• KOREAN JOURNAL OF CROP SCIENCE
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• v.69 no.1
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• pp.49-60
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• 2024

A region can be divided into cultivation zones based on homogeneity in weather variables that have the greatest influence on crop growth and yield. This study classified the cultivation zone of soybean using weather indices as a prior study to classify the agroclimatic zone of soybean. Meteorological factors affecting soybeans were determined through correlation analysis over a 10 year period (from 2013 to 2022) using data from the Miryang and Suwon regions collected from the soybean yield trial database of the Rural Development Administration, Korea and the meteorological database of the Korea Meteorological Administration. The correlation between growth characteristics and the minimum temperature, daily temperature range, and precipitation were high during the vegetative growth stages. Moreover, the correlation between yield components and the maximum temperature, daily temperature range, and precipitation were high during the reproductive growth stages. As a result of k-means clustering, soybean cultivation zones were divided into three zones. Zone 1 was the central inland region and southern Gyeonggi-do; Zone 2 was the southern part of the west coast, the southern part of the east coast, and the South Sea; and Zone 3 included parts of eastern Gyeonggi-do, Gangwon-do, and areas with high altitudes. Zone 1, which has a wide latitude range, was further subdivided into three cultivation zones. The results of this study may provide useful information for estimating agrometeorological characteristics and predicting the success of soybean cultivation in South Korea.

• Korean Journal of Soil Science and Fertilizer
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• v.44 no.5
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• pp.717-721
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• 2011

In case of plastic film greenhouses cultivating fresh vegetables on paddy soil, soil characteristics must be considered as more important factor than any other factors. Generally after the four years of cultivation, soils tend to increase electrical conductivity value, nutrient unbalance and soil pests. As a result, degradation of agricultural products occurred, therefore it is necessary to improve soil conditions. In this study, yield and economic cost of cucumber were analyzed. The best soil conditions for cucumber cultivation were alluvial or valley in soil topology, moderately or poorly drainage in soil drainage classes, coarse loamy soil in texture. In addition, rich-sunlight and-deep groundwater would be proper for the cucumber cultivation. Good environmental managements of plastic film greenhouse were as follows. The temperature needed to be adjusted three times. The optimal daytime temperature could be $22{\sim}28^{\circ}C$, the one from 12 until night could be $14{\sim}15^{\circ}C$, and the temperature from 24 to sunrise could be $10{\sim}12^{\circ}C$. During plant growth period, soil moisture content was as low as 10~15%, and it needed to be maintained as 15~20% during reproductive growth period. To control pests, catch crop cultivation and solar treatment were carried out, after those EC was reduced and the root-knot nematode was controled too. Cucumber yield from the plot with improved soil managements increased to $158.4Mg\;ha^{-1}$, but plot with successive cropping injury yielded $140.3Mg\;ha^{-1}$. The income from the plot with improved soil managements was 215,676 thousand won $ha^{-1}$, the plot with successive cropping injury was 131,649 thousand won $ha^{-1}$. Income rate of each plot was 51.8% and 38.4%, respectively.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.30 no.3
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• pp.259-270
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• 1985

Meteorological year variations for rice crop from 1973 to 1984 were compared by using air temperature and sunshine hour for nursery period, cooling index for reproductive stage and meteorological yield productivity index for ripening period. The most optimum transplanting date and heading date for crop yield based on real transplanting date-grain yield relationship or heading date-grain yield relationship, meteorological yield productivity index and actual results showed good agreement each other. Around May 26 for transplanting and August 10 for heading were the most optimum date in Indica/Japonica hybrid cultivars while these were about June 8 and August 23 for Japonica cultivars, respectively. On the other hand, theoretical late limiting heading date for safe ripening were August 20 for Indica/Japonica hybrid cultivars and August 30 for Japonica cultivars, respectively, for both methods, cumulative temperature method during ripening with 80% believable frequency and meteorological yield productive index method having 1000(kg/10a) yielding potential. Based on the yield forecast trial, the highest values of photosynthetic efficiency, 2.5%, and crop growth rate, 23g/㎡/day, were recorded during 30 days before rice heading. Considering the photosynthetic efficiency and solar radiation, the potential crop growth rate was more or less 30g/㎡/day and the biological grain yielding potential in a existing cultural practices was approximately 900-1000(kg/10a) in Milyang weather condition. To increase further yielding potential, either photosynthetic efficiency or harvest index or both should be improved by manipulating appropriate canopy architecture, plant spacing, fertilizer, chemical, etc.

• Horticultural Science & Technology
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• v.29 no.6
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• pp.539-548
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• 2011

This study was conducted to control unseasonable flowering in a standard chrysanthemum 'Baekma' bred in Korea by 2-chloroethylphosphonic acid (ethephon) and night temperature (NT) through suppression of the transition from a vegetative to a reproductive stage under long day length caused by high NT in summer season. Ethephon was applied either once or twice at a concentration of 0, 200, 400, or $800mg{\cdot}L^{-1}$. The NT within controlled mini-plastic houses was maintained at 13, 17, or $21^{\circ}C$. The NT at $13^{\circ}C$ showed the greatest inhibiting effect of unseasonable flowering among all NTs regardless of various combinations of ethephon concentration and frequency. Moreover, the inhibition tendency of unseasonable flowering was distinctly decreased in a NT-dependant manner. Higher NTs reduced cut flower length and number of leaves, but increased the number of young leaves attached to top part of the flower. Higher ethephon concentrations and lower NTs increased cut flower length and the fresh weight of total, stem, and leaves due to the extension of vegetative growth period. Thus, if it is difficult to control the NT below $21^{\circ}C$ in greenhouses in the summer season, we recommended to spray more than $200mg{\cdot}L^{-1}$ ethephon once after planting to suppress unseasonable flowering and to ensure sufficient length of cut flowers.

• Asian-Australasian Journal of Animal Sciences
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• v.23 no.12
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• pp.1566-1577
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• 2010

Nandrolone, 19-nortestosterone, is a synthetic androgenic-anabolic steroid promoting muscle growth. Nandrolone is also present in pig meat and sera at non-negligible levels. A number of scientific reports have suggested a positive relationship between incidence of infertility and increased meat consumption in humans. The present study was designed to determine out the effect of feeding nandrolone on the testis of the male reproductive tract. Mixtures of food and nandrolone at different concentrations (0.005 ppm and 0.5 ppm) were supplied to pubertal male rats for 6 weeks. Body weight was recorded every week during the entire experimental period. At the end of the treatment, the testis, epididymis, and epididymal fat were collected and weighted. Sperm numbers in the caudal epididymis were counted. Differential gene or protein expression of steroidogenic enzymes in the testes among experimental groups was determined by semi-quantitative real-time PCR or western blotting analysis, respectively. Histological changes of the testis induced by nandrolone treatment were examined by hematoxylin and eosin staining. Immunohistochemical analysis was employed to detect changes in the localization of steroidogenic enzymes in the testes among experimental animals. There were no significant changes on body, testis, epididymis, and epididymal fat weights among experimental groups. A significant increase of caudal sperm number was found in the 0.5 ppm nandrolone-treated group. Histological examination of the testes noted a high frequency of germ cell sloughing in seminiferous tubules of 0.5 ppm nandrolone-treated rats. Even though transcript levels of $3{\beta}$-hydroxysteroid dehydrogenase (HSD) I, $17{\beta}$-HSD4, and $17{\alpha}$-hydroxylase were influenced by nandrolone treatments, protein levels of all molecules examined in the present study were not significantly affected. Immunohistochemical analysis showed no visible changes in the localization of steroidogenic enzymes in the testes among experimental groups. The current study showed that oral intake of nandrolone in male rats for 6 weeks did not cause significant damage to the testis. It is considered that a feeding effect of nandrolone on male fertility would not be remarkable.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.32 no.3
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• pp.323-329
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• 1987

Five soybean varieties of two early maturing Karikei73 and SS 79168, and three late maturing Tohoku76, Baegunkong and Jangbaegkong were used and evaluated in the study. Of the varieties examined, Karikei73 was characterized by the delayed leaf senescence. The varieties were planted in the pots of 1/3500 a filled with volcanic ash soil at the experimental fields of the National Institute of Agrobiological Resources in Japan. Major agronomic characteristics including the activity of nitrogen fixation for root nodules during the grain filling period were measured. Measurements during the stages were followed by the stage of development descriptions for soybeans made by Fehr and Carviness (1977). The acetylene reducing activity (ARA) per dry weight of root nodule measured using acetylene reduction assays was the highest at R4-R4.5 with decreasing trends thereafter for the early matruing varieties, while it continuously increased up to R6 but decreased rapidly thereafter for the late maturing varieties. The dry weights of root nodules and all parts of the host plant at each stage checked were greater in the late maturing varieties being the same in ARA per pot.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.32 no.4
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• pp.447-454
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• 1987

Five soybean varieties of two early maturing; Karikei 73 and SS79168, and three late maturing; Tohoku 76, Baegunkong and Jangbaegkong, were used and evaluated in the study, Of the varieties examined, Karikei 73 was characterized by the delayed leaf senescence, To investigate the periodical trends of sugars in plant organs and their roles to the nitrogen fixing activity of root nodules, the concentrations of reducing and non-reducing sugar in root and nodules during the grain filling period were measured. The concentration of non-reducing sugar in roots was not changed up to the stage of R6 for all of the varieties but it decreased rapidly thereafter for the varieties except Karikei 73. No such rapid decrease in the concentration of non-reducing sugar in the roots was observed for Karikei 73 having the characteristics of delayed leaf senescence. The concentration of reducing sugar in the root nodules was not greatly changed for all of the varieties up to the stage of R6 regardless of the earliness of varieties but increased temporarily at R6.5 when there was a rapid decrease in ARA. The phenomenon explained the fact that nitrogen fixing activities were controlled not only by supplying sugars as the source of energy for nitrogen fixation, but also by the need for fixed nitrogen of the plant. The concentration of non-reducing sugar in root nodules also increased up to the stage of R6-R6.5 but decreased at R7, which could apply the same explanation as in the concentration of reducing sugar of the root nodules.

• Animal Bioscience
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• v.34 no.4
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• pp.546-557
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• 2021

Objective: If fertilization does not occur within a specific period, the quality of unfertilized oocytes in the oviduct (in vivo aging) or in culture (in vitro aging) will deteriorate over time. Icariin (ICA), found in all species of Epimedium herbs, has strong antioxidant activity, and is thought to exert anti-aging effects in vitro. We asked whether ICA protects oocytes against age-related changes in vitro. Methods: We analyzed the reactive oxygen species (ROS) levels and expression of antioxidant, maternal, and estrogen receptor genes, and along with spindle morphology, and the developmental competence and quality of embryos in the presence and absence of ICA. Results: Treatment with 5 μM ICA (ICA-5) led to a significant reduction in ROS activity, but increased mRNA expression of glutathione and antioxidant genes (superoxide dismutase 1 [SOD1], SOD2, peroxiredoxin 5, and nuclear factor erythroid 2-like 2), during aging in vitro. In addition, ICA-5 prevented defects in spindle formation and chromosomal alignment, and increased mRNA expression of cytoplasmic maturation factor genes (bone morphogenetic protein 15, cyclin B1, MOS proto-oncogene, serine/threonine kinase, and growth differentiation factor-9). It also prevented apoptosis, increased mRNA expression of antiapoptotic genes (BCL2-like 1 and baculoviral IAP repeat-containing 5), and reduced mRNA expression of pro-apoptotic genes (BCL2 antagonist/killer 1 and activation of caspase-3). Although the maturation and cleavage rates were similar in all groups, the total cell number per blastocyst and the percentage of apoptotic cells at the blastocyst stage were higher and lower, respectively, in the control and ICA-5 groups than in the aging group. Conclusion: ICA protects oocytes against damage during aging in vitro; therefore, it can be used to improve assisted reproductive technologies.

• Journal of Korean Society of Forest Science
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• v.83 no.3
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• pp.311-321
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• 1994

Experiments were conducted to evaluate the efficacy of ground and foliar sprinkling of natural water for control of the pine needle gall midge, Thecodiplosis japonensis, by disturbing the reproductive behavior of adults such as copulation and oviposition. Diurnal ground spray for whole area application and foliar spray for single tree treatment were tested at day time during the period of adult emergence. The results obtained are as follows : 1. The population density of overwintering larvae in soil was not affected by the water spray during the adult emergence period. 2. Spraying the water showed no effect on the whole period and number of adult emergence, but retarded early emergence and facilitated Late emergence. The difference in the emerging time by 50% emergence day was approximately 7 days. 3. Ground spray was significantly different from control in gall formation rates but was not sufficient for effective control. As a single-tree treatment, the foliar spray was found to be highly effective for control of the pine needle gall midge, Average gall formation of spray plots and untreated ones were 2.6% and 38%, respectively ; control value exceeded 90%. 4. Ground spray of water was not effective in reducing larvae in gall of needle. Foliar spray, however, reduced 45% of larval numbers. 5. Foliar spray accelerated shoot growth by 15%-18%. 6. Foliar spray was highly effective for the control of sucking insects, such as mites and aphids on pine trees.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.34 no.s02
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• pp.34-44
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• 1989

The stability of rice cultivation in Korea is largely depended on climatic conditions, especially, low temperature at the period of early growth stage and after heading. The improvement of cold tolerant varieties and appropriate cultural practices in rice are very effective to minimize the cold damage. This paper is summarized the mechanism and counterplans of cold injury of rice plants. The paddy area having commonly cold injury in Korea is approximately 15, 522ha in 1,709 sites on the national scale. The cold damage at seedling stage in nursery bed appeared to poor germination, leaf discoloration, dead seedlings and seedling rot ect.. At the vegetative stage, the decreased tiller number due to poor rooting and the delayed heading caused by slow growth and panicle differentiation are commonly showed. The cold injury at early reproductive stage appeared to the degeneration of spikelets and rachis - branches, while that at meiosis stage showed to increased sterility due to poor development of pollen and shortened panicle length with delaying heading, therefore the grain yield is largely decreased. The cold damage at heading and ripening stages showed to poor pollination and fertilization, low panicle exsertion, poor grain filling and finally grain quality became low. To minimize the cold injury to rice plants by low temperature, following counterplans would be recommonded ; Improvement of the cold toelrant rice varieties for the regions of midmountains and alpines. Raising healthy seedlings at upland nursery beds and by using of growth regulators such as ABA, Fuchiwang and Tachiace. Soil improvement and organic matter application to reduce cold damage by increasing water and fertilizer holding capacities in the paddy field having commonly cold water and in the place where cold damage is regularly occurred. Appropriate fertilization for raising healthy rice plants to tolerate under low temperature condition. Water management to increase water temperature in the paddy such as depth watering, round channels and polyethylene tubes around the field. Establishment of the optimum cultivation time of rice based on minimum, mean and maximum temperatures at different regions with appropriate rice varieties.