• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.19-19
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• 2017

The indica ${\times}$ japonica rice (Oryza sativa L.) cultivars released in Japan since 1980 are high-yielding. However, occasionally in these cultivars their high yield potentials cannot be realized, particularly depending on climate conditions. The objectives of this study were to identify the reason for yield instability and the critical yield component factor causing lower grain yield in these high-yielding cultivars. Standard-yield japonica, high-yielding japonica-dominant, and indica-dominant cultivars were grown in western Japan. Rough grain yield (RY) in these high-yielding cultivars ranged from 450 to $980g\;m^{-2}$, and was positively correlated with potential grain yield (PRY). By fluctuations of solar radiation, RY changed with spikelet number (SNO), and SNO was correlated with cumulative radiation during the panicle formation period of 30 days before heading. Even if higher SNO was achieved under higher radiant conditions, RY was lower than PRY. The lower grain-filling in plants bearing higher SNO resulted from a lower filling percentage of spikelets (%F, RY/PRY), and %F was strongly correlated with spikelet fertility (%S) across all cultivars. %S was highly influenced by cumulative radiation per PRY during pollen development and establishment around heading. Inhibition of assimilation by leaf removal lowered %S. Conversely, stem thinning and removal of upper panicles around heading increased %S in spikelets of the lower part of the panicle in which sterility was higher. These results suggest that limitation of assimilate-supply due to low irradiance at the spikelet-formation and flowering stages restrains the potential of the high-yielding cultivars, depending on reduction of SNO and %S, respectively.

• Horticultural Science & Technology
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• v.32 no.5
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• pp.584-589
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• 2014

Jeffersonia dubia is a spring-flowering perennial found in rich forests in Korea and Northern China and has potential as an ornamental or medicinal plant. However, illegal picking and land use change have decreased the number of populations and overall population size of this plant in its natural habitat. Although J. dubia has been reported to be a shade-preferring plant, no study has determined the optimum light intensity for its growth. The objectives of this work were to observe the effects of various shading levels on the physiological responses of J. dubia and to determine the proper shading level for cultivation. Treatments consisted of four shading levels (0%, 50%, 75%, and 95% shade) imposed using black mesh cloth. The number of leaves and dry weight increased with decreased shading. The shoot-to-root ratio increased with increased shading, mainly due to decreased root dry weight under shading. Plants showed low net $CO_2$ assimilation rates and $F_v/F_m$ values combined with low dry matter levels when grown under 0% shade (full sunlight). These results indicate that J. dubia plants experience excessive irradiance without shading, resulting in damage to the photosynthetic apparatus. By contrast, the net photosynthesis rate increased as the shading level increased. $F_v/F_m$, the potential efficiency of PSII, was 0.8 under 95% shade, indicating that J. dubia is well-adapted under heavy shading. However, the low dry matter of plants in the 95% shade treatment indicated that the low light intensity under 95% shade led to a decline in plant growth. Thus, moderate light (50% shading) is recommended for cultivating J. dubia without physiological defects.

• Horticultural Science & Technology
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• v.31 no.1
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• pp.38-49
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• 2013

Prohexadione-calcium (Pro-Ca), ethephon and transient water stress were evaluated in a factorial design, as potential inhibitors of early-season shoot growth of high density orchard management of apple (Malus domestica Borkh.) trees. In the experiment, water stress was imposed to one-half of the 7-year-old 'Golden Delicious'/M.9 apple trees in each of 5 blocks, by stopping irrigation for 3 weeks between 35 and 56 days after full bloom (AFB). Within each whole unit, the following Pro-Ca and ethephon treatments were randomly allocated at $2{\times}2$ factorial: a) 0 or 250 $mg{\cdot}L^{-1}$ a.i. Pro-Ca applied at 28 days AFB and b) 0 or 300 $mg{\cdot}L^{-1}$ a.i. ethephon applied twice (35 and 71 days AFB). All trees were hand thinned to king flowers prior to treatments. Vegetative shoot growth was markedly reduced by Pro-Ca, with its effect being obvious within 14 days after application, while ethephon and water stress treatments were less effective. Pro-Ca had no effect on fruit set and yield but slightly increased fruit size. Ethephon substantially reduced the fruit size and yield but had no effect on fruit set. Water stress reduced fruit set, fruit size and yield. With regard to fruit quality, Pro-Ca did not influence fruit shape, flesh firmness and soluble solids contents (SSC) but slightly reduced titratable acidity. Ethephon had no effect on fruit shape but increased firmness, SSC and acidity, while water stress did not influence these fruit quality attributes. Dry weight of dormant spur buds was reduced by both Pro-Ca and water stress, while increased by ethephon. The larger dormant buds led to the larger spur flowers at the tight cluster stage the following spring. Return flowering was promoted only by ethephon, especially on previous season's shoots. There were no significant interactions between Pro-Ca and ethephon or water stress on most variables observed in this study.

• Proceedings of the National Institute of Ecology of the Republic of Korea
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• v.2 no.2
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• pp.129-138
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• 2021

Living modified organisms (LMOs) are managed by seven government agencies according to their use in South Korea. The Ministry of Environment is responsible for LMOs used for environmental remediation. This study aimed to develop guidelines for assessing potential risks posed by transgenic plants used for remediation to insect ecosystems by investigating arthropod communities in sunflower fields. A total of 2,350 insects and spiders belonging to 134 species of 10 orders and 71 families were collected from sunflower fields over four growth stages ranging from anthesis to seed maturity. At the R3 phase of flower-bud formation, Chironomidae sp. of a decomposer insect guild presented the highest density, while Apis mellifera of a pollinator guild was the most abundant in the R5.8 phase of flowering. During the R7 seed-filling phase and the R9 phase of seed maturity, herbivorous Pochazia shantungensis predominated. During the R9 phase, richness and diversity indices of arthropod communities were distinctly lower whereas their dominance indices were significantly higher than those at other phases. In addition, the composition of arthropod communities was strongly correlated not only with the sampling date, but also with the sampling method depending on the growth stage of sunflowers. Our results suggest that appropriate sampling timing and methods should be considered in advance and that long-term field trials that cover a variety of environmental conditions should be carried out to evaluate potential risks to insect ecosystems.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.42 no.2
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• pp.202-213
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• 1997

In order to find out a high potential black soybean lines, of which demand has been increasing in Korea, twenty eight local cultivars were evaluated on agronomic characteristics and the classification of the cultivars was made by the cluster analysis. Days to maturity and days to growing of black soybeans were widely ranged from 58 to 82 days, and 117 to 148 days, respectively. Late maturing group showed over 140 maturity days, and heavy 100 seed weight. There was shown low yield potential in late maturing group, and growing days was positively correlated with flowering days, days to maturity, 100-seed weight and stem length, respectively. From the principal component analysis upper two components composed 76.5％ cumulative eigen value to total. Nine varietal groups were identified in relations to their affinity of the black soybeans. Selected black soybeans, Namhae-2 and Hamyang-l were field-tested and those characteristics of many pod, small seed and high yield were found out to be suitable for sprouting.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.26 no.2
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• pp.174-178
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• 1981

The experiment was dealt with an investigations on the agronomic potential of primary octraploid triticale in comparion with Chokwang, a major common wheat, local rye cultivar and new triticale selection Suweon #1 and Suweon #2. This octaploid triticale was originated from the cross of Jukoku #81 x Local rye cultivar. The results obtained were summarized as follows; Cold tolerance of the P-Tcl was better than those of the wheat cultivar Chokwang, triticale varieties Suweon #1 and Suweon #2, and comparable to local rye. Culm length of P-Tel was 113cm that was intermediate between the wheat and rye, and its culm thickness was thiner than the checks except the rye. Lateness of heading and maturing date of the P-Tel seemed to be over-dominant. However, flowering date after heading was 3 to 7 days earlier than the Suweon #1 and Suweon #2. Yield potential of the P-Tel was poor in comparision with the triticale cultivar Suweon #1 and Suweon #2 which was attributed to the low fertility and less number of the heads per squ are meter. If it was . improved the low fertility and less number of the valid tillers through the cross with the good secondary triticale it seemed to be an useful material for triticale breeding, expecially for improving cold tolerant winter triticale varieties in Korea.

• Ocean and Polar Research
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• v.27 no.2
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• pp.125-133
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• 2005

This study described the phonology and reproductive potential of four species of Korean seagrasses, Zostera caespitosa, Z. caulescem, Z. Japonica and Z. marina. Z. caespitosa and Z. caulescens sampled from a mixed stand at the subtidal area of Yulpo Bay, Geojedo of the South Sea of Korea in November 2002 and August 2003. Z japonica and Z. marina occurred at the depth between the middle intertidal and shallow subtidal (<1m below mean sea level) of Seungbongdo (in Yellow Sea) samples collected in February and October 2003. The sexual reproductive phase of the four Zostera species was apparently different in timing of flowering, reproductive period, fruiting and seed maturing. Z. caespitosa flowered from February to early May $(10-16^{\circ}C)$, and its seed production completed in early May. The reproductive shoots of Z. caulescens began to appear in January $(9^{\circ}C)$, and its flowering followed from February to June $(10-19^{\circ}C)$. The flowers of Z. japonica were observed from July to September $(18-22^{\circ}C)$, and its seeds matured from August to September. The most commonly I marina flowered from April to August $(7-21^{\circ}C)$ and developed into seeds in July. Z. caulescens, the largest plant, had the highest number of seeds per shoot and longest spadix length. Z. marina, which was intermediate In size, recorded the highest reproductive potential. The study indicates that the reproductive phase and potential of the four species of seagrass from Korea are highly related to water temperature, and the populations of these species show a perennial lifespan with a low sexual reproductive input.

• Journal of the Korean Institute of Landscape Architecture
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• v.40 no.6
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• pp.35-46
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• 2012

This study attempts to specifically analyze green volume and scenery characteristics by classifying the streets in Seoul and suggest improvements accordingly. The subject streets for research were limited to those that have high occupancy ratio and are wide enough to have a big potential in improving green volume. In terms of green volume and scenery according to the types of streets, Platanus occidentalis and Ginkgo biloba were most common regardless of the street type, and the green ratio was 51.6% in residential areas, 50.4% in commercial areas, and 43.7% in business areas. Apart from the residential area, there was almost no green areas, and the ratio of green coverage was 71.0% in business areas, 64.0% in green areas, 37.3% in residential areas, and 36.2% in commercial areas, while the green volume coefficient was $1.9m^3/m^2$ on average. Based on the study results, it was set as a goal to provide the residential areas with a green community space and flowering trees throughout the year for scenery, and commercial areas with flowering trees and maples to emphasize the stores' image while not interfering with service and walking. For business areas, the goals were to improve green ratio and create streets that suit the urban image, and to set up spaces to provide habitat for wild animals with multi-layer planting and link to surrounding forests.

• Korean Journal of Plant Resources
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• v.34 no.4
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• pp.339-345
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• 2021

'Gondalbi' (Ligularia stenocephala (Maxim.) Matsum. & Koidz.) is the most cultivated Gomchwi species because of higher yield and low in aromatic flavor and bitter taste, But 'Gondalbi' is susceptible to powdery mildew disease and leaf shriveling after harvest in Summer. To improve powdery mildew disease resistance and post-harvest leaf shriveling problem in 'Gondalbi', 'Handeari-gomchwi' resistant to powdery mildew disease and having higher yield potential used as a paternal trait donor. Powdery mildew disease resistance and post-harvest leaf shriveling as well as agronomic performance of a new variety, 'Greenbear' were tested under field and green house conditions in Pyungchang, Korea from 2007 to 2016. Expression of both maternal and paternal characteristics in 'Greenbear' including purple colored petiole ears, glossy leaf and paternal, petiole trichome, absent at the back of a leaf were confirmed. Plant size and flowering time of 'Greenbear' were similar to check line, 'Gommany', while leaf number per plant and yield were higher in 'Greenbear'. 'Greenbear' has thinner leaves (0.66mm) compared to 'Gommany (0.69 mm)', and hardness appeared slightly higher in 'Greenbear(25.1 kg/cm²)'. The resistance to powdery mildew disease of the 'Greenbear' variety was slightly lower than that of the 'Gommany' variety, but somewhat showed high resistance.

• Korean Journal of Weed Science
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• v.9 no.3
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• pp.183-200
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• 1989

An experiment was conducted at the greenhouse of the International Rice Research Institute in 1987 to find out the character of dry matter production, the potential seed production ability and the ecological and physiological strategies to adaptation. For these, two rice cultivars, IR64(lowland rice) and UPLRi-5(upland rice), and seven weed species were used ; Echinochloa glabrescens Munro ex Hook. f., E. cress-galls ssp. hispidula (Retz.) Honda, E. colons (L.) Link, Monochoria vaginalis (Burin. f.), Ludwigia octovalvis Jacq.) Raven, Fimbristylis miliacea Vahl and Cyperus difformis L. Adaptation strategies of weed species varied by species. However, they had efficient seed production strategy through different ways. In general, sedge weed species (F. miliacea and C. difformis) produced great amount of seeds at the expense of seed size through greater ratooning ability and low relative dry weight for flowering. For broadleaved weed species, greater number of descendants were obtained through high plasticity and low relative dry weight for flowering (M. vaginalis) or greater growth ability through effective photosynthetic efficiency (L. octovalvis). Grass weed species, on the other hand, produced their seeds through effective growth (net assimilation rate and relative growth rate), high ratooning ability (except E. crus-galls ssp. hispidula) or low relative dry weight to maximum dry weight for flowering (E. glabrescens). The harvest indices of the weed species were considerably lower than those of rice. Fimbristylis miliacea had the greatest ratooning ability followed by C. difformis, E. colons and E. glabrescens. The greatest seed productivity was recorded by C. difformis (279, 000) and L. octovalvis (268,000) while rice produced the least number of seeds (1300-6100). Log seed weight had a negative linear relationship with log seed number (y=6.30-1.48X, $R=-0.965^{**}$). For all species plant plasticity response was not directly correlated with mortality response.