• Horticultural Science & Technology
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• v.30 no.5
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• pp.568-572
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• 2012

Determination of ploidy level for the mother plant is prerequisite for effective breeding. The study was carried out to determine the ploidy level in 7 different plant materials by FISH karyotype analysis. Among the seven plant varieties analyzed, all exhibit tetraploid (2n = 4x = 28) based on the results observed in chromosome analysis. Four signals of 45S rDNAs were detected on the terminal region of the short arm of chromosome 7. The length of somatic metaphase chromosomes ranges from 1.67 to $2.67{\mu}m$ in 'Alexandra', 1.40 to $2.04{\mu}m$ in 'Freud', 1.64 to 2.24 in 'Little Silver', 1.69 to $2.26{\mu}m$ in 'Teresa', 1.70 to $2.65{\mu}m$ in 'Tineke', 1.35 to $2.08{\mu}m$ in 'Vital', 1.39 to $2.04{\mu}m$ in 'Yellow Mimi'. Total length of the chromosome ranges from $11.23{\mu}m$ in 'Freud' as minimum to $15.05{\mu}m$ in 'Alexandra' as maximum. The karyotypes were composed of metacentric, submetacentric, and subtelocentric chromosome but there is no subtelocentric chromosome.

• Korean Journal of Plant Tissue Culture
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• v.24 no.4
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• pp.239-256
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• 1997

Plants belonging to the category of 2n apomixis or agamospermy form embryos and seeds without the processes of normal meiosis and syngamy. Seeds produced in this way have identical genotype of their maternal parent. Three different types of agamospermy are recognized: diplospory, apospory, and adventitious (adventive) embryony. $F_1$ hybrid cultivars cannot be used as seed sources in the next ($F_2$) generation because this generation would be extremely variable as a result of genetic segregation. Hybrid vigor is also reduced in the $F_2$ generation. Therefore, parental stocks for hybrid seed production need to be maintained and cross must be continuously repeated. Agamospermic 2n apomixis would make it possible to fix the genotype of a superior variety so that clonal seeds faithfully representing that genotype could be continuously and cheaply produced independent of pollination. That is, $F_1$ hybrid seeds could be produced for many generations without loss of vigor or genotype alteration. Production of apomictic $F_1$ hybrid seed would be simplified because line isolation would not be necessary to produce seed or to maintain parental lines, and the use of male-sterile lines could be avoided. Overall, apomixis would enable a significant reduction in hybrid seed production costs. Additionally, the production of clonal seed is not only important for seed propagated crops, but also for the propagation of heterozygous fruit trees and timbers. Clonal seed would help avoid costly and time-consuming vegetative propagating methods that are currently used to ensure the large-scale production of these plants. Apomixis is scattered throughout the plant kingdom, but few important agricultural crops possess this trait Therefore, most research to date has centered on introgressing the trait of apomixis into agricultural crops such as wheat, maize, and some forage grasses from wild distant relatives by traditional cross breeding. The classical breeding approach, however is slow and often impeded by many breeding barriers. These problems could be surmounted by taking mutagenesis or molecular approach. Arabidopsis thaliana is a tiny sexually reproducing plant and is convenient in constructing and screening in molecular researches. Male-sterile mutants of Arabidopsis are particularly suitable genetic background for mutagenesis and screening for apomictic mutants. Molecular approaches towards isolating the genes controlling the apomictic process are feasible. Direct isolation of genes conferring apomixis development would greatly facilitate the transfer of this trait to wide variety of crops. Such studies are now in progress.

• Current Research on Agriculture and Life Sciences
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• v.17
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• pp.21-29
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• 1999

This study was carried out to determine the promising method for the production of mother bulbs using garlic bulbs at the experimental field of Ange high school, Eusung in Korea from 1996 to 1998. The bulbs and bulbils were taken from a local cultivar 'Eusung' garlic. The growth of bulbil and yield potential were compared with different harvesting times and cultivation methods of bulbil. The harvesting time of bulbils which were capable of producing the mother bulbs was ranged from 15 days to 30 days after the emergence of flower stalks. The best results based on the yield and number of bulbs were obtained from the bulbils sampled at the just before garlic harvesting, 30 days after flower-stalk emergence. The mulching with transparent polyethylene(PE) film in bulbil cultivation was more effective for the plant growth and bulb formation than that with black PE film. The PE mulching from 30 days after seeding of bulbils to 30 days (late-April) before bulb harvesting was the moot effective for the increase of bulb yield. In the cultivation of garlic bulbils, application of lime (150 kg/10a) and compost (3,000 kg/10a) without any chemical fertilizers produced more bulbs in comparison with the standard level of fertilizer (N - $P_2O_5$ - $K_2O$ - compost - lime = 24.8 - 8.0 - 19.2 - 3,000 - 150 kg/10a). It was determined that the involucre seeding and assemble seeding of bulbils was effective and labour-saving methods for the production of mother bulbs from garlic bulbils. Input of labour force for the involucre seeding was decreased up to 61% as compared with the conventional drill seeding of bulbils. Mean yield from the cultivation of bulbil-derived single cloves was remarkably increased up to 95% in comparison with that of the common cloves. The larger size of single clove produced more yields, and the optimum planting density of single clove was $20{\times}10cm$. The cloves differentiated directly from bulbil showed to have higher yield potential than that from common cloves.

• Korean Journal of Child Studies
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• v.7 no.2
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• pp.1-15
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• 1986

Korea is a rapidly industrializing nation. As a consequence, more mothers are working outside the home. This trend is likely to continue into the future and raises the problem of infant-toddler care during the mother's working hours. Considering that Korea is making such rapid economic advances, quality care for children of working mothers Is not only desirable but affordable as well. Variety in options for child care is recommended by Beck (1982). Some of the alternatives in child care have been discussed elsewhere (KWDI, 1984). This paper, thus, concentrated on center-based, worksite child care. Because the human environment is the most important aspect of the center, qualified staff and a low ratio of children per staff member is Vital. Philosophy of program and its actualization ensures that the children have a worthwhile experience at the center. The physical plant houses the center and includes provision for space, materials, and equipment for staff and child use in carrying out the program. Adequate health protection is a critical factor in infant-toddler group care programs.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.34 no.4
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• pp.378-383
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• 1989

For selection of mutants two rice varieties, Sangpungbyeo and Seomjinbyeo, were irradiated with 20 kR and 25 kR of gamma rays. One panicle per each plant was harvested in Ml, and single needling per hill was planted for M2 and M3 generations. Mutations for short culm, earliness and the major traits were examined. 1. The mutation rates were varied with the rice varieties and the doses of radiation, higher in Sangpungbyeo and 25kR than in Seomjinbyeo and 20 kR, respectively. 2. The rates in Sangpungbyeo with the 20 kR and 25 kR were 1.10％ and 1.47％. respectively and those of Seomjinbyeo were 0.51％ and 1.25％, respectively. 3. The culm lengths of short-culm mutants derived from Sangpungbyeo and Seomjinbyeo were reduced about 10％ compared to their mother varieties, especially it was possible to select the dwarf mutants reducing 57％ and 40％ of culm length in Sangpungbyeo and Seomjinbyeo, respectively with the dose of 25 kR irradiation. 4. The range of heading date of the mutant ion in the M3 generation was comparatively wide. Many earliness mutants shortened about 7 days were selected as compared with their mother varieties, some mutants of the irradiated group had early matured by 20 days and 30 days, respectively in both Seomjinbyeo and Sangpungbyeo.

• Korean Journal of Environmental Agriculture
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• v.18 no.1
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• pp.35-40
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• 1999

$N(^{15}N)$ and $P(^{32}P)$ absorption by 2 year-old Cymbidium Jungfrau in solution culture were investigated. Growth, photosynthesis rate, chlorophyll content and mineral composition of Cymbidium in the solution culture with bark or granular rockwool were compared with these parameters in the conventional pot culture. Nitrogen absorption by Cymbidium was higher in full sunlight than in 60% of sunlight while P absorption was higher in 60% of sunlight. Sixty seven % of N absorbed in plant was redistributed to the bulb(39%) and leaves(28%) while 46% of P absorbed was fund in the bulb (36.2%) and leaves (10.2%). Accumulation of P in leaves was 3-fold lower than that of N. N and P absorption in 0.5 or 1 year- old daughter plant Bowing vigorously were greater than in immature daughter or mother plant. The absorption rate of phosphorus in Cymbidium was 350-fold lower than that of barley. Greater shoot length and bulb diameter, and higher fresh weight, photosynthesis rate and chloroployll content were observed in the solution culture than in the conventional pot culture. Solution culture had-also more content of N, P, K and Mg in leaves, bulb and root than conventional pot culture but did not that of Ca. A large part of the nutrient absorption was occurred during vegetative growth. Also, There was no difference between bark and rockwool in the solution culture due to the improvement of poor dispersion of nutrient solution in bark.

• Journal of Bio-Environment Control
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• v.19 no.2
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• pp.117-121
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• 2010

To investigate effects of binding treatments of branches (FMB, fruiting mother branch; PSB, secondary scaffold branch; SSB, primary scaffold branch) on enlargement and coloring of persimmon 'Fuyu' fruits in ripening period, the branches were bound by steel wire. For eight weeks after binding treatments, Hunter $a^*$ of fruit peel in FMB and SSB binding treatments was more increased than in the others. In fruit characteristics harvested at eight weeks after the binding treatments, the fruit weight was heavier in the binding treatments than in control, the first of those was in SSB binding. The fruit height was higher in SSB binding than in the others, but the fruit diameter was longer in FMB and SSB binding treatments. Solid soluble content was higher in FMB and PSB binding treatments. $Chroma^*$ of the fruit peel was higher in FMB and PSB binding treatments as Hunter $a^*$ and $b^*$ values were higher and lower in FMB and SSB binding treatments, respectively. Lycopene and $\beta$-carotene content in the fruit peel were higher significantly in PSB and SSB binding treatments, total chlorophyll content in all the binding treatments was lower than in control.

• Korean Journal of Plant Taxonomy
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• v.42 no.4
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• pp.260-266
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• 2012

Because the embryological features of Jeffersonia dubia are poorly understood, we conducted the first embryological study comparing it to other related genera of Berberidaceae. Important embryological features of J. dubia are as follows: the anther is tetrasporangiate, anther wall formation confirms basic type, glandular tapetum cells are two nucleate, the epidermis persistent, and the endothecium develops fibrous thickenings, anther dehiscence by two valves, meiosis in a microspore mother cell is accompanied by simultaneous cytokinesis, microspore tetrads are usually tetrahedral, pollen grains two cells at the time of anthesis. The ovule is bitegmic, anatropous and crassinucellate, archesporium single celled, development of the embryo sac Polygonum type, a mature embryo sac is ellipsoidal in shape. Endosperm formation is of Nuclear type and embryogeny Onagrad type. Seeds are arillate and seed coat exotestal type. Embryological comparisons showed that Jeffersonia resemble to Epimedium and Vancouveria rather than Berberis and Mahonia in some features, like as number of tapetal cells, cytokinesis in meiosis, and thickness of exotesta. It also resembles to Gymnospermium in mode of anther wall formation, number of tapetal cells, formation of nucellar cap, and nature of antipodal cells. Nevertheless, Jeffersonia and Gymnospermium differ from several other embryological features and molecular data too. Therefore, embryological evidences support that Jeffersonia is closely related with Epimedium and Vancouveria.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.37 no.4
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• pp.305-312
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• 1992

This experiment was carried out to investigate seed set, variation in chromosome number, and agronomic characteristics of the progeny in the cross between hexaploid triticale variety, Sinkihomil(P$_1$) and tetraploid rye variety, Dooroohomil(P$_2$). Seed set rate obtained was 30.5% in the cross of Sinkihomil with Dooroohomil, whereas 3.26% in reciprocal cross using Dooroohomil as female. Alsoseed set was 8.75% in F$_1$/P$_1$, 7.20% in F$_1$/P$_2$, and 1.53% in F$_2$(=F$_1$ /F$_1$, respectively. Germination rate of crossed seed was 37% in cross of P$_1$ with P$_2$, 39.0% in F$_1$/P$_1$(BC$_1$), 50% in F$_1$/P$_2$(BC$_2$) and 43.0% in F$_1$/F$_1$(F$_2$), and 1,000 grain wight was 20.7g in the cross of P$_1$ with P$_2$, which have 41.9g and 47.7g, respectively, 24.5g in F$_1$/P$_1$, 23.6g in F$_1$/P$_2$, and 24.5g in F$_1$/F$_1$, respectively. In pollen fertility of F$_1$ plant, 69.8% turned out to be abnormal or sterile pollen grains, whereas 30.2% was fertile or normal. In meiosis of pollen mother cell of F$_1$ plant, 13.5 univalents, 8.89 bivalent and 1.24 trivalent were appeared. Somatic chromosome number of 35 in F$_1$, both 32 to 33 and 35 to 36 in F$_2$, 35 to 39 in BC$_1$ and 28 to 36 in BC$_2$ which mean producing female gamate was 14 to 18 chromosome in PMC of F$_1$ plant. Rate of fertile plant turned out to be 100% in F$_1$, 4.5% in F$_2$, 42.9% in BC$_1$, and 50.0% in BC$_2$, respectively. Number of seed set per spike appeared to be 1.17 in F$_1$ plant, 13.3 in F$_2$, 2.36 in BC$_1$, and 3.75 in BC$_2$, respectively. Days to heading of F$_1$ was intermediate, but F$_2$ was later than both parents. Plant height of F$_1$ , BC$_1$ ,and BC$_2$ was shorter than both parent, but F$_2$, longer than both parents.

• Horticultural Science & Technology
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• v.33 no.1
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• pp.47-54
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• 2015

This research was conducted to investigate the changes in moisture retention capacities of expanded rice-hull (ERH)-based root media and their influences on the growth of mother and daughter plants in vegetative propagation of 'Seolhyang' strawberry. The proportion of water at the container capacity of ERH medium was in the range of 20 to 23%. This range was lower than the 60 to 66% of strawberry-specialized medium, the 30 to 34% of soil mother material (SMM) and the 30 to 35% of loamy sand. The moisture content of ERH was reduced to 10 to 12% at 8 hours after irrigation, and there were large variations among replications of ERH medium. Among four kinds of root media formulated to contain ERH, the medium of ERH + coir dust (CD) (55 + 45%, v/v) had 26.5 and 32.5% water contents at 20 and 40 days after irrigation to daughter plants, respectively. The m edia o f ERH + sandy loam (S L) and E RH + S MM showed similar trends i n moisture r etention. The pH and EC i n the all root media tested were in the range of 6.7 to 7.1 and 0.03 to $0.08dS{\cdot}m^{-1}$, respectively. The pHs and ECs measured at 20 and 40 days after irrigation were not significantly different in each root medium. Among the root media formulated to contain ERH, the growth of daughter plants was the highest in the treatment of ERH + SL (55 + 45%, v/v). As the blending rate of coir dust was elevated in the ERH + CD media, moisture retention capacity increased gradually, but the growth of daughter plants became worse even though the medium showed higher moisture retention capacity than other root media tested. The growth of roots and aboveground tissues of daughter plants deteriorated in the root media formulated by blending ERH + perlite (PE) at various ratios. The results of this research suggest the optimum formulations of root media and management of moisture content in raising of strawberry daughter plants when ERH is a component of root media.