• Journal of Aquaculture
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• v.18 no.3
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• pp.142-146
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• 2005

In this study, the reattachment processes of small and medium size of spot of Mytilus coruscus and M. edulis were observed. The small spats (Shell length, SH, $3{\sim}7mm$) of hard shelled mussel, M. coruscus showed 100% reattachment rate within 7 minutes after the detachment of byssus thread and 100% survival rate. While large spats (SH 25 mm) showed 85% reattachment rate within 5 hours and 100% survival rate for 24 hours. The reattachment rate of M. edulis (SH 30 mm) was higher than that of M. coruscus (SH, 28 mm). The thread consisted of three identifiable structures; adhesive disc, adhesive thread and adhesive root. The adhesive disk and adhesive thread of M. coruscus were larger and thicker than those of M. edulis, whereas the thickness of adhesive root was the other way round. Further studies are required to identify the relationship between the structure of byssus thread and attachment ability. This study suggests that the sizes of spats could be an important factor in determining the timing of removing and reattaching mussel seedling for aquaculture or releasing to the sea.

• Research in Plant Disease
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• v.22 no.4
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• pp.293-296
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• 2016

In late June 2016, stalk rot symptoms were observed on five vatieties of sorghum (Sorghum bicolar) at organic paddy-upland rotation system in Anseong city, Korea. The initial symptom on stalk surfaces was red color with a dark red spot lesion. A fungus was isolated from the initial lesion, and cultured on potato dextrose agar. Size of microconidia mostly extend to $5-19{\times}2-{\mu}m$ in culture, with 0-1 septa and macroconidia extend to $29-52{\times}3-4{\mu}m$ with 4-6 septa. Pathogenicity was investigated using conidial suspension spray to seedling of sorghum. After 3 days of inoculation, the dark red lesion was produced on stalks. On the basis of mycological characteristics, pathogenicity, and internal transcribed spacer (ITS) rDNA sequence analysis, this fungus was identified as Fusarium thapsinum. This is the first report of stalk rot on sorghum caused by F. thapsinum in Korea.

• Horticultural Science & Technology
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• v.30 no.3
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• pp.334-337
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• 2012

A new promising kiwifruit, 'Halla Gold' variety with yellow flesh and being harvested in October, was developed at the Agricultural Research Center for Climate Change, National Institute of Horticultural and Herbal Science, Rural Development Administration, Korea in 2007. This variety was derived from the seedling population crossed between Actinidia chinensis cv. Golden Yellow and A. chinensis cv. Songongu in 1997. It was selected out of 2,971 seedlings. Characteristic trials were carried out from 2001 to 2003. After the selection, adaptability test was also conducted at kiwifruit orchards in Jeju Island from 2003 to 2007. Shoots of 'Halla Gold' sprout slightly stronger than those of 'Jecy Gold' but weaker than 'Hort16A' and the color of leaf is green. Fruit shape is oblong and fruit skin color is yellowish-dark green without hair. The average weight of fruit is 106.3 g. Fruit has a moderate size soft core, yellow pericarp, and fragile and juicy flesh. Soluble solids content is $14.7^{\circ}$ Brix and acidity is 1.4%. The harvesting time is about 10 days earlier than 'Jecy Gold' and about 20 days ahead of 'Hort16A'. The storage life is about 90 days at $2^{\circ}C$. This variety can be recommended for cultivating at low land area bellow 100 m sea level in Jeju Island or under shelter to prevent disease and cold injury.

• Korean Journal of Soil Science and Fertilizer
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• v.26 no.3
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• pp.155-159
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• 1993

This study was initiated to obtain the scientific information for the improvement of paddy soil. Mean values and mutual relationships of bulk density, pH values and the content of organic matter were investigated at the 124 field sites shown to be nationwide high-yielding, young seedling field s and their neighboring fields under the different soil textures and depths. The soil samples were collected and those samples were analyzed in the laboratory of Agricultural Sciences Institute. Mean values among the different soil textures and depths were estimated with loam-textured. Bulk density were significantly correlated with sand and silt in topsoil, and that were appeared to be correlated to sand, silt + clay, pH and content of organic matter highly significant in 1% level. Regression equation of soil bulk density(Y) to clay(C), orgnic matter (OM) and content of silt + clay(S+C) were as follows for the topsoil, Y=1.365+0.006C-0.003(S+C)~0.034OM (R=0.067*), and for the subsoil, Y=1.548 -0.002C-0.0007 (S+C) -0.036OM (R=0.122**).

• Journal of Korean Society of Forest Science
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• v.95 no.3
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• pp.316-322
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• 2006

This study was conducted to examine the changes of seed characteristics and germination properties and to determine the most suitable collection time in Ulmus davidiana var. japonica. Seeds were collected six times with the interval of seven days after April 21, 2005 at Jeong-seon. There were differences in seed characteristics and germination properties among seed collection times. The sizes of seed and fruit increased with the collection time, but seed moisture contents decreased with the collection time after increasing until May 5. The 1,000 seeds weight decreased with the collection time after increasing until May 12. Collection time showed high positive correlations (r=0.790, p<0.01) with seed size and negative correlations (r=-0.919, p<0.01) with moisture contents. Percent germination (PG) presented the highest value in seeds collected at May 5, and decreased with the collection time. Mean germination time(MGT), germination speed(GS), and germination performance index(GPI) also showed the highest values in seeds collected at May 5. PG, MGT, and GS had correlations with other seed characteristics except the 1,000 seed weight. The relative growth rate of height and root collar diameter of seedlings presented the highest values in seedling germinated from seed collected at May 5, and seedlings germinated from seeds collected at May 5 and 12 showed the highest values in chlorophyll contents. Consequently it will be possible to product a number of seedlings when the seeds of U. davidiana var. japonica are collected just before drying morphologically.

• Journal of The Korean Society of Grassland and Forage Science
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• v.6 no.3
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• pp.151-156
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• 1986

There are differences in recommendations in the USA as to whether nitrogen fertilizer should be applied when establishing alfalfa (Medicago sativa L). The reason for not applying nitrogen is because some researchers found the addition of nitrogen reduced nodulation of alfalfa plants. A replicated experiment was conducted under controlled environmental conditions at the University of Nevada-Reno, Reno, Nevada, USA, to determine the effects of nitrogen application on seedling growth and nodulation of alfalfa when grown in a cool environment. A sterile sand was used in the growing media to which a complete nutrient solution minus nitrogen was applied volumetrically to each pot daily. Half of the pots received $NH_4NO_3$, at the rate of 11.2 kg/ha, at seeding and two and four weeks after planting, giving a total nitrogen application rate of 33.6 kg/ha. Rhizobia inoculant (R-12) consisted of a mixture of strains 171-15a. 1682c and 80 PI 265 of Rhizobium meliloti. Inoculant was applied to the seeds prior to planting and to the sand media at two and four weeks after seeding. Twenty seeds were planted in pots 14.0 cm in diameter and 11.5 cm deep. Seedlings were thinned after emergence to ten plants per pot. They were grown in a controlled environment chamber with a 16-hour light period. Soil temperatures at 6 cm depth ranged from $5.7^{\circ}C\;to\;21.5^{\circ}C$ and had a daily mean of $16.2^{\circ}C$ Plants were harvested at weekly intervals for seven weeks at which time root, shoot and total length, dry weight, volume and number of nodules per plant were determined. Root, shoot and total length were not affected by nitrogen fertilizer. However, application of nitrogen increased the size of the seedlings as determined by dry weight and volume when compared to plants which were not fertilized. This indicates that rhizobia did not fix enough atmospheric nitrogen to promote good growth. Nitrogen application resulted in significantly more nodules per plant. The effect of nitrogen fertilizer became more apparent as the plant became older. Results of this experiment show there are benefits from applying nitrogen at a low rate when establishing alfalfa under a cool environment.

• Horticultural Science & Technology
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• v.30 no.4
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• pp.417-425
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• 2012

Salinity stress is one of the most serious factors limiting the productivity of agricultural crops. The aim of this study was to assess inter-cultivar (intraspecific) variation for salinity tolerance in six Korean rapeseed (Brassica napus L.) cultivars at the seedling stage. The effect of three different salinity stress levels (EC 4, 8, and 16 $dS{\cdot}m^{-1}$) on seedlings of six cultivars was investigated through leaf size, leaf dry weight, and leaf chlorosis. At the highest salinity level (16 $dS{\cdot}m^{-1}$), the mean decrease of leaf dry weight in 'Sunmang', 'Tammi', 'Tamla', 'Naehan', 'Youngsan', and 'Halla' was about 56.2, 56.9, 78.4, 79.3, 77.4, and 80.9%, respectively. 'Tammi' and 'Sunmang' showed much less reduction in leaf dry weight than all the other cultivars. In addition, diluted seawater treatments increased the occurrence of leaf chlorosis in six cultivars. At EC 8 and 16 $dS{\cdot}m^{-1}$, 'Naehan', 'Youngsan', and 'Halla' showed a higher level of leaf chlorosis than 'Tammi' 'Sunmang', and 'Tamla'. On the basis of these results, six cultivars were placed into salinity-tolerant and sensitive groups. 'Tammi' and 'Sunmang' were the salinity-tolerant cultivars, while 'Naehan', 'Halla', 'Youngsan', and 'Tamla' were the salinity-sensitive cultivars. 'Tammi' and 'Naehan' rated as the most tolerant and most sensitive cultivar, respectively. To further analyze protein expression profiles in 'Tammi' and 'Naehan', 2-D proteomic analysis was performed using the plants grown under diluted seawater treatments. We identified eight differentially displayed proteins that participate in photosynthesis, carbon assimilation, starch and sucrose metabolism, amino acid metabolism, cold and oxidative stress, and calcium signaling. The differential protein expressions in 'Tammi' and 'Naehan' are likely to correlate with the differential growth responses of both cultivars to salinity stress. These data suggest that 'Tammi' is better adapted to salinity stressed environments than 'Naehan'.

• Journal of Bio-Environment Control
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• v.12 no.3
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• pp.166-172
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• 2003

Rockwool slabs used for hydroponic cultures are expected to have potential to be reused after breakdown as a growing medium component for hydroponic culture of vegetables and cut flowers, pot plants, or plug plants. This study was conducted to test the feasibility of using particles of used rockwool slabs (PURS) mixed with woodchips for growing plug seedlings of ‘Nokkufang’ pepper. In the first experiment growth of pepper seedlings was tested in media of steam sterilized PURS mixed with chestnut woodchips (CW), which was weatherized for six months and screened through 2.8 mm or 5.6 mm sieves, at 100:0, 75:25, 50:50, 28:75 or 0:100 (%, v/v). In the second experiment growth of pepper seedlings was tested in 20 different media containing steam sterilized PURS mixed with 4 mm chestnut woodchips (CW), 4 mm pinc woodchips (PW), coir, peatmoss, or perlite. In the first experiment, there were no significant growth differences as affectcd by particle size of CW, while the overall best growth was achieved il1 the control and l00% PURS. In the second experiment, seedling growth was enhanced as compared to the control in 100% PURS or PURS mixed with peatmoss, coir, or perlite. In contrast, growth was suppressed as the proportion of peatmoss or coir mixed with PURS decreased and the proportion of CW increased. Growth was better in the PURS + peatmoss than in the 100% PURS or PURS + coir, and when woodchips were mixed with coir than peatmoss.

• Journal of Korean Society of Forest Science
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• v.108 no.4
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• pp.513-521
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• 2019

With rapid climate change and increasing global warming, the distribution of evergreen broad-leaved trees (EBLTs) is gradually expanding to the inland regions of Korea. The aim of the present study was to analyze the survival rate of 148 EBLT plantations measuring 180 ha and to determine the optimal plantation size that would help in coping with climate change in the warm, temperate climate zone of the Korean peninsula. For enhancing the reliability of our estimated survival model, we selected a set of 11 control variables that may have also influenced the survival rates of the EBLTs in the 148 plantations. The results of partial correlation analysis showed that the survival rate of 67.0±26.9 of the EBLTs in the initial plantation year was primarily correlated with plantation type by the crown closure of the upper story of the forest, wind exposure, and precipitation. For predicting the probability of survival by quantification theory, 148 plots were surveyed and analyzed with 11 environmental site factors. Survival rate was in the order of plantation type by the crown closure of upper story of the forest, wind exposure, total cumulative precipitation for two weeks prior to planting, and slope stiffness in the descending order of score range in the estimated survival model for the EBLTs with the fact that survival rate increased with shade rate of upper story to some extent.

• Korean Journal of Plant Resources
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• v.30 no.4
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• pp.372-377
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• 2017

This research was performed to develop mass propagation method of Alpine modest primrose (Primula modesta var. hannasanensis T.Yamaz.) for improving the conservation and utilization of the species. Seeds were collected on August 2011 in Jeju-city and well-selected seeds were dry-stored at $4{\pm}1.0^{\circ}C$. Seed size ranged $0.44{\pm}0.07{\times}0.61{\pm}0.04mm$, and weight of 1,000 seeds was $51.78{\pm}0.021mg$. Thus the seed was classified as 'dwarf seeds'. As the result of dormancy characteristics, moisture content of freshly matured seeds increased rapidly by water-soaking treatment and seeds did not germinate at $20^{\circ}C$ for 4 weeks under the light condition. Therefore, seeds were estimated to have physiological dormancy. Germination conditions of dry-stored seeds were found to be $20^{\circ}C$ and light condition, and seeds did not germinated under dark condition regardless of all temperature regimes. Therefore, Alpine modest primrose seed was considered as photoblastic type. Percent germination (PG) and germination energy (GE) were greatly improved by soaking the seeds in $GA_3$ and kinetin for 24 hours. Especially, 200~500 mg/L $GA_3$ treatment resulted in the highest PG (95.5%) and GE (98.3%). So, chemical treatment such as $GA_3$ was thought to be a useful method for raising seedling uniformly.