• Journal of Crop Science and Biotechnology
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• v.10 no.1
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• pp.33-38
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• 2007

Nitrogen management at the panicle initiation stage(PI) should be fine-tuned for securing a concurrent high yield and high quality rice production. For calibration and testing of the recommendation models of N topdressing rates at PI for target grain yield and protein content of rice, three split-split-plot design experiments including five rice cultivars and various N rates were conducted at the experimental farm of Seoul National University, Korea from 2003 to 2005. Data from the first two years of experiments were used to calibrate models to predict grain yield and milled-rice protein content using shoot fresh weight(FW), chlorophyll meter value(SPAD), and the N topdressing rate(Npi) at PI by stepwise multiple regression. The calibrated models explained 85 and 87% of the variation in grain yield and protein content, respectively. The calibrated models were used to recommend Npi for the target protein content of 6.8%, with FW and SPAD measured for each plot in 2005. The recommended N rate treatment was characterized by an average protein content of 6.74%(similar to the target protein content), reduced the coefficient of variation in protein content to 2.5%(compared to 4.6% of the fixed rate treatment), and increased grain yield. In the recommended N rate treatments for the target protein content of 6.8%, grain yield was highly dependent on FW and SPAD at PI. In conclusion, the models for N topdressing rate recommendation at PI were successful under present experimental conditions. However, additional testing under more variable environmental conditions should be performed before universal application of such models.

• Journal of Plant Biology
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• v.14 no.3
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• pp.21-28
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• 1971

Dry matter production, leaf area growth and total nitrogen changes were studied in Glycine max. soybean communities, which were grown in sandy loam soils controlled to provide various moisture levels, i.e., 5-7%(level 1), 8-10%(level 2), 11-13%(level 3), 14-15%(lev디 4), 17-20%(level 5) and 22-24%(level 6). A summary of the results is shown. The maximum dry matter production of leaves, stems and nodules and the maximum leaf area per unit area were at level 5, but the maximum of root dry matter production was at level 4. Total nitrogen content of the soybean plant decreased with growth, but each level of soil moisture content also showed a little difference. Water content of the plant decreased with plant age and soil water deficiency, especially in roots and nodules. Nodule formation increased in proportion to soil moisture content. total nitrogen content of the soil on which the soybeans grew, increased from 0.23% before sowing to 0.30% at 100 days after sowing. It seems that soil water content acts as a linear factor in the elongation or dry weight increase of shoots and roots until increasing to level 5. Considering the pattern of plant growth through analysis of the shoot and root dry weight ratio, or the photosynthetic organ and non-photosynthetic organ dry weight ratio, the asymptote of plant growth at a high soil water content exceeded that at a low soil water content.

• Korean Journal of Environmental Agriculture
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• v.40 no.4
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• pp.359-365
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• 2021

BACKGROUND: Prohexadione-calcium (PC) is a plant growth regulator of cyclohexanedione family acting on inhibiting gibberellin biosynthesis and has been used to regulate shoot elongation of turfgrass in the golf course during the summer season. This study was conducted to investigate the effects of PC on the inhibition of shoot elongation, growth, and nitrogen uptake in Zoysia matrella. METHODS AND RESULTS: Treatments were as follows; non-treatment, control (TE 0.01 a.i. g/m²/100 mL), 0.0025PC (PC 0.0025 a.i. g/m²/100 mL), 0.005PC (PC 0.005 a.i. g/m²/100 mL), 0.01PC (PC 0.01 a.i. g/m²/100 mL) and 0.02PC (PC 0.02 a.i. g/m²/100 mL). Visual quality and chlorophyll content were not significantly different. As compared to non-treatment, shoot length and clipping yield in 0.005PC, 0.01PC and 0.02PC treatments were decreased by 29-36% and 65-82%, respectively, and those of 0.0025PC were not significantly different. N uptake of Z. matrella after applying PC was decreased by 28.9-77.8% than that of non-treatment. Inhibition effects of PC treatment in Z. matrella were not significantly different from those of control. CONCLUSION(S): These results indicated that the application of prohexadione calcium inhibited shoot elongation, clipping yield and N uptake amount in Z. matrella, and trinexapac-ethyl could be replaced with prohexadione-calcium in turfgrass management.

• The Korean Journal of Ecology
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• v.22 no.3
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• pp.131-137
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• 1999

This study was carried out to investigate the activity of nitrogen fixation and accumulation of heavy metal and inorganic matter in Vicia amoena community at lower region in Kumho riverside, including Youngchon, Chimsangyo, Paldalgyo, Talseochon and Kumhogyo. The contents of inorganic matter and heavy metal of Kumho riverside soil increased in the down stream in each organ of the plant growing in the riverside. Generally, V. amoena community showed rapid growth of shoot and high value of Top/Root ratio. V. amoena community showed higher water content of shoot at late growth stage and higher chlorophyll content. The root nodule of V. amoena community appeared in April and increased by 0.30, 0.27, 0.24, 0.06 and 0.14 g/plant, and nitrogen fixation activity of nodule attained 20.1, 16.8, 15.4, 8.5 and 5.3 μmol·C₂H₄·g fw nodule/sup -1/·h/sup -1/ for non-contaminated area Youngchon, Chimsangyo, Paldalgyo, Talseochon and Kumhogyo, respectively, in June:. Nodule formation and nitrogen fixation activity were reduced in the down stream by the soil contamination and heavy metal accumulation and showed minimum values. at Talseochon and Paldalgyo. V. amoena showed growth adaptation against heavy metal toxicity by restricting heavy metal such as Pb, Cu, Zn, Fe from transport, and by accumulating high Ca ion in shoot, nitrogen and phosphorus in root at late growth stage than those at early one, respectively, but total heavy metal per plant showed higher values in shoot than those in root by high T/R ratio of plant growth.

• The Korean Journal of Ecology
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• v.21 no.3
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• pp.187-193
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• 1998

Seasonal changes of nitrogen fixation and growth characteristics of Melilotus suaveolens population under different light conditions were quantitatively analyzed during growting period. Height growth of M. suaveolens population was promoted after April and the shade (site 2) showed 10-20% increase of height growth in compared with that of sunny (site 1). Seasonal changes of biomass were in creased after March, the biomass at site 1 attained 78.5% that of site 2 in May. Chlorophyll content was maintained high value from March to April but, Chlorophyll content of leaf at site 1 was decreased 11.7% compared to that of site 2 in May. The nitrogen content of each organ of M. suaveolens showed higher value in March and then decreased, the high nitrogen contents of reproductive organ were achieved at the flowering stage at site 1. The root nodule of M. suaveolens population appeared in March and showed maximum value in early June and decreased remarkably after July, the amount of nodule formation of M. suaveolens at site 2 showed higher than that of site 1. The nitrogen fixation activity of root nodule of M. suaveolens initiated with shoot growth and showed maximum value in mid April, and attained second peak in early June and then decreased after July. The total nitrogen fixation of the plant showed higher value at site 2 than that of site 1. From the overall results, M. suaveolens showed increased growth under half-shady, well ventilated barren soil than fertile sunny site.

• The Korean Journal of Ecology
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• v.22 no.3
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• pp.139-144
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• 1999

In order to clarify ecological survival strategy of Rumex crispus community dominating under contaminated area of lower region of Kumho riverside including Chimsangyo (CS), Paldalgyo (PD), Talseochon (TS) and Kumhogyo (KH), we analyzed the content of heavy metals and inorganic matter and vegetative growth. R. crispus showed rapid formation of community by high growth rate, high T/R ratio and showed maximum T/R ratio at the contaminated area Talseochon. Nitrogen and phosphorus contents in R. crispus showed high value in shoot than that of root. T/R ratio of nitrogen and phosphorus showed 3.1∼3.6 and 1.5∼4.5 for the early growth stage, and 6.7∼17.3 and 3.9∼8.3 for the late one, respectively. The absorbed heavy metals by riot were translocated to shoot, the heavy metal content in shoot higher than those in root of Cu, Zn, Fe, and Pb for 3.6, 1.7, 1.5 and 4.8 times, respectively. Distribution ratio of the heavy metals in each organ showed 61∼85% and 15∼39% for shoot and root, respectively. R. crispus accumulated heavy metals in the order of Fe>Zn>Cu>Pb in shoot, and showed maximum values of Cu, Zn, Fe and Pb for 89.7, 376.6, 2946.1 and 13.2 ㎍/g dw, respectively at Talseochon in April. A physiological and morphological characteristics of R. crispus showed thickened leaf, increased water content above 80% and rapid growth of shoot. R. crispus showed ecological adaptation to the contaminated area by transportation of heavy metals and inorganic matter to shoot, and by accumulation of Ca ion in root.

• Proceedings of the Korean Society of Crop Science Conference
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• 2005.04a
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• pp.172-173
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• 2005

• Korean Journal of Plant Resources
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• v.19 no.2
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• pp.265-272
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• 2006

This study was conducted to investigate the efficient propagation method of Cyrtomium caryoptideum var. coreanum by sporophyte culture. The influence of origin of explant sources (rhizome, blade, or stipe) and homogenization of culture materials on shoot regeneration were investigated. As a result, only rhizome explant exhibited the organogenic capacity and the shoot regeneration was promoted by homogenization of culture material. Vigorous and excellent growth of multiple shoots was induced on the half-strength of inorganic salts containing MS medium. It was appeared that optimum nitrogen content of shoot regeneration was half-strength of nitrogen containing MS medium (30mM) and optimum sucrose concentration was 1%. Addition of $NaH_2PO_4$ to culture medium generally enhanced shoot multiplication and promoted growth of the regenerants. The organogenic capacity of homogenized rhizomes was especially promoted on medium supplemented with $5{\mu}M$ kinetin plus $5{\mu}M$ IBA. The incorporation of $0.1\sim0.2%$ activated charcoal on medium supplemented with growth regulators prevented the formation of multiple bud primordia - nodule-like bud clusters and improved the normal morphogenesis of sporophytes.

• Weed & Turfgrass Science
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• v.5 no.3
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• pp.170-176
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• 2016

Superintendents have used a silicate fertilizer to improve a resistance of turfgrass against several diseases, drought damage and wear stress. This study was conducted to evaluate the effect of liquid fertilizer containing silicate (LFSi) on changes of turfgrass quality and growth by investigating visual quality, chlorophyll content-chlorophyll a, chlorophyll b, and total chlorophyll, root length, shoot length, dry weight of clipping, and nutrient content in leaves tissue. Treatments were designed as follows; control fertilizer (CF), SiF-1 (CF + $1ml\;m^{-2}$ LFSi), SiF-2 (CF + $2ml\;m^{-2}$ LFSi), and SiF-3 (CF + $4ml\;m^{-2}$ LFSi). As compared with CF, soil chemical properties, visual turfgrass quality, chlorophyll content, and dry weight of clipping of LFSi treatments were not significantly. Contrastingly, shoot density, root length, and the content of nitrogen or potassium were increased by application of LFSi. The content of Si in the tissue was positively correlated with potassium content or shoot length, and similarly shoot density positively with chlorophyll content or visual quality, respectively. These results suggested that the application of LFSi improved the turfgrass quality by increasing shoot density or K content in leaf tissue of creeping bentgrass.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.54 no.1
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• pp.45-54
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• 2009

This experiment was conducted to clarify the effects of source and sink related characteristics on grain weight increase and grain nitrogen accumulation in rice. Source was modified by leaf removing treatment with no sink modification in 2002 and sink and source were modified at the same time by different sowing dates, N fertilization rates, row spacings, and thinning treatments at heading in 2007. Grain weight (GW) and grain assimilates produced by photosynthesis during grain-filling ($GW_P$) increased with the increase of source, while the grain assimilates retranslocated from leaf and stem ($GW_T$) decreased. Among the source-related characters, shoot dry weight were most closely related with GW. GW was dependant on $GW_P$ rather than on $GW_T$. Grain nitrogen content (GN) and grain nitrogen absorbed from soil during grain-filling ($GN_S$) increased with the increase of source, while the grain nitrogen retranslocated from leaf and stem ($GN_T$) decreased. Shoot nitrogen content among the source-related characters was related most closely with GN. The contribution of $GN_T$ to GN was relatively large although GN depended more largely on $GN_S$ than $GN_T$. In addition, GN was supplied firstly from $GN_S$ or from $GN_S$ and $GN_T$ at the same time.