• Proceedings of the Korean Society of Embryo Transfer Conference
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• 2002.11a
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• pp.103-103
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• 2002

This study was conducted to investigate cryopreservation of pearl oyster, Pinctada fucata martensii larvae. Four cooling rates (-0.25, -0.5, -0.75 and -1.0$^{\circ}C$/min.) were used to examine a proper cooling rate during cryopreservation of trochophores before seeding temperature (-12$^{\circ}C$). Seven developmental stages (early and late trochophores, early and late D-shaped larvae and early, middle and late umbo stage larvae) and different sugars (fructose, glucose and sucrose) were used to investigate optimal larval stage and effective sugar in cryopreservation of larvae. The survival rates of frozen-thawed trochophores increased at cooling rate of -1.0$^{\circ}C$/min. As larval developing, survival rate of frozen-thawed larvae increased, except umbo stage larvae, and especially late D-shaped larvae highly survived as 91%. Addition of sugar revealed positive effect on cryopreservation in this experiment and 0.2 M glucose and sucrose mixed with 2.0 M dimethyl sulfoxide significantly enhanced survival rate of larvae (P<0.05). The results of our study indicate that desirable cooling rate, developmental stages of larvae and effective sugar far cryopreservation of pearl oyster, P. fucata martensii larvae are -1$^{\circ}C$/min, late D-shaped larvae and 0.2 M glucose and sucrose, respectively.

• Journal of The Korean Society of Grassland and Forage Science
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• v.18 no.1
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• pp.43-48
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• 1998

No-tillage silage corn with legume hairy vetch(Vicia villosa Roth, HV) has renewed interest in supply of mineral N, soil erosion control at sloping land and weed control by cover of HV killed. This study was conducted to monitor concentration of soil mineral N ($NO_3^-$ -N + $NH_4^+$-N) and to find out variation of growth, yield and N uptake of silage corn according to quantity of HV cover; HV-removed, 1X-HV, 2X-HV at field of Crop Experiment Station in 1996. HV groM in early spring decreased the mineral N of soil depth 7.5 -22cm before corn seeding. But, killed HV cover increased the concentration of soil mineral N at surface soil (0-7.5cm) up to 45.4mglkg at early growth stage of corn. Dry matter(Dh4) of corn at harvest was lower in W-removed than in Okg FNlha. But DM and N uptake of corn at harvest were increased by quantity of HV-cover increasing liom HV-removed to 2X-HV. Hairy vetch could substitute N fertilizer for silage corn by N mineralized h m HV killed, but reduced early growth and N uptake of corn before silk by reducing soil mineral N of plow layer.

• Journal of the Korean Institute of Landscape Architecture
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• v.26 no.3
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• pp.8-18
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• 1998

This study was to make a effective seed mixture types with Korean native plants by researching te seed timing of suitable woody plants and competitive germination results of various plants for the purpose of cut-slotes revegetation. The results are summarized as follows. 1. In field polystand experiment, comparative among severalcomposition combination for early coverage shows good condition. 2. In combination for early-coverage, mixture of native woody plants only seeded in May and June shows over 90% coverage. It was not inferior to the other mixture types. So mixture of Albizzia Julibrissin, Cymbopogon doeringii, Alnus hirsuta and Indigfera pseudo-tinctoria is able to use to mixture type. 3.In case of combination for scenic beauty, Rhus chinensis shows low germination in the mixture for scenic beauty. But 90 days after seeded in May, it recorded maximum 44 cm height, seeded in June recorede 18 cm height. 4. Lespedeza crytobotrya shows good elongation in the combination for early coverage and scenic beauty, but that effects on elongation of other plants. So, it demands close investigation about suitable mixing rate of plants. 5. Alnus hirsuta, Pinus thunbergii, Betula platyphylla, Spiraea prunifolia var. simpliciflora have been rarely germinated. So, the mixture of these plants wasn't adequate to use for revegatation.

• Horticultural Science & Technology
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• v.19 no.1
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• pp.22-28
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• 2001

An optimum seeding date for carrots growing in Jeju was determined. In early growth stage, the number of leaves was more in Hyang-yang #2 cultivar (HY2) than that in the others, meanwhile that of Hukjun 5 chon (H5) and Shinhukjun 5 chon (S5) was higher in the latter half of the growing season. The weight of leaves was greater in HY2 until 2 months after seeding, but thereafter drastically increased and resulted significant difference at harvest in S5. The length of roots was greater in H5 and S5 than in HY2 when seeded on July 17 and measured after September 13, but it was similar in all cultivars when seeded on August 1 and later. The diameter of the roots was greatest in HY2, regardless of seeding dates, meanwhile no difference was found among other cultivars. The weight of roots was greatest in HY2 when seeded on July 17, August 1 or later, meanwhile it was greater in H5 after November, when seeded on August 15. The percentage of roots cracked was 20, 15, and 10% respectively for HY2, S5 and H5. The percentage of roots branched was 0.3% in HY2. The percentage of roots cracked or branched was much higher when seeded on August 1 than on July 17, and was high (40%) in HY2 and S5, compared to H5 when seeded on August 15. The content of sucrose, glucose and fructose increased until 110 days after seeding in all cultivars, but fructose and glucose contents decreased in about 135 days after seeding, but sucrose contents increased continuously even after 135 days. Sucrose content increased and fructose and glucose contents decreased in S5, but this trend was reversed after late November. Sugar contents was different among the cultivars seeded on August 15, while sucrose content decreased and glucose and fructose contents increased with time. The content of ${\beta}$-carotene was more than 12,000 IU in all cultivars, but decreased in 170 days after seeded on July 17. The content was highest in HY2 and followed by S5 and H5 in order. It was not different among the cultivars in 170 days after seeding on August 1, but was higher in S5 than the other cultivars in 170 days after seeded on late and decreased with seeding date.

• Korean Journal of Soil Science and Fertilizer
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• v.17 no.4
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• pp.375-380
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• 1984

A pot experiment was conducted to learn the effect of non-compounded and compounded (with super phosphate) liquid fertilizers made of amino acid fermentation by product and the time of their application on the emergences and yield of orchard grass. Results obtained as follows; 1. The Application of the liquid fertilizers, on seeding day of the orchard grass raised soil pH and salt concentration more than the application on the days before seeding and decreased the number of sprouts of the grass which also lead to a lower yield of the grass compared with the latter. 2. Liquid compound fertilizer, however, tended to reduce the harmful effect on sprouting orchard grass compared with non-compounded liquid fetilizer, particulary in soil of on-lime applied. 3. The application of liquid and liquid compound fetilizers on somewhat acidic bare land a quite ahead of seeding or transplanting crops may not only reduce the effect of the fertilizers, provided the land is free from washing by rain or irrigation water, but also provide better conditions for sprouting and early growth of plant seedings than the use at the pre-seeding or pro-transplanting time.

• Korean Journal of Weed Science
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• v.32 no.3
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• pp.280-284
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• 2012

No-tillage direct seeding of rice is consumed less labor and oil energy by no plowing and rotary tillage. And it has other advantages of soil and water conservation and accumulation of organic matter on paddy surface due to crowded water foxtail (Alopecurus aequalis var. amurensis). When no-tillage seeding of rice, many water foxtail occurred in winter paddy field. In this experiment their covering degrees were 97.6% and 95.2% in clay loam and sandy loam paddy soils, respectively. Because of this, Stellaria alsine var. undulata, Cardamine flexuosa, Rorippa indica and Ixeris chinensis etc. annual and perennial wintering weeds occurrence was reduced. And annual weeds Chenopodium serotinum and Polygonum hydropiper that occurred early in spring were also reduced. As well as Echinochloa crusgalli var. praticola, Cyperus difformis, Monochoria vaginalis and Lindernia procumbens etc. summer annual weeds that occurred after irrigation were also reduced. In conclusion, no-tillage direct seeding of rice has another advantages of weed management by water foxtail.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.34 no.3
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• pp.246-251
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• 1989

A medicinal legume crop, Cassia tora L., was grown with four different seeding dates in 1986 field condition to find the flowering and pod setting characteristics. Initial flowering date and flowering duration were almost same between plants sown from April 20 to May 30, but those of plants seeded at June 20 were significantly delayed and shortened. Last flowering date, however, was not different between plants sown from April 20 to June 20. C. tora plants showed indeterminate flowering habit, and bloomed vigorously from fourth date after initial flowering. Numbers of flowers, ovules and pods per plant were decreased along with delaying seeding date, and ovule to flower ratio and pod to flower ratio were greatly decreased in June 20 seeding plot. Flowers bloomed on second week from initial flowering showed the highest number of ovules and pods, and flowers bloomed after early September did not develop to matured pods. Maximum values of pod length, number of seeds per pod and 1000-grain weight were obtained from flowers bloomed on second week from initial flowering of plants sown from April 20 to May 30, and first week in June 20 seeding plot.

• Korean Journal of Soil Science and Fertilizer
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• v.39 no.5
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• pp.298-302
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• 2006

This study was carried out to establish low-input fertilization and seeding technique using the simultaneous with seeding and fertilizer application machine and band spotty applicator which were manufactured for experiment during cultivation of mulching for peanut(Arachis hypogaea L.). The labor hour for seeding by simultaneous with seeding and fertilizing machine was appeared over 90% reduction effect compared with control plot($17.3hr\;10a^{-1}$). In band spotty fertilization plots, the emergence date was delayed about 4 days and the seedling stand rate was decreased 11~18% compared with control plot(man power). The content of total nitrogen of soil after experiment was increased while the contents of organic matter, available phosphate and exchangeable potassium were decreased than before experiment. The content of nitrogen forming nitrate was increased in band spotty fertilization(BSF) plots by increasing the amount of applied fertilizer from early growth stage till the middle growth stage. Growth rate was increased in band spotty fertilization plots and the absorbed amount of phosphate and potassium for peanut were increased in 70% band spotty fertilization plot compared with control plot. Yield of peanut was increased 70% in band spotty fertilization plot due to high pod kernel ratio and ripened pod rate compared with control plot($3,150kg\;ha^{-1}$). It was found that 70% band spotty fertilization was more effective as fertilization method to reduce both environmental pollution and chemical nitrogen fertilizer in plastic film mulching cultivation of peanut.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.40 no.5
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• pp.629-636
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• 1995

This study was carried out to clarify the proper nitrogen application methods under the different seedling density in puddled-soil drill seeding of rice. Seedling density was adjusted as 30, 60, 90, 120 and 150ea/$m^2$ just after emergence and nitrogen was applied with five methods including conventional respectively. The maximum tillering stage was shorten as the seedling density was increase but decreased the percentage of productive tillers. Lodging was occurred serverely as the seedling was more than 120ea/$m^2$, when nitrogen was applied at panicle initiation stage. Grain yield wasn't significantly different among seedling densities when it was more than 60ea/$m^2$, but the density of 30ea/$m^2$ was decreased. It wasn't significantly different among the nitrogen application methods when it was more than 90ea/m, but was higher at early application of tillering fertilizer (T$_2$) than conventional method when the seedling density was less than 60ea/$m^2$. Supposing that the yield of reseeding is the same as optimum seedling density, minimum seedling density needs for reseeding would be less than 55 ea/$m^2$ as the aspect of income allowed for managing expense.

• Korean Journal of Weed Science
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• v.16 no.2
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• pp.88-99
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• 1996

In recent years dry direct-seeding of rice has been encouraged by the government and increasingly practiced by farmers in Korea. This has been bringing up an increased occurrence of weedy rites. Some farmers in the southern region dare to sow the rice before winter after harvest, while most farmers wish to sow as early as possible in the spring to secure the growing period, and to disperse the intensive labor in early May. The purpose of this study was to determine the feasibility of moving the sowing of rice to an earlier date under dry direct-seeding, and to elucidate the nature of emergence of an old strain of rice, weedy rites, and barnyardgrasses tinder this farming practice and their adaptive competence over present cultivate. The presently recommended rice cultivar, Dongjinbyo and an old rice strain, Dadajo which prevailed in early 1900s, almost could not emerge from soil deeper than 6cm and could emerge to only 5.3% at best from 1cm deep loamy soil field when the seeds were sown on Nov. 28. However, two strains of weedy rites being weedy for over 200 years emerged by 17.0 to 63.0% from the loamy and sandy clay loam field 1 to 6cm deep. Emergence of the weedy rites was greater in the loamy soil and at a shallow depth, and negligible from the soil depth of 9cm. Barnyardgrasses sown on Nov. 28 emerged by 13.4 to 51 % from the 1 to 3cm deep loamy soil, and 8.6 to 46.7% from the 1cm deep sandy clay loam. Echinochloa crus-galli var. crus-galli emerged more than var. praticola, and var. oryzicola least. Most of the non-emerged barnyardgrasses seem to have entered secondary dormancy. Seeding rice a month earlier than the season lowered the emergence of Dongjinbyo by ca. 10, 18, and 26%, respectively at 1, 3, and 6cm soil depths, indicating that moving the seeding date a month earlier is impractical. The old strain, Dadajo sown in the soil at a depth of 6cm responded similarly. However, the strain has shown a significantly higher ability in emergence from 9cm deep soil. Weedy rices sown a month earlier A month earlier sown weedy rices have shown very similar emergence rates at various soil depths to those sown on May 1. Barnyardgrasses have also shown similar emergence rates when sown between April 3 and May 1. Like barnyardgrasses, the old strain and weedy rices apparantly posessed a greater adaptability to emerge under lower temperatures, and from deeper soil ; Dongjinbyo${\leq}$ Echinochloa species in that order. However, emergence- speed under lower temperature(sown on April 3) was faster in the order of weedy rice