• Journal of the Korean Institute of Landscape Architecture
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• v.48 no.5
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• pp.80-88
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• 2020

With the issuance of one-week fine dust emergency reduction measures in March 2019, the public's anxiety about fine dust is increasingly growing. In order to assess the application of air purifying plant-based bio-filters to public facilities, this study presented a method for measuring pollutant reduction effects by creating an indoor environment for continuous discharge of particle pollutants and conducted basic studies to verify whether indoor air quality has improved through the system. In this study conducted in a lecture room in spring, the background concentration was created by using mosquito repellent incense as a pollutant one hour before monitoring. Then, according to the schedule, the fine dust reduction capacity was monitored by irrigating for two hours and venting air for one hour. PM₁₀, PM_2.5, and temperature & humidity sensors were installed two meters front of the bio-filters, and velocity probes were installed at the center of the three air vents to conduct time-series monitoring. The average face velocity of three air vents set up in the bio-filter was 0.38±0.16 m/s. Total air-conditioning air volume was calculated at 776.89±320.16㎥/h by applying an air vent area of 0.29m×0.65m after deducing damper area. With the system in operation, average temperature and average relative humidity were maintained at 21.5-22.3℃, and 63.79-73.6%, respectively, which indicates that it satisfies temperature and humidity range of various conditions of preceding studies. When the effects of raising relatively humidity rapidly by operating system's air-conditioning function are used efficiently, it would be possible to reduce indoor fine dust and maintain appropriate relative humidity seasonally. Concentration of fine dust increased the same in all cycles before operating the bio-filter system. After operating the system, in cycle 1 blast section (C-1, β=-3.83, β=-2.45), particulate matters (PM₁₀) were lowered by up to 28.8% or 560.3㎍/㎥ and fine particulate matters (PM_2.5) were reduced by up to 28.0% or 350.0㎍/㎥. Then, the concentration of find dust (PM₁₀, PM_2.5) was reduced by up to 32.6% or 647.0㎍/㎥ and 32.4% or 401.3㎍/㎥ respectively through reduction in cycle 2 blast section (C-2, β=-5.50, β=-3.30) and up to 30.8% or 732.7㎍/㎥ and 31.0% or 459.3㎍/㎥ respectively through reduction in cycle 3 blast section (C-3, β=5.48, β=-3.51). By referring to standards and regulations related to the installation of vegetation bio-filters in public facilities, this study provided plans on how to set up objective performance evaluation environment. By doing so, it was possible to create monitoring infrastructure more objective than a regular lecture room environment and secure relatively reliable data.

• Magazine of the Korean Society of Agricultural Engineers
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• v.12 no.2
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• pp.1937-1947
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• 1970

This experiment was conducted, making use of the 'NONG-RIM No, 6' a recommended variety of rice plant for the year of 1969. Main purpose of the experiment are to explore possibilities of; a) ways and means of saving irrigation water and, b) overcoming drought at the same time so that an increaded yield in rice production could be resulted in Specifically, it was tried to determine the effects of the Rotation Irrigation method combined with differentiated thickess of Lining upon the growth and Yield of rice production. Some of the major finding are summarized in the follows. 1) The Different thicknesses show a significant relationship with the weight of 1000 grains. In the case of 3cm Lined plot, the grain weight is 39.0 Grams, the heaviest. Next in order is 6 cm lined plnt, 5 day control plot, 6 day control plot. 2) In rice yield, it is found that there is a considerably moderate signicant relationship with both the different thickness of lining and the number of irrgation, as shown in the table No,7. 3) There is little or no difference among different plot in terms of; a) physical and chemical properties of soil, b) quality of irrgation water, c) climatic condition, and rainfalls. 4) It is found that there is no significant relationship between differences in the method of rotation irrgation and the number of ears per hill because of too much rainydays and low temperature during irrigation season. 5) In uyny1-treated plots, it is shown that there is on difference among different plots, but the irrigation water requirement saved as much as 1/2 to actual irrigation water compare to uncontroled plot. 6) The irrigation water requirement for 48 days is saved as much 67% compared to uncontroled plot, the order are; the 9cm lined plot, the plot of vinyl with no hole, the plot with a hole of $1cm/m^2$ as shows in fig 15. 7) The rate of percolation of 40-30mm/day is decreased to 30-20/day. It is found that the decreasad rate of percolation due to vinyl-cutoff in footpath. 8) The growing condition was fine, and there was no found that decease and lageing as always submerged plot. 9) It is found that it must be constructed irrigation and drainage system, inlet and outlet perpect, respectly, of which could be irrigation water saved and would be inereased the irrigation water temperature.

• Journal of Korean Society of Forest Science
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• v.84 no.1
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• pp.87-96
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• 1995

We examined the effects of seed treatment on field germination rate and seedling growth for four woody species, Euonymus alatus, Thea sinensis, Zanthoxylum piperitum, Nandina domestia which are economically useful in Korea. The seeds of each species were purified carefully after collection during Oct. and Nov.. E. alatus, T. sinensis, and Z. piperitum were sowed in the experimental field after stored in open ground with treatment of Pon-Pon. $H_2O_2$, $GA_3$, scarification. and N. domestica was sowed in container within green house after treatment of three different periods(7, 15, 21days) in growth chamber(4, 25, $32^{\circ}C$). Germination rate and seedling growth were measured in mid-Oct.. In E. alatus germination rate was higher in storaging in open ground after soaking in $GA_3$(67.1%) than in only storaging in open ground(18.4%). But the rate in T. sinensis showed no differences between storage in open ground after treatment of $GA_3$, and scarification, and only storage in open ground, Germination rate of Z. piperitum was much higher in storaging in open ground after treatment of Pon-Pon(80.3%) than in only storaging in open ground(12.4%). In N. domestica. seeds stored for 7 days at $32^{\circ}C$ were germinated faster than those stored for 7 days at $4^{\circ}C$, and germination rate of the former was also higher than that of the latter. Peak Times of seed germination in field were order of E. alatus (32 days). Z. piperitum (49 days). T. sinensis (83 days), N. domestica (87 days). The growth of seedling germinated in field showed a good result because of early germination following the effect of seed treatment. The periods of highest growth performances of the seedlings were 72 days in late Jun.-mid Jul. in E. alatus. 59 days in late Jun.- mid Jul. in Z. Piperitum, and 45 days in mid Aug.- mid Sep. in T. sinensis.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.13 no.2
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• pp.65-80
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• 1980

Processing conditions of the krill products such as paste food, krill protein concentrate, seasoned dried krill, powdered seasoning, meat ball, and snack have been examined and the quality was evaluated chemically and organoleptically. In the processing of paste food, krill juice was yielded $71\%$ and krill scrap $29\%$. The yields of paste and broth from the krill juice showed $53\%$ and $43\%$, respectively. In amino acid composition of the krill paste, proline, glutamic acid, aspartic acid, lysine, and leucine were abundant, while histidine, methionine, tyrosine, serine and threonine were poor. The optimum condition for solvent extraction in the processing of krill protein concentrate was the 5 times repetitive extraction using isopropyl alcohol at $80^{\circ}C$ for 5 mins. The yield of krill protein concentrate when used fresh frozen materials was $10.2\%$ in isopropyl alcohol solvent and $8.8\% in ethyl alcohol, and when used preboiled frozen materials, the yield was $13.0\%$ in isopropyl alcohol and $11.8\%$ in ethyl alcohol. Amino acid composition of krill protein concentrate showed a resemblance to that of fresh frozen krill meat. In quality comparison of the seasoned dried krill, hot air dried krill was excellent as raw materials and sun dried krill was slightly inferior to hot air dried krill, but preboiled frozen krill showed the poorest quality. The result of quality evaluation for seasoning made by combination of dried powdered krill, parched powdered sesame, salt, powdered beef extract, monosodium glutamate, powdered red pepper and ground pepper showed that the hot air dried krill was good in color and sundried krill was favorable in flavor. When krill meat ball was prepared using wheat flour, monosodium glutamate and salt as side materials, the quality of the products added up to $52\%$ of krill meat was good and the difference in quality upon the results of the organoleptic test for raw materials was not recognizable between fresh frozen and preboiled frozen krill. In the experiment for determining the proper amount of materials such as dried Powdered krill, $\alpha-starch$, sweet potato starch, sugar, salt, monosodium glutamate, glycine, potassium tartarate, ammonium bicarbonate, and sodium bicarbonate in processing krill snack, sample B(containing $7.7\%$ of dried powdered krill) and sampleC (containing $10.8\%$ of dried powdered krill) showed the most palatable taste from the view point of organoleptic test. Sweet potato starch in testing side materials was good in the comparison of suitability for processing krill snack. Corn starch and kudzu starch were slightly inferior to sweet potato starch, while wheat flour was not proper for processing the snack. In the experiment on frying method, oil frying showed better effect than salt frying and the suitable range of frying temperature was $210-215^{\circ}C$.

• Korean Journal of Agricultural Science
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• v.4 no.1
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• pp.10-20
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• 1977

An expriment was conducted to determine the rate of germination under low temperature and effects of low temperature on seedling of varieties derived from the cross between Indica and Japonica type of rice. Total of 30 varieties including leading variety, Tongil, were germinated at the temperature of $10^{\circ}C$. and $15^{\circ}C$. to determine the rate of germination, and six varieties also including Tongil were planted in pot, and seedlings were exposed to the temperature of $5^{\circ}C$. and $1^{\circ}C$. for 15 days and damage of plant growth due to low temperature was observed. 1. Under the condition of $10^{\circ}C$., varieties such as Iri #323, Suwon #253, Iri #325, Milyang #22, Suwon #251, and Suwon #267 were showing over 70 percent of germination ratio, while varieties, Dodolokiwase, Milyang #23, Yusin, Iri #328, and Iri #329 were below 10 percent in germination ratio. 2. Under the condition of $15^{\circ}C$., variety Suwon #262 was shown 100 percent of germination and varieties such as Milyg an#22, Dodlokiwase, Tongil, Milyang #29, Suwon #258, Milyang #23, Milyang #24, Milyang #28 and Milyang #21 were over 90 percent in germination ratio. However, varieties such as Iri #328, Iri #329, Jinheung, and Minehikari were below 50 percent in germination rate. 3. Considering the germination rate and average days required to germination, Milyang #22 and Iri #323 were highly resistant varieties to low temperature. The rate of germination of varieties from the cross between Indica and Japonica under low temperature was not always lower than that of varieties from Japonica type of rice. 4. Most of the seedlings of varieties used were quite resistant to $1^{\circ}C$. at least for six hours. However, leaves of rice were exposed to the the temperature of $1^{\circ}C$. for 12 hours, and the withered leaves were recovered soon when put in under normal temperature. The degree of leaf withering under low temperature was lower in Milyang #15, Japonica type than in varietieties belonging to $Indica{\times}Japonica$ type of rice. 5. When the seedlings of varieties such as Josaengtongil, Tongil and Yusin were exposed to the temperature of $1^{\circ}C$. for 36 hours, 70 percent of leaves were withered and when the time of expose were doubled, the leaves were completely died. When the temperature was fluctuated, over 75 percent of leaves were died, while 65 percent of leaves of Milyang #15 were died when exposed to $1^{\circ}C$, for 72 hours. 6. Significant growth retardation was observed for all entries when exposed to $1^{\circ}C$. for 24 to 36 hours. The growth retardation was apparently increased as the time of expose was extended.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.21 no.1
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• pp.136-179
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• 1976

Effects of seeding pattern and rate on the yield and some agronomic characters of barley under different cultural conditions were observed at Suweon, Daejeon and Jinju during the barley growing season from 1972 to 1974. Plant height and culm length were increased by dense seeding, shading, heavy fertilization, moving location down to the lower latitude. The tiller number per plant, dry matter weight, leaf number on main stem, percentage of valid tillers, RGR, NAR, and $R_{A}$ were increased by heavy fertilization, sparse seeding, reduced furrow width and drilling likewise the length, width and angle of leaf. The newer cultivar had higher RGR and NAR. The higher yielding cultivars had higher potential for carbohydrate assimilating ability. Straw weight and grain yield were increased by dense seeding, reduced furrow width, drilling, heavier fertilization and moving the location to the south, and then decreased by shading and late seeding. High yield increase by drilling was found in late seeding. The optimum seeding rate for the yield increase were 15l/10a for furrow and 25l/10a for drilling. The spike number type cultivars were favourable for the sparse seeding and the spike weight type cultivars seemed to be suitable to the dense seeding, The repeatability of days to heading due to location and fertilizer level was higher than that of seeding time and seeding method. Repeatability of culm length was extremly high in seeding method and comparatively high in fertilizer level while low in location. The repeatability of yield due to location and seeding methods was comparatively high, but the tendency was different along with different cultivars. Also the repeatability of yield due to the fertilizer level was generally high except cultivar Haganemngi.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.10
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• pp.1-43
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• 1971

Experiment I: The objective of this study was to know variation in some selected agronomic characters of sweet sorghum when planted in several growing seasons. The 17 different sweet sorghum varieties having various maturities, and plant, syrup and sugar types were used in this study which had been carried out for the period of two years from 1968 to 1969 at Industrial Crops Division of Crop Experiment Station in Suwon. These varieties were planted at an interval of 20 days from April 5 to August 25 both in 1968 and 1969. The experimental results could be summarized as follows: 1. As planting was made early, the number of days from sowing to germination was getting prolonged while germination took place early when planted at the later date of which air temperature was relatively higher. However, such a tendency was not observed beyond the planting on August 25. In general, a significant negative correlation was found between the number of days from sowing to germination and the average daily temperature but a positive correlation was found between the former and the total accumulated average temperature during the growth period. 2. The period from sowing to heading was generally shortened as planting was getting delayed. The average varietal difference in number of days from sowing to heading was as much as 30.2 days. All the varieties were grouped into early-, medium and late-maturing groups based upon a difference of 10 days in heading. The average number of days from sowing to heading was 78.5$\pm$4.5 days in the early-maturing varieties, 88.5$\pm$4.5 days in the medium varieties and 98.5$\pm$4.5 days in the late-maturing varieties, respectively. The early-maturing varieties had the shortest period to heading when planted from July 15 to August 5, the medium varieties did when planted before July 15 and the late-maturing varieties did when planted before June 5. 3. The relationship between the sowing date (x) and number of days from sowing to heading could be expressed in an equation of y=a+bx. A highly positive correlation was found between the coefficient of the equation(shortening rate in heading time) and the average number of days from sowing to heading. 4. The number of days from sowing to heading was shortened as the daily average temperature during the growth period was getting higher. Early-maturing varieties had the shortest period to heading at a temperature of 24.2$^{\circ}C$, medium varieties at 23.8$^{\circ}C$ and late-maturing varieties at 22.9$^{\circ}C$, respectively. In other words, the number of days from sowing to heading was shortened rapidly in case that the average temperature for 30 days before heading was 22$^{\circ}C$ to $25^{\circ}C$. It prolonged relatively when the temperature was lower than 21$^{\circ}C$. 5. There was a little difference in plant height among varieties. In case of early planting, no noticeable difference in the height was observed. The plant height shortened generally as planting season was delayed. Elongation of plant height was remarkably accelerated as planting was delayed. This tendency was more pronounced in case of early-maturing varieties rather than late-maturing varieties. As a result, the difference in plant height between the maximum and the minimum was greater in late-maturing varieties than in early-maturing varieties. 6. Diameter of the stalk was getting thicker as planted earlier in late-maturing varieties. On the other hand, medium or early-maturing varieties had he thickest diameter when they were planted on April 25. 7. In general, a higher stalk yield was obtained when planted from April 25 to May 15. However, the planting time for the maximum stalk yield varied from one variety to another depending upon maturity of variety. Ear]y-maturing varieties produced the maximum yield when planted about April 25, medium varieties from April 25 to May 15 and late-maturing varieties did when planted from April 5 to May 15 respectively. The yield decreased linearly when they were planted later than the above dates. 8. A varietal difference in Brix % was also observed. The Brix % decreased linearly when the varieties were planted later than May 15. Therefore, a highly negative relationship between planting date(x) and Brix %(y) was detected. 9. The Brix % during 40 to 45 days after leading was the highest at the 1st to the 3rd internodes from the top while it decreased gradually from the 4th internode. It increased again somewhat at the 2nd internode from the ground level. However, it showed a reverse relationship between the Brix % and position of internode before heading. 10. Sugar content in stalk decreased gradually as planting was getting delayed though one variety differed from another. It seemed that sweet sorghum which planted later than June had no value as a sugar crop at all. 11. The Brix % and sugar content in stalk increased from heading and reached the maximum 40 to 45 days after heading. The percentage of purity showed the same tendency as the mentioned characters. Accordingly, a highly positive correlation was observed between. percentage of purity and Brix % or sugar content in stalk. 12. The highest refinable sugar yield was obtained from the planting on April 25 in late-maturing varieties and from that on May 15 in early-maturing varieties. The yield rapidly decreased when planted later than those dates. Such a negative correlation between planting date(x) and refinable sugar yield(y) was highly significant at 1% level. 13. Negative correlations or linear regressions between delayed planting and the number of days from sowing to germination. accumulated temperature during germination period, number of days to heading, accumulated temperature to heading, plant height, stem diameter, stalk weight, Brix %. sugar content, refinable sugar yield or Purity % were obtained. On the other hand, highly positive correlations between the number of days from sowing to heading(x) and Brix %, sugar content, purity %, refinable sugar yield, plant height or stalk yield, between Brix %(x) and purity %, refinable sugar yield or stalk yield, between sugar content(x) and purity% or refinable sugar yield(y), between purity %(x) and refinable sugar yield and between daylength at heading(x) and Brix %. number of days from sowing to heading, sugar content, purity % or refinable sugar yield (y), were found, respectively. Experiment II: The 11 varieties were selected out of the varieties used in Experiment I from ecological and genetic viewpoints. Complete diallel cross were made among them and the heading date, stalk length, stalk yield, Brix %, syrup yield, combining ability and genetic behavior of F$_1$ plants and their parental varieties were investigated. The results could be summarized as follows: 1. In general, number of days to heading showed a partial dominance over earliness or late maturity or had a mid-value, though there were some specific combinations showing a complete dominance or transgressive segregation in maturity. Some combinations showed relatively high general or specific combining abilities in maturity. Therefore, a 50 to 50 segregation ratio in heading date could be estimated in this study and it might be positive to have a selection in early generation since heritability of the character was relatively high. 2. A vigorous hybrid vigor was observed in stalk length. A complete or partial dominant effect of long stalk was obtained. The general combining ability and specific combining ability of stalk length were generally high. Long and short stalks segregated in a ratio of 50:50 and its heritability was relatively low. 3. Except for several specific combinations, high stalk yield seemed to be partial dominant over the low yield. Some varieties demonstrated relatively high general as well as specific combining abilities. It was assumed that several recessive genes were involved in expression of this character. The interaction among regulating recessive genes was also obtained. Accordingly, the heritability of stalk yield seemed to be rather low. 4. The Brix % of hybrid plants located around mid-parental value though some of them showed much higher or lower percentage. It could be explained by the fact that such behavior might be due to partial dominance of Brix %. The varieties with, relatively higher Brix % were high both in general. and specific combining abilities. Therefore, it could be recommended to use the varieties having higher sugar content in order to develop higher-sugar varieties. 5. The syrup yield seemed to be transgressively segregated or completely dominant over low yield. Hybrid vigor of syrup yield was relatively high. No-consistent relationship between general combining ability and specific combining ability was observed. However, some cases demonstrated that the varieties with relatively higher general combining ability had relatively lower specific combining ability. It was assumed that the frequencies of dominant and recessive alleles were almost same.

• Journal of the Korean Wood Science and Technology
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• v.14 no.1
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• pp.3-44
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• 1986

In order to obtain the basic physical and mechanical properties of steel wire reinforced particleboard, particleboards were formed with large particles through 2.11 mm (12 meshes) and retained on 1.27mm (20 meshes) sieves and small particles through 1.27mm (20 meshes) and retained on 0.42mm (60 meshes) sieves from the plywood mill wastes of meranti (Shorea spp.) in the form of pallmanchips, applying urea-formaldehyde resin as an adhesive on the particle surface in 10 percent on the oven dried weight of particles, and arranging steel wires of 1mm in diameter 5,10,15,20, and 25mm in longitudinal and transverse direction with crossing in the mid of the board depth in single layer boards, 10mm in longitudinal or transverse direction without crossing in two layers and 10mm in longitudinal and transverse directions with and without crossing in three steel wire layers boards. The stepwise 9-minutes-multi-pressing schedule in 5 minutes at 35 kgf/$cm^2$, 2.5 minutes at 25 kgf/$cm^2$. and 1.5 minutes at 15 kgf/$cm^2$ was applied for $300{\times}200{\times}13$mm board at the temperature of 160$^{\circ}C$ in a hot press. Specific gravity, thickness swelling, bending properties of modulus of rupture (MOR), modulus of elasticity(MOE), work to proportional limit, and work to ultimate load, internal bond (IB), and screw holding power(SHP) of the reinforced boards were analyzed on the wire openings and wire layers. The results obtained are summarized as follows; 1) In specific gravity, particleboards with large particles and small particles had higher value with more steel wire placements and more steel layers composition, 2) Particleboards with large particles in accordance with more steel wire liners composition gave very poor thickness swelling. 3) The mechanical properties of particleboards formed with large or small particles were reinforced with more steel wire layers. Therefore, bending strength was improved in modulus of rupture, modulus of elasticity, and work to ultimate load. Especiallv, particleboards with two or three steel wire layers showed the tension lamination effect when the steels in lower steel wire layer were oriented parallel to the board length. 4) The modulus of rupture, modulus of elasticity, and work to ultimate load in bending varied with opening area, distance of lengthwise wires multipled by distance of transverse wires. Particleboards formed with large particles resulted in higher value in modulus of rupture with 1.5-3 $cm^2$ opening area, 1-2cm distance between transverse wires, and 1.5-2.5cm distance between lengthwise wires. Particle boards formed with small particles showed higher value with 0.5-1.5$cm^2$ or 3.75-6.25 $cm^2$ opening area, 0.5 or 2.5cm distance between transverse wires. 5) In modulus of elasticity, particleboards formed with large particles with one steel wire layer suggested higher value with 5-3$cm^2$ opening area, 1-2.5cm distance between transverse wires and also 1-2.5 cm distance between lengthwise wires. Particleboards formed with small particles showed higher value with 0.75-1.25$cm^2$ or 3-6.25$cm^2$ opening area and 0.5 or 2.5cm distance between transverse wires. 6) Particleboards formed with large particles gaved higher value in work to ultimate load with 1-3$cm^2$ opening area. Particleboards formed with small particles showed increasing tendancy with decreasing opening area. 7) In internal bond and screw holding power, particleboards formed with large particles had increasing value in two and three steel wire layers compositions, but particleboards formed with small particles showed no difference. Particleboards formed with large particles containing one steel wire layer showed no difference in internal bond and screw holding power, and particleboards formed with small panicles containing one steel wire layer resulted in increasing value in internal bond and decreasing value in screw holding power in accordance with increase in opening area.

• Korean journal of applied entomology
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• v.13 no.4 s.21
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• pp.181-204
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• 1974

The study has been carried out to investigate the occurrence, damage, host range, transmission and control of rice stripe virus in Korea since 1965. 1 Disease occur「once and damage : The virus infection during the seedling stage ranged from 1.3 to $8\%$. More symptom expression was found in regrowth of clipped rice than infected intact plants, and the greater infection took place in early seasonal culture than in ordinary seasonal culture. A higher incidence of the disease was found on the rows close to the bank, and gradually decreased toward the centre of the rice paddy. Disease occurrence and plant maturity was highly correlated in that the most japonica rice types were diseased when they were inoculated within 3 to 7 leaf stage, and$50\%$, $20\%$ and no diseaseb were found if they were inoculated at 9, 11 and 13 leaf stages, respectively. Symptom expression required 7-15 days when the plants were inoculated during 3-7 leaf stages, while it was 15-30days in the plants inoculated during 9-15 leaf stages. On Tongil variety the per cent disease was relatively higher when the plants were infected within 1.5-5 leaf stages than those at 9 leaf stage, and no disease was found on the plants infected after 15 leaf stage. The disease resulted in lowered growth rates, maturity and sterility of Tongil variety although the variety is known as tolerant to the virus. 2. Host range: Thirty five species of crops, pasture grasses and weeds were tested for their susceptibility to the virus. Twenty one out of 35 species tested were found to be susceptible. and 3 of them, Cyperus amuricus Maximowics var. laxus, Purcereus sanguinolentus Nees and Eriocaulon robustius Makino, were found as new hosts of the virus. 3. Transmission: The vector of the virus, Laodelphax striatellus, produces 5 generations a year. The peak of second generation adults occurred at June 20th and those of third was at about July 30th in Suweon area. In Jinju area the peak of second generation adult proceeded the peak at Suweon by 5-7 days. The peaak of third generation adult was higher than the second at Jinju, but at Suweon the reverse was true. The occurrence of viruliferous Laodelphax striatellus was 10-15, 9, 17, 8 and about $10\%$ from overwintered nymph, 1st generation nymph, 2nd generation adult, End generation nymph and the remaining generations, respectively. More viruliferous L. striatellus were found in the southern area than in the central area of Korea. The occurrence of viruliferous L. striatellus depended on the circumstances of the year. The per cent viruliferous vectors gin 2nd and 3rd generation adult, however, was consistantly higher than that of other generations. Matings of viruliferous L. striatellus resulted in $90\%$ viruliferous progenies, and the 3rd, 4th and 5th instars of the vector had higher infectiviey than the rest of the vector stages. The virus acquisition rate of non-viruliferous L. striatellus was $7-9\%$, These viruliferous L. striatellus, however, could not transmit the virus for more than 3 serial times. The optimum temperature for the transmission of the viru3 was $25-30^{\circ}C$, while rare transmission occurred when the temperature was below $15^{\circ}C$. The per cent of L. striatellus parasitization by Haplogonatopus atratus were $5-48\%$ during the period from June to the end of August, and the maximum parasitization was $32-48\%$ at around July 10. 4. Control: 1) Cultural practices; The deeper the depth of transplanting more the disease occurrence was found. The higher infection rate, $1.5-3.5\%$, was observed during the late stages of seedling beds, and the rate became lower, $1.0-2.0\%$, in the early period of paddy field in southern area. Early transplanting resulted in more infection than early seasonal culture, and the ordinary seasonal culture showed the lowest infection. The disease also was favored by earlier transplanting even under tile ordinary seasonal culture. The higher the nitrogen fertilizer level the more the disease occurrence was found in the paddy field. 2) Resistant varieties; Tongil varieties shelved the resistant reaction to the virus in greenhouse tests. In the tests for resistance on 955 varieties most japonica types shelved susceptible reactions, while the resistant varieties were found mostly from introduced varietal groups. 3) Chemical control; Earlier applications of chemicals, Disyston and Diazinon, showed better results when the test was made 4 days after inoculation in the greenhouse even though none of the insecticides shelved the complete control of the disease. Three serial applications of chemicals on June 14, June 20 and June 28 showed bettor results than one or two applications at any other dates under field conditions.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.18
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• pp.88-123
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• 1975

To obtain useful fundamental informations for improving cultural practices of barley, an investigation was made on the influences of different fertilizer level and seeding rate as well as seeding date on yield and yield components and their balancing procedure using barley variety Suwon ＃ 18, and at the same time, 8 varieties including Suwon ＃ 18 were also tested to clarify the varietal responses in terms of their yield and yield components under different seeding date at Crop Experiment Station, Suwon, during the period of 1969 and 1970. The results obtained were summarized as follows; 1. Days to emergence of barley variety Suwon ＃ 18 at Suwon, took 8 to 19 days in accordance with given different seeding date (from Sept. 21 to Oct. 31). Earlier emergence was observed by early seeding and most of the seeds were emerged at 15$0^{\circ}C$ cumulated soil temperature at 5cm depth from surface under the favorable condition. 2. Degree of cold injury in different seeding date was seemed to be affected by the growth rate of seedlings and climatic condition during the wintering period. Over growth and number of leaves less than 5 to 6 on the main stem before wintering were brought in severe cold damage during the wintering period. 3. Even though the number of leaves on the main stem were variable from 11 to 16 depending upon the seeding date. this differences were occurred before wintering and less variation was observed after wintering. Particularly, differences of the number of main stem leaves from September 21 to October 11 seeding date were occurred due to the differences of number of main stem leaves before wintering. 4. Dry matter accumulation before wintering was high in early seeded plot and gradually decreased in accordance with delayed seeding date and less different in dry matter weight was observed after wintering. However, the increment rate of this dry matter was high from regrowth to heading time and became low during the ripening period. 5. Number of tillers per $\m^2$ was higher in early seeding than late one and dense planting was higher in the number of tillers than sparse planting. Number of tillers per plant was lower in number and variation in dense planting, and reverse tendency was observed in sparse planting. By increasing seedling rate in early seeding date the number of tiller per plant was remarkably decreased, but the seeding rate didn't affect the individual tillering capacity in the late seeding date. 6. Seedlings were from early planting reached maximum tillering stage earlier than those from the late planting and no remarkable changes was observed due to increased seeding rate. However. increased seeding rate tends to make it earlier the maximum tillering stage early. 7. Stage of maximum tillering was coincided with stage of 4-5 main stem leaves regardless the seeding date. 8. Number of heads per $\m^2$ was increased with increased seeding rate but considerable year variation in number of heads was observed by increased fertilizer level. Therefore, it was clear that there is no difficulties in increasing number of heads per $\m^2$ through increasing both fertilizer level and seeding rate. This type of tendency was more remarkable at optimum seeding time. In the other hand, seeding at optimum time is more important than increasing seeding rate, but increasing seeding rate was more effective in late seeding for obtaining desirable number of heads per $\m^2$. 9. Number of heads per $\m^2$ was decreased generally in all varieties tested in late seeding, but the degree of decrease by late seeding was lower in Suwon ＃ 18. Yuegi, Hangmi and Buheung compared with Suwon ＃ 4, Suwon ＃ 6, Chilbo and Yungwolyukak. 10. Highly significant positive correlations were obtained between number of head and tillers per $\m^2$ from heading date in September 21 seeding, from before-wintering in October 1 seeding and in all growth period from October 11 to October 31 seeding. However, relatively low correlation coefficient was estimated between number of heads and tillers counted around late March to early April in any seeding date. 11. Valid tiller ratio varied from 33% to 76% and highest yield was obtained when valid tiller ratio was about 50%. Therefore, variation of valid tiller ratio was greater due to seeding date differences than due to seeding rate. Early seeding decreased the valid tiller ratio and gradually increased by delaying seeding date but decreased by increasing seeding rate. Among the varieties tested Suwon ＃ 18, Hangmi, Yuegi as well as Buheung should be high valid tiller ratio not only in late seeding but also in early seeding. In contrast to this phenomena, Chilbo, Suwon ＃ 4, Suwon ＃ 6 and Yungwolyukak expressed low valid tiller ratio in general, and also exhibited the same tendency in late seeding date. 12. Number of grains per spike was increased by increasing fertilizer level and decreased by increasing seeding rate. Among the seeding date tested. October 21 (1969) and October 11 (1970) showed lowest number of grains per spike which was increased in both early seeding and late seeding date. There were no definite tendencies observed along with seeding date differences in respective varieties tested. 13. Variation of 1000 grain weight due to fertilizer level applied, seeding date and seeding rate was not so high as number of grains per spike and number of heads per $\m^2$, but exhibited high year variation. Increased seeding rate decreased the 1000 grain weight. Among the varieties tested Chilbo and Buheung expressed heavy grain weight, while Suwon ＃ 18, Hangmi and Yuegi showed comparatively light grain weight. 14. Optimum seeding date in Suwon area was around October 1 to October 11. Yield was generally increased by increasing fertilizer level. Yield decrease due to early seeding was compensated in certain extent by increased fertilizer application. 15. Yield variations due to seeding rate differences were almost negligible compare to the variations due to fertilizer level and seeding date. In either early seeding or law fertilizer level yield variation due to seeding rate was not so remarkable. Increment of fertilizer application was more effective for yield increase especially at increased seeding rate. And also increased seeding rate fairly compensated the decrease of yield in late seeding date. 16. Optimum seeding rate was considered to be around 18-26 liters per 10a at N-P-K=10.5-6-6 kg/10a fertilizer level considering yield stabilization. 17. Varietal differences in optimum seeding date was quite remarkable Suwon ＃ 6, Suwon ＃ 4. Buheung noted high yield at early seeding and Suwon ＃ 18, Yuegi and Hangmi yielded higher in seeding date of October 10. However, Buheung showed late seeding adaptability. 18. Highly significant positive correlations were observed between yield and yield components in all treatments. However, this correlation coefficient was increased positively by increased fertilizer level and decreased by increased seeding rate. Significant negative correlation coefficients were estimated between yield and number of grains per spike, since increased number of heads per m2 at the same level of fertilizer tends to decrease the number of grains per spike. Comparatively low correlation coefficients were estimated between 1000 grain weight and yield. 19. No significant relations in terms of correlation coefficients was observed between number of heads per $\m^2$ and 1000 grain weight or number of grains per head.