• The Korean Journal of Pesticide Science
• /
• v.10 no.2
• /
• pp.124-130
• /
• 2006

Rice plant extracts of brown planthopper (BPH) resistant rice varieties, Jangseongbyeo (JSB) and Hwacheongbyeo (HCB) at different growth stages (seedling, tillering, heading and ripening) were sequentially fractioned using hexane, ethyl ether, ethyl acetate, butanol, and distilled water. The extracts were applied to BPH susceptible rice variety, Dongjjnbyeo (DJB), to investigate the insecticidal and repellent effects against BPH. BPH insecticidal effects were not clearly observed with almost all of the extract fractions obtained from both JSB and HCB varieties for 12 h, whereas the ethyl ether and hexane extract fractions showed about 10 to 30% of BPH mortality in 24 to 48 h of application periods. An effective BPH repellent activity was found with the applications of ethyl ether extract fractions obtained from JSB variety. The extract fractions obtained from HCB variety did not show any different repellence among the various fractions. The BPH repellent effects of the extract fractions obtained at different growth stages of either JSB or HCB varieties did not show any correlations. The effect of ethyl ether fraction on BPH repellent was continually increased by 30 h after treatment and thereafter decreased. In addition, the first sub-fraction separated by a flash column chromatography eluted with chloroform:methanol (9:1, v/v) from the BPH effective ethyl ether faction in JSB variety might be meaningful to repel BPH from BPH susceptible target rice plants. The results indicated that the ethyl ether fraction obtained from JSB was higher in repellent activity than in insecticidal activity, and suggesting that there might be specific substance(s) in the first sub-fraction (sF1) of the ethyl ether fraction in JSB that could provide repellent activity against BPH.

• Clinical and Experimental Pediatrics
• /
• v.52 no.2
• /
• pp.205-212
• /
• 2009

Purpose : Chronic urticaria is a disorder characterized by the appearance of wheals for more than 6 weeks; in most cases, the etiology is unknown. This study was aimed to discover the clinical aspects, the etiologic factors, and the course of chronic urticaria. Methods : 51 children who were diagnosed with chronic urticaria in the past 4 years, and who had had follow-ups more than 6 months after diagnosis in the pediatric department of Soonchunhyang University Hospital in Bucheon, were enrolled in the study. The laboratory findings, clinical aspects, and courses were retrospectively investigated by medical record review and telephone interview. Results : The median age of children with chronic urticaria was 4 years (8 months to 16 years) and the ratio of male to female was 1.4:1. Of the total, 39.2% of patients had a history of atopy. Angioedema occurred concurrently with urticaria in 11.8% of patients, and dermographism was seen in 41.2%. Results of thyroid function tests were normal and thyroid autoantibodies were absent in all cases. Regarding etiology, most cases (74.5%) were forms of idiopathic urticaria. Urticaria was induced by physical factors in 19.6% of patients. Open challenge tests revealed that 3 patients were allergic to food additives (glutamate 2, glutamate, and sulfite 1). In this study, most of the patients reported good response after medication of 1st- or 2nd-generation antihistamines alone. Follow-up at 6 months revealed that 70.6% of patients had experienced remission, and 84.8% of children who had follow-up at 1 year presented remission. Conclusion : Chronic urticaria in most patients was idiopathic. Remission occurred within 1 year of diagnosis, in most cases so chronic urticaria in children seems to have good prognosis.

• The Journal of Natural Sciences
• /
• v.5 no.2
• /
• pp.49-62
• /
• 1992

This study was carried out to investigate the emergence, growth and yield components in rice inassoccation with Several cultivation methods direct sowing flooded paddy field(DSF), direct sowing by airplane(DSA), direct sowing in dry paddy field(DSD), 8days seedling planting(8DS), and 35days seedlingplanting(35DS). Also this study was attempeted to know the effects of calcium peroxide on germinationand early growth of rice under different soil conditions, seeding depth, application of organic matter,indirect sowing flooded paddy field.1. Rate of emergence was 73% in DSF, 70% in DSA, 62% in DSD, respectively, under the different cultivation method of rice in reclaimed paddy field.2. Degree of lodging in relation to cultivation was 5 at both DSF and DSA, 3 at DSD, 2 at both 8DS and 35DS respectively.3. Maximum tiller number was 568 per m2 at DSF and 527 at DSA. Heating was delayed for 4 days at DSF, 8 days at DSD and 2 days at 8DS as comparison with that at 35DS.4. Yield was higher 1% to 3% at DSF than that at DSA and DSD while decreased by 12% as compared with that of seedling planting.5. Total dry weight of seedling was decreased by 57% at 8DS, 60% at DSF 63% at DSD, respectively, under 0.3% of salinity. Ratio of decreasing in dry weight was higher with high salinity.6. The amount of O2 released was recorded highest to 2 to 3days after irrigatition, thereafter remaining constant to 10 days after irrigatition.7. The optimum coating amount of calcium peroxide for germination was a half of rice seed weight with 1 cm sowing depth and one-fold with 2-cm sowing depth when rice straw was not applied. With rice straw applied, on the other hand, the amount of peroxide was one-fold with 1-cm sowing depth. It was found that, under the condition of applied 600kg/10a, of 2-cm soil depth with rice straw calcium peroxide coating had no effect on emergence of rice seedling.8. In reclaimed paddy field, lodging degree was 7 with direct sowing by machine and 9 with direct sowing by hand.9. Yield was increased by 5% by applying rice straw with direct sowing by machine.

• Journal of Aquaculture
• /
• v.6 no.3
• /
• pp.133-146
• /
• 1993

Monthly variation of fatness index of the shortnecked clam was investigated at Moonhangri in Namhaedo of the southern coast of Korea from April 1991 to March 1992. The standing crops of umbo stage larvae and spats of this bivalve were also investigated. The results are as follows: The ranges of a monthly average water temperature and salinity were $6.9\~23.5^{\circ}C$ and $29.6\~33.1%o$ during the investigation period. Fatness index of the shortnecked clam decreased suddenly from June to September, which seemed to be spawning season. The umbo stage larvae of the clam were observed from May to November. The standing crops of the larvae were $883\;inds./m^3$ in August and$68\;inds./m^3$ in November. The observed number per ~ of the spats varied with the month and the different exposure time zones. The highest density $(1,508\;inds./m^3)$ was observed 1 hour exposure zone in August, and the lowest one $(28 inds./m^3)$ at 1 hour exposure station in April. Even the observed number of the spats below 4 mm in shell length were high in 1 and 3 hour exposure zones, the spats above 4 mm in shell length were observed mainly at 3 hour exposure zone.

• Journal of Bio-Environment Control
• /
• v.26 no.1
• /
• pp.35-42
• /
• 2017

This research was conducted to investigate the influence of post-planting fertilizer concentrations on the growth of seedlings and changes of nutrient concentrations of media in tomato seedling production through sub-irrigation. Two root media such as peat moss (grade of 0 to 6 mm, PM06) plus perlite (grade of 1 to 2 mm (PE2)(7:3, v/v) and peat moss (grade of 5 to 15 mm, PM515) plus PE2 (7:3, v/v) were formulated and filled into 72-cell plug trays. After seeds of 'Dotaerang Dia' tomato were sown and germinated at $28^{\circ}C$, the trays were moved to greenhouse and seedlings were raised 35 days. When the cotyledons were emerged, post-planting fertilizers of 13-2-13, 15-0-15 and 20-9-20 ($N-P_2O_5-K_2O$) were applied in a sequence. The fertilizer concentrations based on N in each plug stage were differed with $25mg{\cdot}L^{-1}$ in three treatments. The fertilizer solutions were supplied when the weight of plug trays decreased to 40 to 50% compared to container capacity. The root media were collected in 1, 2, 4, and 5 weeks after sowing and were divided into top, middle, and bottom parts, then were analysed for pH, EC and macro-nutrient concentrations. The seedling growth was investigated 5 weeks after sowing. The pH and EC in PM06+PE2 was higher than those of PM515+PE2. The bottom and mid-part had higher pH and lower EC compared to upper part in each medium. The differences of EC between upper and bottom parts were around 2 times in each medium. The $NH_4-N$ and K concentrations in program 3 of PM06+PE2 showed the highest concentrations among all treatments. The $NO_3-N$ concentrations in PM06+PE2 increased gradually and this rising tendency become severe as post-planting fertilizer concentrations were elevated. The seedling growth in terms of fresh and dry weights was the highest in the treatment of program 2 in PM06+PE2 among all treatments tested. Above results indicate that the gradual increases of fertilizer concentrations from 25 to $125mg{\cdot}L^{-1}$ in plug stages 2, 3, and 4 plug stages are desirable for

• The Korean Journal of Malacology
• /
• v.24 no.2
• /
• pp.153-159
• /
• 2008

We investigated artificial mass seed production of a Chinese scallop, Patinopecten yessoensis, in 2004. The GSI(gonad somatic index) of the Chinese scallop, P yessoensis was 17.2 on mid-February, 20.2 on mid-March, while that of Korean scallop, P yessoensis was 6.9 on mid-February, 10.8 on mid-March. Matured 120 females and 350 males were selected for artificial mass production. They were exposed in air for 1 hr at over $20^{\circ}C$, and placed into a spawning tank(20 ton) containing sea water treated with UV radiation at $12^{\circ}C$. We gained a total of 228,000 thousand scallop embryos between March 10th and 15th, and reared larvae at the indoor tank during 25 days. When the mean shell length of larvae reached 250 ${\mu}m$ and they have eye-spots, the number of pre-settling larvae was 47,500 thousand. We gained 1,850 thousand attached scallop spats from two kinds of collectors. Attached spats were reared in indoor tank for different periods from 5 days to 60 days. They were divided into 5 groups according to the length of reared days. Each group of attached spats was moved to intermediate rearing sites at Yangyang fishing port in Gangreung-city for acclimation to ocean environments. The highest survival rate of attached spats was 13.0% shown at the group reared for 12 days, but the significant difference in their growth was not found between the groups. The shell length of artificial attached spats increased from 0.9 ${\mu}m$ on July 10th to 24.7 ${\mu}m$ on December 16th with the survival rate of 85.0% while that of natural attached spats increased from 0.6 ${\mu}m$ on July 10th to 23.9 ${\mu}m$ on December 16th with the survival rate of 85.7%.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.40 no.4
• /
• pp.494-503
• /
• 1995

The selection of salt tolerant rice variety needs an effective method in its testing. Salinity of irrigated water, 0.5% at seedling stage, 0.6% at tillering stage, and 0.9% at panicle formation stage were treated to test salt tolerance of rice using 45 cultivars. At tillering stage, salty water irrigation reduced plant height to 22.6% in early maturing rices(EMR), 30.5% in medium maturing rices(MMR), and 20.9% in medium-late maturing rices(MLMR), and also reduced number of tillers to 11.2% in EMR, 36.2% in MMR, and 36.0% in MLMR compared to rices grown in non-salty water irrigation. At panicle formation stage of rice, salty water irrigation affected plant height and tiller numbers that showed varietal differences. As salt tolerant rice cultivars, Daegwangbyeo, Namweonbyeo, Sinseonchalbyeo, Gyehwabyeo, and Daeyabyeo were selected. Jinbubyeo, Donghaebyeo, and Tamjinbyeo were weak in salty water irrigation.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.39 no.4
• /
• pp.389-396
• /
• 1994

Poor establishment of white dover (Trifolium repens L.) into grass-dominant pastures has been limited its availability. The experiment was done to clarify the effects of timing of initial defoliation, defoliation frequency on the regrowth and nodule formation of the clover cultivars during 28-day regrowing period. Individual plants of cv. Regal, Louisiana S-1 (La. S-1), Grasslands Huia (Huia) and Aberystwyth S184 (S184) were grown in containers until grown to unifoliolate, 1, 2, 4, or 8 trifoliolate stage, and then clipped to 1cm in height every 7 or 28 day for 28 days. To measure the effects, plants were sampled immediately after final harvest, and 1, 3, 7, 14 and 28 days after the harvest. Shoot, root dry weight and biomass were reduced with earlier, more frequent defoliation or shorter regrowing period. In frequent defoliation shoot dry weight and biomass were increased with delayed initial defoliation while in less frequent defoliation steeply done when initial defoliation was delayed to 4 trifoliolate stage. Shoot /Root ratio inclined with more frequent defoliation or lengthened regrowing period, and was greater in initial defoliation of unifoliolate to 2 trifoliolate than the others. Although nodules no. per plant declined with earlier or more frequent defoliation, the effect disappeared to some extent after 14-day regrowth. In comparison with the others, Regal had the highest shoot. dry weight and biomass to 2 trifoliolate stage while S184 did the most nodules regardless of defoliation timing. On 7-day after last defoliation nodule formation of Regal, Huia and S184 but on 28-day after last defoliation that of La. S-1, Huia and S184 was positively correlated to shoot and root dry weights upto 2 trifoliolate stage. On the former day, however, that was negatively correlated to Shoot /Root ratio upto 1 trifoliolate stage although on the latter day it was not, meaning that in addition to more frequent defoliation earlier defoliation was harmful in nodule formation of white clover.

• Journal of Aquaculture
• /
• v.15 no.2
• /
• pp.95-101
• /
• 2002

During the periods from lily to October, 2000 in Hongseong and lucy to October, 2001 in Taean in the west coast of Korea, the following environmental conditions prevailed : water temperature : 22.0~26.817, salinity 27.23 ~30.80%, dissolved oxygen 4.12 ~6.26 ml/l, pH 7.89 ~8.09, phosphate 0.39 ~0.65 $\mu m$ , inorganic nitrogen 5.05~9.26 $\mu m$, suspended solid 5.4~20.8 mg/l and chemical oxygen demand 1.12~1.87 mg/l. The B-shaped veliger larvae of the Ark shell occurred in maximum number at $25^{\circ}C$ prevailing from mid-August at Hongseong and Taean. Full grown larvae reached maximum abundance from late August. To identify the effectiveness of the substratum for spat collection, raschel net were tested to Larval settlement. The most effective depth to collect the larvae in natural environment was the collectors suspended at 7~8 m depth. At these depths, about 49 to 94 spats were found on the collector (40$\times$50 cm), The growth of shell height (Y) to shell length (X), and total weight (W) to shell length (L) could be formulated as follows respectively: Hongseong: SH = 0.7168 SL -0.6466 ( $r^2$ = 0.9839), TW = $0.0001SL^{3.1705}$ ($r^2$ = 0.9882) Taean: SH = 0.736 SL -0.8824 ($r^2$ : 0.9899), TW : 0.00005 $SL^{3.3731}$ ($r^2$ : 0.9899)

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.34 no.s02
• /
• pp.34-44
• /
• 1989

The stability of rice cultivation in Korea is largely depended on climatic conditions, especially, low temperature at the period of early growth stage and after heading. The improvement of cold tolerant varieties and appropriate cultural practices in rice are very effective to minimize the cold damage. This paper is summarized the mechanism and counterplans of cold injury of rice plants. The paddy area having commonly cold injury in Korea is approximately 15, 522ha in 1,709 sites on the national scale. The cold damage at seedling stage in nursery bed appeared to poor germination, leaf discoloration, dead seedlings and seedling rot ect.. At the vegetative stage, the decreased tiller number due to poor rooting and the delayed heading caused by slow growth and panicle differentiation are commonly showed. The cold injury at early reproductive stage appeared to the degeneration of spikelets and rachis - branches, while that at meiosis stage showed to increased sterility due to poor development of pollen and shortened panicle length with delaying heading, therefore the grain yield is largely decreased. The cold damage at heading and ripening stages showed to poor pollination and fertilization, low panicle exsertion, poor grain filling and finally grain quality became low. To minimize the cold injury to rice plants by low temperature, following counterplans would be recommonded ; Improvement of the cold toelrant rice varieties for the regions of midmountains and alpines. Raising healthy seedlings at upland nursery beds and by using of growth regulators such as ABA, Fuchiwang and Tachiace. Soil improvement and organic matter application to reduce cold damage by increasing water and fertilizer holding capacities in the paddy field having commonly cold water and in the place where cold damage is regularly occurred. Appropriate fertilization for raising healthy rice plants to tolerate under low temperature condition. Water management to increase water temperature in the paddy such as depth watering, round channels and polyethylene tubes around the field. Establishment of the optimum cultivation time of rice based on minimum, mean and maximum temperatures at different regions with appropriate rice varieties.