• Journal of Photoscience
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• v.5 no.4
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• pp.169-174
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• 1998

Photosynthetic responses to dehydration were examined by the simulataneous measurement of O2 evolution and chlorophyll (Chl) fluorescence in green pepper leaves. Dehydration was induced by immersing the plant roots directly in the Hoagland solution containing varying concentration (2-30%) of polyethylene glycol(PEG-6000) . Water potential of the leaf was decreased time-and concentation -dependently by PEG-treatment. The decrease in water potential of leaf was correlated with the decrease in both the maximal photosynthesis (Pmax) and quantum yield of O2 evolution, but Pmax dropped more rapidly than quantum yield at all water deficit conditions tested. However, Chl fluorescence parameters were not affected much. Dehydration did not change the initial fluorescence (Fo) and maximum photochemical efficiency(Fv/Fm) of photosystem(PS) II. Both the photochemical quenching (qP) and non-photochemical quenching(NPQ) were not changed by dehydration under low PFR(50 $\mu$mols m-2s-1 ). In contrast, under high PFR(270$\mu$mols m-2s-1)qP was slightly decreased while NPQ was greatly increased. The fast induction kinetics of Chl fluroecence showed no change in Chl fluorescence pattern by dehydration at high PFR (640 $\mu$mols m-2s-1 ), but exhibited a significant drop in peak level(Fp)at low PRFR (70$\mu$mols m-2s-1 ). PS I oxidation and reduction kinetics revealed normal reduction but delayed oxidation to P-700+, suggesting no lesionin electron flow from PSII to PSI , but impaired electron transport to NADP+,These results suggest that water stress caused by PEG-treatment results in the reduction of photosynthesis, promarily due to the reducted electron trasport from PSI to NADP+ or hampered subsequent steps involving Calvin Cycle.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.38 no.6
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• pp.507-512
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• 1993

Pre-sowing treatments of tobacco seeds (cv. NC82) were evaluated as a means of improving the speed of emergence, early seedling growth and uniformity of the seedlings. Seeds were treated through the use of polyethylene glycol 6000(PEG), solid matrix priming(SMP), chilling and dark-preincubati(DPI). Under the laboratory condition of 15$^{\circ}C$, all the treated seeds germinated more rapid and the time to 50% germination(T50) reduced than control. Among the treatments, SMP was the best to reduce the T50 for germination. All the treatments did not affect the final germination percentage, while the chilling showed of little benefit for germination and T50. Under the greenhouse condition, seedling from SMP emerged earlier and more uniformity and also greater mean fresh and dry weight showed than other treatments. The advantage of T50 from SMP was affected more in temperature than in water content of Agro-Lig during the treatment.

• Journal of Plant Biotechnology
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• v.46 no.4
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• pp.331-337
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• 2019

Digitaria exilis L. is an under-utilized crop with high nutritional and medicinal values. It thrives in and is well-adapted to arid areas with low soil nutrients. Using biochemical markers, this study investigates the mechanisms by which D. exilis responds to osmotic stress. Three accessions Dinat Iburua (DIN), Jakah Iburua (JAK) and Jiw Iburua (JIW) were collected from National Cereal Research Institute, Niger State. Two accessions, NG/11/JD/061 and NG/11/JD/062 were also collected from National Centre for Genetic Resources and Biotechnology, Ibadan. Murashige and Skoog medium of approximately 1.2 L was supplemented with polyethylene glycol 6000 to create osmotic pressures of -9.29, -13.93, -20.13, -26.32, -32.51, and 0 MPa (control). Sterilized seeds were inoculated in the medium and placed in the growth room for 4 weeks. Proline accumulation was significantly high in all JAK plants under osmotic stress. Proline and ascorbate peroxidase (p<0.05) activities were directly correlated, thus reinforcing the survivability of JAK during stress. Catalase (CAT) activity was also significantly induced in JAK under osmotic stress, which synergistically improved its tolerability. As a result, >50% of OH-, H₂O₂, and NO radicals were scavenged. However, other accessions including DIN, NG061, NG062, and JIW showed variations in their responses to different levels of osmotic stress, although not significant. Therefore, JAK possesses a well-equipped free radical quenching system that is protected by the accumulation of the osmolyte proline; therefore, accession JAK is considered osmotolerant. CAT and superoxide dismutase activities were osmostabilized against oxidative stress by proline.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.37 no.2
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• pp.134-140
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• 1992

Carrot(Daucus carota L.) seeds (CV Danver 126) were primed and then separated by density differences to improve both the percentage and time of radicle emergence. Seeds for priming were soaked in aerated distilled water for 2 days (water imbibed), 25% solution of polyethylene glycol(PEG) 6000 for 6 or 10 days, salt solution of 0.2M KNO$_3$＋0.1M $K_2$HPO$_4$ for 6 or 10 days, or mixed with Agro-Lig with 90% moisture content for 6 days and 70% moisture content for 6 or 10 days (SMP) at 2$0^{\circ}C$, respectively. The greatest embryo growth and the highest radicle emergence were observed from the seeds treated SMP with 90% moisture content for 6 days among the primed treatments. After the SMP treatment, the seeds were separated into density classes with a float-sink procedure using aqueous solution of Maltrin 600 with 0.02/cm$^3$ density increments. The lower density classes of the carrot seeds, the more embryo growth, the higher and the faster rates of radicle emergence were exhibited in order from 1.06 to 1.14 density classes of the carrot seeds treated SMP.

• Korean Journal of Agricultural Science
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• v.12 no.1
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• pp.17-21
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• 1985

In order to shorten the time of germination and emergence of red pepper seeds of cv. Serona and cv. King were soaked at 20, 25, and 30% PEG solutions for 6 and 12 days and effects of osmotic treatments with PEG were determined. 1. Osmotic treatments with 20 and 25% PEG for 12 days were proven effective in reducing germination time of cv. Serona and cv. King. Final germination percentages were not significantly different among PEG treatments. 2. Osmotic treatment with 25% PEG for 12 days showed effective in reducing the time between sowing and emergence of red pepper and shortened 4 and 5 days for emergence of cv. King and cv. Serona, respectively. 3. It is anticipated that germination and emergence of red pepper can be greatly hastened under unfavorable low temperature condition by osmotic treatment with 20 and 25% PEG for 6 and 12 days.

• Journal of Korean Society of Forest Science
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• v.71 no.1
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• pp.14-21
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• 1985

This study was carried out in order to prevent the devaluation of wood itself and wood products causing by anisotropy, hygroscopicity, shrinkage and swelling - properties that wood itself only have, in order to improve utility of wood, by emphasizing the natural beautiful figures of wood, to develop the dimensional stabilization techniques of wood with PEG that it is a cheap, non-toxic and the impregnation treatment is not difficult, on the effects of PEG molecular weights (200, 400, 600, 1000, 1500, 2000, 4000, 6000) and species (Pinus densiflora S. et Z., Larix leptolepis Gordon., Cryptomeria japonica D. Don., Cornus controversa Hemsl., Quercus variabilis Blume., Prunus sargentii Rehder.). The results were as follows; 1) PEG loading showed the maximum value (137.22%, Pinus densiflora, in PEG 400), the others showed that relatively slow decrease. The lower specific gravity, the more polymer loading. 2) Bulking coefficient didn't particularly show the correlation with specific gravity, for the most part, indicated the maximum values in PEG 600, except that the bulking coefficient of Quercus variabilis distributed between the range of 12-18% in PEG 400-2000. In general, the bulking coefficient of hardwood was higher than that of softwood. 3) Although there was more or less an exception according to species, volumetric swelling reduction was the greatest in PEG 400. That is, its value of Cryptomeria japonica was the greatest value with 95.0%, the others indicated more than 80% except for Prunus sargentii, while volumetric swelling reduction was decreased less than 70% as the molecular weight increase more than 1000. 4) The relative effectiveness of hardwood with high specific gravity was outstandingly higher than softwood. In general, the relative effectiveness of low molecular weight PEG was superior to those of high molecular weight PEG except that Quercus variabilis showed more than 1.6 to the total molecular weight range, while it was no significant difference as the molecular weight increase more than 4000. 5) According to the analysis of the results mentioned above, the dimensional stabilization of hardwood was more effective than softwood. Although volumetric swelling reduction was the greatest at a molecular weight of 400. In the view of polymer loading, bulking coefficiency reduction of swelling and relative effectiveness, it is desirable to use the mixture of PEG of molecular weight in the range of 200-1500. To practical use, it is recommended to study about the effects on the mixed ratio on the bulking coefficient, reduction of swelling and relative effectiveness.

• Journal of Life Science
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• v.14 no.3
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• pp.396-399
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• 2004

This study was investigated the changes of root length, tissue structure of root tip, and dry matter production of a Dongjinbyeo (DJ) cultivar subjected to 0.4 % agar medium with various concentration of NaCl (salt stress)- and polyethylene glycol 6000 (PEG, drought stress). Root length and dry weight of DJ plant were declined along the high concentration of PEG and NaCl in rice plants. To elucidate the changes of tissue structure in root tip to PEG- and NaCl-treatments, we examined the microscopic observation of root tip in NaCl- and PEG-treated rice plants using Toluidine blue O. By Toluidine blue O staining, methyl-lignin accumulation was found in the epidermis and outer cortex of the elongation zone at an early stage of PEG treatment, whereas was found only the outer cortex of the elongation zone of NaCl-treated root tip. The epidermis of NaCl-treated root tip became soften instead of methyl-lignin accumulation. TR ratio was increased along the high concentration in PEG- and NaCl-treated rice plant as a result of inhibited root elongation under PEG- and NaCl-treatment. From these morphological changes in root stimulated by drought and salt stress, we suggest that agar medium is useful to identify tolerant variety in germination stage under stressful environments.

• Korean Journal of Food Science and Technology
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• v.23 no.5
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• pp.561-567
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• 1991

This study was designed to investigate the productivity of L-methionine by the method of protoplast fusion between Brevibacterium flavum ATCC 14067 and Corynebacterium glutamicm ATCC 13032, and then L-methionine production was performed to continuous fermentation using the immobilized fusant cells. Mutants B. flavum K 104($thr\;met\;Km^{r}\;Et^{r}\;Sm^{r}\;Tm^{r}\;as\;genetic\;marker$) and C. glutamicum B 70($thr\;Hos\;Km^{r}\;Et^{r}\;Sm^{r}\;Tm^{r}as\;genetic\;marker$) were isolated by MNNG treatment. On the other hand, protoplast of mutants were formed to treat with lysis solution containing $500{\mu}g/ml$ of lysozyme. The ratios of protoplast formation and regeneration were 99% and $64{\sim}66%$ respectively. Fusion frequency between B. flavum K 104 and C. glutamicum B 70 showed the $3.5{\times}10^{5}$ in the 35% polyethylene glycol(PEG6000) containing 3% PVP solution. The productivity of L-methionine by fusant BFCG 37 immobilized with sodium alginate was 0.89 g/l the batch fermentation and was $18.75mg/^{1}hr\;^{1}$ on the continuous fermentation at $30^{\circ}C$ for 72 hr.

• Microbiology and Biotechnology Letters
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• v.16 no.4
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• pp.275-281
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• 1988

To develop cellulase and xylanase-producing strain by protoplast fusion, alkalophilic Bacillus sp. F204 and K17 were treated with NTG(N-methyl-N'-nitro-N-nitrosoguanidine) and isolated anti-biotics resistant strains of S20 (Km$^r$ , Cm$^r$) and G70 (Str$^r$). The frequency of protoplast formation was about 95% when cells of mid-log phase were treated with 200$\mu\textrm{g}$/ml Iysozyme at 37$^{\circ}C$ for 30-45 minutes. Under addition of 0.4-0.5M sodium succinate, 0.5% casamino acid, 1.5% polyvinylpyrrolidone, 25mM MgC1$_2$ and 50mM CaC1$_2$ to the regeneration medium, the regeneration frequency of Bacillus sp. F204 and K17 was 24.9% and 26.2%, respectively. The fusion frequency was 6.6$\times$10$^{-6}$ in the presence of 30% polyethylene glycol 6000 containing 50mM $Ca^{++}$ at 45$^{\circ}C$ for 5 minutes. Cellulase complex and xylanase activities of fusant were compared with parental strains.