• KOREAN JOURNAL OF CROP SCIENCE
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• v.42 no.5
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• pp.604-608
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• 1997

Ten selected soybean genotypes, consisting of nine from a pedigree breeding programme and one recommended variety, were evaluated in nine different locations and over two years for stability of yield performance. Variance component analysis revealed that soybean regional yield trials should be performed at more locations rather than in more years. Five stability parameters, which were coefficient of variability, regression coefficient, deviation parameter, variance component for genotype$\times$environment interaction, and ecovalence, were employed in the evaluation. Significant genotype$\times$environment interaction was present with respect to soybean yield. The highest average yield over nine locations and two years was shown in Suwon 145, which was considered to be stable in all stability statistics. In rank correlation among stability parameters, there were highly significant correlations among stability parameters derived from three Eberhart and Russell's, Plaisted's, and Wricke's methods. Due to the different ranking of genotypes by different stability parameters, a comprehensive method should be employed to identify the promising genotype as well as to characterize the relationship between genotype and environment.

• Korean Journal of Remote Sensing
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• v.35 no.6_1
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• pp.883-893
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• 2019

In this study, crop coefficients were calculated in two different methods and the results were evaluated. In the first method, appropriateness of GLDAS-based evapotranspiration was evaluated by comparing it with observed data of Cheongmi-cheon (CMC) Flux tower. Then, crop coefficient was calculated by dividing actual evapotranspiration with potential evapotranspiration that derived from GLDAS. In the second method, crop coefficient was determined by using MLR (Multiple Linear Regression) analysis with vegetation index (NDVI, EVI, LAI and SAVI) derived from MODIS and in-situ soil moisture data observed in CMC, In comparison of two crop coefficients over the entire period, for each crop coefficient GLDAS K_c and SM&VI K_c, shows the mean value of 0.412 and 0.378, the bias of 0.031 and -0.004, the RMSE of 0.092 and 0.069, and the Index of Agree (IOA) of 0.944 and 0.958. Overall, both methods showed similar patterns with observed evapotranspiration, but the SM&VI-based method showed better results. One step further, the statistical evaluation of GLDAS K_c and SM&VI K_c in specific period was performed according to the growth phase of the crop. The result shows that GLDAS K_c was better in the early and mid-phase of the crop growth, and SM&VI K_c was better in the latter phase. This result seems to be because of reduced accuracy of MODIS sensors due to yellow dust in spring and rain clouds in summer. If the observational accuracy of the MODIS sensor is improved in subsequent study, the accuracy of the SM&VI-based method will also be improved and this method will be applicable in determining the crop coefficient of unmeasured basin or predicting the crop coefficient of a certain area.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.45 no.6
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• pp.374-381
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• 2000

This study was conducted to select sesame varieties with high cultural stabilities by comparing several parameters of agronomic traits under the different cultural environments. Of the six areas, Iksan and Jinju areas which showed positively larger environment index values were relatively adequate cultural conditions for sesame. At the comparison of cultural stability of agronomic traits by Eberhart and Russell regression model among sesame breeding lines, Suwon 169 showed more stable regression coefficient values to the number of capsules per plant, number of seeds per capsule and seed weight per plant, and Iksan 12 showed more stable regression coefficient values to culm length and weight per plant. At the comparison of cultural stability of yield per 10a, Suwon 169 and Iksan 12 among sesame breeding lines showed more stable respectively, deviation values of 0.99, 0.98 respectively, and more less regression deviation values of 0.074, 0.167 respectively. Therefore those breeding lines are comparatively higher stabilities to yield determining agronomic traits under the different cultural environments, and it was concluded that those two breeding lines had the possibility to recommend promising breeding lines in the future.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.66 no.1
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• pp.8-17
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• 2021

As rice originates from tropical regions, low temperature stress during the germination stage in temperate regions leads to serious problems inhibiting germination and seedling establishment. Identifying and characterizing quantitative trait loci (QTLs) for low-temperature germination (LTG) resistance help accelerate the development of rice cultivars with LTG tolerance. In this study, we identified QTLs for LTG tolerance (qLTG5, qLTG9) and germination coefficient of velocity under optimal conditions (OGCV) (qOGCV7, qOGCV9) using 129 recombinant inbred lines (RILs) derived from the cross between a low-temperature sensitive line Milyang23 and a low-temperature tolerant variety Gihobyeo. qLTG9 and qOGCV9 were detected at the same location on chromosome 9. At both LTG QTLs (qLTG5 and qLTG9), the alleles for LTG tolerance were contributed by the japonica variety Gihobyeo. At qOGCV7 and qOGCV9, the alleles for low temperature tolerance were derived from Milyang23 and Gihobyeo, respectively. The RILs with desirable alleles at two or more QTLs, i.e., GroupVII: qLTG5+qLTG9 (qOGCV9) and GroupVIII: qLTG5+qOGCV7+qLTG9 (qOGCV9), showed stable tolerance under low-temperature stress. Our results are expected to contribute to the improvement of tolerance to low-temperature and anaerobic stress in japonica rice, which would lead to the wide adoption of direct-seeding practices.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.47 no.4
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• pp.323-327
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• 2002

Plant growth and the two components of respiration, growth and maintenance, were compared between low and high nitrogen applications in hydroponic culture on a high-yielding rice cultivar 'Takanari' (Oryza sativa L.). Grain yield decreased by high nitrogen application, and thus this cultivar has low adaptability to nitrogen. Growth efficiency (GE) and net assimilation rate (NAR) were lower in the high-nitrogen plot. The maintenance coefficient (m) and growth coefficient (g) of dark respiration were 0.0111 $d^{-1}$ and 0.196 in the low-nitrogen plot and 0.0166 $d^{-1}$ and 0.237 in the high-nitrogen plot, respectively. Thus, high nitrogen application increased both g and m. Calculated $R_m$ (maintenance respiration rate) was 70 and 90% of total respiration rate at heading, respectively. The significance of nitrogen adaptability and g was discussed.

• Proceedings of the Korean Society of Crop Science Conference
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• 2000.04a
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• pp.100-101
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• 2000

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 1999.10c
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• pp.123-129
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• 1999

Evapotranspiration is one of the important water budget components . An experiment was conducted to measure evapotranspiration. Three lysimeters were used to measure daily evapotranspiration. Lysimetrically measured values were compared with estimated values of various methods in REF-ET model , and then crop coefficient was computed.

• Journal of The Korean Society of Agricultural Engineers
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• v.47 no.2
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• pp.3-12
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• 2005

The objective of this study is securement of upland irrigation water using storage level management of small dams. However, it is not new development of water resources but securement of water using storage level management of existing dam. This study has enhanced the water utilization coefficient of dam, after extra available water had been calculated by application of periodical management storage level and this water is used to other water like the upland irrigation water demand. As the result of application, it can secure extra available water except the water requirement. Minimum extra available water except flood is about $20,000,000\;m^3$ and crop irrigation water demand of 10yr frequency is about $2,033,000\;m^3$ in Seongju. The utilization of crop irrigation water can be possible. And extra available water is about $3,102,000\;m^3$ in 2000, $1,959,000\;m^3$ in 2001 except flood period and crop irrigation water demand of 10yr frequency is about $2,272,000\;m^3$ in Donghwa. It is judged that extra available water cannot be used to crop irrigation water during the dry season in Dongwha. Consequently, when management storage level is determined and more efficient use of water is gotten like this study, water utilization coefficient will be enhanced.

• Proceedings of the Korean Society of Crop Science Conference
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• 2000.04a
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• pp.102-103
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• 2000

• Magazine of the Korean Society of Agricultural Engineers
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• v.29 no.2
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• pp.23-29
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• 1987

This study was fulfilled by the floating lysimeter method at the experimental farm of Kon-Kuk University from August to November of 1986 to investigate the amount of evapotranspiration by the growing periods, evapotranspiration ratio, amount of watering per one time, days of intermission, soil moisture extraction pattern and crop coefficient of the Chinese cabbage cultivated in the sandy loam soil at the watering point of pF2.O. The results obtained are summarized as follows: 1.The total evapotranspiration during the growing period was 267.2mm, which was 3. 99mm by daily average, and the maximum evapotranspiration showed in the mid ten days of September with the value of 5.81mm I day. 2.The evapotranspiration ratio by the growing stages increased from the last ten days of September and showed maximum in the beginning of October, and the average evapotranspiration ratio was 1.4. 3.The days of watering intermission at the watering point of pF2.O was 2.4 days, and the average yield per plant was 3,228 g. 4. The soil moisture extraction pattern in the initial stage was 78.9 % in the 1st and 2nd soil layer and 21.1 % in the 3rd and 4th layer, and the mid-season stage, the moisture extraction proportion of the under layer accounted for 38.8 % which showed that the root elongated to the lowest soil layer. 5.The average crop coefficient(Kc) of the tested crop during the growing period was 0.67 by Penman equation and 2.36 by Pan Evaporation equation, which showed high difference by the calculation methods, and the changes of crop coefficient by the growing stages by Penman equation was favorable than those calculated by other met-hods.