• Korean Journal of Environmental Agriculture
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• v.16 no.2
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• pp.175-180
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• 1997

This experiment was conducted to find out the effects of lime materials application on reducing injury of simulated acid rain(SAR) in soybean grown in pot contained with sandy loam. Six treatments including control, slaked lime(SL), 1% and 2% lime water(LW) and composite treatments with SL+LW were applied. Slaked lime was applied to soil in pot before planting, and lime water was applied to leaves a day prior to the spray of SAR(pH 2.7) and normal rain(pH 6.0), and these were sprayed at 2-day intervals. Growth, yield and yield components, foliar injury rate, chrolophyll content and photosynthetic activity in leaves, content of mineral nutrients in plant and soil chemical properties were analyzed and investigated. These results obtained are summarized as follows : Seed yield of all lime treatment was reduced by SAR compared with control. But seed yield of all lime treatment was increased with treatment of lime material in soil and on leaves. After 15 and 45 times spray of SAR, all lime treatments were effective in injury reducing visible injury of leaves compared with none treatment. Chlorophyll content in leaves was highest in plants treated with slaked lime+ 1% lime water and photosynthetic activity was highest with treatment of slaked lime. Concentration of total nitrogen, phosphate, and sulfur in soybean plant were increased by the spray of SAR. Concentration of total nitrogen, potassium and calcium in soybean plant were increased with treatment of slaked lime into soil. By treatments of SAR, soil pH was decreased, and total nitrogen and sulfur concentration in soil were increased. However, available phosphate and exchangeable cations in soil such as calcium, magnesium and potassium were reduced. Soil pH, calcium and silicate concentration were increased with treatment of slaked lime into soil.

• Journal of Bio-Environment Control
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• v.16 no.3
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• pp.167-173
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• 2007

This study was conducted to improve light environment of oriental melon cultivation in winter season. Three polyolefin foreign films (J-1, J-2, J-3) and three polyethylene domestic films (K-1, K-2, K-3) with different film thickness, ultraviolet ray interception and infrared ray absorption were used. As the result of this experiment, soluble solid of oriental melon fruit in K-3 was $14.3^{\circ}Brix$, those in J-3 and J-2 were higher by 1.3 and $0.8^{\circ}Brix$, respectively. Chromaticity (a value) of pericarp in K-3 was 0.5, those in J-3, J-1 and J-2 were higher by 3.3, 2.3 and 1.9, respectively. Especially, fermented and malformed fruit rates in J-1, J-2 and J-3 were decreased and marketable fruit rates were increased. Marketable yield in K-3 was 1,622 kg per 10a, those in J-1, J-3 and J-2 were increased by 31.2%, 23.8% and 18.5% compare to K-3, respectively. In this study, Polyolefin films (J-1, J-2, J-3) with thickness and infrared ray absorption ratio keeping higher heat conservation, therefore, soluble solid and chromaticity of fruit were increased, fermented fruit rate was decreased, and marketable fruit rate and yield were increased.

• Korean journal of applied entomology
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• v.54 no.1
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• pp.1-6
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• 2015

This study was conducted to estimate the economic injury level (EIL) to leaf broccoli (leaf vegetable) by the diamondback moth (Plutella xylostella L.) in 2007 and obtain basic data for pest management. To investigate the relationship between initial density of diamondback moth larvae and broccoli leaf yield, experimental plots with five treatments (0, 0.5, 1.0, 1.5 and 2.0 larvae per plant) as initial density were established. We inoculated larvae on cheesecloth covering to survey changes in larval density. When grown for consumption, leaves of broccoli are harvested in periods. High levels of larvae were associated with significant reductions in leaf yield. There were 0%, 15%, 35%, 42%, 44% yield reductions due to a density of 0, 0.5, 1.0, 1.5, 2.0 diamond back moth larvae per plant, respectively, 25 days after larva inoculation. The regression equation used to predict leaf yield based on the number of initial larvae per plant was y = 1636-394x($R^2=0.79^{***}$>). EIL of the diamondback moth on leaf broccoli was 2~3 larvae per 10 plants for a damage level of 5%. The economic threshold was 1~2 larvae per 10 plants. Thus, diamondback moth management should be initiated when 1~2 larvae appear on 10 plants.

• Korean Journal of Soil Science and Fertilizer
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• v.42 no.6
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• pp.492-499
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• 2009

Effect of drip irrigation on soil salinity control and growth of vegetable crops was studied in the three reclaimed lands of Korea in 2007. Drip irrigation was done one or two times per month for reduction of salt stress by using vinyl hose with tiny holes laid on ridge surface under black plastic film mulch during growing season of cabbage and chinese cabbage. It was observed that drip irrigation was generally effective to soil salinity control, but soil salinity variation of some place was not fully solved to lower down under level of free salt stress. It is also considered that high salinity of runoff water spilled out from cultivation ridge plays another key role for soil salinity management. Consequentially, this soil salinity variation might be one of factors brought low average yield and low commercial ratio of agricultural products. Relation between soil salinity and head growth of cabbage and chinese cabbage was well expressed as logarithmic function. Surface soil EC to reach at 50% of growth reduction to the heaviest head can be estimated was $6.1dS^{\circ}{\S}m^{-1}$ for cabbage and $5.7dS\;m^{-1}$ for chinese cabbage transplanted at optimum season.

• Korean Journal of Environmental Agriculture
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• v.20 no.4
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• pp.218-224
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• 2001

To find out the optimum level of slow release N fertilizers (MS 10, MS S10, LCU 80, and LCU 100), total amount of nitrogen required throughout the growing season were applied in the seedling box or incorporated into paddy soil. Four levels of the slow release N fertilizers (0, 6, 9 and 12 kg N/10 a) were mixed with commercial rice nursery bed soil. N release rate and electrical conductivity(EC) of the slow release fertilizers were greater in the order of MS 10 > LCU 80 ${\fallingdotseq}$ LCU 100 > MS S10 and higher as temperature increased. No seedlings were emerged in all MS 10 plots. The seedling emergence rate of LCU 80 and LCU 100 decreased as the N level increased and seedlings were wilted severely on the 13th day after sowing at 9 and 12 kg N/10 a. In MS S10 plots the emergence rate was higher than 80% at all N levels and seedling growth was normal until 30 days after sowing. Yield of rice was similar between seedling box application and soil incorporation in paddy of MS S10. Yield of rice among the 6, 9, 12 kg N/10 a of MS S10 and conventional 12 kg N/10 a of urea split application was similar, but it was significantly higher compared with no N plot. Fertilizer N recovery of MS S10 decreased as fertilizer level increased and it was significantly higher compared with conventional urea split application.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.31 no.3
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• pp.260-269
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• 1986

This experiment was conducted to investigate the effect of mulching materials on the emergence rate, root dry weight and grain weight of sesame using variety Poong Nyun Ggae and also their effects on physical properties of soil, evapotranspiration and weed growth on the respective plots were studied. The effect of soil water holding capacity at mulching with polyethylene film and straw increased 5.4%, 2.8% to non-mulched plot respectively. The maximum soil temperature was raised up to 4$^{\circ}C$ by applying clear film and was dropped down to 7$^{\circ}C$ by straw. The minimum soil temperature was raised up to 2$^{\circ}C$ by clear film and was dropped down to 3$^{\circ}C$ by straw. In the early stage, the soil physical properties of clear film mulching were better than those of non mulching, and so was in emergence rate. In the late stage, soil strength was high at non mulching, and soil porosity, soil aeration and water infiltration rate were high at film and straw mulchings. Total root dry weight was great at clear film mulching, and root dry weight was concentrated mainly in the upper 10 cm of soil profile. The amount of weeds collected was the least at black film mulching. There were of little difference in evapotranspiration among treatments. The grain yield of sesame was increased to 57% by polyethylene film and 25% by straw mulching.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.38 no.6
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• pp.554-559
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• 1993

This experiment was carried out at Chuncheon substation, Crop Experiment Station to investigate the effect of cold water irrigation on the growth and grain yield of rice in 1990. Irrigation of cold water (17$^{\circ}C$) delayed 10 to 19 days of heading, and reduced about 17 to 31% of plant height in terms of culm and panicle length. Number of panicle per plant was decreased and / or increased by cold water irrigation. Cold water irrigation reduced spikelet number per panicle and percent of filled grain. Grain yield was increased but, straw weight was decreased according to water temperature gradient from inlet to outlet. There was varietal differences in head rice recovery by cold water treatment. In general the dark brown and / or black colored kernel increased at cold water inlet but decreased percent of green kernel. Alkali digestible value increased and amylose content decreased at cold water inlet.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.47 no.3
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• pp.157-160
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• 2002

This study was carried out to the harvesting efficiency of equipment used fer harvesting of rhizomes of Saururus chinensis Bail. Labor-saving efficiency showed 60-67% enhancement by using tillage operations with power tiller, digger attached to power tiller, and digger attached to tractor compared with manual harvest. Loss percentage of rhizomes by harvesting equipments was 2.2-8.8% lower than by manual harvest. Fresh rhizome yield and income index were increased 3-10% and 13-27% respectively by harvesting equipments, showing the highest yield and index in digger attached to tractor, Thus, digger attached to tractor showed the most effective harvest equipment for Saururus chinensis rhizome.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.42 no.6
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• pp.687-692
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• 1997

The barley grown in pot-soil was treated with the NaCl solution of -20 bar in osmotic potential for 10 days, varying the time of treatment: from 20th day before heading; from 10th day before heading and the time of heading. The greatest injury was observed in the case of salt stress at heading or at 10th day before heading: Culm length decreased by 87% : the number of spikes per plant by 82% ; the number of grain per spike by 92% : 1, 000-grain weight by 94% ; yield per pot by 75%. The results also greatly varied depending upon the cultivars and the time of salt stress. Salt stress at the time of heading or at 10th day before heading remarkably decreased yield and yield components. And in terms of grain yield the salt resistance was high in the order of Baegdong, Albori, Hyangmaeg, Olbori and Durubori.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.49 no.3
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• pp.188-193
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• 2004

Fifty-day-old plug seedlings of yacon (Polymnia sonchiflolia Poeppig ＆ Endlicher) were transplanted on Mar. 23, Apr,8, Apr,23, May 8, May 23, and June 7,2002 at Jeju to evaluate the effect of transplanting date on the growth and yield of yacon in Jeju island. Delaying the transplanting until May 23 greatly decreased plant height stem height, main stem diameter and number of nodes per plant. The number of marketable tuberous roots was about 6.0 per plant with the early transplanting from March 23 to April 231 but decreased to 1.9 per plant with the latest transplanting time, June 7. The yield of marketable tuberous roots of early transplanted (March 23 to April 23) yacon was about 27 MT/ha, and was 32.4 MT/ha at April 23 transplanting, but was remarkably reduced at the three later transplantings, May 8, May 23, and June 7. Dry matter and soluble solid contents of marketable tuberous roots were 14％ and 15％, respectively, regardless of transplanting date. The weight of a marketable tuberous root ranged from 153 to 183.9 g at the first three transplantings, but gyeatly reduced with delaying transplanting until May 7. The optimum transplanting date for yacon in Jeju island seems to be from mid-April to late April considering tuberous root yields, the risk of late-spring frost, and cost of seedling raising.