• KOREAN JOURNAL OF CROP SCIENCE
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• v.34 no.1
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• pp.55-59
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• 1989

Sodium methyl arsenate has been evaluated as a male sterilizing agent for the system of producing hybrid rice seeds. The compound was the most effective at the concentration of 0.02％. When applied as a foliar spray to four rice varieties at 15 days before heading, sodium methyl arsenate has produced 99％ male sterility. But the most effective time for application of the compound was 5 days before heading because of its phytotoxic effects. Effective application volume of the compound solution has depended on the growth of the plants treated. Varietal difference on the activity of the compound has been detected.

• Applied Biological Chemistry
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• v.9
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• pp.125-147
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• 1968

This experiment was carried out as a part of the studies on reasonable application of nitrogen in rice plant to determine: (I) Nitrogen absorption. and rooting of rice seedlings as affected by urea foliar application at late seedling stage (II) Effect of leaf prunning and foliar application of urea at late heading stage on the maturation and yield of rice (III) Effect of foliar application of urea and its time during the stage of ear formation on yield of rice plant. Results obtained are summarized as follows. Exp.I: Nitrogen absorption and rooting of rice seedlings as affected be urea foliar application at late seedling stage. 1 : The foliar application of urea plots$(T_{1},T_2)$ snowed mare N-content than non-urea foliar application plot(T0) at lane seedling stage, being significant among treatments and foliar application of urea seemed more effective in increasing the N-content of seedlings. and promoted root settlement and early growth alter the transplanting. 2 : The carbon contents of the plants of $T_1$, and $T_2$ at late seedling stage increased than T0, and the carbon contents. of $T_1$ and $T_2$ plots became higher in amount in proportion to the nitrogen absorption as compared with those of $T_0$. 3 : C/N ratio appeared significant among soil application plots($N_1, \;N_2$) and foliar application of urea plots ($T_1$, $T_2$ and $T_0$). C/N ratio was lower in case of increased amount of nitrogen. The higher contents of nitrogen and carbon and lower C/N ratio resulted in the increment of root numbers and root lengths. Exp.II: Effect of leaf prunning and foliar application of urea at late heading stage on the maturation and yield of rice. 1 : There was a highly significant decrease in the maturing rate by severe leaf prunning. In the mean time, significant increase in maturing rate was observed with urea foliar application and it was found the more frequent application the more effective for higher maturing rate with a moderate significance. A correlationship between the level of prunning and maturing rate was enumerated to 0.961 of correlation coefficient, which indicated an increased maturing rate by the increased number of remaining leaves. 2 : The 1.000 grain weight, grain weight and hulled rice yield increased by leaf prunning in order (plot a$A_1$, $A_3$, $A_2$ and $A_0$ were 89.8%, 89.4%, 87.8% and 87.5% respectively, showing the highest of rate in $A_1$ and $A_3$ in methods of ear fertilization and being highly significant between its treatment. 3 : 1000 grain weights were highly significant between time of application, showing a tendency of increase of weights with the time lagging until days before earings as that of maturing rates. High significance was recognized between methods of ear fertilization, showing the highest in $A_2$ 23.18 gr. 4 : Yields per $3.3m^2$ were not significant between time of ear fertilization, whereas were highly significant between methods of ear fertilization. Those of $A_1$, $A_3$, $A_2$ and $A_0$ were 1.486 kg, 1.491 kg, 1.381 kg and 1.328 kg, respectively, showing the highest in $A_1$ and $A_3$. 5 : Hulling ratios showed significant different between time of ear fertilization, showing the highest in $T_2$, whereas those of methods of ear fertilization were highly significant between its treatment, Those of $A_1$, $A_3$, $A_2$ and $A_0$ were 84.72%, 84.06%, 83.29%, and 82.56% respectively, showing the highest m $A_2$ and $A_3$ among others. 6 : Yields of hulled rice per $3.3m^2$ showed significant different between time of ear fertilization, showing the highest in $T_1$ 1.192 kg. Whereas, those were highly significant between methods of ear fertilization. Those of $A_1$, $A_3$, $A_2$ and $A_0$ were 1.259 kg, 1.254 kg, 1.149 kg and 1.095 kg, respectively, showing the highest in $A_1$ and $A_2$. 7 : Contents of nitrogen on rice plant increased in case of nitrogen application as ear fertilizer and showed that the case of urea foliar application was more effective than that of soil application, showing the increased nitrogen content of rice plant was accompanied by carbon content.

• Journal of Bio-Environment Control
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• v.28 no.2
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• pp.178-184
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• 2019

Strawberry ($Fragaria{\times}ananassa$) is one of the most important and popular fruit crops in the world, and 'Sulhyang' is one of the principal cultivars cultivated in the Republic of Korea for the domestic market. The growth and flower induction in strawberry is the process which influences directly on fruit bearing and yield of this crop. In this study, effect of benzyladenine (BA), gibberellic acid ($GA_3$), and salicylic acid (SA) on growth and flower bud induction in strawberry 'Sulhyang' was investigated. The 3-week-old runner plants, grown in 21-cell propagation trays, were potted and cultivated in growth chambers with $25^{\circ}C/15^{\circ}C$ (day/night) temperatures, 70% relative humidity (RH), and light intensity of $300{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$ photosynthetic photon flux density (PPFD) provided by white light emitting diodes (LEDs). The runner plants were treated with one of three concentrations, 0 (control), 100, and $200mg{\cdot}L^{-1}$ of BA, $GA_3$, or SA solution. The chemicals were sprayed two times on leaves of runner plants at an interval of two weeks. After 9 weeks the results showed that the application of all chemicals caused reduction of root length and chlorophyll (SPAD) content as compared to the control. The lowest chlorophyll (SPAD) content was recorded in plants treated with $GA_3$. However, the treatment of $200mg{\cdot}L^{-1}$ $GA_3$ promoted leaf area, leaf fresh weight, and plant fresh weight. The greatest flower induction (85%) and number of inflorescences (4.3 inflorescences per plant) were observed in the treatment of $200mg{\cdot}L^{-1}\;SA$, followed by $100mg{\cdot}L^{-1}\;SA$. Overall, results suggest that foliar application of $GA_3$ solution could accelerate plant growth, while foliar application of SA solution could induce hastened flowering. Further studies may be needed to find out the relationship between $GA_3$ and SA solutions treated in a combination, and the molecular mechanism involved in those responses observed.

• Horticultural Science & Technology
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• v.32 no.6
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• pp.872-878
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• 2014

This study aimed to enhance storage and freshness of strawberry fruits and foliage vegetables by spray treatment with Chlorella vulgaris as a bio-fertilizer. The tested strain, C. vulgaris CHK0008, was isolated from an organically cultivated rice paddy and identified as C. vulgaris by its morphology and 18S rDNA and 23S rDNA sequence homology. We successfully cultured C. vulgaris CHK0008 in BG11 modified medium (BG11MM) and adjusted $2.15{\times}10^6cell/mL$ C. vulgaris CHK0008 to one OD value by measuring the optical density at 680 nm using a UV-vis spectrophotometer. The soluble solid content of 'Seolhyang' and 'Yukbo' strawberry fruits treated by spray application with C. vulgaris CHK0008 was enhanced by 22.2% and 11.5% respectively, compared to untreated controls. Additionally, the decay rates of treated 'Seolhyang' and 'Yukbo' strawberry fruits decreased 63.8% and 74.4% respectively, compared to untreated control. Surface color changes and chlorosis of leaves in leaf vegetables such as lettuce, kale, red ornamental kale, white ornamental kale and beet were observed in samples treated with water spray for 10 days after cold storage. However, the decay rate of leafy vegetables treated with foliar application of 25% C. vulgaris CHK0008 liquid culture was significantly decreased compared to that of the untreated control during storage at $4^{\circ}C$.

• Korean Journal of Weed Science
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• v.13 no.4
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• pp.210-233
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• 1993

The herbicide has become indispensable as much as nitrogen fertilizer in Korean agriculture from 1970 onwards. It is estimated that in 1991 more than 40 herbicides were registered for rice crop and treated to an area 1.41 times the rice acreage ; more than 30 herbicides were registered for field crops and treated to 89% of the crop area ; the treatment acreage of 3 non-selective foliar-applied herbicides reached 2,555 thousand hectares. During the last 25 years herbicides have benefited the Korean farmers substantially in labor, cost and time of farming. Any herbicide which causes crop injury in ordinary uses is not allowed to register in most country. Herbicides, however, can cause crop injury more or less when they are misused, abused or used under adverse environments. The herbicide use more than 100% of crop acreage means an increased probability of which herbicides are used wrong or under adverse situation. This is true as evidenced by that about 25% of farmers have experienced the herbicide caused crop injury more than once during last 10 years on authors' nationwide surveys in 1992 and 1993 ; one-half of the injury incidences were with crop yield loss greater than 10%. Crop injury caused by herbicide had not occurred to a serious extent in the 1960s when the herbicides fewer than 5 were used by farmers to the field less than 12% of total acreage. Farmers ascribed about 53% of the herbicidal injury incidences at their fields to their misuses such as overdose, careless or improper application, off-time application or wrong choice of the herbicide, etc. While 47% of the incidences were mainly due to adverse natural conditions. Such misuses can be reduced to a minimum through enhanced education/extension services for right uses and, although undesirable, increased farmers' experiences of phytotoxicity. The most difficult primary problem arises from lack of countermeasures for farmers to cope with various adverse environmental conditions. At present almost all the herbicides have"Do not use!" instructions on label to avoid crop injury under adverse environments. These "Do not use!" situations Include sandy, highly percolating, or infertile soils, cool water gushing paddy, poorly draining paddy, terraced paddy, too wet or dry soils, days of abnormally cool or high air temperature, etc. Meanwhile, the cultivated lands are under poor conditions : the average organic matter content ranges 2.5 to 2.8% in paddy soil and 2.0 to 2.6% in upland soil ; the canon exchange capacity ranges 8 to 12 m.e. ; approximately 43% of paddy and 56% of upland are of sandy to sandy gravel soil ; only 42% of paddy and 16% of upland fields are on flat land. The present situation would mean that about 40 to 50% of soil applied herbicides are used on the field where the label instructs "Do not use!". Yet no positive effort has been made for 25 years long by government or companies to develop countermeasures. It is a really sophisticated social problem. In the 1960s and 1970s a subside program to incoporate hillside red clayish soil into sandy paddy as well as campaign for increased application of compost to the field had been operating. Yet majority of the sandy soils remains sandy and the program and campaign had been stopped. With regard to this sandy soil problem the authors have developed a method of "split application of a herbicide onto sandy soil field". A model case study has been carried out with success and is introduced with key procedure in this paper. Climate is variable in its nature. Among the climatic components sudden fall or rise in temperature is hardly avoidable for a crop plant. Our spring air temperature fluctuates so much ; for example, the daily mean air temperature of Inchon city varied from 6.31 to $16.81^{\circ}C$ on April 20, early seeding time of crops, within${\times}$2Sd range of 30 year records. Seeding early in season means an increased liability to phytotoxicity, and this will be more evident in direct water-seeding of rice. About 20% of farmers depend on the cold underground-water pumped for rice irrigation. If the well is deep over 70m, the fresh water may be about $10^{\circ}C$ cold. The water should be warmed to about $20^{\circ}C$ before irrigation. This is not so practiced well by farmers. In addition to the forementioned adverse conditions there exist many other aspects to be amended. Among them the worst for liquid spray type herbicides is almost total lacking in proper knowledge of nozzle types and concern with even spray by the administrative, rural extension officers, company and farmers. Even not available in the market are the nozzles and sprayers appropriate for herbicides spray. Most people perceive all the pesticide sprayers same and concern much with the speed and easiness of spray, not with correct spray. There exist many points to be improved to minimize herbicidal phytotoxicity in Korea and many ways to achieve the goal. First of all it is suggested that 1) the present evaluation of a new herbicide at standard and double doses in registration trials is to be an evaluation for standard, double and triple doses to exploit the response slope in making decision for approval and recommendation of different dose for different situation on label, 2) the government is to recognize the facts and nature of the present problem to correct the present misperceptions and to develop an appropriate national program for improvement of soil conditions, spray equipment, extention manpower and services, 3) the researchers are to enhance researches on the countermeasures and 4) the herbicide makers/dealers are to correct their misperceptions and policy for sales, to develop database on the detailed use conditions of consumer one by one and to serve the consumers with direct counsel based on the database.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.41 no.4
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• pp.441-449
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• 1996

This study was conducted to find the changes of growth, seed yield and several characteristics of sesame by leaf spray of boron as a solution which is likely to be lack in the soil. It is carried out at low land developed 5 years ago. The amount of 200l /l0a boron as boric acid is sprayed in each treatment at the 11 node stage of sesame in main stem. The spraying concentrations of boric acid are 0.0, 0.2 and 0.4% in each treatment of the level low plot and the ridge height 15cm plot. The result shows that leaf area is increased in proportion to the concentration of boric acid in each treatment of the level low and the ridge height 15cm, and the degree of increase of each node order is remarkable in lower leaves and is more remarkable in the treatment of level low plot. The effects of leaf spray of boric acid are not only the increase of leaf area but also dry weight, no. of capsule per plant, 1,000 grains weight of capsule setting under middle position. As a result, the amount of seed is increased in 53% in the treatment of level low. The change of major characteristics according to leaf spray of boric acid is generally great in the treatment of level low. Especially the increase of leaf area in the part of upper leaves and low leaves is effective to improve other characteristics.

• The Korean Journal of Pesticide Science
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• v.20 no.1
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• pp.56-65
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• 2016

Pine wood nematode, Bursaphlenchus xylophilus is a fatal damaging pest, infecting pinewood trees and is one of the serious forest pest in Korea. Trunk injection is one of the most effective method to protect the live pine trees from nematode infection. The aim of this research was to reveal the efficacy of the nematicidal materials from 46 Kyrgyzstan, 88 Vietnam plant materials and 21 active materials (${\alpha}$-terpinene, ${\alpha}$-pinene, ${\beta}$-thujaplicin, cinnamaldehyde, eugenol, emodin, geraniol, limonone, methyl palmitate, matrine, myrcene, methyl gallate, nicotine, quassin, resveratrol, rotenone, thymol, thujaplicin, terthiophene, tuberstemonine, ${\gamma}$-terpinene) isolated from plants for using as trunk injection agents. Eclipta prostrata extract was highly effective against pine wood nematode in plant extracts and terthiophene has the best nematicidal activity from active materials isolated from plants. Foliar spray of terthiophene on Japanese black pine (Pinus thunbergii) tree reduced proliferation of inoculated pine wood nematode at 22 days after treatment, however no efficacy was found over 22 days. Eclipta prostrata extract and terthiophene can be used as nematicide for further nematicidal efficacy test against any other plant parasitic nematodes and trunk injection efficacy against pine wood nematode.

• Korean journal of applied entomology
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• v.26 no.1 s.70
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• pp.9-12
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• 1987

The control effect of three systemic insecticides on the brown planthopper; carbofuran 3G, disyston 3G, and omethoate 50% EC, which have been used to control of the insect pests on rice crop in its early growing season, were evaluated. Soil incorporation and water broadcasting methods before transplanation were used for carbofuran and disyston, and omethoate was applied as foliar spray 6 days after transplanation. Ten pairs of newly emerged adults were inoculated on June 11, 21, July 2, 11, and 25. The number of the brown planthoppers on the rice plane were examined by means of direct reading. The three insecticides were effective for about ten days regardless of application methods, thereafter, fail to control of the insects except carbofuran. By means of soil incorporation, carbofuran could control the insects effectively for 45 days or longer, and it seemed to be able to control the progeny of the migrated brown planthopper until middle or late June.

• Journal of Bio-Environment Control
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• v.12 no.2
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• pp.72-76
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• 2003

This study was conducted to estimate stimulation of plant growth of green and red leafy lettuces (Lactuca sutiva L. cv. Chungchima and Jugchima) at affected by covering method and time with protected film materials containing concentrated PO film and GA$_3$ foliar spray. Plants were covered with ‘Pasraido’ material from October 26 to November 31 (direct 1), from November 5 to November 31 (direct 2), or with a tunnel, or direct 2＋ tunnel. Mean air temperature and relative humidity under the covering were higher in direct and tunnel, direct and non-covering, in that order. The fresh weight and dry weight of red and green lettuces increased in direct and tunnel followed by direct 1, direct 2, tunnel and the control. GA$_3$ treatment promoted the growth in all covering methods, but decreased the chlorophyll contents. Fresh weight and dry weight were higher in red lettuce than in green lettuce in the control.

• Journal of Bio-Environment Control
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• v.15 no.4
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• pp.377-384
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• 2006

This study was conducted to investigate the effects of chemical application and amout of soil moisture on low temperature stress of cucumber seedling under the greenhouse conditions. When chilling treatments ($2^{\circ}C$) were begun at 07:00AM, survival rates of seedlings of two conditions; -0.3 bar and -5.5 bar were 28.3% and 83.3% respectively. But when chilling treatments were begun at 6:00PM - even the soil moisture condition was -0.3 bar - the survival rate was above the 87%. When reducing the soil moisture from -0.3 bar to -9.0 bar, ABA content in leaf was inc.eased by 6.5fo1d. Spraying of abscisc acid (ABA) before or after the chilling significantly increased the survival rates of seedlings, decreased the amounts of leaking electrolytes and prevented the yield reductions. ABA application on the soil before the chilling appeared to be more effective than the application after the chilling with foliar spray. Spraying of ABA ($10^{-5}M$), urea (0.2%) or $KH_2PO_4$ was effective in counteracting the low temperature, which causes growth deterioration and yield reduction in cucumbers.