• Research in Plant Disease
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• v.14 no.3
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• pp.143-152
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• 2008

Mixed-planting of two rice cultivars, HP ('Hopyeongbyeo') and NP ('Nampyeongbyeo'), having a dissimilar susceptibility to rice blast was practiced for chemical-free control of rice blast in the field. The HP/NP combination was selected for applying under mechanized agricultural conditions. Because they have similar genetic characteristics such as seed germination and heading time, culm length, rice quality and size of rice grains except susceptibility to blast. Incidence of panicle blast was reduced 50.4 % compare with supposed blast incidence by HP/NP mixed-planting when the seeds of two cultivars were combined 1 to 1 as weight. Supposed blast incidence was estimated from reduction of rice blast caused by addition of a resistant cultivar NP. Race diversity of Magnaporthe oryzae was examined for correlation with control effect of HP/NP mixed-planting on rice blast. The population of dominant race KJ-101 was diminished and replaced with various co-existing races and eleven new races were appeared in mixed-planting plot. Total number of race isolated from mixed-planting plot was not largely different from mono-culture. However, detection frequency of the new race was increased and variation of the population size of each race was decreased in mixed-planting plots. It was shown that a biased community with a dominant race (KJ-101 or KI-181) was altered to a balanced one of coexisting races. From these results, it was supposed that the balanced diversity among co-existing races within a community might be correlated to control effect by HP/NP mixed-planting on rice blast. Further more, it should be studied that genetic characteristics of the individual race including a virulence on cv. HP and NP was examined for verifying a correlation of mixed-planting effect and race diversity.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.56 no.3
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• pp.264-272
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• 2011

It needs to develop high phosphate-available rice that is able to minimize environmental pollution caused by phosphate fertilizer. Then we have transformed 4 rice transporter genes, OsPT(Oryza sativa Phosphate Transporter)1, OsPT4, OsPT7 or OsPT8, to rice (Oryza sativa cv. Dongjin) via Agrobacterium-mediated transformation. We tested adaptation in the P-deficient condition of Dongjin (parental) and each transgenic line in the pot and the field conditions. Definite physiological changes have been observed in OsPTs transgenic lines including culm length, root formation and heading date. Phosphate uptake at harvesting stage was about three times higher in OsPT1-OX (overexpression) and OsPT4-OX than in Dongjin (wt) without P application. There are no variations in total phosphate-content of brown rice of OsPT1-OX in spite of high phosphate uptake. Practically the expression of OsPT1 has contributed to stabilize grain production without P fertilization in rice cultivation than Dongjin.

• Journal of The Korean Society of Grassland and Forage Science
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• v.29 no.1
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• pp.7-12
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• 2009

This experiment was conducted to compare the agronomic characteristics and productivity in introduced forage pea cultivars at the experimental field. The experiment was arranged in a randomized block design with three replications. The forage pea used in this study were two cultivars ('Livioletta', 'Austrian Pea') and one Chinese milk vetch cultivar (Chinese domestic cultivar). Flowing of 'Livioletta' cultivar was May 16th and 'Austrian Pea' cultivar was 18th May, 20 days later than the former. The 'Livioletta' cultlvar showed stronger than winter hardiness of 'Austrian Pea' cultivar. Dry matter (DM) content of 'Liviotetta' and 'Austrian Pea' cultivars were 22.5% and 20.9% chinese milk vetch showed the lowest content with 17.7%. 'Austrian pea' cultivar showed the highest DM yield with 5,617 kg/ha but the DM yield of 'Livioletta' cultivar was low with 3,652 kg/ha. The yield of CP (crude protein) and TDN (total digestible nutrient) set high at 'Austrian Pea' cultivar. And 'Livioletta' and 'Austrian Pea' cultivars showed CP content with 15.5% and 14.4% but Chinese milk vetch with 19.3%. The acid detergent fiber (ADF) and neutral detergent fiber (NDF) content of 'Austrian Pea' cultivar were 23.2% and 40.3%. Therefore 'Austrian pea' cultivar seems to be suitable varieties in paddy field as winter forage crops.

• Journal of Bio-Environment Control
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• v.9 no.3
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• pp.171-178
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• 2000

Gross photosynthetic rats of leaves of hydroponically grown cucumber plants(Cucumis sativus L. cv. Guwoosalichungjang) were measured under various conditions of photosynthetic photon flux(PPF), ambient $CO_2$ concentration, air temperature and leaf nitrogen contents. Light compensation point of leaf photosynthesis appeared to be in the range of 10~20$\mu$mol.m$^{-2}$ .s$^{-1}$ and light saturation point be above 1000$\mu$mol.m$^{-2}$ .s$^{-1}$ . Gross photosynthetic rates increased persistently and asymptotically as air temperature rose from 12$^{\circ}C$ to 32$^{\circ}C$. However, there were only small differences in gross photosynthetic rates in the range of 24-32$^{\circ}C$, so that the range seemed to be optimal for photosynthesis of cucumber plants at the condition of $CO_2$ concentration of 400$\mu$mol.mol$^{-1}$ and PPF of around 400$\mu$mol.m$^{-2}$ .s$^{-1}$ . $CO_2$ compensation point of leaf photosynthesis appeared to be in the range of 20-40$\mu$mol.mol$^{-1}$ and $CO_2$ saturation point be above 1200$\mu$mol.mol$^{-1}$ . Gross photosynthetic rates increased sigmoidally as leaf nitrogen content increased. These environmental factors interacted synergistically to enhance gross photosynthetic rate, so that the rate increased multiplicatively s level of one factor increased progressively with higher levels of he other factors. Mathematical models wer developed to estimate the gross photosynthetic rate in accordance with the variations of these environmental factors. These modes can be used not only to explain he variation of growth or yield of cucumber plants under different environmental conditions but also as building blocks of plant growth model or expert system of cucumber plants.

• Journal of Bio-Environment Control
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• v.12 no.3
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• pp.152-159
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• 2003

This study was conducted to analyze the water consumption in closed transplants production system (CTPS) for the production of quality transplants and to investigate the effect of relative humidity on the water balance in CTPS. Potato (Solanum tuberosum L. cv. Dejima) plug seedlings were grown for 15 days at air temperature of 20$^{\circ}C$, relative humidity of 70%, photoperiod of 16/8 h, and photosynthetic photon flux (PPF) of 200 ${\mu}mol{\cdot}m^{-2}{\cdot}s^{-l}$ following rooting for 5 days in CTPS. Amount of humidified, dehumidified, irrigated and evapotranspirated water were 67.9 kg${\cdot}m^{-2},\;196.9{\cdot}m^{-2},\;44.3\;kg{\cdot}m^{-2},\;33.5\;kg{\cdot}m^{-2}$, respectively. Water content of media and plants were 1.2 kg${\cdot}m^{-2},\;6.9\;kg{\cdot}m^{-2}$, respectively. Three relative humidity levels of 60, 70, and 80% were provided to analyze the effect of humidity on the water balance in CTPS. Amount of humidified, dehumidified, irrigated, evapotranspiratad water and water contents of media and plants increased with increasing relative humidity. Since the water consumption required to produce plug seedlings in CTPS dec1eased with decreasing relative humidity, the available water utilization efficiency of CTPS increased with decreasing relative humidity. CTPS showed high available water utilization efficiency of 0.92 - 0.97 if dehumidified water in CTPS was recycled. The development of CTPS with recycling system of dehumidified water will not only reduce the water consuming for the production of transplants but contribute to the establishment of plant production economizing in water consumption.

• Korean Journal of Plant Resources
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• v.12 no.2
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• pp.95-101
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• 1999

Higher and uniform germination should be necessary because many commercial pepper (Capsicum annum L.) seedlings were nowadays sold to farmer. The experiment was carried out to determine the effect of its cultivars (Daemyung; Wanggochu), GA$_3$ (concentration; period), light quality (red; far-red; blue; dark) during GA$_3$imbibition, and germination temperature (GT: 25 or 15$^{\circ}C$ constant; 25/15$^{\circ}C$ alternating) on the rate of germination done under incandescent lamps until 9 days after sowing. Final seed germination was not different between GA$_3$0 to 1.0 mM concentrations but the elapsed days to 50% germination $(T_{50})$ were more reduced by GA$_3$ treatment than water imbibition. Under $25^{\circ}C$ constant germination temperature, earlier germination was enhanced by GA$_3$treatment showing the lowest rate at darkness, although the final germination rates of water imbibition and GA$_3$ treatments were same. The final germination rates of alternating and 25 $^{\circ}C$ constant GT in cv. Daemyng was also equal, while the germination rates of $25^{\circ}C$ and 15$^{\circ}C$ constant GT were the highest and the lowest regardless of cultivars. There was no difference between light quality treatments impelled during GA$_3$ imbibition when light treated seeds were germinated at alternating and $25^{\circ}C$ constant GT. At 15$^{\circ}C$ constant GT, however, red light or dark treatment during GA$_3$imbibition increased the germination rate since 5 days after sowing.

• 한국균학회소식:학술대회논문집
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• 2014.10a
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• pp.25-25
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• 2014

Three species of Fusarium, F. fujikuroi, F. verticillioides and F. proliferatum, are known to be associated with bakanae disease of rice [1, 2]. F. fujikuroi infects rice flowers and survive in endosperm and embryo of the seeds. Infected seed is an important source of primary inoculum of pathogens [3]. Seeds of rice (Oryza sativa cv. Boramchan) collected from bakanae-infected field were found to be 96% infected with Fusarium sp., 52% with F. fujikuroi, 42% with F. verticillioides, and 12% with F. proliferatum as determined by incubation method and species-specific PCR assays. F. fujikuroi was detected at lemma/palea, endosperm and embryo whereas F. verticillioides and F. proliferatum were recovered only from lemma/palea by means of component plating test. Seed disinfection methods have been developed to control bakanae disease and prochloraz has been most widely used for rice seeds. Two chemicals formulated with prochloraz (PC 1) and prochloraz + hexaconazole (PC 2) that inhibit biosynthesis of ergosterol strongly reduced the incidence of Fusarium spp. on selective media to 4.7% and 2.0%, respectively. Disease symptoms of rice seedlings in nursery soil were alleviated by chemical treatment; seedlings with elongated leaves or wide angle between leaf and stem were strikingly reduced from 15.6 to 3.2% (PC 1) and 0 (PC 2), stem rots were reduced from 56.9 to 26.2% (PC 1) and 32.1% (PC 2), and normal seedling increased from 0.4 to 13.3% (PC 2). Prochloraz has some disadvantages and risks such as the occurrence of tolerant pathogens [4] and effects on the sterol synthesis in animals and humans [5]. For these reasons, it is necessary to develop new disinfection method that do not induce fungal tolerance and are safe to humans and animals. Chlorine dioxide ($ClO_2$), that is less toxic, produces no harmful byproducts, and has high oxidizing power, has been reported to be effective at disinfection of several phytopathogenic fungi including Colletotrichum spp. and Alternaria spp. [6]. Gaseous $ClO_2$ applied to rice seeds at a concentration of 20 ppm strongly suppressed mycelial growth of Fusarium fujikuroi, F. verticillioides and F. proliferatum. The incidence of Fusarium spp. in dry seed with 8.7% seed moisture content (SMC) tended to decrease as the concentration of $ClO_2$ increased from 20 to 40 ppm. Applying 40 ppm $ClO_2$ at 90% relative humidity, incidence was reduced to 5.3% and resulted in significant reduction of disease symptoms on MS media. In nursery soil, stem rot was reduced from 56.9 to 15.4% and the number of normal seedlings increased from 0.4 to 25.5%. With water-soaked seeds (33.1% SMC) holding moisture in the endosperm and embryo, the effectiveness of disinfection using $ClO_2$ increased, even when treated with only 20 ppm for four hours. This suggests that moisture was a key element for action of $ClO_2$. Removal of the palea and lemma from seeds significantly decreased the incidence of Fusarium spp. to 3.0%. Seed germination appeared to decrease slightly by water-soaking at $30^{\circ}C$ because of increased SMC and by physical damage of embryos from hulling. These results indicate that the use of gaseous $ClO_2$ was effective as a means to disinfect rice seeds infected with Fusarium spp. and that moisture around the pathogens in the seed was an important factor for the action of $ClO_2$. Further investigations should be conducted to ascertain the best conditions for complete disinfection of Fusarium spp. that infect deep site of rice seeds.

• Korean Journal of Soil Science and Fertilizer
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• v.31 no.4
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• pp.342-349
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• 1998

In order to evaluate the effects of nitrogen (N) rate and application method on the recovery of N fertilizer applied in spring and summer by Satsuma mandarins (cv. Miyakawa Wase), N as urea was surface-applied at the rates of 50 (applied with 20 mm water; 50% N application) and 100% (three treatments; applied as solid, with 5 or 20 mm water) of the recommended rate ($150kg\;ha^{-1}\;yr^{-1}$) on 25 March and 12 June with an application ratio of 50 and 20%. The labeled N was applied only once in spring or summer. There were no differences among the four treatments in fruit yield, fruit quality except acid content of juice, and N content of leaves. The recovery of fertilizer N applied in spring by a tree ranged from 7.8 to 8.3% and that of N applied in summer ranged from 11.3 to 14.2% at the three recommended N rates and was 18.0% for the 50% N application. The recovery of fertilizer N applied in spring in the upper 40 cm of soil ranged from 32.1 to 37.7% at the three recommended N rates and was 55.8% at the 50% N application. For N applied in summer, it was 69.8% for surface application of the recommended N rate and ranged from 80.7 to 84.4% for the three N applications with water. The total (tree+soil) recovery of N fertilizer applied in spring was highest (64.1%) for the 50% N application and ranged from 40.3 to 45.5% for the three recommended N rates. The total recovery of N fertilizer applied in summer was also highest (99.4%) for the 50% N application and tended to be higher for the application of N with water than surface application and to increase with increasing irrigation amount of N application.

• Horticultural Science & Technology
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• v.29 no.1
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• pp.1-9
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• 2011

This study was performed to investigate the role of plant growth substances on the bulbing of cold type of garlic (Allium sativum L. cv. Uiseongmaneul) during long and short day conditions. The change in endogenous plant hormones such as abscisic acid (ABA), jasmonic acid (JA) and sugar contents in leaf blade and sheath was examined during the growth stage from bulb differentiation (starting at April 16) to bulbing (April 24 to May 18) in cold type of garlic. In the long day condition, ABA contents were higher than short day condition and ABA contents of leaf sheath were higher than leaf blade. ABA contents of growth stage in garlic were not changed during growth stage from April 16 to May 2, however it rapidly increased during bulbing (May 2 to May 18). On the other hand, endogenous JA contents in short day condition did not change in long day condition, it increased from April 16 to May 2. JA contents in the leaf sheath (33.85-62.04 $ng{\cdot}g^{-1}$ DW) were higher than leaf blade (15.39-30.04 $ng{\cdot}g^{-1}$ DW). These results showed that garlic bulb differentiation and bulbing was induced by JA in leaf sheath. In long day condition, total sugar contents in the leaf blade were increased from bulb differentiation (April 16) to bulbing (May 4) and it was decreased during bulbing (May 4 to May 18) while the total sugar content in leaf sheath were gradually increased from bulb differentiation (April 16) to bulbing (May 18). In conclusion, our results showed that there is a significant correlation between the bulb development of garlic and hormonal content in the leaf sheath.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.38 no.4
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• pp.350-359
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• 1993

The effect of gibberellic acid ($GA_3) and abscisic acid (ABA) on KCl-enhanced proteolysis of senescing leaves of rice(Oryza sativa L. cv. Chilsung) was studied. Emphasis was given to their effects on KCI-enhanced efflux of amino acids and proteinase activity. When treated singly, $GA_3 affected leaf proteolysis little, while ABA increased proteolysis, the rate of amino acid efflux, and ribulose -1,5 -bisphosphate carboxylase / oxygenase (Rubisco)-degrading endoproteinase activity. An additive increase in all three parameters mentioned above was observed when leaves were treated with ABA and KCl. No such an additive effect was found when $GA_3 was treated with KCl. Both $GA_3 and ABA helped to alleviate the KCI-suppressed activity of Rubisco-degrading exoproteinases. The additive increase in proteolysis of rice leaves in the presence of both ABA and KCl could thus be ascribed to a further increase in the efflux of protein hydrolyzates and Rubisco-degrading endoproteinase activity. An increase in proteolysis was accompanied by a decrease in water absorption, and the combined treatment of ABA with KCl resulted in a further reduction of water absorption.