• Korean Journal of Soil Science and Fertilizer
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• v.38 no.1
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• pp.38-44
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• 2005

In addition to the variation in nitrate accumulation of vegetables due to environmental conditions, there is also a distinct genetic variation. The variation of nitrate accumulation in some cultivars of lettuce and spinach commonly cultivated in Korea was investigated. Ten cultivars for both lettuce and spinach were grown in plastic containers filled with a 1:1 mixture of perlite and vermiculite with application of Hoagland No. 2 nutrient solution of high nitrate content (17.3 mM N) in a greenhouse condition. Plants were harvested four weeks after transplanting four-leaf stage seedlings. Plant growth was measured by fresh and dry matter of shoot, and contents of nitrate and other inorganic ions and organic solutes including sugar, amino acids and organic acids were measured. Large and significant genotypical variations in the nitrate content of the plants were found for both lettuce and spinach, and high negative correlations between nitrate content and fresh or dry weight were found in lettuce and spinach. Variation in nitrate accumulation of lettuce and spinach cultivars was not directly related to the differences in contents of organic and inorganic solutes, and this result indicates that photosynthesis and osmotic regulation are not directly related with the nitrate accumulation. Considering the correlations between nitrate content and plant growth of this study, it can be simply suggested that different cultivars of lettuce and spinach have their own inherited growth and physiological characteristics and also optimum nitrogen level required for the growth. Therefore when available nitrogen in root media is higher than the optimum level required for the inherited growth potential, some of the excess nitrate supplied can be accumulated in plants.

• Journal of Korean Society of Forest Science
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• v.86 no.2
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• pp.119-127
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• 1997

Japanese red pines growing along the Taebaek mountains have been called "Kangsong" and considered to be superior in growth and wood quality. An attempt was made to determine whether their boundaries for planting may be expanded by testing their early growth at eight experimental plantations of the Republic of Korea. Seeds were collected from the six different natural populations including Uljin in Kyongbuk province. For the provenance test, they were planted in eight different regions including Taean in the spring of 1987. Experimental planting was a randomized complete block design with 3 replications. Height growth was measured at the ages of 2, 4, and 6 after planting, and the diameter at root collar at the age of 6 after planting. Significant variation in height growth was observed among the plantations. The height growth measured at the age of 6 after planting showed a positive correlation with the latitude of the test plantation, and the contents of phosphate, potassium and calcium in the soil. A negative correlation, however, was observed between the longitude of the test plantation and height growth. Ponghwa provenance appeared to be the best among the provenances in that the trees from the area grew 16% better in volume growth than the average of all the trees tested in the study, while the worst one was Kyongju from which trees grew 11% less than the average.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.28 no.4
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• pp.421-427
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• 1995

To know the variation in the growth of the sea urchin, Pseudocentrotus depressus according to their localities, three different populations including the culture populations, the released populations, and the wild populations were investigated using the cluster analysis. For this purpose, pigment banding pattern on the genital plate was used as an age character. The population composed of the same year class was born between September 25th and October 5th every year. The population of 9 to 10 months old had no $r_1,\;whereas\;r_1$, was observed in the population of either 1 year and 10 or 11 months old, and both $r_1,\;and\;r_2$ in the population of either 2 year and 9 or 10 months old. Therefore, $r_1,\;and\;r_2$ radius were regarded as an annual ring. Growth in the culture populations was much better than that In either the released or the wild populations. However, when the cultured populations composed of 8 to 12 mm in test diameter was released to the shove near a culture farm, its growth appeared to be similar to that of the wild Populations. The wide distribution patterns of test diameter measured from the same year class of both the cultured and the wild populations were probably due to either long spawning period or growth differences between individuals. Except Yamaguchi and Cheju populations, the move closely located populations showed the more similar growth pattern. However, the growth of Cheju population appeared to be similar to that of Aba, Mogi, Toishi rather than Kasiwazima although Cheju Island was more closely located with Kasiwazima than other localities. In addition, the population of Yamaguchi, located at the highest latitute, revealed the similar growth pattern to that of Nomozaki, located at the lowest latitute.

• The Korean Journal of Malacology
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• v.27 no.3
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• pp.205-211
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• 2011

This study presents physiological rates of oxygen consumption, ammonia excretion, feeding rates, O/N ratio and assimilation efficiency of the blood cockle, Scapharca subcrenata, determined from specimens collected in Yeoja bay on the south coast of Korea. Physiological parameters were measured monthly under static, laboratory controlled conditions with ambient conditions, and measurements were performed seasonally in order to estimate scope for growth and its probable sources of variation. Oxygen consumption and ammonia excretion rates have been increased as temperature increased with the highest value of August, 2008. Feeding rate was the highest during April whereas the lowest was during August which is a period of gametogenesis with minimum biomass of phytoplankton around sampling area. Assimilation efficiency was not significantly different seasonally and O/N ratio decreased during July to August. The scope for growth was negative during high temperature months(July to August), reflecting the high temperature and low feeding rate, and had its highest positive values during spring and autumn. Data on the physiological parameters and scope for growth of Scapharca subcrenata obtained in this study will be used to assess the carrying capacity for blood cockle cultivation.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.49 no.5
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• pp.389-393
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• 2004

This study was carried out to investigate the difference of growth characteristics, yield and extract content between upland and paddy ginseng cultured with 4­year-old ginseng in 2003. Although upland ginseng showed larger variation in yield than that of paddy ginseng, the average of it was greater than that of paddy ginseng because it showed better growth of aerial part and higher survival rate than that of paddy ginseng. Moisture content of fresh root was $71.8\%\;(68.5\~73.1\%),\;and\;72.7\%\;(70.2 \~74.9\%)$ on average in upland and paddy ginseng, respectively. Paddy ginseng showed higher hardness in taproot, and higher rate of rusty colored root than that of upland ginseng. The ratio of taproot dry weight in upland ginseng was smaller than that of paddy ginseng, while that of lateral root was larger in upland ginseng. Ratio of marketable root (>60g) to total harvested roots was $13.7\%\;(0.82\~8.0\%)\;and\;7.7\%\;(1.6\~12.6\%)$ in upland and paddy ginseng, respectively. Extract content did not show distinct difference between upland and paddy ginseng, but it showed large variation from $16.1\;to\;25.1\%$ in taproot, and from $24.2\;to\;32.5\%$ in lateral root depanding on the ginseng field examined.

• Korean Journal of Community Nutrition
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• v.1 no.3
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• pp.366-375
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• 1996

The effect of carbohydrates, fat and protein consumption on the blood pressure of adolescents was investigated from the cross sectional data. The two major areas of inquiry were : 1)measuring the variation of blood pressure at various levels of macronutient intake. 2)measuring the relative importance between the factor of nutrient intake and physical growth. A total of 726 students(341 boys and 385 girls) in the first grade of middle school in Kangwha country were studied for their dietary consumption and physical growth as well as blood pressure. Multiple regression analysis was used as the analytical method to identify the relative importance between the factors. Besides the macronutrient consumption, other nutrients such as vitamin and mineral intakes were included in the regression model. The results showed a variation of blood pressure by macronutrient intake level was in consistant both in blood pressure and by gender. Systolic and diastolic blood pressure decreased with increasing protein intake for girls(p<0.05). However, it was not observed in the case of boys. The systolic blood pressure of boys showed a tendency to decrease with fat intake increase, while their diastolic blood pressure showed the opposite trend. Results of the regression analysis showed that physical growth was a more influential factor than nutrition on blood pressure for both sexes. This could imply that the dietary hypertension factors observed in adults may not be operative generally in a population with normotensive blood pressure during growth.

• Korean Journal of Breeding Science
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• v.40 no.1
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• pp.15-21
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• 2008

It was previously pointed out that mutation is the ultimate source of variation. Adequate variation is needed for plant breeding if there is a limitation in natural genetic resources. When the ionizing radiation has been known to cause chromosomal and genomic alternations, it is widely used for inducing mutagenesis. The electron beam as an ionizing radiation is the principal physical mutagens that induces mutation and effectively used in plant breeding. Since dose-response relationships of electron beam in plant species are rarely known, we investigated the seed germination rate and early seedling growth of irradiated seeds of creeping bentgrass (Agrostis palustris Huds., cv Penn-A1) with various electron beam irradiating conditions (1, 1.3, 2 MeV at both 0.03 mA and 0.06 mA with dose of 100 Gy (Gray) and 0.03, 1, 1.3, 2 MeV at 0.03 mA with dose of 200 Gy, respectively) using electron accelerator at Korea Atomic Energy Research Institute. The growth parameters in terms of shoot length, primary root length, and secondary root length showed similar response between 0.06 / 1 (mA / MeV) at 100 Gy and 0.03 / 0.3 (mA / MeV) at 200 Gy. Bentgrass seed germination was mainly affected by the intensity of irradiated dose (Gray). Germination rate was lowered as the irradiated dose increased. On the other hand, early seedling growth was mainly governed not by the dose of radiation but by voltage.

• Korean Journal of Ecology and Environment
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• v.33 no.2 s.90
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• pp.128-135
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• 2000

The authors surveyed the seasonal variations of environmental factors, the distributions of heterotrophic bacteria and Anabaena cylindrica growth-inhibiting bacteria at each water layer in Daechung Reservoir to verify the role of bacteria during the extinction of bloom. Average water depth at site 1, 2, and 3 were 25.5 m, 15.0 m and 12.3 m, respectively. Water temperature showed a typical pattern seasonally. The variation of DO was relatively inverse proportional to that of water temperature, although it was irregular during summer time. DO decreased gradually to early May, fluctuated sharply after then, and followed by gradual increasement after middle of September. This variation pattern was notable at surface layer. There was remarkable difference in DO concentraion between surface layer and the other water layers during the period in which DO irregulary varied. The variation range of chlorophyll-a concentraion at surface layer in summer time was broad, and it was relatively high when DO was high. The population size of heterotrophic bacteria was high from Spring to Autumn, an declined after September when the water temperature droped rapidly. Especially this variation pattern was prominent at the surface layer. Bacteria that inhibit the growth of A. cylindrica was almost not detected by June, and its distribution increased in July. Afterward, it showed different variation pattern between each site. The distribution of A. cylindrica growth-inhibiting bacteria was higher at the middle and bottom layer than the surface layer in July and October, when it was larger at all sites for the study period. This result suggests that the antagonistic bacteria exhibit higher activity when host activity drops. These results also suggest that natural water bacteria control the distirbution of cyanobacteria, especially its activity as controller is remarkable when cyanobacterial growth declines.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.34 no.4
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• pp.299-308
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• 2001

We examined the growth variation with water depth, interval between suspended lines and locality of seedling production of sea squirt. Halocpthia roretzi, measuring approximately $10.1\~15.3$ mm in tunic height, was cultured at the farm near Guryongpo, Pohang city from 7 January to 6 December 1998 (333 days). Growth condition depending on culture depth was most favourable at the depth of $10\~12$m, It was concluded that nutritional conditions were better at the depth since there was a greater mount of phytoplankton than at any other depth in the water column. Growth condition depending on distance between suspended lines was most favourable at the interval of 2 m and 2.5 m than at the interval of t m and 1.5 m, There was no significance difference in growth variation with locality of seedling. The seasonal variations in growth of tunic height, meat and total weight were correlated with temperature and chlorophyll a, In the depth of $10\~12m$ the rate of increase in tunic height was generally greatest in the growth period II ($244{\mu}m/day$) and IV ($338{\mu}m/day$), lower in the period I ($108{\mu}m/day$), and slightly increased during the period III ($185{\mu}m/day$). The water column have showed a typical seasonal pattern with temperature ranged between $12.07{\sim}24.14^{\circ}C$ and over $20^{\circ}C$ between July and September.

• Proceedings of the Korean Society of Crop Science Conference
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• 2005.04a
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• pp.260-261
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• 2005