• Journal of the Korean Society of Food Science and Nutrition
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• v.42 no.9
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• pp.1412-1418
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• 2013

The nutritional components of 14 new cultivars of pak choi (Brassica rapa L. ssp. chinensis) from China were analyzed and compared with 4 cultivars of Chinese cabbage (Brassica rapa L. ssp. pekinensis) popular in Korea. Leaves were separated into green parts (GP) and white parts (WP) for the analyses. The moisture and ash content in the 14 new cultivars of pak choi were not significantly different from the currently popular cultivars of Chinese cabbage. In addition, the levels of vitamin C and E were very similar between the two kinds of Brassica rapa. In contrast, the overall mineral content was higher in the new pak choi cultivars. Specifically, minerals important for human health, calcium and magnesium, were significantly greater in pak choi cultivars (calcium GP 2.57, WP 2.04; magnesium GP 0.422, WP 0.301 mg/g fresh weight) compared to currently popular cultivars (calcium GP 0.805, WP 0.477; magnesium GP 0.244, WP 0.101 mg/g fresh weight). Although the content of reducing sugars was similar, cellulose content (which correlates with the hardness of plant tissue) was four times higher in the new pak choi cultivars compared to currently popular cultivars. These results demonstrate that the new pak choi cultivars have superb nutritional benefits for human health and could be a good food source as a daily staple vegetable.

• Korean Journal of Agricultural and Forest Meteorology
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• v.3 no.1
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• pp.22-29
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• 2001

In Korean high yielding varieties developed by crosses between indica and japonica rice, the most limiting factor for yield may be attributed to the less number of the tillers in the unit area. The goals of this study is to find out the effect of the temperature factors as well as cultural practices on the development and increase of tillers of Dasanbyeo, the high yielding indica crossed japonica cultivar. The effect of temperature was examined under controlled phytotron condition with 6 levels of temperature, 15, 17, 19, 22, 24 and 26$^{\circ}C$, respectively, For the experiment, the leading japonica variety in Korea, Hwaseongbyeo, was used for the check cultivar for the comparison with Dasanbyeo. The high temperature also accelerated the initiation and termination of tiller development. The cultivar difference in the speed of tiller development was observed, for example, more rapid development of tiller in Dasanbyeo than in Hwaseongbyeo was observed at the high temperature range of 24-26$^{\circ}C$, while the vice versa phenomena was observed at lower temperature range of 17-22$^{\circ}C$. The first secondary tiller of Dasanbyeo was observed on the 16, 17, 23, 27 and 38 days after transplanting (DAT) at 26$^{\circ}C$, 24$^{\circ}C$, 22$^{\circ}C$, 19$^{\circ}C$, and 17$^{\circ}C$, respectively. Those of Hwaseongbyeo was 19-22, and 26 DAT at 19-26$^{\circ}C$ and 17$^{\circ}C$, respectively. The last effective tiller of Dasanbyeo was observed on 27-33 DAT for the primary tiller, 20-41 DAT for the secondary tiller. Those of Hwaseongbyeo were 23-40 DAT for primary tiller, and 24-40 DAT for the secondary tiller, and 24-40 DAT for the secondary tiller.

• Korean Journal of Agricultural and Forest Meteorology
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• v.4 no.3
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• pp.151-158
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• 2002

In Korean high yielding varieties developed by crosses between indica and japonica rice, the most limiting factor for yield increase may be attributed to the less number of tillers per unit area. The goal of this study is to find out the effect of the environmental factors as well as cultivation practice on the development and increase of tillers of Dasanbyeo, the high yielding indica / japonica hybrid cultivar. The effect of temperature was examined with 3 different light intensity, 220,600, and 1220 $\mu$㏖/s/$m^2$, respectively. For all the experiments, the leading japonica variety in Korea, Hwaseongbyeo, was used fur the check cultivar for the comparison with Dasanbyeo. The increase of the tillers was more prominent in Dasanbyeo than in Hwaseongbyeo at 220 $\mu$㏖/s/$m^2$ of light intensity, while the similar increase of tiller no. was found at 600 $\mu$㏖/s/$m^2$ of light intensity treatment. However, Hwaseongbyeo showed more rapid increase of tiller at 1220 $\mu$㏖/s/$m^2$ of light intensity. The mean number of the primary tiller ranged 5 to 7 in Dasanbyeo, and 2 to 7 in Hwaseongbyeo, showing greater variation in the latter case. However, the secondary tiller number ranged from 2 to 13 for the former, and 2 to 12 for the latter. The earliest initiation of tiller node of Dasanbyeo and Hwaseongbyeo was observed on 6 and 4 days after transplanting(DAT), respectively, at 600 $\mu$㏖/s/$m^2$ of light intensity, while 10, and 7 DAT, respectively, at 1,220 $\mu$㏖/s/$m^2$. No cultivar difference was observed at 600 $\mu$㏖/s/$m^2$ with the 18 DAT. The ratio of effective tiller was lower in Dasanbyeo, ranging from 47 to 55% than in Hwaseongbyeo, ranging from 72 to 100%.

• Weed & Turfgrass Science
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• v.5 no.4
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• pp.203-212
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• 2016

In order to investigate actual pesticide usage, this survey was carried out with farmers growing four crop groups, leaf vegetables, fruit vegetables, fruits, and rice from 2012 to 2015. Five hundred sixty farmers were selected in main crop production areas and were asked about their pesticide uses during the growing season. Investigations on pesticide damages to crop in recent 5 years showed that fruit vegetables had the highest proportion of damage at 14%, followed by rice at 11%, orchards at 11%, and leaf vegetables at 8%. Compared to the results of a pilot study which took place from 2009 to 2011, fruit vegetable damage increased by 4% while damage to rice and orchards decreased by 7-9%. This means continuous education on mixed spraying, usage methods, and precaution is required. In the survey on the safety guidelines for pesticide use, 6 items were well observed (89.0-95.0%), but one item for use of protective gear had the lowest observance (81.7%). A measure for protective gear for poisoning prevention is required. The survey of pesticide usage per area ($kg\;a.i.\;ha^{-1}$) showed that 1.65, 4.93, 10.98, and $3.16kg\;a.i.\;ha^{-1}$ of pesticides were applied to leaf vegetables (6 species), fruit vegetables (6 species), fruits (6 species), and rice, respectively, which decreased from the usage reported in the pilot study. This change was likely caused by more effective pesticides and fewer pest outbreaks; therefore, shipments of pesticides have been decreasing. In the case of paddy rice herbicides, 43 products, including butachlor, were used for $1.3kg\;ha^{-1}$. Herbicides represent 44% of pesticides used in paddy rice.

• Korean Journal of Organic Agriculture
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• v.23 no.3
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• pp.549-565
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• 2015

This study was conducted to investigate the growth characteristics and functional materials of baby vegetables as affected by different LEDs and luminous intensity at Anseongsi, Gyeonggi Province, in 2014. Test crops were beet, chicory, spinach, red leaf lettuce, crown daisy and red mustard purchased from the seed company of Dongbu Hannong and Jinheung. Growth characteristics were measured and the content of functional materials was analyzed 40 days after seeding at plug plate. Treatment of Red+Blue (4:1) at $150{\mu}mol\;m^{-2}s^{-1}$ luminous intensity showed the highest number of leaves in five baby vegetables of beet, chicory, red leaf lettuce, crown daisy and red mustard. The highest shoot length of chicory, spinach, red leaf lettuce, crown daisy and red mustard was obtained from the treatment of Red+Blue (4:1) at $150{\mu}mol\;m^{-2}s^{-1}$ luminous intensity. Fresh weight and dry weight of all six baby vegetables were the highest in treatment of Red+Blue (4:1) at $150{\mu}mol\;m^{-2}s^{-1}$ luminous intensity. Content of chlorophyll a and chlorophyll b of spinach, red leaf lettuce and red mustard showed the highest in Fluorescent lamp at $150{\mu}mol\;m^{-2}s^{-1}$ luminous intensity whereas other crops did not show definite trend under different LEDs lights and luminous intensity. The highest total content of anthocyanins and polyphenol were obtained from the treatment of Red+Blue (4:1) at $150{\mu}mol\;m^{-2}s^{-1}$ luminous intensity in all six baby vegetables. Free radical scavenging activity was highest in all six vegetable crops at $150{\mu}mol\;m^{-2}s^{-1}$ luminous intensity, but it was not different significantly between LEDs. As a result, the growth and the content of functional material of baby vegetables are generally to be increased in Red+Blue (4:1) at $150{\mu}mol\;m^{-2}s^{-1}$ luminous intensity. Mixed light of Red+Blue is thought to give good effect on the growth and the content of functional material in baby vegetable crops. Because there are many differences in regard of LED lights, crop varieties, cultivation and experimental methods in their impact on the growth and functional materials of baby vegetables among researchers, it is considered that a more precise studies are needed for the crop responses to LED light and luminous intensity.

• Horticultural Science & Technology
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• v.31 no.5
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• pp.552-557
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• 2013

This study was carried out to investigate the different DIF (day/night temperature differential) treatments on early growth of sweet pepper plants (Capsicum annuum L.) after planting. The DIF treatments were thus as follows. DIF levels are DIF-6 ($20-26^{\circ}C$) and DIF 0 ($23^{\circ}C$), DIF 3 ($24.5-21.5^{\circ}C$) and DIF 6 ($26-20^{\circ}C$). The DIF 3 and DIF 6 treatments significantly increased plant height of the sweet pepper plants during ten weeks after planting compared to DIF-6 and DIF 0. Leaf area per plant of DIF 3 treatment constantly increased and the level was greatest leaf area at ten weeks after planting. Fresh weight per plant treated with DIF-6 was lower and was reduced 74-77% range compared to other treatments. DIF 0 and DIF 3 treatments significantly affected dry weight and percentage of dry matter compared to DIF-6 and DIF 6. Especially DIF 6 treatment significantly decreased from eight weeks after planting. Percentage of dry matter of the leaf treated with DIF 0 and DIF 3 consistently increased from six weeks after planting, however, DIF-6 and DIF 6 treatments dramatically decreased from eight weeks after planting. High levels of DIF management cause growth retardant on early growth of sweet pepper plants, especially when night temperature is higher than day temperature, plants are indicated to be greater growth retardant.

• Korean Journal of Breeding Science
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• v.43 no.1
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• pp.42-49
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• 2011

QTL analysis for blast resistance was carried out using 140 $BC_3F_3$ lines derived from a cross between Ilpum as a recurrent parent and Moroberekan as a donor parent. 140 $BC_3F_3$ lines with the parents were inoculated with nine blast isolates. To identify QTLs for resistance to nine blast isolates, 134 SSR markers showing polymorphisms between the parents were genotyped for the 140 $BC_3F_3$ lines. A total of 17 resistance QTLs to nine isolates were detected on chromosomes 2, 3, 4, 6, 7, 9 and 10. The phenotypic variance explained by each QTL ranged from 8.2% to 26.4%. The Moroberekan alleles contributed the positive effect at these 17 QTL loci. In a previous study, the QTL, Pi45(t) for durable resistance to blast was identified using a sequential planting method. To know the relationship between Pi45(t) and the isolate-specific resistance gene, an $F_2$ population was developed from a cross between Ilpum and an introgression line harboring Pi45(t). $F_3$ lines segregating for the Pi45(t) were inoculated to three isolates. $F_3$ lines from the $F_2$ plants with the Moroberekan segment at the target region showed resistance to two isolates. This result seems to indicate that the Pi45(t) and the isolate-specific resistance gene are tightly linked or the resistance is controlled by the same gene(s). The markers linked to genes controlling blast resistance would be useful in developing blast resistance lines in the breeding program.

• Journal of agriculture & life science
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• v.46 no.2
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• pp.179-190
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• 2012

This study was performed to obtain a heat saving effect and enhance the efficiency of a greenhouse by using a hot water piping in order to minimize the operating costs of a greenhouse as oil prices continue to rise. This method also reduces the likelihood of accidents caused by snowdrifts in regions with heavy snowfall. In general, the experimental plot was $2.0{\sim}6.0^{\circ}C$ higher than the control plot. When the skylight felt was opened, the minimum temperature was in the range of $3.0{\sim}12.0^{\circ}C$. Therefore, we judged that damage caused by snowdrifts may be prevented partly by active heating. The temperature difference inside of the greenhouse by height was insignificant. The maximum heating load of the greenhouse according to crop was respectively about $37,000kcal{\cdot}h^{-1}$ and $41,700kcal{\cdot}h^{-1}$. During the experiment, the heat value of each designed temperature in the range of the minimum ambient temperature $-11.9{\sim}4.0^{\circ}C$ was about 95,000~322,000 kcal and it was in the range of $6,050{\sim}20,900kcal{\cdot}h^{-1}$. If it is compared with the maximum heating load, it can be shown that about 15~56% of the heating energy can be supplied. The total heat value and the amount of power consumption were 2,629,025 kcal and 677.3 kWh respectively during the experiment. If it is heated with diesel, a fossil fuel, the consumption during the experiment was 291 L and the cost was 331,700won. Total cost of using electric power was about 24,400 won and it is shown that it is about 7.5% of the cost of diesel consumption. Also, if the total amount of power consumption is converted into energy, it is approximately 582,200 kcal and the energy was just about 22% of the total heat value.

• Journal of Bio-Environment Control
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• v.28 no.4
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• pp.429-437
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• 2019

This study was conducted to examine the effect of humidification and shading during cutting propagation on growth and development of strawberry (Fragaria x ananassa Duch.) 'Maehyang' plants at a propagation stage. The runner cuttings were stuck on Nov. 23, 2017 in propagation benches set in a Venlo-type glasshouse. Four shading treatments, no shading (control, C), 55% shading with white lawn (W55), 55% black shading net (B55), or 100% black plastic film (B100) with either an intermittent fog system (H) or without fog system. The shading and fog systems were removed 2 weeks after sticking of strawberry cuttings. A nutrient solution for strawberry, which was developed by Yamazaki, was supplied once a day with electrical conductivity (EC) $1.6dS{\cdot}m^{-1}$ and pH 5.8. Growth parameters such as plant height, longest root, crown diameter, leaf chlorophyll, leaf area and fresh and dry weight were measured at 7 days and 26 days after sticking. There was no significant difference in growth of above-aerial part of strawberry. The overall growth of the strawberry roots was better grew by providing fog than that not provide fog. The root fresh weight and root dry weight after 26 days after sticking of strawberry cutting was the best in the treatment that provided fog system without shading (CH). The longest root after 26 days after sticking of strawberry cutting was the best in the treatments that provided fog system with either 55% white lawn (W55H) and 55% black shading net (B55H). These results suggest that morphogenesis of these plants were affected by humidification and shading types. In a broader perspective, these results can be used to optimize studies of other crops grown from cuttings.

• Korean Journal of Soil Science and Fertilizer
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• v.39 no.6
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• pp.329-333
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• 2006

Most of volcanic ash soils in South Korea are distributed in Jeju province which is an island placed on southern part of Korea and has steep slope mountain area. There are many soils containing high contents of organic matter (OM) derived from volcanic ash in Jejudo, also. Therefore, irrigation and drainage in volcanic ash soil different with general soil which has low OM content have to be applied with another management way, but studies searching appropriate methods for them are set on insufficient situation because the area of volcanic ash soil in South Korea is only 1.3% (130,000ha). This study was conducted for analysis of soil water content and irrigation quantity appropriate for crops cultivated in volcanic ash soil with high OM content. Although soils with different soil color have the same soil texture, soil water characteristics curve by soil color showed the difference of water retention capability by OM content. But, this characteristics classified with soil color could be unified by scaling technique with similitude analysis method which get dimensionless water content using a present water content, a residual water content and saturated water content (or water content at 10kPa). A relation of gravimetric soil water content (GSWC) and dimensionless water content by the results showed a form of power function. The dimensionless water content (DWC) express a relative saturation degree of present water content. This was also expressed by van Genuchten model which describe the relation between relative saturation degrees and matric potentials. These results on soil water characteristics curve (SWCC) of volcanic ash soil will be the basic of irrigation plan in area having high organic contents into soil.