• Title/Summary/Keyword: E6 protein

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Disturbance of $\alpha$-Amylase Secretion from Bacillus amyloliquefaciens Cells by the Treatment of Puromycin and Magnesium (Bacillus amyloliquefaciens에서 Puromycin 과 Magnesium에 의한 $\alpha$-Amylase 의 분비저해)

  • 안순자;김순옥;이동희;송방호
    • Microbiology and Biotechnology Letters
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    • v.17 no.5
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    • pp.412-420
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    • 1989
  • To know how the ribosomes involved in secretory protein synthesis were attached to the cytoplasmic membrane in Bacillus amyloliquefaciens, the cells were treated with puromycin combinated with magnesium at the logarithmic phase, and the variation of cell-bound and extracellular $\alpha$-amylase activity was assayed for determining the $\alpha$-amylase translocation blocking through the cytoplasmic membrane. In the abnormal $\alpha$-amylase producing mutant in which the C-terminal of the $\alpha$-amylase structure was deleted, B. umytotiquefaciens CH10-2, the $\alpha$-amylase was translocated normally through the cytoplasmic membranes, and the translocation blocking by puromycin was revealed to have a similar pattern as that in the wild type. This means that the C-terminal part of the enzyme structure may not have a signal for secretion. The cell death of the logarithmic phase cells in both strains was not affected much under 20$\mu\textrm{g}$/$m\ell$ of puromycin, however, the $\alpha$-amylase translocation was blocked markedly under less than 10$\mu\textrm{g}$/$m\ell$ of the puromycin concentration. The blocking of the enzyme secretion by puromycin may be due to the detachment of the ribosomes from cytoplasmic membranes by disturbing the nascent polypeptide synthesis. Further evidence for confirming this was that the detachment was increased in 50 mM of magnesium ion because the extracellular $\alpha$-amylase activity was decreased more under this condition. If the cells were treated with trypsin combinated with Iysozyme, the extracellular $\alpha$-amylase activity from the cultured medium was reduced markedly, however, the activity from the cells treated with trypsin only was not reduced. This means that the nascent polypeptides protruding from the cytoplasmic membrane were sensitive to the trypsin digestion, whereas the matured ones were not. Therefore, the protruding polypeptides from the cytoplasmic membranes may be truncated by trypsin before forming their final tertiary structures by folding in the cell wall layer.

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Studies on Salient Metabolites of Plant Tissues (I) -Nitrogen Metabolism and Proline Accumulation in Halophytes- (식물조직계(植物組織系)의 유효성분(有效成分)에 관(關)한 연구(硏究) [1] -내염성(耐鹽性) 식물(植物)의 Proline축적(蓄積) 및 질소대사(窒素代謝)-)

  • Cho, I.H.
    • Applied Biological Chemistry
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    • v.20 no.2
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    • pp.221-227
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    • 1977
  • Contents of proline and chloride in halophytes were $80-1700\;{\mu}g/gfw$ and 0.13-0.45 mM/gfw respectively. The content of proline was inversely proportional to that of chloride. Rhizomes of Phargmites communis Trin, a halophyte, were grown in non-saline medium and then taken to saline treatment for one or two weeks. Growth of P. communis was inhibited when salinized with 0.25M NaCl. Total nitrogen decreased and alcohol soluble nitrogen and proline increased when growth was retarded. The quantity of Fraction 1 protein decreased at 0.25M NaCl treatment. The accumulation of proline at high concentration in P. communis suggested that it might play a role in osmotic adjustment.

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Mammalian Cloning by Nuclear transfer, Stem Cell, and Enzyme Telomerase (핵치환에 의한 cloning, stem cell, 그리고 효소 telomerase)

  • 한창열
    • Korean Journal of Plant Tissue Culture
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    • v.27 no.6
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    • pp.423-428
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    • 2000
  • In 1997 when cloned sheep Dolly and soon after Polly were born, it had become head-line news because in the former the nucleus that gave rise to the lamb came from cells of six-year-old adult sheep and in the latter case a foreign gene was inserted into the donor nucleus to make the cloned sheep produce human protein, factor IX, in e milk. In the last few years, once the realm of science fiction, cloned mammals especially in livestock have become almost commonplace. What the press accounts often fail to convey, however, is that behind every success lie hundreds of failures. Many of the nuclear-transferred egg cells fail to undergo normal cell divisions. Even when an embryo does successfully implant in the womb, pregnancy often ends in miscarriage. A significant fraction of the animals that are born die shortly after birth and some of those that survived have serious developmental abnormalities. Efficiency remains at less than one % out of some hundred attempts to clone an animal. These facts show that something is fundamentally wrong and enormous hurdles must be overcome before cloning becomes practical. Cloning researchers now tent to put aside their effort to create live animals in order to probe the fundamental questions on cell biology including stem cells, the questions of whether the hereditary material in the nucleus of each cell remains intact throughout development, and how transferred nucleus is reprogrammed exactly like the zygotic nucleus. Stem cells are defined as those cells which can divide to produce a daughter cell like themselves (self-renewal) as well as a daughter cell that will give rise to specific differentiated cells (cell-differentiation). Multicellular organisms are formed from a single totipotent stem cell commonly called fertilized egg or zygote. As this cell and its progeny undergo cell divisions the potency of the stem cells in each tissue and organ become gradually restricted in the order of totipotent, pluripotent, and multipotent. The differentiation potential of multipotent stem cells in each tissue has been thought to be limited to cell lineages present in the organ from which they were derived. Recent studies, however, revealed that multipotent stem cells derived from adult tissues have much wider differentiation potential than was previously thought. These cells can differentiate into developmentally unrelated cell types, such as nerve stem cell into blood cells or muscle stem cell into brain cells. Neural stem cells isolated from the adult forebrain were recently shown to be capable of repopulating the hematopoietic system and produce blood cells in irradiated condition. In plants although the term$\boxDr$ stem cell$\boxUl$is not used, some cells in the second layer of tunica at the apical meristem of shoot, some nucellar cells surrounding the embryo sac, and initial cells of adventive buds are considered to be equivalent to the totipotent stem cells of mammals. The telomere ends of linear eukaryotic chromosomes cannot be replicated because the RNA primer at the end of a completed lagging strand cannot be replaced with DNA, causing 5' end gap. A chromosome would be shortened by the length of RNA primer with every cycle of DNA replication and cell division. Essential genes located near the ends of chromosomes would inevitably be deleted by end-shortening, thereby killing the descendants of the original cells. Telomeric DNA has an unusual sequence consisting of up to 1,000 or more tandem repeat of a simple sequence. For example, chromosome of mammal including human has the repeating telomeric sequence of TTAGGG and that of higher plant is TTTAGGG. This non-genic tandem repeat prevents the death of cell despite the continued shortening of chromosome length. In contrast with the somatic cells germ line cells have the mechanism to fill-up the 5' end gap of telomere, thus maintaining the original length of chromosome. Cem line cells exhibit active enzyme telomerase which functions to maintain the stable length of telomere. Some of the cloned animals are reported prematurely getting old. It has to be ascertained whether the multipotent stem cells in the tissues of adult mammals have the original telomeres or shortened telomeres.

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Effect of Soybean Meal and Soluble Starch on Biogenic Amine Production and Microbial Diversity Using In vitro Rumen Fermentation

  • Jeong, Chang-Dae;Mamuad, Lovelia L.;Kim, Seon-Ho;Choi, Yeon Jae;Soriano, Alvin P.;Cho, Kwang Keun;Jeon, Che-Ok;Lee, Sung Sil;Lee, Sang-Suk
    • Asian-Australasian Journal of Animal Sciences
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    • v.28 no.1
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    • pp.50-57
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    • 2015
  • This study was conducted to investigate the effect of soybean meal (SM) and soluble starch (SS) on biogenic amine production and microbial diversity using in vitro ruminal fermentation. Treatments comprised of incubation of 2 g of mixture (expressed as 10 parts) containing different ratios of SM to SS as: 0:0, 10:0, 7:3, 5:5, 3:7, or 0:10. In vitro ruminal fermentation parameters were determined at 0, 12, 24, and 48 h of incubation while the biogenic amine and microbial diversity were determined at 48 h of incubation. Treatment with highest proportion of SM had higher (p<0.05) gas production than those with higher proportions of SS. Samples with higher proportion of SS resulted in lower pH than those with higher proportion of SM after 48 h of incubation. The largest change in $NH_3$-N concentration from 0 to 48 h was observed on all SM while the smallest was observed on exclusive SS. Similarly, exclusive SS had the lowest $NH_3$-N concentration among all groups after 24 h of incubation. Increasing methane ($CH_4$) concentrations were observed with time, and $CH_4$ concentrations were higher (p<0.05) with greater proportions of SM than SS. Balanced proportion of SM and SS had the highest (p<0.05) total volatile fatty acid (TVFA) while propionate was found highest in higher proportion of SS. Moreover, biogenic amine (BA) was higher (p<0.05) in samples containing greater proportions of SM. Histamines, amine index and total amines were highest in exclusive SM followed in sequence mixtures with increasing proportion of SS (and lowered proportion of SM) at 48 h of incubation. Nine dominant bands were identified by denaturing gradient gel electrophoresis (DGGE) and their identity ranged from 87% to 100% which were mostly isolated from rumen and feces. Bands R2 (uncultured bacterium clone RB-5E1) and R4 (uncultured rumen bacterium clone L7A_C10) bands were found in samples with higher proportions of SM while R3 (uncultured Firmicutes bacterium clone NI_52), R7 (Selenomonas sp. MCB2), R8 (Selenomonas ruminantium gene) and R9 (Selenomonas ruminantium strain LongY6) were found in samples with higher proportions of SS. Different feed ratios affect rumen fermentation in terms of pH, $NH_3$-N, $CH_4$, BA, volatile fatty acid and other metabolite concentrations and microbial diversity. Balanced protein and carbohydrate ratios are needed for rumen fermentation.

Effects of Feeding Rhus verniciflua Extract on Egg Quality and Performance of Laying Hens (옻나무 추출액 급여가 산란계의 생산성 및 계란 품질에 미치는 영향)

  • Kang, Hwan-Ku;Kang, Geun-Ho;Na, Jae-Cheon;Yu, Dong-Jo;Kim, Dong-Wook;Lee, Sang-Jin;Kim, Sang-Ho
    • Food Science of Animal Resources
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    • v.28 no.5
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    • pp.610-615
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    • 2008
  • This experiment was conducted to investigate the effects of drinking of Rhus tree-extract on laying performance and egg quality in hens. Four hundred eighty, 55-wk-old ISA brown, laying hens were divided into six groups, control, Rhus tree-extract 500 ppm, 1,000 ppm, 2,000 ppm, 3,000 ppm and 5,000 ppm. The hens were fed a supplemented drink containing Rhus tree-extract for 12 weeks. Egg production and egg mass increased by drinking Rhus tree-extract (p<0.05) and the feed conversion ratio also improved in Rhus tree-extract groups. Cecal numbers of Lactobacillus spp., E. coli and Salmonella were not different in treatments. Availability of protein and ash improved in the Rhus extract groups. The eggshell breaking strength and egg shell thickness were significantly increased in Rhus tree-extract 3,000 ppm and Rhus tree-extract 2,000 ppm groups compared to the other groups. Also, egg yolk color and Haugh unit were significantly improved by the dietary Rhus tree-extract (p<0.05).

Manufacturing and Characteristics of Fruit Wine from Acanthapanax sessiliflorus (오가피 열매 발효주의 제조 및 특성)

  • Choi, Jae-Myoung;Kim, Kwang-Yup;Lee, Sang-Hwa;Ahn, Jun-Bae
    • Food Engineering Progress
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    • v.14 no.1
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    • pp.1-6
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    • 2010
  • Fruit wine from Acanthopanax sessiliflorus(A. sessiliflorus) including many pharmacological components was manufactured and its functional properties were investigated. The fruit part of A. sessiliflorus contained 75.74${\pm}$0.49%(w/w) moisture, 12.51${\pm}$1.23%(w/w) crude protein, 4.20${\pm}$0.51.%(w/w) crude fat and 5.21${\pm}$1.64%(w/w) crude ash. Minerals of fruit were potassium(12.94${\pm}$0.08 mg/g), calcium(1.53${\pm}$0.06 mg/g) and magnesium(1.12${\pm}$0.05 mg/g). Initial soluble solid and fermentation temperature were 24-30$^{\circ}$Brix and 20${^{\circ}C}$ for manufacturing fruit wine from A. sessiliflorus. When initial soluble solid of a must was adjusted to more than 30$^{\circ}$Brix, ethanol production was suppressed slightly. The polyphenol content of the fruit wine fermented at 20${^{\circ}C}$(125.24${\pm}$1.86 mg/mL) was higher than those at 25${^{\circ}C}$(99.69${\pm}$2.11 mg/mL) and 30${^{\circ}C}$(95.55${\pm}$1.54 mg/mL). Electron donating activities of wines fermented at 20, 25 and 30${^{\circ}C}$ were 85.9${\pm}$2.3, 55.7${\pm}$2.5 and 55.2${\pm}$3.4%, respectively. The content of eleutheroside B increased up to 146.58${\pm}$4.10 $\mu$g/mL during fermentation. There was no significant effect of fermentation temperature on eleutheroside B content. The fruit part of A. sessiliflorus can be used as a valuable resource for development of nutraceutical foods.

Two new triterpenoid saponins derived from the leaves of Panax ginseng and their antiinflammatory activity

  • Li, Fu;Cao, Yufeng;Luo, Yanyan;Liu, Tingwu;Yan, Guilong;Chen, Liang;Ji, Lilian;Wang, Lun;Chen, Bin;Yaseen, Aftab;Khan, Ashfaq A.;Zhang, Guolin;Jiang, Yunyao;Liu, Jianxun;Wang, Gongcheng;Wang, Ming-Kui;Hu, Weicheng
    • Journal of Ginseng Research
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    • v.43 no.4
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    • pp.600-605
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    • 2019
  • Background: The leaves and roots of Panax ginseng are rich in ginsenosides. However, the chemical compositions of the leaves and roots of P. ginseng differ, resulting in different medicinal functions. In recent years, the aerial parts of members of the Panax genus have received great attention from natural product chemists as producers of bioactive ginsenosides. The aim of this study was the isolation and structural elucidation of novel, minor ginsenosides in the leaves of P. ginseng and evaluation of their antiinflammatory activity in vitro. Methods: Various chromatographic techniques were applied to obtain pure individual compounds, and their structures were determined by nuclear magnetic resonance and high-resolution mass spectrometry, as well as chemical methods. The antiinflammatory effect of the new compounds was evaluated on lipopolysaccharide-stimulated RAW 264.7 cells. Results and conclusions: Two novel, minor triterpenoid saponins, ginsenoside $LS_1$ (1) and 5,6-didehydroginsenoside $Rg_3$ (2), were isolated from the leaves of P. ginseng. The isolated compounds 1 and 2 were assayed for their inhibitory effect on nitric oxide production in LPS-stimulated RAW 264.7 cells, and Compound 2 showed a significant inhibitory effect with $IC_{50}$ of $37.38{\mu}M$ compared with that of NG-monomethyl-L-arginine ($IC_{50}=90.76{\mu}M$). Moreover, Compound 2 significantly decreased secretion of cytokines such as prostaglandin $E_2$ and tumor necrosis factor-${\alpha}$. In addition, Compound 2 significantly suppressed protein expression of inducible nitric oxide synthase and cyclooxygenase-2. These results suggested that Compound 2 could be used as a valuable candidate for medicinal use or functional food, and the mechanism is warranted for further exploration.

Anti-inflammatory and Antioxidative Effects of Lotus Root Extract in LPS-PG-Stimulated Human Gingival Fibroblast-1 Cells (치주염 원인균 LPS-PG로 유도된 인체 치은섬유아세포에서 연뿌리 추출물에 대한 항염증 및 항산화 효과)

  • Lee, Young-Kyung;Kim, Chul Hwan;Jeong, Dae Won;Lee, Ki Won;Oh, Young Taek;Kim, Jeong Il;Jeong, Jin-Woo
    • Korean Journal of Plant Resources
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    • v.35 no.5
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    • pp.565-573
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    • 2022
  • Gingival inflammation is one of the main causes that can be related to various periodontal diseases. Human gingival fibroblast (HGF) is the major constituent in periodontal connective tissue and secretes various inflammatory mediators, such as nitric oxide (NO) and prostaglandin E2 (PGE2), upon lipopolysaccharide stimulation. This study is aimed at investigating the anti-inflammatory and antioxidative activities of Lotus Root extract (LRE) in Porphyromonas gingivalis derived lipopolysaccharide (LPS-PG)-stimulated HGF-1 cells. The concentration of NO and PGE2, as well as their responsible enzymes, inducible NO synthase (iNOS), and cyclooxygenase-2 (COX-2), was analyzed by Griess reaction, ELISA, and western blot analysis. LPS-PG sharply elevated the production and protein expression of inflammatory mediators, which were significantly attenuated by LRE treatment in a dose-dependent manner. LRE treatment also suppressed activation of Toll-like receptor 4 (TLR4)/myeloid differentiation primary response gene 88 (MyD88) and nuclear factor-κB (NF-κB) in LPS-PG-stimulated HGF-1 cells. In addition, one of phase II enzyme, NAD(P)H quinone dehydrogenase (NQO)-1, and its transcription factor, Nuclear factor erythroid 2-related factor 2 (Nrf2), were significantly induced by LRE treatment. Consequently, these results suggest that LRE ameliorates LPS-PG-induced inflammatory responses by attenuating TLR4/MyD88-mediated NF-κB, and activating NQO-1/Nrf2 antioxidant response element signaling pathways in HGF-1 cells.

Food Components of Wild and Cultured Fresh Water Fishes (천연 및 양식산 담수어의 식품성분)

  • KIM Kyung-Sam;LEE Eung-Ho
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.19 no.3
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    • pp.195-211
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    • 1986
  • The object of this study is to obtain fundamental data on cultured fishes produced in Korea to improve their food components. For this purpose, the food components of cultured fresh water fishes such as eel, Anguilla japonica, snakehead, Channa argus, and common carp, Cyprinus carpio, were investigated and compared with those of the wild ones. The results obtained are summarized as follows: 1. Common characteristics in the proximate composition were that wild fish was higher in crude protein content and lower in crude lipid content than those of cultured one. 2. Among the 9 kinds of minerals analyzed in all the samples, sodium, potassium, calcium and magnesium contents were absolutely predominant being more than $99.52\%$. These four elements in feedstuff also occupied $99.68{\sim}99.92%$ of total minerals. 3. The neutral lipids of wild and cultured eel, snakehead and common carp occupied $55.7{\sim}95.8%$ of lipid fractions, while the content of the phospholipids in snakehead was particularly higher than those of others. 4. The neutral lipids of wild and cultured eel, snakehead and common carp mainly consisted of triglycerides ($85{\sim}95%$), and a little quantity of diglycerides, monoglycerides, free sterol ester and hydrocarbon were also identified in the neutral lipid. 5. The phospolipids of eel and common carp were mainly occupied by phosphatidyl choline ($71.3{\sim}83.9%$), followed by phosphatidyl ethanolamine ($12.1{\sim}23.5%$) and phosphatidyl serine ($7.5{\sim}13.8%$). The phospholipids of snakhead consisted of phosphatidyl choline ($50.7{\sim}64.5%$), phosphatidyl ethanolamine ($28.0{\sim}35.5%$) and phosphatidyl serine ($7.5{\sim}13.8%$). Generally, phosphatidyl choline content was higher in wild fish than in cultured one, while phosphatidyl ethanolamine and phosphatidyl serine contents were higher in cultured one. 6. The major fatty acids in total lipid of wild eel, snakehead and common carp were $C_{16:0}\;and\;C_{20:5}$, while those in cultured ones were $C_{18:1},\;C_{18:2}\;and\;C_{22:6}$. The fatty acid composition of neutral lipids showed similar tendency to that of total lipid, and the main fatty acids in phospholipids of cultured fishes were $C_{18:1}\;and\;C_{18:2}$. In glycolipids, $C_{20:5}\;and\;C_{22:6}$ were higher in wild fishes, while $C_{18:2}$ were higher in cultured ones. 7. Total amino acids contents of wild and cultured eel were nearly the same, being $16.65\%$ ana $15.99\%$ respectively. The major amino acids of wild and cultured fish were glutamic acid, leucine, aspartic acid and lysine in order. In snakehead, the contents of aspartic acid and proline in cultured fish were higher than those in wild one, while the contents of glutamic acid, alanine, glycine were higher in the wild one. Total amino acid content of cultured common carp was $21.7\%$ compared with $17.08\%$ in wild one. The contents of glutamic acid, aspartic acid, glycine, proline and alanine occupied higher quantities in cultured common carp compared with those in wild one while the other amino acids revealed no significant difference. 8. Aspartic acid in free amino acids of cultured eel held $1.0\%$ of total free amino acids, while that in wild eel held $2.9\%$. Histidine, arginine and tyrosine content of cultured fish were two times higher than those of wild one. But free amino acid composition of samples seemed to be no marked differences according to cultured places. The contents of arginine, aspartic acid, glutamic acid, methionine and phenylalanine of snakehead ware higher in wild one than in cultured one, while the contents of lysine, histidine, glycine, and alanine ware higher in cultured one. In free amino acids content of wild common carp, histidine, glycine and lysine occupied $76.9\%$ of total free amino acids. Lysine, histidine, aspartic acid, alanine, valine and leucine were higher in wild one compared with those of cultured one, while glycine and tyrosine contents were higher in cultured fish.

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Agronomical studies on the major environmental factors of rice culture in Korea (수도재배의 주요환경요인에 관한 해석적 조사연구)

  • Yung-Sup Kim
    • KOREAN JOURNAL OF CROP SCIENCE
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    • v.3
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    • pp.49-82
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    • 1965
  • For the stable and high yields of low-land rice in Korea, the characteristics of rice plant for the vegetative and physiological responses, plant type formation, and yield components have been studied in order to obtain the fundamental data for the improvement of cultural practices, especially for the ideal fertilizer application. Furthermore the environmental conditions in Korea including temperatures, light, precipitation, and soil conditions have been compared in the broad sense with those in Japan, and the application of nitrogen, phosphorus, potassium, silicate and other micro-nutrients were described in relation to the characteristics of environmental conditions for the improvement of fertilizer application. 1. The average yield of polished-rice per 10 are in Korea is about 204 kg and this values are much less than those in Japan and Taiwan where they produce 77% to 13% more than in Korea. The rate of yield increase a year in Korea is 4.2 kg, but in Japan and Taiwan the rates of yield increase a year are 81 % and 62%, respectively. It was also found that the coefficient of variation of yield is 7.7% in Korea, 6.7% in Japan and 2.5% in Taiwan. This means that the stability of producing rice in Korea is very low when compared with those in Japan and Taiwan. 2. It was learned from the results obtained from the 'annual yield estimation experiment' that there are big differences in the respect of plant type formations between rice crops grown in Japan and Korea. The important differences found were as follows: (1) The numbers of spikelets per 3.3 square meters are 891 in Korea and 1, 007 in Japan(13% more than in Korea). (2) The numbers of tillers per 3.3 square meters at the stage of maximum tillering are 1, 150 in Korea, but in Japan they showed 19% more than in Korea. (3) The ratio of effective tillers to total tillers is 77.5% in Korea and 74.7% in Japan, which seems to be higher in Korea than in Japan. But the ratio in Korea is very low when considered the numbers of total tillers in both countries. (4) The ratio of grain to straw is 85.4% in Korea and 96.3% in Japan. 3. The average temperatures during the growing season at the area of Suwon, Kwangjoo and Taegu are almost same as those in the district of Jookokoo(Fookoo yama) in Japan, i.e., the temperatures during the rice-growing season in Korea are similar to those in the southern-warm regions of Japan. 4. Considering the minimum temperatures at the stage of limiting transplanting, 13$^{\circ}C$, the time of transplanting might be 30 to 40 days earlier than presently practicing transplanting time, which comes around June 10. 5. The temperatures during the vegetative growth in Korea were higher than those temperatures that needed in the protein synthesis which ate the main metabolism during this stage. However, the temperatures at the time of reproductive growth was lower than the temperatures that needed in the sugar assimilation which is main metabolism in this stage. In this point of view, it might be considered that the proper time of growing rice plant in Korea would be rather earlier. 6. The temperatures and the day light conditions at the time of first tillering stage of rice plant, when planted as presenting transplanting practices, are very satisfactory, but the poor day light length, high temperatures and too wet conditions in the time of last-tillering stage(mid or last July) might cause the occurrence of disease such as blast. 7. The heading stage of rice plants at each region through nations when planted as presently practicing method comes when the day light length is short. 8. It was shown that the accumulated average air-temperature at the time of maturing stage was not enough and the heading time was too late, when considered the annual deviations of mean temperatures and low minimum temperatures. 9. The nitrogen content of each plant part at the each growing stage was very high at the stage of vegetative growth when compared with the nitrogen content at the stage of reproductive growth after heading. In this respect it was believed to be important to prevent the nutrient shortages at the reproductive stages, especially after the heading. 10. The area of unsatisfactory irrigation paddy fields and natural rain-fed paddy fields are getting reduced in Korea. The correlation between the rate of reducing unsatisfactory irrigation and natural rain-fed paddy fields and the rate of yield increase were computed. The correlation coefficients(r) between the area of unsatisfactory irrigation paddy fields and yield increase were +0.525, and between the natural rain-fed paddy fields and yield increase, +0.832 and between the unsatisfactory irrigation plus natural rain-fed paddy fields and yield increase, +0.84. And there were. highly significant positive correlations between natural rain-fed paddy fields and yield increases indicating that the less the area of natural rain-fed paddy fields, the greater the yields per unit area. 11. The results obtained from the fertilizer experiments (yield performance trials) conducted in both Korea and Japan showed that the yield of non-fertilized plots per 10 are was 231 kg in Korea and 360 kg in Japan. On the basis of this it might be concluded that the fertility of soil in Korea is lower than that in Japan. Furthermore it was. also found that the yields of non-nitrogen applied plots per 10 are were 236 kg in Korea and 383 kg in Japan. This also indicates that the yields of rice in Korea are largely depending on the nitrogen content in the soil. 12. The followings were obtained when the chemical natures of soils in both Korea and Japan were compared. (1) The content of organic matter, total nitrogen, exchangeable calcium, and magnesium in Korea were no more than the half those in Japan. (2) The content of N/2 chloride and soluble silicate in low-land soil were on the average lower in Korea. (3) The exchange capacity of bases in Korea was no more than half that in Japan. 13. It was also observed by comparing the soil nature of the soil with high yielding capacity with the soil with low yielding capacity that the exchange capacity of bases, exchangeable calcium and magnesium, potassium, phosphorus, manganese, silicate and iron were low in the soil with low yielding capacity. 14. The depth of furrow slice was always deeper in the soil with high yielding capacity, and the depth of furrow slice in Korea was also shallower than that in Japan. 15. Summarizing the various conditions mentioned previously and considering the effects of silicate and trace elements such as manganese and iron besides three elements on the physiological and plant type formation of rice crops, more realistic and more ideal fertilizing practices were proposed. proposed.

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