceeding speed, eccentricity, and the source positions. The two-row source arrangement in the air bearing produces quite unique hydrodynamic effects with respect to pressure distribution of the air film. Optimal arrangement of the two-row sources improves performance of an air bearing in film reaction force and loading capacity of high speed spindles. This study compares the pressure distribution by numerical simulation as a function of eccentricity of proceeding and the source positions. The air source position 1/7L form one end of an air bearing was found to be superior to source position of 1/4L. The dynamic stiffness were obtained using a two-dimensional cutting method which can directly measure the cutting reaction forces and the displacements of the spindle in two directions using a tool dynamometer and transducer sensors. Heat generation in the air film can not be negligible over the speed of DN 2,000,000. In order to analysis effects of heat generation on the characteristics of air bearing, high cooling bearing spindle and low cooling bearing spindle were tested and compared. Characteristics of the frequency response of shaft and motion of run out errors were different for the spindle. The test results show that, in the case of low cooling bearing spindle, the stiffness became smaller due to heat generation. The results, which were obtained for high speed region, may be used as a design information for spindle which can be applied to precision devices such as ultra precision grinding and ultra high speed milling.

• Journal of Advanced Research in Ocean Engineering
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• v.1 no.4
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• pp.239-251
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• 2015

In this study, a spectral fatigue analysis was performed for the topside structure of an offshore floating vessel. The topside structure was idealized using beam elements in the SACS program. The fatigue analysis was carried out considering the wave and wind loads separately. For the wave-induced fatigue damage calculation, motion RAOs calculated from a direct wave load analysis and regular waves with different periods and unit wave heights were utilized. Then, the member end force transfer functions were generated covering all the loading conditions. Stress response transfer functions at each joint were produced using the specified SCFs and member end force transfer functions. fatigue damages were calculated using the obtained stress ranges, S-N curve, wave spectrum, heading probability of each loading condition, and their corresponding occurrences in the wave scatter diagrams. For the wind induced fatigue damage calculation, a dynamic wind spectral fatigue analysis was performed. First, a dynamic natural frequency analysis was performed to generate the structural dynamic characteristics, including the eigenvalues (natural frequencies), eigenvectors (mode shapes), and mass matrix. To adequately represent the dynamic characteristic of the structure, the number of modes was appropriately determined in the lateral direction. Second, a wind spectral fatigue analysis was performed using the mode shapes and mass data obtained from the previous results. In this analysis, the Weibull distribution of the wind speed occurrence, occurrence probability in each direction, damping coefficient, S-N curves, and SCF of each joint were defined and used. In particular, the wind fatigue damages were calculated under the assumption that the stress ranges followed a Rayleigh distribution. The total fatigue damages were calculated from the combination with wind and wave fatigue damages according to the DNV rule.