• Journal of Plant Biotechnology
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• v.42 no.3
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• pp.215-222
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• 2015

The radish (Raphanus sativus L.) is an important Brassicaceae root vegetable crop worldwide. Several studies have been conducted concerning radish breeding. There are major challenges to prevent premature bolting in spring plantings. Here, we performed the characterization of two inbred radish lines which vary in bolting time. "Late bolting radish" (NH-JS1) and "early bolting radish" (NH-JS2) were generated by a conventional breeding approach. The two inbred lines showed different bolting phenotypes depending on vernalization time at $4^{\circ}C$. NH-JS1, the late bolting radish, was less sensitive to cold treatment and the less sensitivity was inversely proportional to the duration of the vernalization. We also measured gene expression levels of the major bolting time related genes in the NH-JS1 and NH-JS2 lines. RsFLC1 plays a central role in the timing of flowering initiation. It is a strong repressor and it's transcript is highly expressed in NH-JS1 compared to NH-JS2 under no treatment and vernalization conditions. RsFRI, a positive regulator of RsFLC, is also highly expressed in NH-JS1 compared to NH-JS2 regardless of vernalization. In contrast, RsSOC1, suppressed by FLC as a floral integrator gene, showed the most difference, a 5-fold increase, between NH-JS1 and NH-JS2 under vernalization conditions. From these results, we conclude that NH-JS1 showed a late flowering phenotype after cold treatment due to the expression differences of flowering time regulator genes rather than difference sensitivity to cold. These results may be useful to understand the control mechanisms of flowering time and may help identify molecular markers for selecting late bolting trait in radish.

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

• Horticultural Science & Technology
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• v.33 no.4
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• pp.501-510
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• 2015

In this study, we investigated the onset and release of endo-dormancy under natural conditions by observing bud break characteristics in 'Fuji' apple trees using water cuttings. Through examinations of bud break rate and days to bud break, we found that the endo-dormancy of 'Fuji' apple tree continues for 70 d from 165 to 255 d after full bloom (DAFB), from late October to early January of the following year. In addition, within 20 d of first bud break, based on a final bud break rate of 60% or more, we able to identify the timing of the changeover from para-dormancy to endo-dormancy, and endo-dormancy to eco-dormancy. Analysis of the chilling requirement during the endo-dormancy period revealed that chilling accumulation up to 255 DAFB to release endo-dormancy amounted to 666 and 517 h based on the CH and Utah models, respectively. Observation of internal changes in the bud during endo-dormancy showed that flower bud differentiation begins from mid-July, and t ime of inflorescence o f the disk f lower is a vailable to f ind. The f lower buds subsequently developed slowly but steadily during endo-dormancy and in the following year in February, the developmental stage of each organ had progressed. Moreover, the flower buds of 'Fuji' apples were mostly healthy during the dormancy period, but some exhibited necrosis of flower primordium, due partial cell damage from the formation of ice crystals rather than a direct effect of the low temperature. Flower buds were formed in both the axillary buds of bourse shoots and terminal buds of spurs, but lower bud differentiation was observed for the terminal buds of spurs at rate of about 65% of total buds, which was directly related to the bud size and shoot diameter.

• Korean Journal of Organic Agriculture
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• v.24 no.2
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• pp.235-251
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• 2016

After carrying out on-the-spot observation targeting each farmhouse of large-scale environment-friendly agricultural district (LEAD), Suncheon, Sancheong, Jangheung, Yeongam, Hamyang, Okcheon, and Jeongseon in 2015, only one LEAD, a farmhouse in Jangheung had used sustainable compost coming out under their own non-antibiotic livestock. The soil pH and EC at a depth of 0-20 cm in the seven LEADs were ranged between 5.3-6.6 and $0.4-1.2dS\;m^{-1}$, respectively, with 0.03- 0.27% for T-N concentration, $22-322mg\;kg^{-1}$ for P, and $0.05-0.29mg\;kg^{-1}$, which were, in particular, low a farmhouse in Jeongseon. When intensively surveying on each farmhouse of Suncheon, Jangheung, and Okcheon for a growing period, seasonal soil pH was maintained above 6.0 and high in a farmhouse in Okcheon, with similar soil EC observed among the three LEADs. Seasonal soil T-N was 0.1% higher on the farmhouse in Suncheon than other two LEADs, with higher seasonal soil P observed on the farmhouse in Okcheon and higher soil K in the Jangheung. T-N concentration in rice (Oryza sativa L.) crops was the highest in Jangheung, and concentrations of T-N, P, and K decreased in a season. Plant height and number of tillers per hill were the highest on the farmhouse in Okcheon, where was similar or low plant diameter and SPAD levels compared to other two LEADs. Dry weight (DW) before harvest was ranged between 52-63 g, and DW, rough rice yield (kg), brown rice/rough rice (%), brown rice yield (kg), head rice (%), and broken rice (%) were not significantly different among the three LEADs. Total annual gross production ha-1 was the highest on the farmhouse in Okcheon (16,230,000 won) planting with high class of variety, 'Milky queen' at early maturation, which was expected to be increased on an agricultural income. However, high amount of fertilizer was applied for growing the following crops on the farmhouse in Okcheon, affecting the highest balance of T-N, P, and K more than $200kg\;ha^{-1}$.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.17
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• pp.79-114
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• 1974

Experiments were conducted to clarify the variations of the ecological characteristics under different day-length and temperature conditions inperilla varieties from 1972 to 1973 in the experimental fields of Crop Experiment Station, O.R.D, Suwon. Thirty-six varieties were tested in the field in 1972 under 6 growing seasons differing seeding dates. from April 5th to June 20th with 15-day interval between each seeding. Pot-experiment also were conducted in 1972 and 1973. The seeds of the 6 varieties tested were sown on May 25th. In this pot-experiment natural condition was regarded as a short-day treatment and 100-W incandescent lamps were used for long-day treatment. Three selected varieties were grown under different. temperature treatments in phytotron in Crop Experiment Station. The results obtained are summarized as follows: 1. Most varieties tested flowered around September 6. The days required to flower were shortened gradually as the planting time was delayed. 2. The varieties used were matured around October 6, but the maturity was shortened when planted early. The days required for maturity after flowering was 26 to 30. 3. The growing period was also shortened gradually when planting time was delayed. 4. Plant height was reduced when planting time was delayed. 5. There were little differences in number of valid branches among planting time I, II and III, while the branch number was reduced as the planting time was delayed. 6. The dry matter weight was gradually increased from planting time I to III, while it was rapidly decreased after planting time IV. 7. It was found that the flowering of perilla was little affected by temperature. The varieties, however, were more sensitive to day-length. 8. No clear tendency was found in the plant height, number of valid branches and dry matter weight by the time and period of day-length and temperature treatments. 9. The highest yield was obtained at planting time III(May 5th) and the yield was decreased at either earlier or later planting. 10. 1, 000 grain weight appeared to be heavier as the planting time was delayed. 11. The number of flower cluster was largest at planting time III (May 5th) and it was decreased as planting time was earlier or later than III. 12. The oil content was also highest at planting time III (May 5th). 13. Days to flowering, days to maturity and total growing period and flowering period did not affect the yield much. 14. The number of valid branches, flower clusters, 1, 000-grain weight and dry matter weight were positively correlated with yield. The relationship between these characters and yield were variable depending upon the planting time.

• Research in Plant Disease
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• v.24 no.2
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• pp.145-152
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• 2018

During 2015-2017, we surveyed the incidence of viral infections of tomato and paprika growing in greenhouses in Cherwon province, Korea. In 2015 and 2016, we collected leaves and fruits from tomato and paprika plants growing in greenhouses. We detected viruses in the samples collected using specific primer sets for Broad bean wilt virus 2 (BBWV2), Cucumber mosaic virus (CMV), Pepper mild mottle virus (PMMoV), Pepper mottle mosaic virus (PepMoV), and Tomato spotted wilt virus (TSWV). We detected PMMoV, CMV, and TSWV in the samples, and CMV and TSWV were the most prevalent. For the prevention of future viral diseases, we then surveyed the routes of infection by these viruses in tomato and paprika plants growing in greenhouses in Cherwon province in 2017. Leaf and fruit samples were collected from seedlings and crops two and four months after transplanting into greenhouses. As a result, we found that TSWV was transferred from seedlings to plants, and outbreaks of the virus occurred at the early stage of cultivation. On the other hand, we found that CMV was a virus indigenous to the soil of some towns in Cherwon province, and thus outbreaks of this virus occurred at the middle stage of cultivation.

• Korean Journal of Weed Science
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• v.1 no.1
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• pp.30-43
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• 1981

On unwedded paddy fields, six cropping patterns of rice cultivation, namely direct broadcast seeding, direct row seeding, machine transplanting, early season hand transplanting, standard season hand transplanting, and late season hand transplanting, were detected with two representative rice cultivars (Milyang 23 and Sadominori) to estimate the comparative fluctuation patterns of weed flora. As a result, number of emerged weed species, most crowding stages, differences of weed growth among cropping patterns, possible tendencies of competition in plant heights among plant groups, variations in Importance Values, and Simpson's Index analysis were discussed, respectively.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.56 no.2
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• pp.134-139
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• 2011

This study was conducted to evaluate the weed suppressing effects of two winter cover crops, hairy vetch and rye in foxtail millet and sorghum fields in 2010. Crop growth and development and weed occurrences in the fields were examined to know the efficiency of proposed cropping system. In hairy vetch treated plots, heading of minor cereals occurred early. The heading date was earlier by 1 day and 2 days in sorghum and foxtail millet, respectively. However, rye treatment delayed heading by 12 days and 8 days in sorghum and foxtail millet, respectively. Besides he effect of cover crop on ear emergence of crops, the Besides changed growth-related characteristics. Plant height, chlorophyll content and chlorophyll fluorescence of sorghum ere increased in hairy vetch treatment by 46.4% 88.7% and 7.9%, respectively. In foxtail millet, the characteristics ere also increased by 45.6%, 50.9% and 37.8%, respectively, s compared to control. Yields of sorghum and foxtail millet were increased by 105.1% and 135% as compared o control by hairy vetch treatment, respectively. However, he yields of cereal crops were decreased by rye cover crop treatment, the yields of sorghum and foxtail millet were decreased by 25.8% and 119.1%, respectively. Rye cover crop treatment inhibited crop growth suggesting nitrogen starvation in rye treated plots. In rye treatment, plant height, chlorophyll contents and chlorophyll fluorescence of sorghum ere slightly decreased by 7.1%, 10.8% and 10.8%, respectively, as compared to control whereas the inhibitory effects were greater in foxtail millet. Weed occurrences based n weed number in hairy vetch and rye plots were reduced n weed number in hairy vetch and rye plots were reduced y 27% and 20%, respectively. The smothering effect was weakened or disappeared after heading of crops. Weed number and dry weight in hairy vetch plot were increased by 159% and 55.2%, respectively, as compared to control. The results implied that weed suppressing of cover crops could be reduced drastically after heading of crops.

• Applied Microscopy
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• v.38 no.2
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• pp.117-124
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• 2008

Salvinia is an aquatic plant forming dimorphic leaves that have been modified into floating and submerged leaves. A air of floating leaves plays an important role for the floating and photosynthesis while the submerged leaves, which are lim and long, have the form and function of root. Many aquatic plants develop trichomes in the epidermis but in Salvinia, richomes grow densely in the epidermis of the dimorphic leaves. The present study examined the differentiation pattern of trichomes developing in the floating leaves of S. natans and S. molesta by scanning and transmission electron microscopy. Trichomes developing in the floating leaves of Salvinia showed very different patterns. In S. natans, they were arranged in a V-shape form, having 20${\sim}$25 rows at $18{\sim}25^{\circ}$ on both sides of the lamina divided by the midrib in the floating leaf. In each row, 8${\sim}$10 oval-shaped cells, $200{\sim}290{\mu}m$ in length, were arranged in a spiral fashion. Four trichomes of this form made a trichome unit, but their apical parts were separated from one another and developed into the so-called 'knuckle-crane' type. On the other hand, in S. molesta, trichomes differentiated in a unique pattern quite different from those of S. natans. At the early stage of differentiation, trichomes protruded from the epidermis and then 4${\sim}$6 cylindrical cells grew $400{\sim}600{\mu}m$ long and the four trichomes formed as an unit. The four grouped trichomes were interconnected through their apex and developed in the 'egg-beater' type. Then $300{\sim}600{\mu}m$ long multi-cellular stalk cells grew and protruded out of the epidermal surface from the basal part of the trichomes. Such a structural characteristic of trichomes is considered to play a very important role along with the aerenchyma tissue in the leaf mesophyll tissue for the floating of Salvinia on the water surface.

• Horticultural Science & Technology
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• v.35 no.1
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• pp.1-10
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• 2017

We investigated growth, clove development, and photosystem II activity in garlic (Allium sativum L.) grown under different day/night temperature regimes using Soil-Plant-Atmosphere - Research (SPAR) chambers to determine the optimum cultivation temperature and to assess the impact of temperature stress on garlic. In the early stages of growth, plant growth increased markedly with temperature. At harvest time, however, the pseudostem diameter decreased significantly under a relatively low day/night temperature range ($14/10-17/12^{\circ}C$), suggesting that these temperature conditions favor regular bulb growth. At harvest time, the bulb diameter and height were great at $14/10-23/18^{\circ}C$, whereas the bulb fresh weight and number of cloves per bulb were greatest at $17/12-20/15^{\circ}C$. However, the number of regularly developed cloves per bulb was highest at the relatively low temperature range of $14/10-17/12^{\circ}C$, as were the clove length and fresh weight. The photochemical efficiency ($F_v/F_m$) and potential photochemical efficiency ($F_v/F_o$) of photosystem II in the leaves of garlic plants were higher at $14/10-20/15^{\circ}C$ and lower at temperatures below $14/10^{\circ}C$ or above $20/15^{\circ}C$, implying that the $14/10-20/15^{\circ}C$ temperature range is favorable, whereas temperatures outside this range are stressful for garlic growth. Furthermore, at temperatures above $20/15^{\circ}C$, secondary growth of garlic, defined as lateral bud differentiation into secondary plants, continuous growth of the cloves of the primary plants, or the growth of bulbil buds into secondary plants, was enhanced. Therefore, to achieve commercial production of fresh scapes and bulbs of garlic, it may be better to grow garlic at relatively low temperature ranges of $14/10-17/12^{\circ}C$.