• ALGAE
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• v.25 no.2
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• pp.99-104
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• 2010

A psychrotolerant cyanobacterium, Nodularia spumigena KNUA005, was isolated from a cyanobacterial bloom sample collected near Dasan Station in Ny-${\AA}lesund$, Svalbard Islands during the Arctic summer season. To generate an axenic culture, the isolate was subjected to three purification steps: centrifugation, antibiotic treatment and streaking. The broad antibacterial spectrum of imipenem killed a wide range of heterotrophic bacteria, while the cyanobacterium was capable of enduring both antibiotics, the remaining contaminants that survived after treatment with imipenem were eliminated by the application of an aminoglycoside antibiotic, kanamycin. Physical separation by centrifugation and streaking techniques also aided axenic culture production. According to the cold-tolerance test, this mat-forming cyanobacterium was able to proliferate at low temperatures ranging between 15 and $20^{\circ}C$ which indicates the presence of cold-tolerance related genes in N. spumigena KNUA005. This suggests the possibility of incorporating cold-resistance genes into indigenous cyanobacterial strains for the consistent production of algae-based biofuel during the low-temperature seasons. Therefore, it is needed to determine the cold-tolerance mechanisms in the Arctic cyanobacterium in the next research stage.

• Environmental Engineering Research
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• v.17 no.4
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• pp.211-216
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• 2012

Quantification of the airborne microorganisms (bacteria and fungi) at a swine wastewater treatment plant was performed. Microbial samples were collected at three different phases of the treatment process over a 1-yr period. Cultivation methods based on the viable counts of mesophilic heterotrophic bacteria and fungi were performed. The concentrations of airborne bacteria ranged up to about $5{\times}10^3$ colony-forming unit (CFU)/$m^3$, and those of airborne fungi ranged up to about $9{\times}10^2CFU/m^3$. The primary treatment (e.g., screen, grit removal, and primary sedimentation) was found to be the major source of airborne microorganisms at the site studied, and higher levels of airborne bacteria and fungi were observed in summer. High levels of the respirable bioaerosol (0.65 to $4.7{\mu}m$ in size) were detected in the aeration phase. Among the environmental factors studied, temperature was strongly associated with fungal aerosol generation (with a Spearman correlation coefficient of 0.90 and p-value <0.01). Occupational biorisks are discussed based on the observed field data.

• The Plant Pathology Journal
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• v.17 no.2
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• pp.101-105
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• 2001

A disease survey on the carnation (Dianthus caryophyllus L.) wilt was conducted during the high temperature period (June through August) and the low temperature period (February through May) in 58 greenhouses of its major cultivation areas, including Pusan, Kimhae, and Changwon in Korea from 1998 to 1999. The disease incidence was averaged 5.4% and 11.9% in the low and high temperature periods, respectively. Severe damage was found in summer with high incidences of around 50% in some greenhouses. Close examination of the symptoms and isolation of the causal agent revealed that there was a new disease different from Fusarium wilt caused by Fusarium oxysporum f. sp. dianthi, which was determined as the stub dieback caused by F. was cetermined as the stub dieback caused by F. graminearum (teleomorph : Gibberella zeae). The stub dieback symptoms involved brown rot of stem that started usually from the portion of cutting without discoloration of inner vascular tissues. Seven out of 38 isolates from the wilted plants were identified as F. graminearum, while the others as F. oxysporum f. sp. dianthi. Mycological characteristics of the stub dieback pathogen including colony color, absence of microconidia, and the shape of macroconidia, were consistent with F. graminearum previously described. This is the first report of the carnation stub dieback in Korea.

• Journal of Bio-Environment Control
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• v.26 no.2
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• pp.100-107
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• 2017

This experiment was carried out to analyze the effects of substrate reuse on the growth and yield of summer paprika in cyclic hydroponics. The test group was divided into a new coco slab, one year reused coco slab two year reused coco slab based on 30% nutrient solution reuse, and was performed from April 18 to November 31, 2016 for 30 weeks. As a result, plant height of early growth was that the 2 year reused slab was longer than the new slab but the final growth period was 56.58 cm shorter. First group flower position was that reused slab was shorter by 2.92 cm than the new slab and the second group flower position was 0.31 cm long. The relative internode length of early growth, when the reused slab was used, the imbalance in the late growth stage was increased compared with the use of the new slab. The number of growth nodes in the 1 and 2 year reused slab was the smallest with 27.4 nodes. However, the number of harvested nodes did not show the difference in the test group, and the ratio of harvested that the 2 year reused slab was the highest at 26.8%. The ratio of unmarketable fruit tended to increase as the growth progressed. Fresh weight was 227.7g for new slab, 219.2g for 2 year reused slab and 21.2g for 1 year reused slab. The dry weight of the new slab increased with the reuse of the slab. It was 17.13g for new slab, 18.26g for 1 year reused, and 19.28g for 2 year reused. The average water content of the entire growth period was smaller as the slab was reused, and the 1 year reused slab was about 20g less than the 2 year reused slab. This trend was steadily occurring throughout the entire growing season. Especially, the reused slab for 1 year was less than 60g after 3 groups compared to other test groups. In conclusion, If will control seriously occurrence of unmarketable fruits by weakening after medium growth in summer-cultivated paprika in EC-based recycling hydroponic cultivation with reused cocopeat substrate, It is not what I have to worry that decrease of the yield and deterioration of the quality due to the change of physical and chemical properties of the slab and the pathogenic bacteria infection.

• Journal of Bio-Environment Control
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• v.21 no.4
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• pp.419-427
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• 2012

This study was carried out to investigate the effect of two shading methods, shading agent spray on the glasshouse and internal shading screen treatment, on the growth and fruit quality of paprika (Capsicum annuum L. 'Cupra' and 'Coletti') in summer season cultivation. In the shading agent treatment, a commercial shading agent diluted with water at a ratio of 1 : 4 was sprayed on the roof of a glasshouse. In the internal shading screen treatment, a 10~20% shaded screen was used during the day time when the sun radiation was greater than $700W{\cdot}m^{-2}$. Compared to the unshaded control, photosynthetic photon flux density (PPFD) decreased in the greenhouse in the shading agent (SA) and shading screen (SS) treatments by 20% and 30%, respectively. Lower air temperatures and higher relative humidities were observed in the SA than in both the control and the SS treatment. Time to reach the break point of humidity deficit $8g{\cdot}m^{-3}$ was 2 hours late in the SA than in both the control and the SS treatment. Compared to control, both the SA and the SS treatments showed lower instantaneous temperatures of leaf, fruit, and flower by $2^{\circ}C$, $5^{\circ}C$ and $3^{\circ}C$, respectively. There were no differences in number of branches, stem diameter, and leaf size among treatments although both shading treatments promoted plant height in both cultivars. Botrytis infection ratio declined with the SA treatment by 14.7% in 'Cupra' and 22.1% in 'Coletti' as compared to that in the control. Shading increased fruit size in both cultivars, whereas no differences were observed in the number of locules and thickness of fruit tissue among treatments. Shading treatment increased mean fruit weight by a range of 10 to 15 g per fruit, while it decreased soluble solids contents as compared to that in the control. Similar Hunter values were observed among treatments, while fruit firmness increased slightly in shading treatments. Compared to the control, shading treatments improved marketable fruits by 11.7~22.6% and increased the number of fruits per plant by 4~9.2 in both 'Cupra' and 'Coletti'. The results of this study indicate that shading agent application on the roof of glasshouse would be one of the most effective options to reduce heat stress imposed on the paprika crop in summer cultivation, resulting in improved crop growth and fruit yield.

• Journal of Mushroom
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• v.6 no.1
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• pp.13-19
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• 2008

This experiment was carried out to examine physiological and cultural characteristics of two strains ASI 19003, 'Poplar field-cap mushroom' Agrocybe cylindracea, and ASI 19016, 'Chaxingo' A. chaxingu, at the bottle cultivation which have very similar morphological characteristics in genus Agrocybe. There was significant difference between the physiological and cultural characteristics of ASI19003 and ASI19016. The optimal temperature for the hyphal growth was $28^{\circ}C$ in the strain ASI19003 and $30^{\circ}C$ in ASI19016. The optimal pH was not different in two strains and these strains grew well at pH 5.5~7.0. But the optimal pH in the submerged culture was 5.5 in ASI19003 and 5.0 in ASI19016. Especially, hyphal growth of the strain ASI19016 was very poor at pH 6.0~7.3. The optimal carbon source for the growth was lactose in the strain ASI19003 and fructose in ASI19016, and nitrate sources were asparagine, alanine, and glycine in the strain ASI19003, and ammonium tartrate, asparagine, glycine, and alanine in ASI19016, respectively. The periods of incubation and fruiting body formation in the bottle cultivation during the spring were 27 and 13 days in the strain ASI19003, 29 and 17 days in ASI19016. The yields of fruit body were 114 g per bottle (850 $m{\ell}$ volume) in the strain ASI19003 and 100 g in ASI19016. In the summer, the periods of hyphal incubation and fruiting body formation were 29 and 11 days in the strain ASI19003, 30 and 12 days in ASI19016. The color of the cap in the ASI19003 strain according to temperature increase during the fruit body development become more pale, but the strain ASI19016 kept dark color relative to ASI19003. The fruiting body formation of the strain ASI19016 was faster than that of ASI19003. Accordingly, the cultivation of A. cylindracea ASI19003 during the spring, fall and winter, and A. chaxingu ASI19016 during the summer can keep high quality and stable supply all year round of these mushrooms.

• Journal of Bio-Environment Control
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• v.22 no.4
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• pp.378-384
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• 2013

This study was conducted to identify the effect of soil water potential on the fruit quality and yield of paprika in summer fertigation cultivation. Treatments of soil water potential during cultivation were composed of -10, -20, and -30 kPa, respectively. The plant height of early growth was increased by high soil water potential (-10 kPa) treatment all of 'Cupra' and 'E499524' (mini-paprika) varieties. Mean fruit weight was increased by -20 kPa soil water potential treatment compared with the other treatments. The fruit number per plant was not affected by soil water potential in 'Cupra' variety but was increased by -20 kPa soil water potential treatment in E499524 variety (mini-paprika). The yield of soil water potential treatment of -20 kPa was higher than those of the other treatments. The flesh thickness and sugar content were not affected by soil water potential in 'Cupra' and 'E499524' (mini-paprika) varieties. The incidence of fruit cracking was decreased with decreasing soil water potential. Mineral contents of plants such as nitrogen, potassium, calcium, magnesium etc. were not affected in soil water potential.

• Korean Journal of Soil Science and Fertilizer
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• v.29 no.4
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• pp.347-352
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• 1996

These experiments were conducted to monitor the change in $NO_3{^-}-N$ in a plastic film house where $NO_3{^-}-N$ have been accumulated in the soil of high level (about 370 mg/kg) The objective of this study was to obtain the information needed to establish the N Fertilizer recommendation based on the available N content in the soil for vegetable cultivation. The cultivated crops were chinese cabbage in the spring, lettuce in the summer, and chinese cabbage in the autumn. The crops were cultivated with and without N application. The concentration of $NO_3{^-}-N$ in the soil was analysed before and after the cultivation of each crop. When $NO_3{^-}-N$ in the soil is as high as 370 mg/kg. even without N application, the yield of the first season crop, cabbage in the spring was 175 ton/ha and that of second season crop, lettuce in the summer was 53 ton/ha. These yields were comparable with those obtained under the application of N fertilizer: meaning that no N application would be needed for those crops when $NO_3{^-}-N$ in the soil is as high as 370 mg/kg. The yield of third crop, cabbage in the autumn was higher under N application than that under no N application by 62%. The fate of $NO_3{^-}-N$ in the soil differed along with the crop sequence. In the first crop, 14.5% was absorbed by crop, 25.4% remained in the soil and 60.1% was unaccounted for. In the second season, 25.3% was absorbed by crop, 51.8% remained in the soil and 22.9% was unaccounted for. In the third crop, 62.8% was absorbed by crop, 19.4% remained in the soil and 16.8% was unaccounted for.

• Journal of Bio-Environment Control
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• v.26 no.1
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• pp.7-12
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• 2017

This experiment was conducted to analyze the effect of drainage reuse rate on the growth and fruiting of summer paprika in closed hydroponic cultivation. The experiment was carried out for 25 weeks from March to September 2015 with 0, 20, 30, 50% mixing ratio of waste nutrient solution using non - recycling hydroponic cultivation as a control. As a result, stem diameter of the test was different in the groups 1 and 2, but no difference showed as the group progressed more than 3 groups. L.A.I tended to decrease with increasing drainage mixing ratio. The number of nodes in the 50% reuse test group was 1.4 compared to the control group, but there was no significant difference. The number of harvested nodes was significantly different in the control group (11.1 nodes) and the 50% reuse test group (8.7 nodes), and the harvested nodes tended to decrease as the drainage was reused. The ratio of harvest was also the same as that of the harvesting node, and the control was the highest at 33.2% and the lowest at the 50% reuse test at 27.6%. Relative yields were reduced by 30%, 35% and 45% in the control group in the first group, and this tendency was also observed in the second and fourth groups. However, in the 3 and 5 groups, the production of 50% test group increased by 13% and 5%. The ratio of unmarketable fruit was increased 2%, 4%, 4%, and 7% in 0%, 20%, 30% and 50% reuse test, respectively. In conclusion, if the decrease in yield due to the decline in early growth is carefully managed, even if the imbalance of inorganic ions occurs after the mid-term growth, the growth of the crop will enter into a stable period and the re-use will not be worried about the growth and the yield decrease.

• Journal of Bio-Environment Control
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• v.33 no.3
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• pp.163-171
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• 2024

This study was aimed to investigate the effects of layer-by-floor environmental conditions and lower shelf supplemental lighting on the productivity of fresh shoots when growing rosemary in multi-layer cultivation. The 10-cm cuttings from stock plants of common rosemary (Rosemarinus officinalis) were planted in a 128-hole tray, rooted, and then transplanted into pots of 750, 1,300, and 2,000 mL. Afterwards, they were placed on multi-layer shelves (width × length × height: 149 × 60 × 57 cm, 3-layer) in a two-linked greenhouse and cultivated using the sub-irrigation. The productivity of young shoots by layer of the multi-layer shelf was the highest on the third floor (top floor), but productivity decreased sharply after September due to stem lignification caused by excessive light during the summer. Conversely, the lower two layers exhibited faster growth rate of young shoots until the late cultivation period, but the quality decreased due to stem softening and leaf epinasty. To address the excessive light problem on the third floor during the summer, shading was implemented at 30% opacity in July and August, resulting in a 210% increase in rosemary young shoots count and a 162% increase in fresh weight per unit area compared to the unshaded control. To improve the lighting deficiency on the lower layer, supplemental lighting with LED at 30 W increased rosemary young shoot harvest by 168% from June to September compared to no supplemental lighting, but it decreased productivity after September. Therefore, when growing rosemary in multi-layer, it is judged that intensive production of young shoots is possible if the third floor (top layer) is shaded with 30% of light from July to August to prevent stem lignification, and the lower layer is temporarily supplemented with LED 30 W from June to September to increase young shoot growth.