• Korean journal of applied entomology
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• v.26 no.4 s.73
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• pp.221-228
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• 1987

The optimum temperature range for conidial germination of Pyriculacia oryzae on a slide glass was $26{\sim}30^{\circ}C$, at which at least four hours of leaf wetness period was required to germinate. Conidial germination was significantly reduced under dry conditions (relative humidity<85%) at $34^{\circ}C$ but not at lower temperature (18, 22, 26, $30^{\circ}C$). Number of lesions developed were greater at $26^{\circ}C$ than at other temperature tested. The average leaf wetness period required for production of a lesion per plant was 22 hours at $18^{\circ}C$, 16 hours at $22^{\circ}C$, 10 hours at $26^{\circ}C$, and 8 hours at $30^{\circ}C$. Less than one lesion per plant occurred at $34^{\circ}C$ even under 24 hours of leaf wetness period. The time period between inoculation and lesion appearance was $7{\sim}8$ days at $18^{\circ}C$, $4{\sim}5$ days at $22^{\circ}C$ and $26^{\circ}C$, and $3{\sim}4$ days at $30^{\circ}C$. The time period required for lesion appearance after inoculation was not affected by leaf wetness period and relative humidity. Lesion length increased most rapidly at $30^{\circ}C$ during the first four days after lesion appearance. Thereater, the rate of increase in lesion length was geratest at $26^{\circ}C$. The average increment of lesion length per day when relative humidity was greater than 90% was 0.7mm at $18^{\circ}C\;and\;22^{\circ}C$, 1mm at $26^{\circ}C$, and 0.8mm at $30^{\circ}C$. When relative humidity was less than 85%, the increments of lesion length per day were approximately $50{\sim}60%$ of those under humid conditions (relative humidity>90%) at all temperature regimes except $30^{\circ}C$. Relative humidity did not significantly affected lesion length at $30^{\circ}C$.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.38 no.4
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• pp.336-342
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• 1993

To obtain the basic information necessary for the development of soybean varieties well adaptable to upland-paddy field rotational croppings, the difference of growth characteristics between upland and paddy-field including yield potentials of current recommending soybean varieties were evaluated. The growth characteristics, both above and under-ground, which were measured at flowering stage were generally greater in paddy-field but the number of root nodules was much greater in upland, thus the artificial inoculation was practically recommended for soybean growing in paddy-fields. Mean seed yield was generally higher in paddy-fields than in upland. All soybean varieties showed higher seed yield in the early planting date, April 20, were somewhat susceptible to soybean mosaic virus(SMV), thus they could be escaped from the disasterous endemic necrotic soybean mosaic virus(SMV-N). Soybean varieties showed over 4.0 tons/ha seed yield in the paddy-field were Williams 79, Union, SS77053, and Namhaekong. At the same time, Jangyeobkong and Danyeobkong were the most stable soybean varieties among the tested soybean varieties with less than 10% of coefficient variation values in all planting dates in paddy fields. Compared with Hwangkeumkong which is most widely being cultivated on farmer's fields, soybean varieties showed high yields in paddy-field were higher in plant height, less in the number of branches, and more in the number of nodes on main stem. At the same time, they had medium seed size which would bring the good germination and stands. Disease resistance especially for necrotic soybean mosaic virus was also one of the most decisive factors in seed yields for the early planted soybeans.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.51 no.5
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• pp.420-424
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• 2006

This experiment was conducted to elucidate the basic physiological phenomena of pollination and fertilization for breeding in perilla (Perilla frutescens) through different 6 varieties derived from 2 genera under 4 temperature conditions at day and night. The pollen germination was observed after 30 minutes and pollen tube reached the lower part of pistil after 1 hour from artificial pollination. Seed formation was affected by temperature condition and a variety. The early maturing variety 'YCPL 25' showed a poor seed formation rate under the night temperature below $15^{\circ}C$, but the late maturing variety 'YCPL263' did not lowered even though the night time temperature was $10^{\circ}C$. The function of pistil was long maintained under the low temperature from the fact that if the live pollen pollinate artificially to the flower that does not form seed under low temperature, fruiting was made. Pollen was created and pollen tube was developed in the time of petal becomes bigger than calyx in five varieties, 'YCPLl77-1' etc. However, pollen was made and pollen tube was made only 71% in a green chajogi 'YCPL205-1'. These physiological phenomena of pollination and fertilization could be applicable to the emasculation and an effective breeding in perilla.

• The Plant Pathology Journal
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• v.17 no.3
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• pp.141-148
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• 2001

Postharvest decay of onion bulbs was examined by inspecting the commercial packages in the market or in storage. Bulb rot incidence was unexpectedly high, and onion bulbs with 1st quality grade were rotten most severely by 51%, followed by 32% for 2nd and 21% for 3rd grades. This indicates that larger bulbs had higher incidences of bulb rots. Major pathogens associated with basal and neck rots were Fusarium oxysporum and Aspergillus sp. or Botrytis allii, respectively, of which basal rot was most prevalent and damaging during storage. Among the epiphytic microorgani는 from onion plants, several Bacillus and Paenibacillus spp. and previously selected Pseudomonas putida and Trichoderma harzianum had inhibitory efficacy against bulb rot pathogens. Among these B. amyloliquefaciens BL-3, Paenibacillus polymyxa BL-4, and P. putida Cha 94 were highly inhibitory to conidial germination of F. oxysporum and B. allii. P. putida Cha 94, B. amyloliquefaciens BL-3, P. polymyxa BL-4, and T. harzianum TM were applied in the rhizoplane of onion at transplanting. Initially antagonist populations decreased rapidly during the first one month. However, among these antagonists, rhizoplane population densities of BL-3, Cha 94, and TM were consistently high thereafter, maintaining about 10$^4$-10$^{5}$ cells or spores per gram of onion root up to harvest time. The other bacterial antagonist BL-4 survived only for two months. TM was the most effective biocontrol agent against basal rot, with the number of rotten bulbs recorded at 4%, while that of the control was 16%. Cha 94 was effective for the first 20 days, but basal rot increased thereafter and had about the same control efficacy as that of BL-3 and BL-4. When the antagonists were applied to the topping areas of onion bulbs at harvest, TM was the most effective in protecting the stored onion bulbs from neck rotting. The second effective antagonist was BL-3. TM and BL-3 completely suppressed the neck rot in another test, suggesting that biocontrol of postharvest decay of onion using these microorganisms either at the time of transplanting or at harvesting may be promising.

• Korean Journal of Weed Science
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• v.8 no.2
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• pp.158-163
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• 1988

Several factors affecting emergence and tuber formation of lowland perennial weeds were studied at the Yeongnam Crop Experiment Station in 1988. Period of tuber germination start to final tuber varied by species. Eleocharis kuroguwai and Sagittaria trifolia required longer than 10 days at $30^{\circ}C$ for this while Cyperus serotinus and S. pygmaea needed about 4 days. Application of gibberellic acid shortened this period while Uniconazole application delayed. E. kuroguwai and C. serotinus had ability to emerge under 20cm depth placement. However, S. trifolia could not emerge under 15cm depth. All species decreased their growth with increase in planting depth. E. kuroguwai had least correlated between dry matter production and tuber formation. Clipping of above ground part negatively related with tuber formation eventhough the effect of clipping time was differed by species. The most critical clipping time was 60 days after eremergence (DAE) for E. kuroguwai and 90 DAE for C. serotinus. Covering of colored polyethylene film was also related with tuber formation with varing effects. In general, the order of effectiveness for tuber formation were black. orange. blue and red. Application of Uniconazole and Pachlobutrazol effectively controlled the formation of tuber of E. kuroguwai and this effect enhanced by early application.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.60 no.4
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• pp.484-490
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• 2015

Thirty-eight Pea (Pisum sativum L.) genotypes were screened to identify varieties to be suitable for sprout. Based on seed yield and sprout qualities such as whole length and sprout yield, five genotypes (PI269803, PI343278, PI343283, PI343300 and PI 343307) were primarily selected as candidates for pea sprouts. In order to determine optimal cultivation condition for pea sprouting, growth characteristics were investigated according to the change of germination temperature and days for sprouting. Whole length and hypocotyl length were observed to increase as a time dependent manner at each tested temperature (20, 23, and $25^{\circ}C$). However, whole length, hypocotyl length, and sprout yield were highly increased at $23^{\circ}C$ compared to 20 and $25^{\circ}C$. Especially, PI269803 and PI343300 showed higher sprout yield than the others. In addition, the effect of the change of germination temperature on antioxidant properties was estimated by measuring total phenolic content (TPC) and free radical scavenging activity (DPPH and ABST activity). TPC and DPPH/ABST activities of PI269803 and PI343300 were higher at $23^{\circ}C$ than at 20 and $25^{\circ}C$, while antioxidant properties of PI343278 and PI343283 were decreased in a temperature-dependent manner. The results show a high degree of correlation between TPC and antioxidant activities and suggest that the temperature change for pea sprouting could be responsible for antioxidant properties. Taken together, these results provide optimal cultivation conditions for pea sprouting and suggest that PI269803 and PI343300 with high sprout yield and antioxidant properties could be used for pea sprouts.

• Journal of The Korean Society of Grassland and Forage Science
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• v.43 no.4
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• pp.216-224
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• 2023

Since maize (Zea mays L.) originated in central and south America, it requires warm climate conditions throughout its growing season. Growth halts when night-time temperatures drop below 10℃, and the plant may die if temperature reach -1.7℃. Thus, temperature should be maintained between 10 and 30℃ from seeding to maturity. The germination temperature for maize should be at least 8-11℃, whit an optimal range 32-34℃. Since temperature significantly affects the germination rate and period, it plays a crucial role in maize growth. In this study, we evaluated the quantity and feed value of 11 major varieties to determine those best suited for maize cultivation as feed in higher latitude, specifically in Democratic People's of Republic of Korea, below 38 degrees north. A cultivation test was also conducted in Suwon in Republic of Korea, to assess adaptability in areas south of Mt. Suyang. Among the varieties tested, Shinhwangok2 reached silking the fastest, in 65 days, while Gwangpyeongok took the longest at 75 days. The stem length of all varieties exceeded 230 cm. Gwangpyeongok had the tallest stems, while Daanok and Shinhwangok2ho displayed the highest ear ratios. Dacheongok presented the highest values in both dry matter and TDN quantity, with 31,420 kg/ha and 21,66 kg/ha respectively. Pyeonggangok had the highest crude protein content at 8.0%. TDN (%) ranged from 57-68%, with Hwangdaok reaching up to 68%. Based on these findings, Dacheongok and Pyeonggangok appear to be the most suitable varieties for cultivation in terms of both quantity and feed value.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.37 no.3
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• pp.257-263
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• 1992

Immature embryos were tested for investigating the effect of cold treatment duration and GA$_3$ concentration on the vernalization response in barley. Immature embryos were cultured on B$_{5}$ medium with GA$_3$ for 5 days, and were transplanted under 20/15$^{\circ}C$ temperature after cold treatment. Germination rate and shoot length were increased more in 20-day-old embryos than those in 13-day-old ones but germination day was decreased. Addition of 1 or 10 ppm of GA$_3$ to B5 medium was effective on the growth of immature embryos. The higher GA$_3$ concentration was, the shorter time from embryo culture to flag leaf emergence and heading was. The earlist flag leaf emergence and heading were showed on treatment of 1 or 10 ppm of GA$_3$, but GA$_3$ did not completely replace vernalization. The days to flag leaf emergence of immature embryo-cultured barley with cold treatment for two and three weeks was shortened by 3 and 18 days at 1 ppm GA$_3$, and 16 and 20 days at 10 ppm GA$_3$, respectively, when compared to 0 ppm GA$_3$ culture with cold treatment for three weeks. It was at 10 ppm GA$_3$ with 3 weeks cold treatment that showed the lowest culm length, spike length and number of grain per spike. GA$_3$ concentration was not correlated significantly with each character in 1 week cold treatment, but was significant with each character in 2 weeks. In 3 weeks cold treatment, it was except for days to heading. Correlation between cold treatment duration and culm length was negative in 0 ppm GA$_3$. In 1 or 10 ppm of GA$_3$, all characters had highly negative correlation with cold treatment duration.n.

• Research in Plant Disease
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• v.11 no.2
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• pp.128-134
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• 2005

This study was conducted to elucidate effect of environmental factors on the development of white rot. In order to identify the causal agents causing white rot of Allium crops, we compared DNA profiles of a representative isolate, Sclerotium cepivorum, introduced from foreign country with Korean isolates using UP-PCR. As a result, Sclerotium isolates forming round-shaped sclerotia were identified as Sclerotium cepivorum pertaining in UP-PCR b group and Sclerotium isolates farming anamorphic-shaped sclerotia presumed to be a novel species of Sclerotium based on DNA profiles of UP-PCR. There was a big difference in DNA band pattern between two species of Sclerotium isolated in Korea. Electron micrographs of scanning electron microscope and transmission electron microscope showed morphological differences in sclerotial surface structure and rind layers between two species of Sclerotium. There were more wrinkles and pore spaces on sclerotial surface of Sclerotium sp. forming anamorphic-shaped sclerotia than that of Sclerotium cepivorum forming round-shaped sclerotia. Both of two white rot pathogens grew well at the temperature range of $10-25^{\circ}C$ with optimal temperature of $20^{\circ}C$. Sclerotia of the two pathogens were well formed at $20^{\circ}C$ and well germinated at the temperature range of $20-24^{\circ}C$, Effect of pre-incubation of sclerotia on destruction of sclerotial dormancy of two pathogens was evaluated through storing sclerotia under different temperature condition. The sclerotia of the two pathogens showed an increased capacity to germinate on potato dextroise agar when the sclerotia were incubated for 7 days at $10^{\circ}C$ after pre-treatment at $35^{\circ}C$ for 7 days. At that time, germination rate of Sclerotium sp. and 5. cepivorum was $100\%\;and\;70\%$, respectively. Flooding period and treatment temperature had an effect on sclerotial survival rate of the two pathogens. As flooding period and treatment temperature increased, sclerotial germination rate of the two pathogens decreased. It was confirmed that soil humidity played an important role on development of white rot. It was the highest disease incidence of garlic white rot when garlic were sown at potted soils infested with the two pathogens and adjusted soil humidity to $15\%$ (field moisture capacity, about -300 mb). As soil humidity increase or decrease based on $15\%$ of soil humidity, disease incidence decreased move and more.

• Horticultural Science & Technology
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• v.31 no.1
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• pp.80-88
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• 2013

Carrot (Daucus carota L. var. sativa) is one of the most extensively used vegetable crops in the world and a significant source of nutrient because of its high content of ${\beta}$-carotene, well known as the precursor of vitamin A carotenoid. However, seed-hairs generated and elongated from the epidermal cell of seeds inhibit absorption and germination by various factors such as carotol and so on. Accordingly, mechanical hair removal process is essential before commercialization of carrot seeds. Because of this process, producers will have additional losses such as time consuming, manpower, capital and so on. Furthermore, physical damage of seeds causes irregular germination rate. To overcome such cumbersome weaknesses, new breeding program for developing hairless-seed carrot cultivar has been needed and studies for molecular markers related to seed-hair characteristic is needed for a new breeding program. Therefore, in this study, cDNA libraries from seeds of short-hair seed phenotype CT-SMR 616 OP 659-1 line, hairy-seed phenotype CT-SMR 616 OP 677-14 line and short-hair seed phenotype CT-ATR 615 OP 666-13 line, hairy-seed phenotype CT-ATR 615 OP 671-9 were constructed, respectively. Furthermore, 1,248 ESTs in each line, total 4,992 ESTs were sequenced. As a result, 19 SNP sites and 14 SNP sites in each of 2 combinations were confirmed by analyzing these EST sequences from short-hair and hairy-seed lines. Then we designed SNP primer sets from EST sequences of SNP sites for high resolution melting (HRM) analysis. Designed HRM primers were analyzed using hairy seed phenotype CT-SMR 616 OP 1040 line and short-hair seed phenotype CT-SMR 616 OP 1024, 1025, 1026 lines. One set of HRM primers showed specific difference between the melting curves of hairy and short-hair seed phenotype lines. Based on this result, allele-specific (AS) PCR primers were designed for easier selection between hairy-seed carrot and hairless seed carrot. These results of HRM and AS-PCR are expected to be useful in breeding of hairless seed carrot cultivar as a molecular marker.