• KOREAN JOURNAL OF CROP SCIENCE
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• v.50 no.1
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• pp.16-21
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• 2005

This study was conducted to establish the elaborate nitrogen fertilization method to enhance N use efficiency in direct-seeded rice on flooded paddy. The nitrogen uptake by rice plants was insignificant until 25 days after seeding, and increased gradually thereafter. During this early growth stage, rice plants absorbed only the $4\%$ of basal applied N, while the $45\%$ of N fertilizer remained in the paddy soil. The absorption of basal N by rice plants was almost completed at 46 days after application. Nitrogen top-dressed at 5-leaf stage was well matched to crop nutrient demand, so it could be absorbed so actively in 8days after application. As a result, we could cut down the amount of N fertilizer to $36\%$ of the basal N level without significant difference in yield. Plant recoveries of fertilizer $^{15}N$ applied with different application timings were $7.8\%$ for basal, $9.4\%$ for 5-leaf stage, $17.1\%$ for tillering stage, and $23.4\%$ for panicle initiation stage, respectively. When urea was applied with nitrogen fertilization practice based on basal incorporation (BN), plant recovery of $^{15}N$ at harvest was $31.0\%$, which was originated from $13.7\%$ for grain, and $21.3\%$ of the fertilizer $^{15}N$ remained in the soil, and the rest could be uncounted. Plant recovery of fertilizer $^{15}N$ applied with nitrogen fertilization practice based on topdressing at 5-leaf stage (TN), where N rate was reduced by $18\%$ compared with BN, was $35.1\%$ (grain $15.6\%$), and $19.9\%$ of the fertilizer $^{15}N$ remained in the soil, and the rest could be uncounted. TN showed a higher $^{15}N$ recovery than BN because it was to apply N fertilizer at a time to well meet the demand of rice plant direct-seeded on flooded paddy. We concluded that TN would be the nitrogen fertilization method to enhance N use efficiency in direct-seeded rice on flooded paddy.

• Fisheries and Aquatic Sciences
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• v.26 no.8
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• pp.500-513
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• 2023

The effects of prolonged photoperiod (additional night lighting) were investigated on the production of Ocimum basilicum (lemon basil) and fish/crayfish raised in a nutrient film technique aquaponic system. Hybrid lemon fin barb and red claw crayfish juveniles were co-cultured with O. basilicum and subjected to 12 h of ambient natural daylight and additional 0, 4, 8, and 12 h of night lighting for 14 weeks (two batches of 7 weeks each). The water quality parameters and the performance characteristics of the fish/crayfish/plant were evaluated, and the nutri- ent uptake (nitrogen, phosphorus, and potassium) in the system by the three organisms was also measured. The fish growth performance showed no significant differences (p > 0.05) in all the growth parameters measured across the treatments. The body proximate and nitrogen, phosphate, and potassium (NPK) composition of the fish and crayfish were not significantly (p > 0.05) different across the treatments. Similarly, there was no significant difference (p > 0.05) in the NPK uptake by the fish and crayfish across the treatments. The plant growth performance showed that there were no significant (p > 0.05) differences in the plant growth parameters measured, except for % plant height gained in the 12 h-light treatment (403.2 ± 26.0%) which was significantly (p < 0.05) higher than other treatments and cycles. Hence, this study demonstrat- ed that varying supplementary night lighting has no significant effect on the growth performance of O. basilicum, hybrid lemon fin barb, and red claw crayfish. This study, therefore, suggests that supplementary night lighting should not be considered for O. basilicum production as it does not significantly improve the performance characteristics of the plant nor the fish co-cultured with it in a polyculture aquaponic system.

• Korean Journal of Soil Science and Fertilizer
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• v.42 no.3
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• pp.207-213
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• 2009

This experiment was performed to understand the relationship between uptake of Fe and Mn by plants, red pepper and tomato, and soil physico-chemical properties under different soil conditions at an environmentally controlled chamber in NAAS(National Academy of Agricultural Science) in 2008. After the dipping for 3 days, four treatments, dipping, dipping+aeration, drainage, drainage+aeration, were set up to investigate the changes in soil redox potential and moisture content. Drainage+aeration changed soil to the oxidation condition from 72 hrs of treatment, and soil moisture content was immediately reduced after treatment. Uptake of Fe and Mn of red pepper was investigated with two treatments, soil only and the mixed[soil(50%) : bed soil(35%) : bark(15%)]. Red pepper leaves taken at 30 days after treatment absorbed excessively Mn from the treatment of soil only and the mixed, and thus uptake of iron was strongly reduced. Also, uptake pattern of Fe and Mn of tomato was examined with four treatment, soil only, soil(50%) + rice straw(50%), soil(50%) + compost(50%) and soil + aeration. Contents of Fe and Mn in tomato leaves was measured at 60 days after treatment. Fe content was the greatest in soil(50%) + compost(50%) whereas Mn content was the highest in soil only. As a result of this experiment, plant growth was stronger influenced by soil moisture content than redox potential or porosity, and the oxidation status of soil was likely to promote that plant predominantly absorbed Mn from soil and thus resulted in Fe deficiency.

• Journal of Plant Biology
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• v.32 no.4
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• pp.343-350
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• 1989

Calcium promoted ethylene production from mungbean hypocotyl segments incubated in the presence of either auxin or cytokinin (kinetin). Time course studies indicated that the calcium effect on ethylene production had a longer latent period (about 6 h) in combination with kinetin than with auxin. Studies on the effects of agents that are known to interfere with either action or transport (uptake) of calcium on ethylene biosynthesis indicated different patterns between auxin- and kinetin-treated tissues. Auxin-induced ethylene production was inhibited by the calmodulin inhibitor, trifluoperazine (TFP), and this inhibition was overcome by high concentrations of calcium applied, but TFP had no significant effect on kinetin-induced ethylene production regardless of calcium in the medium. The calcium channel blocker, verapamil, inhibited auxin-induced, but had little effect on kinetin-induced, ethylene producton. In vivo activity of "ethylene forming enzyme (EFE)" was found to be substantially promoted by calcium treatment. The enzyme activity was further increased by kinetin when segments were simultaneously treated with calcium, but auxin did not have such an effect.an effect.

• Journal of Plant Biology
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• v.31 no.3
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• pp.205-215
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• 1988

The effects of simetryne on light induced electron transport and phosphorylation in isolated spinach (Spinacia oleracea L.) chloroplasts were investigated in comparison with sencor and DCMU. Simetryne, like sencor and DCMU, completely, inhibited PSII electron transport and phosphoryltion with 10-6 M treatment but did not inhibit PSI electron transport. Interference with the electron transport pathway was evidenced by the greater sensitivity of oxygen evolution and uptake than phosphorylation. The following order of decreasing inhibitory effectiveness was exihibited; DCMU>simetryne>sencor. The photoacoustic technique was also used to monitor the relative photosynthetic activity in the leaves treated with the herbicides (simetryne, sencor or DCMU) in vivo and in vitro. Photoacoustic measurements on intact leaves provide quantitative information on two related aspects of the photosynthetic process, namely, photochemical energy storage and oxygen evolution. The relative photoacoustic signal of leaves treated with the herbicides showed low level in 21 Hz, but high level in 380 Hz and on isolated chloroplasts (both 21 Hz and 380 Hz) in comparison with that of the untreated leaves. These results suggest that some of photochemical energy is converted into the heat owing to the inhibition of electorn transport pathway by the herbicides.

• Journal of Plant Biology
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• v.34 no.4
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• pp.317-323
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• 1991

Partial recovery in auxin transport capacity from inhibition by N-naphthylphthalamic acid (NPA) was observed when corn coleoptile segments were subjected to a prolonged NPA treatment. Kinetic data indicated that the recovery time is a function of the concentration of NPA applied. Desensitization to NPA was also seen in tissue slices where NPA increased net uptake of auxin, indicating that the apparant adaptation in the auxin transport system did not results possibly from auxin accumulated during transport inhibition. Studies on in vitro binding of NPA to membrane vesicles isolated from the coleoptile indicated that preincubation of the tissue with NPA resulted in the reduced binding activity. Scatchard analysis of the data indicated that this was due to decreases in the number of NPA binding sites. The possibility of causal relationship of modified NPA receptors to the sensory adaptation in auxin transport observed in coleoptile segments will be discussed.

• KSBB Journal
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• v.8 no.2
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• pp.104-109
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• 1993

A vector for plant transformation which had two reporter genes(Gus and Hpt genes) in a single plasmid was constructed. After rice embryos imbibed DNA solution, DNA uptake and gene expression in rice were monitored. Main expression sites of the Gus gene were meristem of root and coleoptiles. There was no difference in Hpt gene expression between a single Hpt vector and the constructed vector in viability of rice in the hygromycin medium after DNA imbibition, The genomic DNA and total RNA extracted from rice transformant survived in the hygromycin medium were subjected to PCR and RT PCR analysis, respectively. As a result, we found the existence of the Hpt gene and its expression in rice.

• International Journal of Industrial Entomology and Biomaterials
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• v.5 no.1
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• pp.131-134
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• 2002

Mulberry being the only food of silkworm, Bombyx mori L., is of great economic importance to the silk industry, The success in cocoon production mainly depends on the supply of quality leaves in sufficient quantity. In mulberry, where the economic product is leaf, the uptake of nitrogen from soil is very heavy and high responses to application of nutrients have been reported. Nitrogen supports vegetative growth particularly the leaf biomass. Variation in nitrogen harvest index and other physiological and yield contributing traits were estimated in five mulberry genotypes. Considerable variation was observed for nitrogen harvest index, protein yield per plant and harvest index. The correlation studies indicated the protein yield per plant was significantly correlated with leaf yield, nitrogen content in leaf, nitrogen harvest index and harvest index. The broad sense heritability estimates revealed that harvest index showed highest heritability (88.07%) followed by nitrogen content (82.52%), protein yield (70.28%) and nitrogen harvest index (66.52%).

• Journal of Plant Biology
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• v.37 no.1
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• pp.37-42
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• 1994

Correlative changes between photosynthetic O2 exchange rates and room temperature Chl fluorescence were investigated in wheat (Triticum aestivum L.) chloroplasts treated with high temperature for 5 min. With increasing treatment temperature, photosynthetic O2 evolution rate mediated by PSII was decreased, showing 50% inhibition at 38$^{\circ}C$ (I50). But PSI activity measured by O2 uptake rates was stimulated as a function of increasing temperature. Dark level fluorescence (Fo)-temperature (T) analysis showed that fluorescence rising temperature (Tr), critical temperature (Tc), and peak temperature (Tp) was 38, 43, and 52$^{\circ}C$, respectively. Quenching analysis of Chl fluorescence showed that both the oxidized fraction of plastoquinone (qQ) and degree of thylakoid membrane energization (qNP) increased up to 4$0^{\circ}C$ and then declined dramatically. These results suggest that Tr is correlated with temperature showing a 50% of inhibition of photosynthesis and under mild high temperature stress, qNP is worth regarding as indicator for heat-induced damage of photosynthesis.

• Journal of Korean Society of Water and Wastewater
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• v.13 no.3
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• pp.29-35
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• 1999

The purpose of this study is to remove the organics, nitrogen and phosphorus using biosorption for the domestic sewage. The new process using biosorption is based on the methods of contact-stabilization, which remove the organics by absorbing them to the surface of the microorganism in the activated sludge. This process consists of biosorption reactor, biosorption clarifier, nitrifying reactor, nitrifying clarifier, denitrifying reactor, phosphorus uptake(polishing) reactor and final clarifier. The efficiency of removal could be reached 91% for organics, 76% for nitrogen, 90% for phosphorus in Eujungbu pilot plant. We operated the plant which irrigated $10m^3$ per day for sewage. During our operation the HRT(Hydraulic Retention time) was maintained for 10.5hr, but it could be reduced as 8.5hr according to our operation results.